Method for measuring an optical length of light path and a laser interferometer for carrying same into effect

Claim 3

A method as claimed in claim 1, wherein the following additional operations are performed for measurement of the optical length of a light path interval: presetting at least one phase value corresponding to at least one known value of the light path optical length; comparing the phase measured values to one of the preset phase values; changing the optical length of said light path interval so as to approximate it to said known value of the light path optical length; noting the value of said change in the optical length of said light path interval at the instant when the measured value of the signal phase is equal to the preset phase value; subtracting said noted value of change in the optical length of said light path interval from said known value of the light path optical length to determine the desired value of the optical length of a preset light path interval.

Claim 6

A method as claimed in claim 1, wherein for determining temporal variation of the light path optical length within a preset interval, temporal variations of the measured phases of the obtained electric signals are registered, and a change in the optical length of said light path interval is judged by the temporal variation of said measured phases.

Claim 11

A digital multiple-beam laser interferometer, comprising: a laser capable of emitting a beam of coherent light; a device for separating from said light beam two collinear light components having mutually independent polarizations, said device being positioned past said laser along the run of the light beam; a device for offsetting the frequency of one of said light components, said device being positioned past said laser as along the run of the light beam; a master oscillator connected to said light frequency offsetting device; at least two reflecting elements placed one after the other as along the run of the original light beam and adapted for presetting a light path interval and forming the interfering light beams by virtue of multiple reflection of the light beam from said reflecting elements; a birefringent plate situated between said reflecting elements and adapted for mutual conversion of the polarizations of said light components; a polarizing element arranged on the axis of said formed interfering light beams past said reflecting elements and adapted for splitting the light of said interfering beams into two interfered light beams having said mutually independent polarizations; at least one photodetector located past said polarizing element on the axis of at least one of said interfered light beams and adapted for photoelectric conversion of the interfered light into an electric signal; at least one phase measuring unit connected to the output of at least one said photodetector and adapted for measuring the phase of at least one said electric signal, from which phase the optical length of a preset light path interval is judged.

Claim 12

A digital multiple-beam laser interferometer, comprising: a laser capable of emitting a beam of coherent light; a device for separating from said light beam two collinear light components having mutually independent polarizations, said device being positioned past said laser along the run of the light beam; a device for offsetting the frequency of one of said light components, said device being positioned past said laser as along the run of the light beam; a master oscillator connected to said light frequency offsetting device; at least two reflecting elements placed one after the other as along the run of the original light beam and adapted for presetting a light path interval and forming the interfering light beams by virtue of multiple reflection of the light beam from said reflecting elements; a birefringent plate situated between said reflecting elements and adapted for mutual conversion of the polarizations of said light components; a polarizing element arranged on the axis of said formed interfering light beams past said reflecting elements and adapted for splitting the light of said interfering beams into two interfered light beams having said mutually independent polarizations; at least one photodetector located past said polarizing element on the axis of at least one of said interfered light beams and adapted for photoelectric conversion of the interfered light into an electric signal; at least one phase measuring unit connected to the output of at least one said photodetector and adapted for measuring the phase of at least one said electric signal, from which phase the optical length of a preset light path interval is judged.

Claim 13

A laser interferometer as claimed in claim 7, wherein the light frequency offsetting device is an electro-optic frequency modulator.

Claim 14

A laser interferometer as claimed in claim 7, wherein the light frequency offsetting device is an acousto-optic frequency modulator.

Claim 15

A laser interferometer as claimed in claim 7, wherein said reflecting elements are made as partially reflecting mirror surfaces.

Claim 16

A laser interferometer as claimed in claim 7, wherein at least one of said reflecting elements is a diffraction grating.

Claim 17

A laser interferometer as claimed in claim 7, wherein at least one of said reflecting elements is a hologram.

Claim 18

A laser interferometer as claimed in claim 7, wherein said birefringent plate is a quarter-wave plate.

Claim 19

A laser interferometer as claimed in claim 11, wherein said birefringent plate features a difference between the phase shifts of light waves in two working diffraction orders equal to a quarter-wave-length.

Claim 20

A laser interferometer as claimed in claim 7, wherein said polarizing element is a polarizer.

Claim 21

A laser interferometer as claimed in claim 7, comprising at least two said photodetectors, a first and a second, wherein said polarizing element is a polarization beam-splitter adapted for dividing the light of the interfering beams into two said beams of interfered light, a first and a second, having linear mutually square polarizations, said first photodetector being set on the axis of said first interfered light beam and being connected to at least one of said phase measuring units, while the second photodetector is set on the axis of said second interfered light beam and is also connected to at least one of said phase measuring units.

Claim 22

A laser interferometer as claimed in claim 7, wherein said device for separating said two light components is adapted for forming two light components with circular polarizations featuring the opposite directions of rotation of the electric field vector.

Claim 23

A laser interferometer as claimed in claim 17, wherein used as the laser, the device for separating the light components with circular polarizations and the device for offsetting the light frequency is a dual-frequency laser.

Claim 24

A laser interferometer as claimed in claim 7, comprising a quarter-wave plate placed across the path of said interfering light beams before said polarizing element and adapted for converting circular light polarizations into linear ones, while the device for separating said two light components is adapted for forming two light components with linear mutually square polarizations.

Claim 25

A laser interferometer as claimed in claim 19, wherein the device for separating two light components with linear polarizations is a dual-beam polarization interferometer in one of whose beams said light frequency offsetting device is situated.

Claim 26

A digital multiple-beam laser interferometer, comprising: a laser capable of emitting a beam of coherent light; a device for separating from said light beam two collinear light components having mutually independent polarizations, said device being situated past said laser as along the run of the light beam; a device for offsetting the frequency of one of said light components, said device being positioned past said laser along the run of the light beam; a master oscillator connected to said light frequency offsetting device; at least two reflecting elements placed one after the other along the run of the light beam and adapted for presetting a light path interval and forming a number of interfering light beams by virtue of multiple reflection of the light beam from said reflecting elements; a birefringent plate situated between said reflecting elements and adapted for mutual conversion of said polarizations of said light components; a beam-splitter element positioned between said light frequency offsetting device and said reflecting elements and adapted for separating said interfering beams reflected from said reflecting elements; a polarizing element situated past said beam-splitter element along the run of said separated interfering beams and adapted for splitting the light of said separated interfering beams into two interfered light beams having said mutually independent polarizations; at least one photodetector located past said polarizing element on the axis of at least one of said interfered light beams and adapted for photoelectric conversion of the interfered light into an electric signal; at least one phase measuring unit connected to the output of at least one said photodetector and adapted for measuring the phase of at least one said electric signal so as to judge of the desired optical length of a preset light path interval by said phase.

Claim 27

A digital multiple-beam laser interferometer, comprising: a laser capable of emitting a beam of coherent light; a device for separating from said light beam two collinear light components having mutually independent polarizations, said device being situated past said laser as along the run of the light beam; a device for offsetting the frequency of one of said light components, said device being positioned past said laser along the run of the light beam; a master oscillator connected to said light frequency offsetting device; at least two reflecting elements placed one after the other along the run of the light beam and adapted for presetting a light path interval and forming a number of interfering light beams by virtue of multiple reflection of the light beam from said reflecting elements; a birefringent plate situated between said reflecting elements and adapted for mutual conversion of said polarizations of said light components; a beam-splitter element positioned between said light frequency offsetting device and said reflecting elements and adapted for separating said interfering beams reflected from said reflecting elements; a polarizing element situated past said beam-splitter element along the run of said separated interfering beams and adapted for splitting the light of said separated interfering beams into two interfered light beams having said mutually independent polarizations; at least one photodetector located past said polarizing element on the axis of at least one of said interfered light beams and adapted for photoelectric conversion of the interfered light into an electric signal; at least one phase measuring unit connected to the output of at least one said photodetector and adapted for measuring the phase of at least one said electric signal so as to judge of the desired optical length of a preset light path interval by said phase.

Claim 28

A laser interferometer as claimed in claim 21, wherein said light frequency offsetting device is an electro-optic frequency modulator.

Claim 29

A laser interferometer as claimed in claim 21, wherein said light frequency offsetting device is an acousto-optic frequency modulator.

Claim 30

A laser interferometer as claimed in claim 21, wherein said reflecting elements are made as partially reflecting mirror surfaces.

Claim 31

A laser interferometer as claimed in claim 21, wherein at least one of said reflecting elements is a diffraction grating.

Claim 32

A laser interferometer as claimed in claim 21, wherein at least one of said reflecting elements is a hologram.

Claim 33

A laser interferometer as claimed in claim 21, wherein said birefringent plate is a quarter-wave plate.

Claim 34

A laser interferometer as claimed in claim 25, wherein said birefringent plate features a quarter-wave difference between the phase shifts of light waves in two working diffraction orders.

Claim 35

A laser interferometer as claimed in claim 21, wherein said polarizing element is a polarizer.

Claim 36

A laser interferometer as claimed in claim 21, comprising at least two said photodetectors, a first and a second, wherein said polarizing element is a polarization beam-splitter adapted for dividing the light of the interfering beams into two said interfered light beams, a first and a second, having linear mutually square polarizations, said first photodetector being set on the axis of said first interfered light beam and being connected to at least one of said phase measuring units, while the other of said photodetectors is set on the axis of said second interfered light beam and is also connected to at least one of said phase measuring units.

Claim 37

A laser interferometer as claimed in claim 21, wherein said device for separating said two light components is adapted for forming two light components having linear mutually square polarizations.

Claim 38

A laser interferometer as claimed in claim 31, wherein said device for separating said light components with linear independent polarizations is made as a dual-beam polarization interferometer, in one of whose beams said light frequency offsetting device is situated.

Claim 39

A laser interferometer as claimed in claim 21, comprising a quarter-wave plate put across the path of said separated interfering light beams past said beam-splitter element and adapted for converting circular light polarizations into linear ones, while the device for separating said two light components is adapted for forming two light components with circular polarizations having the opposite directions of rotation of the electric field vector.

Claim 40

A laser interferometer as claimed in claim 33, wherein used as said laser, said device for separating said light components with independent circular polarizations and said light frequency offsetting device is a dual-frequency laser.

Claim 41

A digital multiple-beam laser interferometer, comprising: a laser capable of emitting a beam of coherent light; a device for separating from said light beam two collinear light components having mutually independent polarizations, said device being situated past said laser along the run of the light beam; a device for offsetting the light frequency of one of said light components, said device being situated past said laser along the run of the light beam; a master oscillator connected to said light frequency offsetting device; at least three reflecting elements positioned one after another as along the run of the light beam at the corners of a closed polygon and adapted for presetting a closed light path interval and for forming a number of interfering light beams by virtue of multiple reflection of the light beam from said reflecting elements; a birefringent plate placed between said reflecting elements and adapted for mutual conversion of said polarizations of said light components; a polarizing element placed on the axis of said formed interfering beams past said reflecting elements and adapted for dividing the light of said interfering beams into two interfered light beams having said mutually independent polarizations; at least one photodetector situated past said polarizing element on the axis of at least one of said two interfered light beams and adapted for photoelectric conversion of the interfered light into an electric signal; at least one phase measuring unit connected to the output of at least one said photodetector and adapted for measuring the phase of at least one said electric signal so as to judge of the desired optical length of a preset light path interval by said phase.

Claim 42

A digital multiple-beam laser interferometer, comprising: a laser capable of emitting a beam of coherent light; a device for separating from said light beam two collinear light components having mutually independent polarizations, said device being situated past said laser along the run of the light beam; a device for offsetting the light frequency of one of said light components, said device being situated past said laser along the run of the light beam; a master oscillator connected to said light frequency offsetting device; at least three reflecting elements positioned one after another as along the run of the light beam at the corners of a closed polygon and adapted for presetting a closed light path interval and for forming a number of interfering light beams by virtue of multiple reflection of the light beam from said reflecting elements; a birefringent plate placed between said reflecting elements and adapted for mutual conversion of said polarizations of said light components; a polarizing element placed on the axis of said formed interfering beams past said reflecting elements and adapted for dividing the light of said interfering beams into two interfered light beams having said mutually independent polarizations; at least one photodetector situated past said polarizing element on the axis of at least one of said two interfered light beams and adapted for photoelectric conversion of the interfered light into an electric signal; at least one phase measuring unit connected to the output of at least one said photodetector and adapted for measuring the phase of at least one said electric signal so as to judge of the desired optical length of a preset light path interval by said phase.

Claim 43

A laser interferometer as claimed in claim 35, wherein said device for light frequency offsetting is an electro-optic frequency modulator.

Claim 44

A laser interferometer as claimed in claim 35, wherein said light frequency offsetting device is an acousto-optic frequency modulator.

Claim 45

A laser interferometer as claimed in claim 35, wherein used as said laser, said device for separating said light components with mutually independent polarizations and said light frequency offsetting device is a dual-frequency laser.

Claim 46

A laser interferometer as claimed in claim 35, wherein said device for separating said light components with mutually independent polarizations is made as a dual-beam polarization interferometer in one of whose beams said light frequency offsetting device is situated.

Claim 47

A laser interferometer as claimed in claim 35, wherein said reflecting elements are made as partially reflecting mirror surfaces.

Claim 48

A laser interferometer as claimed in claim 35, wherein at least one of said reflecting elements is a diffraction grating.

Claim 49

A laser interferometer as claimed in claim 35, wherein at least one of said reflecting elements is a hologram.

Claim 50

A laser interferometer as claimed in claim 35, wherein said birefringent plate is a quarter-wave plate located close to one of said reflecting elements.

Claim 51

A laser interferometer as claimed in claim 41, wherein said birefringent plate is located close to said diffraction grating and features a quarter-wave difference between the phase shifts of light waves in two working diffraction orders.

Claim 52

A laser interferometer as claimed in claim 35, wherein said birefringent plate is a half-wave plate.

Claim 53

A laser interferometer as claimed in claim 35, wherein said polarizing element is a polarizer.

Claim 54

A laser interferometer as claimed in claim 35, comprising at least two said photodetectors, a first and a second, wherein said polarizing element is a polarization beam-splitter adapted for dividing the light of the interfering beams into two said beams, a first and a second, having linear mutually square polarizations, said first photodetector being set on the axis of said first interfered light beam and being connected to at least one said phase measuring unit, while the second of said photodetectors is arranged on the axis of said second separated beam of interfered light and is also connected to at least one said phase measuring unit.

Claim 55

A digital multiple-beam laser interferometer, comprising: a laser capable of emitting a beam of coherent light; a device for separating from said light beam two collinear light components having mutually independent polarizations, said device being situated past said laser as along the run of the light beam; a device for offsetting the light frequency of one of said light components, said device being situated past said laser along the run of the light beam; a master oscillator connected to said light frequency offsetting device; an optical system adapted for expanding an original light beam and located past the light frequency offsetting device; at least two reflecting elements placed one after the other along the run of the light beam and adapted for presetting a light path interval and for forming a number of interfering beams by virtue of multiple reflection of the light beam from said reflecting elements; a birefringent plate placed between said reflecting elements and adapted for mutual conversion of said polarizations of said light components; a polarizing element positioned on the axis of said formed interfering beams past said reflecting elements and adapted for dividing the light of said interfering beams into two interfered light beams having said mutually independent polarizations; at leeast one photoelectric converter of interfered light into an electric signal, located past said polarizing element on the axis of at least one of said two interfered light beams; at least one phase measuring unit connected to the output of at least one of said photoelectric converters and adapted for measuring the phase of at least one said electric signal so as to judge of the desired optical length of a light path interval by said phase.

Claim 56

A digital multiple-beam laser interferometer, comprising: a laser capable of emitting a beam of coherent light; a device for separating from said light beam two collinear light components having mutually independent polarizations, said device being situated past said laser as along the run of the light beam; a device for offsetting the light frequency of one of said light components, said device being situated past said laser along the run of the light beam; a master oscillator connected to said light frequency offsetting device; an optical system adapted for expanding an original light beam and located past the light frequency offsetting device; at least two reflecting elements placed one after the other along the run of the light beam and adapted for presetting a light path interval and for forming a number of interfering beams by virtue of multiple reflection of the light beam from said reflecting elements; a birefringent plate placed between said reflecting elements and adapted for mutual conversion of said polarizations of said light components; a polarizing element positioned on the axis of said formed interfering beams past said reflecting elements and adapted for dividing the light of said interfering beams into two interfered light beams having said mutually independent polarizations; at leeast one photoelectric converter of interfered light into an electric signal, located past said polarizing element on the axis of at least one of said two interfered light beams; at least one phase measuring unit connected to the output of at least one of said photoelectric converters and adapted for measuring the phase of at least one said electric signal so as to judge of the desired optical length of a light path interval by said phase.

Claim 57

A laser interferometer as claimed in claim 48, wherein said light frequency offsetting device is an electro-optic frequency modulator.

Claim 58

A laser interferometer as claimed in claim 48, wherein said light frequency offsetting device is an acousto-optic frequency modulator.

Claim 59

A laser interferometer as claimed in claim 48, wherein used as said laser, said device for separating said light components with mutually independent polarizations and said light frequency offsetting device is a dual-frequency laser.

Claim 60

A laser interferometer as claimed in claim 48, wherein said device for separating said light components with mutually independent polarizations is made as a dual-beam polarization interferometer in one of whose beams said light frequency offsetting device is situated.

Claim 61

A laser interferometer as claimed in claim 48, wherein said reflecting elements are made as partially reflecting mirror surfaces.

Claim 62

A laser interferometer as claimed in claim 48, wherein at least one of said reflecting elements is a diffraction grating.

Claim 63

A laser interferometer as claimed in claim 48, wherein at least one of said reflecting elements is a hologram.

Claim 64

A laser interferometer as claimed in claim 48, wherein said birefringent plate is a quarter-wave plate.

Claim 65

A laser interferometer as claimed in claim 54, wherein said birefringent plate features a quarter-wave difference between the phase shifts of light waves in two working diffraction orders.

Claim 66

A laser interferometer as claimed in claim 48, wherein said polarizing element is a polarizer.

Claim 67

A laser interferometer as claimed in claim 48, comprising at least two said photoelectric converters, a first and a second, wherein said polarizing element is a polarization beam-splitter adapted for dividing the light of the interfering beams into two said beams, a first and a second, of interfered light with linear mutually square polarizations, the first of said photoelectric converters being arranged on the axis of said first interfered light beam and being connected to at least one said phase measuring unit, while the second of said photoelectric converters is arranged on the axis of said second interfered light beam and is also connected to at least one said phase measuring unit.

Claim 68

A laser interferometer as claimed in claim 48, wherein said photoelectric converter is a quadratic photodetector.

Claim 69

A laser interferometer as claimed in claim 48, wherein said photoelectric converter is a photodetector array whose photodetectors are connected to the phase measuring unit through a switching device.

Claim 70

A laser interferometer as claimed in claim 48, wherein said photoelectric converters is a photodetector array, each of said photodetectors being connected to its own phase measuring unit.

Claim 71

A laser interferometer as claimed in claim 48, comprising a scanning device connected to at least one said photoelectric converter and adapted for converting the interfered light at different points across the interfering light beams.

Claim 72

A digital multiple-beam laser interferometer adapted for measuring the distribution of the light path optical length, comprising: a laser capable of emitting a beam of coherent light; a device for separating from said light beam two collinear light components having mutually independent polarizations, said device being located past said laser along the run of the light beam; a device for offsetting the light frequency of one of said light components, said device being located past said laser along the run of the light beam; a master oscillator connected to said light frequency offsetting device; a device for displacing the original light beam parallel to itself in two mutually square directions, said device being located past the light frequency offsetting device along the run of the light beam; a least two reflecting elements positioned one after the other as along the run of the light beam and adapted for presetting a light path interval and for forming a number of intefering light beams by virtue of multiple reflection of said light beam; a birefringent plate positioned between said reflecting elements and adapted for mutual conversion of said mutually independent polarizations of said light components; a polarizing elements arranged on the axis of said formed interfering beams past said reflecting elements and adapted for dividing the light of said interfering light beams into two interfered light beams with said mutually independent polarizations; at least one photoelectric converter of interfered light into an electric signal, said converter being located past said polarizing element on the axis of at least one of said two beams of interfered light; at least one phase measuring unit connected to the output of at least one of said photoelectric converters and adapted for measuring the phase of at least one said electric signal so as to judge of the distribution on the desired light path optical length by said phase.

Claim 73

A digital multiple-beam laser interferometer adapted for measuring the distribution of the light path optical length, comprising: a laser capable of emitting a beam of coherent light; a device for separating from said light beam two collinear light components having mutually independent polarizations, said device being located past said laser along the run of the light beam; a device for offsetting the light frequency of one of said light components, said device being located past said laser along the run of the light beam; a master oscillator connected to said light frequency offsetting device; a device for displacing the original light beam parallel to itself in two mutually square directions, said device being located past the light frequency offsetting device along the run of the light beam; a least two reflecting elements positioned one after the other as along the run of the light beam and adapted for presetting a light path interval and for forming a number of intefering light beams by virtue of multiple reflection of said light beam; a birefringent plate positioned between said reflecting elements and adapted for mutual conversion of said mutually independent polarizations of said light components; a polarizing elements arranged on the axis of said formed interfering beams past said reflecting elements and adapted for dividing the light of said interfering light beams into two interfered light beams with said mutually independent polarizations; at least one photoelectric converter of interfered light into an electric signal, said converter being located past said polarizing element on the axis of at least one of said two beams of interfered light; at least one phase measuring unit connected to the output of at least one of said photoelectric converters and adapted for measuring the phase of at least one said electric signal so as to judge of the distribution on the desired light path optical length by said phase.

Claim 74

A laser interferometer as claimed in claim 64, wherein said light frequency offsetting device is an electro-optic frequency modulator.

Claim 75

A laser interferometer as claimed in claim 64, wherein said light frequency offsetting device is an acousto-optic frequency modulator.

Claim 76

A laser interferometer as claimed in claim 64, wherein used as said laser, said device for separating said light components with mutually independent polarizations and said light frequency offsetting device is a dual-frequency laser.

Claim 77

A laser interferometer as claimed in claim 64, wherein said device for separating said light components with mutually independent polarizations is made as a dual-beam polarization interferometer in one of whose beams said light frequency offsetting device is situated.

Claim 78

A laser interferometer as claimed in claim 64, wherein said reflecting elements are made as partially reflecting mirror surfaces.

Claim 79

A laser interferometer as claimed in claim 64, wherein at least one of said reflecting elements is a diffraction grating.

Claim 80

A laser interferometer as claimed in claim 64, wherein at least one of said reflecting elements is a hologram.

Claim 81

A laser interferometer as claimed in claim 64, wherein said birefringent plate is a quarter-wave plate.

Claim 82

A laser interferometer as claimed in claim 70, wherein said birefringent plate features a quarter-wave difference between the phase shifts of light waves in two working diffraction orders.

Claim 83

A laser interferometer as claimed in claim 64, wherein said polarizing element is a polarizer.

Claim 84

A laser interferometer as claimed in claim 64, comprising at least two said photoelectric converters, a first and a second, wherein said polarizing element is a polarization beam-splitter adapted for dividing the light of the interfering beams into two beams, a first and a second, of interfered light with linear mutually square polarizations, the first of said photoelectric converters being arranged on the axis of said first interfered light beam and being connected to at least one said phase measuring unit, while the second of said photoelectric converters is arranged on the axis of said second interfered light beam and is also connected to at least one said phase measuring unit.

Claim 85

A laser interferometer as claimed in claim 64, wherein said photoelectric converter is a quadratic photodetector.

Claim 86

A laser interferometer as claimed in claim 76, comprising converging lens located before said photodetector and adapted for continuously directing the beam of interfered light to said photodetector as the original light beam is being displaced parallel to itself.

Claim 87

A laser interferometer as claimed in claim 76, comprising a scanning device connected to said photodetector and linked to said device for displacing the original light beam parallel to itself, said scanning device being adapted for providing a possibility of converting the interfered light as the original light beam is being displaced parallel to itself.

Claim 88

A laser interferometer as claimed in claim 64, wherein said photoelectric converter is a photodetector array whose photodetectors are connected to the phase measuring unit through a switching device linked to said device for displacing the original light beam parallel to itself.

Claim 89

A digital multiple-beam laser interferometer, comprising: a laser capable of emitting a beam of coherent light; a device for separating from said light beam two collinear light components with mutually independent polarizations, said device being located past said laser along the run of the light beam; a device for offsetting the light frequency of one of said light components, said device being located past said laser along the run of the light beam; a master oscillator connected to said light frequency offsetting device; an optical system adapted for expanding the original light beam and located past the light frequency offsetting device; at least two reflecting elements positioned one after the other along the run of the light beam and adapted for presetting a light path interval and for forming a number of interfering light beams by virtue of multiple reflection of said light beam; a birefringent plate located between said reflecting elements and adapted for mutual conversion of said independent polarizations of said light components; an optical element arranged on the axis of said formed interfering beams past said reflecting elements and adapted for separating part of the light of the interfering beams; a first polarizing element arranged on the axis of said interfering light beams past said optical element and adapted for splitting the light of said interfering light beams into two beams, a first and a second, of interfered light with said mutually independent polarizations; a second polarizing element arranged on the axis of the beam of said separated part of the light of the interfering light beams past said optical element and adapted for dividing the light of said beam of separated part of light into two beams, a third and a fourth, of interfered light with said mutually independent polarizations; at least one main photoelectric converter of interfered light into an electric signal, said main photoelectric converter being located past said first polarizing element at no less than one preset point across at least one of said two, the first and the second, beams of interfered light; at least one additional photoelectric converter of interfered light into an electric signal, said additional photoelectric converter being located past said second polarizing element at no less than one reference point across at least one of said two, the third and the fourth, beams of interfered light; at least one main phase measuring unit connected to the output of at least one said main photoelectric converter and adapted for measuring the phase of at least one said electric signal so as to judge of the optical length of a preset light path interval at no less than one said preset point across said light beam by said measured phase; at least one additional phase measuring unit connected to the output of at least one said additional photoelectric converter and adapted for measuring the phase of at least one said electric signal so as to judge of the optical length of a preset light path interval by said measured phase, at no less than one said preset reference points across said light beam.

Claim 90

A digital multiple-beam laser interferometer, comprising: a laser capable of emitting a beam of coherent light; a device for separating from said light beam two collinear light components with mutually independent polarizations, said device being located past said laser along the run of the light beam; a device for offsetting the light frequency of one of said light components, said device being located past said laser along the run of the light beam; a master oscillator connected to said light frequency offsetting device; an optical system adapted for expanding the original light beam and located past the light frequency offsetting device; at least two reflecting elements positioned one after the other along the run of the light beam and adapted for presetting a light path interval and for forming a number of interfering light beams by virtue of multiple reflection of said light beam; a birefringent plate located between said reflecting elements and adapted for mutual conversion of said independent polarizations of said light components; an optical element arranged on the axis of said formed interfering beams past said reflecting elements and adapted for separating part of the light of the interfering beams; a first polarizing element arranged on the axis of said interfering light beams past said optical element and adapted for splitting the light of said interfering light beams into two beams, a first and a second, of interfered light with said mutually independent polarizations; a second polarizing element arranged on the axis of the beam of said separated part of the light of the interfering light beams past said optical element and adapted for dividing the light of said beam of separated part of light into two beams, a third and a fourth, of interfered light with said mutually independent polarizations; at least one main photoelectric converter of interfered light into an electric signal, said main photoelectric converter being located past said first polarizing element at no less than one preset point across at least one of said two, the first and the second, beams of interfered light; at least one additional photoelectric converter of interfered light into an electric signal, said additional photoelectric converter being located past said second polarizing element at no less than one reference point across at least one of said two, the third and the fourth, beams of interfered light; at least one main phase measuring unit connected to the output of at least one said main photoelectric converter and adapted for measuring the phase of at least one said electric signal so as to judge of the optical length of a preset light path interval at no less than one said preset point across said light beam by said measured phase; at least one additional phase measuring unit connected to the output of at least one said additional photoelectric converter and adapted for measuring the phase of at least one said electric signal so as to judge of the optical length of a preset light path interval by said measured phase, at no less than one said preset reference points across said light beam.

Claim 91

A laser interferometer as claimed in claim 80, wherein at least one said main phase measuring unit is also connected to the output of at least one additional photoelectric converter, and a ratio of the optical lengths of the light path interval at no less than one preset point and at no less than one reference point across said light beam is judged by the phase value as measured by said phase measuring unit.

Claim 92

A laser interferometer as claimed in claim 80, comprising a scanning device connected to at least one main photoelectric converter.

Claim 93

A laser interferometer as claimed in claim 80, wherein said light frequency offsetting device is an electro-optic frequency modulator.

Claim 94

A laser interferometer as claimed in claim 80, wherein said light frequency offsetting device is an acousto-optic frequency modulator.

Claim 95

A laser interferometer as claimed in claim 80, wherein used as said laser, said device for separating said light components with mutually independent circular polarizations and said light frequency offsetting device is a dual-frequency laser.

Claim 96

A laser interferometer as claimed in claim 80, wherein said device for separating said light components is made as a dual-beam polarization interferometer in one of whose beams said light frequency offsetting device is situated.

Claim 97

A laser interferometer as claimed in claim 80, wherein said reflecting elements are made as partially reflecting mirror surfaces.

Claim 98

A laser interferometer as claimed in claim 80, wherein at least one of said reflecting elements is a diffraction grating.

Claim 99

A laser interferometer as claimed in claim 80, wherein at least one of said reflecting elements is a hologram.

Claim 100

A laser interferometer as claimed in claim 80, wherein said birefringent plate is a quarter-wave plate.

Claim 101

A laser interferometer as claimed in claim 88, wherein said birefringent plate features a quarter-wave difference between the phase shifts of light waves in two working diffraction orders.

Claim 102

A laser interferometer as claimed in claim 80, wherein said first polarizing element is a polarizer.

Claim 103

A laser interferometer as claimed in claim 80, wherein said second polarizing element is a polarizer.

Claim 104

A laser interferometer as claimed in claim 80, comprising at least two said main photoelectric converters, a first and a second, wherein said first polarizing element is a polarization beam-splitter adapted for dividing the light of the interfering beams into two beams, a first and a second, of interfered light with linear mutually square polarizations, the first of said photoelectric converters being arranged on the axis of said first beam of interfered light and being connected to at least one said phase measuring unit, while the second of said photoelectric converters is arranged on the axis of said second beam of interfered light and is also connected to at least one said phase measuring unit.

Claim 105

A laser interferometer as claimed in claim 80, wherein said main photoelectric converter is a quadratic photodetector.

Claim 106

A laser interferometer as claimed in claim 80, wherein said additional photoelectric converter is a quadratic photodetector.

Claim 107

A laser interferometer as claimed in claim 80, wherein said main photoelectric converter is a photodetector array whose photodetectors are connected to said main phase measuring unit via a switching device.

Claim 108

A laser interferometer as claimed in claim 80, wherein said main photoelectric converter is made as a photodetector array, each of the photodetectors of said array being connected to its own phase measuring unit.

Claim 109

A laser interferometer as claimed in claim 80, wherein said additional photoelectric converter is a photodetector array whose photodetectors are connected to said additional phase measuring unit through a switching device.

Claim 110

A laser interferometer as claimed in claim 80, wherein said additional photoelectric converter is in fact a photodetector array, each of the photodetectors of said array being connected to its own phase measuring unit.

Claim 111

a digital multiple-beam laser interferometer, comprisng: a laser capable of emitting a beam of coherent light; a device for separating from said light beam two collinear light components with mutually independent polarizations, said device being located past said laser along the run of the light beam; a device for offsetting the light frequency of one of said light components, said device being located past said laser along the run of the light beam; a master oscillator connected to said light frequency offsetting device; at least two reflecting elements positioned one after the other along the run of the light beam and adapted for presetting a light path interval and for forming a number of interfering light beams by virtue of multiple reflection of said light beam from said reflecting elements; a birefringent plate located between said reflecting elements and adapted for mutual conversion of said independent polarizations of said light components; at least one device for changing the optical length of light path within a preset interval, said device being located between said reflecting elements and adapted for controlled variation of the light path optical length along at least one ray in a light beam; at least one transducer for sensing a change in the light path optical length, said transducer being connected to said device for changing the light path optical length; a polarizing element arranged on the axis of said formed interfering beams past said reflecting elements along the run of the light beam and adapted for dividing the light of said interfering beams into two beams of interfered light with said mutually independent polarizations; at least one photodetector located past said polarizing element on the axis of at least one of said two beams of interfered light and adapted for photoelectric conversion of the interfered light into an electric signal; at least one phase measuring unit connected to the output of at least one of said photodetectors and adapted for measuring the phase of at least one said electric signal; at least one phase value presetting unit adapted for presetting phase values corresponding to the known values of the light path optical length; at least one phase comparator unit whose inputs are connected to at least one said phase measuring unit and to at least one said phase value presetting unit, while the output of said phase comparator unit is connected to at least one said device for changing the light path optical length, said phase comparator unit being adapted for comparing the measured phase value with a preset value thereof, generating an error signal dependent upon the results of phase comparison and controlling, by means of said error signal, a change in the light path optical length along at least one ray of a light beam; a computer device connected to the outputs of at least one said phase measuring unit and of at least one said transducer for sensing a change in the light path optical length, said computer device being adapted for determining the desired optical length of a preset light path interval from the results of measurement of the phases of electric signals and from the value of a change in the light path optical length.

Claim 112

a digital multiple-beam laser interferometer, comprisng: a laser capable of emitting a beam of coherent light; a device for separating from said light beam two collinear light components with mutually independent polarizations, said device being located past said laser along the run of the light beam; a device for offsetting the light frequency of one of said light components, said device being located past said laser along the run of the light beam; a master oscillator connected to said light frequency offsetting device; at least two reflecting elements positioned one after the other along the run of the light beam and adapted for presetting a light path interval and for forming a number of interfering light beams by virtue of multiple reflection of said light beam from said reflecting elements; a birefringent plate located between said reflecting elements and adapted for mutual conversion of said independent polarizations of said light components; at least one device for changing the optical length of light path within a preset interval, said device being located between said reflecting elements and adapted for controlled variation of the light path optical length along at least one ray in a light beam; at least one transducer for sensing a change in the light path optical length, said transducer being connected to said device for changing the light path optical length; a polarizing element arranged on the axis of said formed interfering beams past said reflecting elements along the run of the light beam and adapted for dividing the light of said interfering beams into two beams of interfered light with said mutually independent polarizations; at least one photodetector located past said polarizing element on the axis of at least one of said two beams of interfered light and adapted for photoelectric conversion of the interfered light into an electric signal; at least one phase measuring unit connected to the output of at least one of said photodetectors and adapted for measuring the phase of at least one said electric signal; at least one phase value presetting unit adapted for presetting phase values corresponding to the known values of the light path optical length; at least one phase comparator unit whose inputs are connected to at least one said phase measuring unit and to at least one said phase value presetting unit, while the output of said phase comparator unit is connected to at least one said device for changing the light path optical length, said phase comparator unit being adapted for comparing the measured phase value with a preset value thereof, generating an error signal dependent upon the results of phase comparison and controlling, by means of said error signal, a change in the light path optical length along at least one ray of a light beam; a computer device connected to the outputs of at least one said phase measuring unit and of at least one said transducer for sensing a change in the light path optical length, said computer device being adapted for determining the desired optical length of a preset light path interval from the results of measurement of the phases of electric signals and from the value of a change in the light path optical length.

Claim 113

A laser interferometer as claimed in claim 101, wherein at least one said phase value presetting unit is also connected to the output of at least one said phase measuring unit.

Claim 114

A laser interferometer as claimed in claim 101, wherein used as at least one said phase value presetting unit, as at least one said phase comparator unit and as said computer device is a computer whose inputs are connected to the outputs of at least one said phase measuring unit and of at least one said transducer for sensing a change in the light path optical length, while the control output of said computer is connected to at least one said device for changing the light path optical length.

Claim 115

A laser interferometer as claimed in claim 101, wherein said device for changing the light path optical length is a knonw-length hermetically sealed cell filled with a known gas and placed between said reflecting elements, and a compressor connected to said cell, while said transducer for sensing a change in the light path optical length is in fact a pressure transducer.

Claim 116

A laser interferometer as claimed in claim 101, wherein said device for changing the light path optical length is a known-length cell made from a known optical material and placed between said reflecting elements, and a heater element having thermal contact with said cell, while said transducer for sensing a change in the light path optical length is in fact a temperature sensor.

Claim 117

A laser interferometer as claimed in claim 101, wherein said light frequency offsetting device is an electro-optic frequency modulator.

Claim 118

A laser interferometer as claimed in claim 101, wherein said light frequency offsetting device is an acousto-optic frequency modulator.

Claim 119

A laser interferometer as claimed in claim 101, wherein used as said laser of the device for separating said light components with mutually independent circular polarizations and of the light frequency offsetting device is a dual-frequency laser.

Claim 120

A laser interferometer as claimed in claim 101, wherein said device for separating said light components is made as a dual-beam polarization interferometer in one of whose beams said light frequency offsetting device is situated.

Claim 121

A laser interferometer as claimed in claim 101, wherein said reflecting elements are made as partially reflecting mirror surfaces.

Claim 122

A laser interferometer as claimed in claim 101, wherein at least one of said reflecting elements is a diffraction grating.

Claim 123

A laser interferometer as claimed in claim 101, wherein at least one of said reflecting elements is a hologram.

Claim 124

A laser interferometer as claimed in claim 101, wherein said birefringent plate is a quarter-wave plate.

Claim 125

A laser interferometer as claimed in claim 111, wherein said birefringent plate features a quarter-wave difference between the phase shifts of light waves in two working diffraction orders.

Claim 126

A laser interferometer as claimed in claim 101, wherein said polarizing element is a polarizer.

Claim 127

A laser interferometer as claimed in claim 101, comprising at least two said photodetectors, a first and a second, wherein said polarizing element is in effect a polarization beam-splitter adapted for dividing the light of the interfering beams into two said beams, a first and a second, of interfered light with linear mutually square polarizations, the first of said photodetectors being arranged on the axis of said first beam of interfered light and being connected to at least one said phase measuring unit, while the second of said photodetectors is arranged on the axis of said second beams of interfered light and is also connected to at least one said phase measuring unit.

Claim 128

A digital multiple-beam laser interferometer capable of simultaneous visual observation of an interference pattern, said interferometer comprising: a laser capable of emitting a beam of coherent light; a device for separating from said light beam two collinear light components with mutually independent polarizations, said device being located past said laser along the run of the light beam; a device for offsetting the light frequency of one of said light components, said device being located past said laser along the run of the light beam; a master oscillator connected to said light frequency offsetting device; an optical system for expanding the light beam, said system being located past the light frequency offsetting device; at least two reflecting elements arranged one after the other as along the run of the light beam and adapted for presetting a light path interval and for forming a number of interfering light beams by virtue of multiple reflection of the light beam from said reflecting elements; a birefringent plate located between said reflecting elements and adapted for mutual conversion of said polarizations of said light components; a beam-splitter element located between said light frequency offsetting device on the one side and said reflecting elements on the other side and adapted for separating the interfering light beams reflected from said reflecting elements; a polarizing element located past said beam-splitter element along the run of said reflected interfering light beams; at least one photoelectric converter of the interfered light into an electric signal, said converter being located past said polarizing element on the axis of at least one of said two beams of interfered light; at least one phase measuring unit connected to the output of at least one said photoelectric converter and adapted for measuring the phase of at least one said electric signal so as to judge of the desired optical length of a preset light path interval by said phase; an optical beam-splitter element located on the axis of the interfering light beams between said reflecting elements on the one side and at least one said photoelectric converter on the other side and adapted for separating part of the light of the interfering beams for visual observation of the interference pattern; a light intensity modulator located past said optical beam-splitter element on the axis of the beam of the separated part of light of the interfering light beams and adapted for the separated part of light of the interfering light beams to pass at preset short time intervals; an interference pattern image recorder located past said light intensity modulator along the run of the beam of the separated part of light of the interfering beams and adapted for recording or visually observing the resulting interference pattern; a pulse generator connected to said light intensity modulator and adapted for controlling said modulator by setting electric pulses within said short time intervals.

Claim 129

A digital multiple-beam laser interferometer capable of simultaneous visual observation of an interference pattern, said interferometer comprising: a laser capable of emitting a beam of coherent light; a device for separating from said light beam two collinear light components with mutually independent polarizations, said device being located past said laser along the run of the light beam; a device for offsetting the light frequency of one of said light components, said device being located past said laser along the run of the light beam; a master oscillator connected to said light frequency offsetting device; an optical system for expanding the light beam, said system being located past the light frequency offsetting device; at least two reflecting elements arranged one after the other as along the run of the light beam and adapted for presetting a light path interval and for forming a number of interfering light beams by virtue of multiple reflection of the light beam from said reflecting elements; a birefringent plate located between said reflecting elements and adapted for mutual conversion of said polarizations of said light components; a beam-splitter element located between said light frequency offsetting device on the one side and said reflecting elements on the other side and adapted for separating the interfering light beams reflected from said reflecting elements; a polarizing element located past said beam-splitter element along the run of said reflected interfering light beams; at least one photoelectric converter of the interfered light into an electric signal, said converter being located past said polarizing element on the axis of at least one of said two beams of interfered light; at least one phase measuring unit connected to the output of at least one said photoelectric converter and adapted for measuring the phase of at least one said electric signal so as to judge of the desired optical length of a preset light path interval by said phase; an optical beam-splitter element located on the axis of the interfering light beams between said reflecting elements on the one side and at least one said photoelectric converter on the other side and adapted for separating part of the light of the interfering beams for visual observation of the interference pattern; a light intensity modulator located past said optical beam-splitter element on the axis of the beam of the separated part of light of the interfering light beams and adapted for the separated part of light of the interfering light beams to pass at preset short time intervals; an interference pattern image recorder located past said light intensity modulator along the run of the beam of the separated part of light of the interfering beams and adapted for recording or visually observing the resulting interference pattern; a pulse generator connected to said light intensity modulator and adapted for controlling said modulator by setting electric pulses within said short time intervals.

Claim 130

A laser interferometer as claimed in claim 117, wherein with the purpose of establishing a static interference pattern by gating the beam of separated light of the interfering beams, said pulse generator is connected to the output of said master oscillator.

Claim 131

A laser interferometer as claimed in claim 117, wherein with the purpose of establishing a static interference pattern, said pulse generator is connected to the output of at least one said photoelectric converter.

Claim 132

A laser interferometer as claimed in claim 117, wherein said light frequency offsetting device is an electro-optic frequency modulator.

Claim 133

A laser interferometer as claimed in claim 117, wherein said light frequency offsetting device is an acousto-optic frequency modulator.

Claim 134

A laser interferometer as claimed in claim 117, wherein used as said laser of the device for separating said light components with mutually independent polarizations and of the light frequency offsetting device is a dual-frequency laser.

Claim 135

A laser interferometer as claimed in claim 117, wherein said device for separating said light components with mutually independent polarizations is made as a dual-beam polarization interferometer in one of whose beams said light frequency offsetting device is situated.

Claim 136

A laser interferometer as claimed in claim 117, wherein said reflecting elements are made as partially reflecting mirror surfaces.

Claim 137

A laser interferometer as claimed in claim 117, wherein at least one of said reflecting elements is a diffraction grating.

Claim 138

A laser interferometer as claimed in claim 117, wherein at least one of said reflecting elements is a hologram.

Claim 139

A laser interferometer as claimed in claim 117, wherein said birefringent plate is a quarter-wave plate.

Claim 140

A laser interferometer as claimed in claim 125, wherein said birefringent plate features a quarter-wave difference between the phase shifts of light waves in two working diffraction orders.

Claim 141

A laser interferometer as claimed in claim 117, wherein said polarizing element is a polarizer.

Claim 142

A laser interferometer as claimed in claim 117, comprising at least two said photoelectric converters, a first and a second, wherein said polarizing element is a polarization beam-splitter adapted for dividing the light of the interfering beams into two said beams, a first and a second, of interfered light with linear mutually square polarizations, the first of said photoelectric converters being arranged on the axis of said first beam of interfered light and being connected to at least one said phase measuring phase, while the second of said photoelectric converters is arranged on the axis of said second beam of interfered light and is also connected to at least one said phase measuring unit.

Claim 143

A laser interferometer as claimed in claim 117, wherein said photoelectric converter is a photodetector array whose photodetectors are connected to the phase measuring unit through a switching device.

Claim 144

A laser interferometer as claimed in claim 117 wherein said photoelectric converter is a photodetector array whose photodetectors are connected to the phase measuring unit through a switching device.

Claim 145

A laser interferometer as claimed in claim 117, wherein said photoelectric converter is made as a photodetector array, each of whose photodetectors is connected to its own phase measuring unit.

Claim 146

A laser interferometer as claimed in claim 117, comprising a scanning device connected to at least one said photoelectric converter and adapted for providing a possibility of converting the interfered light at different points across the interfering beams.

Claim 147

A digital multiple-beam laser interferometer, comprising: a laser capable of emitting a beam of coherent light having different wavelengths; a device for separating from said light beam two collinear light components with mutually independent polarizations, said device being located past said laser along the run of the light beam; a device for offsetting the light frequency of one of said light components, said device being located past said laser along the run of the light beam; a master oscillator connected to said light frequency offsetting device; at least two reflecting elements positioned one after the other along the run of the light beam and adapted for presetting a light path interval and for forming a plurality of interfering light beams by virtue of multiple reflection of the light beam from said reflecting elements; a birefringent plate located between said reflecting elements and adapted for mutual conversion of said polarizations of said light components; a beam-splitter element located between said light frequency offsetting device on the one side and said reflecting elements on the other side and adapted for separating said interfering light beams reflected from said reflecting elements; a polarizing element located past said beam-splitter element along the run of said separated interfering light beams and adapted for dividing the light of said interfering beams into two beams of interfered light with said independent polarizations; at least one photoelectric converter of the interfered light into an electric signal, said converter being located past said polarizing element on the axis of at least one of said two beams of interfered light; at least one phase measuring unit connected to the output of at least one said photoelectric converter and adapted for measuring the phase of said electric signal so as to judge of the desired optical length of a preset light path interval by said phase; a computer device connected to the output of at least one said phase measuring unit and to said laser and adapted for calculating an integral and a fraction part of the periods of the desired value of the optical length of a preset light path interval from the results of measuring the phases of electric signals at different known values of said laser wavelengths.

Claim 148

A digital multiple-beam laser interferometer, comprising: a laser capable of emitting a beam of coherent light having different wavelengths; a device for separating from said light beam two collinear light components with mutually independent polarizations, said device being located past said laser along the run of the light beam; a device for offsetting the light frequency of one of said light components, said device being located past said laser along the run of the light beam; a master oscillator connected to said light frequency offsetting device; at least two reflecting elements positioned one after the other along the run of the light beam and adapted for presetting a light path interval and for forming a plurality of interfering light beams by virtue of multiple reflection of the light beam from said reflecting elements; a birefringent plate located between said reflecting elements and adapted for mutual conversion of said polarizations of said light components; a beam-splitter element located between said light frequency offsetting device on the one side and said reflecting elements on the other side and adapted for separating said interfering light beams reflected from said reflecting elements; a polarizing element located past said beam-splitter element along the run of said separated interfering light beams and adapted for dividing the light of said interfering beams into two beams of interfered light with said independent polarizations; at least one photoelectric converter of the interfered light into an electric signal, said converter being located past said polarizing element on the axis of at least one of said two beams of interfered light; at least one phase measuring unit connected to the output of at least one said photoelectric converter and adapted for measuring the phase of said electric signal so as to judge of the desired optical length of a preset light path interval by said phase; a computer device connected to the output of at least one said phase measuring unit and to said laser and adapted for calculating an integral and a fraction part of the periods of the desired value of the optical length of a preset light path interval from the results of measuring the phases of electric signals at different known values of said laser wavelengths.

Claim 149

A laser interferometer as claimed in claim 135, wherein said laser features a tunable wavelength.

Claim 150

A laser interferometer as claimed in claim 135, comprising an optical unit adapted for splitting the beam of interfered light into a number of separate beams depending upon the light wavelength, said optical unit being located between said polarizing element and at least one said photoelectric converter as along the run of the beam of interfered light so that arranged on the axis of each of said separated beams is at least one photoelectric converter connected to its own phase measuring unit, while the laser emits light of at least two wavelengths at a time.

Claim 151

A laser interferometer as claimed in claim 135, wherein said light frequency offsetting device is an electrooptic frequency modulator.

Claim 152

A laser interferometer as claimed in claim 135, wherein said light frequency offsetting device is an acousto-optic frequency modulator.

Claim 153

A laser interferometer as claimed in claim 135, wherein used as said laser, said device for separating said light components with mutually independent polarizations and said light frequency offsetting device is a dual-frequency laser.

Claim 154

A laser interferometer as claimed in claim 135, wherein said device for separating said light components with mutually independent polarizations is made as a dual-beam polarization interferometer in one of whose beams said light frequency offsetting device is situated.

Claim 155

A laser interferometer as claimed in claim 135, wherein said reflecting elements are made as partially reflecting mirror surfaces.

Claim 156

A laser interferometer as claimed in claim 135, wherein at least one of said reflecting elements is a diffraction grating.

Claim 157

A laser interferometer as claimed in claim 135, wherein at least one of said reflecting elements is made as a hologram.

Claim 158

A laser interferometer as claimed in claim 135, wherein said birefringent plate is a quarter-wave plate.

Claim 159

A laser interferometer as claimed in claim 143, wherein said birefringent plate features a quarter-wave difference between the phase shifts of light waves in two working diffraction orders.

Claim 160

A laser interferometer as claimed in claim 135, wherein said polarizing element is a polarizer.

Claim 161

A laser interferometer as claimed in claim 135, comprising at least two said photoelectric converters, a first and a second, wherein said polarizing element is a polarization beam-splitter adapted for dividing the light of the interfering beams into two said beams, a first and a second, of interfered light with linear mutually square polarizations, the first of said photoelectric converters being arranged on the axis of said first beam of interfered light and being connected to at least one said phase measuring unit, while the second of said photoelectric converters is arranged on the axis of said second beam of interfered light and is also connected to at least one said phase measuring unit.

Claim 162

A laser interferometer as claimed in claim 135, wherein said photoelectric converter is a quadratic photodetector.

Claim 163

A laser interferometer as claimed in claim 135, wherein said photoelectric converter is a photodetector array whose photodetectors are connected to the phase measuring unit through a switching device.

Claim 164

A laser interferometer as claimed in claim 135, wherein said photoelectric converter is a photodetector array, each of whose photodetectors is connected to its own phase measuring unit.

Claim 165

A laser interferometer as claimed in claim 135, comprising a scanning device connected to at least one said photoelectric converter and adapted for providing a possibility of converting the interfered light at different points across the interfering beams.