Dynamic mirror alignment control

Claim 2

A closed loop servo control for dynamically aligning mirrors of an interferometer used for spectroscopic measurements, comprising: means for producing a laser beam having a plurality of light frequencies which are heterodyned through the interferometer to obtain a continuous and constant intensity modulation of a select frequency usable to indicate the distance between the surface of a first mirror in the interferometer and a reflected image of the surface of a second mirror in the interferometer; detector means for detecting said continuous intensity modulation in said laser beam to obtain a plurality of electrical signals each having a frequency characteristic of said intensity modulation frequency and of a modified intensity modulation when either said first or second mirror is moved relative to the other at selected locations in a cross section of said laser beam; control means for comparing the phase of signal frequency of each of the plurality of electrical signals with the average of their phase, to obtain a plurality of correction signals, each of said correction signals indicating a correction in distance required between a portion of the surface of the first mirror and a corresponding portion of the image of the surface of the second mirror to bring said first mirror and said image into parallel alignment; and a plurality of adjusting means mounting one of said mirrors and responsive to said correction signals for changing the alignment between said controllably separating the surface of said first mirror and the image of the surface of said second mirror.

Claim 3

The closed loop servo of claim 1 wherein said detector means comprises a detector array having a plurality of photodetectors positioned at selected locations in the cross section of the laser beam, to receive selected light rays for phase comparison.

Claim 4

The closed loop servo control of claim 2 wherein said adjustment means comprises a plurality of controlled adjustable length elements for mounting one of said mirrors of said interferometer, each of said elements positioned to correspond with a photodetector of said detector means to provide adjustment in response to the correction signal generated from the respective electrical signal said related photodetector produces.

Claim 5

The closed loop servo control of claim 3 wherein said adjustable length elements are piezoelectric transducers responsive to a voltage signal to adjust in length.

Claim 6

The closed loop servo control of claim 1 wherein said means for producing said laser beam comprises a laser and means for generating a magnetic field applied to said laser to effect Zeeman splitting phenomenon in the laser beam generated by said laser so that said laser beam exhibits a plurality of light frequencies which heterodyne to continually produce an intensity beat characteristic in said beam.

Claim 7

A closed loop servo control for equalizing the difference in path length of all rays in a laser beam passing through differing length optical paths in an interferometer, comprising: means for producing a single laser beam having a plurality of light frequencies which are heterodyned through the interferometer to obtain a continuous and constant intensity modulation with a measurable frequency and directing said single laser beam through said inteferometer; a plurality of photodetectors each positioned at a difference location in a cross section of the laser beam exiting the interferometer to receive a select group of rays in said beam and generate an electrical signal having a frequency indicative of the intensity modulation frequency of the group of rays received by the detector; signal comparator means comparing each electrical signal with the other electrical signals for continuously generating a plurality of correction signals each indicative of a difference in modulation frequency between the compared electrical signals; and means responsive to the correction signals for moving an optical element in said interferometer to correct differences in ray path lengths indicated by the correction signals to equalize ray path lengths for the laser beam.

Claim 8

A closed loop servo control for equalizing the difference in path length of all rays in a laser beam passing through differing length optical paths in an interferometer, comprising: means for producing a single laser beam having a plurality of light frequencies which are heterodyned through the interferometer to obtain a continuous and constant intensity modulation with a measurable frequency and directing said single laser beam through said inteferometer; a plurality of photodetectors each positioned at a difference location in a cross section of the laser beam exiting the interferometer to receive a select group of rays in said beam and generate an electrical signal having a frequency indicative of the intensity modulation frequency of the group of rays received by the detector; signal comparator means comparing each electrical signal with the other electrical signals for continuously generating a plurality of correction signals each indicative of a difference in modulation frequency between the compared electrical signals; and means responsive to the correction signals for moving an optical element in said interferometer to correct differences in ray path lengths indicated by the correction signals to equalize ray path lengths for the laser beam.

Claim 9

A closed loop servo control for dynamically aligning mirrors of an interferometer used for spectroscopic measurements, comprising: means producing a laser beam having a plurality of light frequencies which are heterodyned through the interferometer to obtain a continuous and constant intensity modulation of a select frequency usable to indicate the distance between corresponding portions of the surface of a first mirror bounding a substantially fixed length optical path in the interferometer and the surface of a second movable mirror bounding a changeable length optical path in the interferometer; detector means for detecting said continuous intensity modulation in said laser beam to obtain a plurality of electrical signals each having a frequency characteristic of said intensity modulation frequency and of a modified intensity modulation when the movable mirror is scanned at selected locations in a cross section of said laser beam; control means for comparing the phase of signal frequency of each of the plurality of electrical signals with the average of their phase, to obtain a plurality of correction signals, each of said correction signals indicating a correction in distance required between a portion of the surface of the first mirror and a corresponding portion of the surface of the second mirror to bring said first and second mirrors into parallel alignment; and a plurality of adjusting means mounting one of said mirrors and responsive to said correction signals for changing the alignment between and controllably separating the surface of said first mirror and the image of the surface of said second mirror.

Claim 10

A closed loop servo control for dynamically aligning mirrors of an interferometer used for spectroscopic measurements, comprising: means producing a laser beam having a plurality of light frequencies which are heterodyned through the interferometer to obtain a continuous and constant intensity modulation of a select frequency usable to indicate the distance between corresponding portions of the surface of a first mirror bounding a substantially fixed length optical path in the interferometer and the surface of a second movable mirror bounding a changeable length optical path in the interferometer; detector means for detecting said continuous intensity modulation in said laser beam to obtain a plurality of electrical signals each having a frequency characteristic of said intensity modulation frequency and of a modified intensity modulation when the movable mirror is scanned at selected locations in a cross section of said laser beam; control means for comparing the phase of signal frequency of each of the plurality of electrical signals with the average of their phase, to obtain a plurality of correction signals, each of said correction signals indicating a correction in distance required between a portion of the surface of the first mirror and a corresponding portion of the surface of the second mirror to bring said first and second mirrors into parallel alignment; and a plurality of adjusting means mounting one of said mirrors and responsive to said correction signals for changing the alignment between and controllably separating the surface of said first mirror and the image of the surface of said second mirror.

Claim 11

The closed loop servo of claim 7 wherein said detector means comprises a detector array having a plurality of photodetectors positions at selected locations in the cross section of the laser beam, to receive selected light rays for phase comparison.

Claim 12

The closed loop servo control of claim 8 wherein said adjustment means comprises a plurality of adjustable length elements for mounting a mirror, each of said elements positioned to correspond with a photodetector of said detector means to provide adjustment in response to the signal said related photodetector produces.

Claim 13

The closed loop servo control of claim 9 wherein said adjustable length elements are piezoelectric transducers responsive to a voltage signal to adjust in length.

Claim 14

The closed loop servo control of claim 7 wherein said means for producing said laser beam comprises a laser and means for generating a magnetic field applied to said laser to effect Zeeman splitting phenomenon in the laser beam generated by said laser so that said laser beam exhibits a plurality of light frequencies which heterodyne to continually produce an intensity beat characteristic in said beam.

Claim 15

A closed loop servo control for equalizing the difference in path length of all rays in a laser beam passing through differing length optical paths an interferometer, comprising: means for producing a single laser output beam having a plurality of light frequencies which are heterodyned through the interferometer to obtain a continuous and constant intensity modulation with a measurable frequency and directing said single laser beam through said interferometer frequency; a plurality of photodetectors each positioned at a different location in a cross section of the laser beam exiting the interferometer to receive a select group of rays in the beam and generate an electrical signal having a frequency indicative of the intensity modulation frequency of the group of rays received by the detector; signal comparator means comparing each electrical signal with an average thereof for continuously generating a plurality of correction signals each indicative of a difference in the modulation frequencies of the electrical signals and their average compared therewith; and means responsive to the correction signals for moving an optical element in said interferometer to correct differences in ray path lengths indicated by the correction signals to equalize ray path length for the laser beam.

Claim 16

A closed loop servo control for equalizing the difference in path length of all rays in a laser beam passing through differing length optical paths an interferometer, comprising: means for producing a single laser output beam having a plurality of light frequencies which are heterodyned through the interferometer to obtain a continuous and constant intensity modulation with a measurable frequency and directing said single laser beam through said interferometer frequency; a plurality of photodetectors each positioned at a different location in a cross section of the laser beam exiting the interferometer to receive a select group of rays in the beam and generate an electrical signal having a frequency indicative of the intensity modulation frequency of the group of rays received by the detector; signal comparator means comparing each electrical signal with an average thereof for continuously generating a plurality of correction signals each indicative of a difference in the modulation frequencies of the electrical signals and their average compared therewith; and means responsive to the correction signals for moving an optical element in said interferometer to correct differences in ray path lengths indicated by the correction signals to equalize ray path length for the laser beam.