Point reference interferometry

Claim 2

A two-wave point-reference interferometer for the study of a transparent or opaque object, comprising: A. a beam source for providing a light beam, B. a beam splitter for splitting the light beam into two parts, C. a plurality of mirrors forming a reflective means for sending the parts of the split light beam along a path from the beam splitter back to the beam splitter for recombination, D. means for maintaining the object to be studied in said path, and E. transparent means for causing a change in the direction of any beam passing through it, the transparent means being placed in said path at a point conjugated with itself with respect to the beam splitter.

Claim 3

An interferometer according to claim 1 particularly intended for macroscopy of objects, wherein said plurality of mirrors comprises an even number of mirrors with a plane of incidence of said light beam which is the same as that of the beam splitter.

Claim 4

An interferometer according to claim 2 further comprising a lens situated between the beam source and the beam splitter for forming a respective real image of the source at a respective point between the beam splitter and each of the mirrors, and wherein the object to be studied is transparent and is placed at one of the real image points between the beam splitter and one of the mirrors.

Claim 5

An interferometer according to claim 1, wherein the object to be studied is opaque and reflecting and comprises mirrors.

Claim 6

An interferometer according to claim 2, wherein the object is opaque and reflecting and wherein the circuit is folded so that the beam arrives normal to the surface of the object and comes back into the circuit loop by means of an auxiliary semi-reflecting separator, the distance between the object and the refracting or diffracting component, via the separator, being constant.

Claim 7

An interferometer according to claim 1, particularly intended for microscopy of transparent objects, wherein the plurality of mirrors comprises an even number of mirrors and further comprising two identical lenses arranged symmetrically with respect to the self-conjugated point, the object to be studied being placed between the self-conjugated point and one of the lenses at a distance from said point which is large with respect to the focus depth of the lenses.

Claim 8

An interferometer in accordance with claim 1, wherein the transparent means is subjected to vibrations or rotations in its plane.

Claim 9

An interferometer according to claim 1, particularly intended for macroscopy or small enlargement microscopy, wherein the plurality of mirrors comprises an even number of mirrors, and further comprising an afocal system interposed in said circuit, the object to be studied being placed within the afocal system and the self-conjugated point where the said transparent means is placed being located outside of the afocal system, and further comprising an instrument placed outside of the interferometer for observing the images.

Claim 10

An interferometer according to claim 8, wherein the self-conjugated point is located at a distance from the interferometer center equal to double the lens focal length of the afocal system.

Claim 11

An interferometer according to claim 8, wherein the object is opaque and reflecting and wherein the beam travels a circuit which is folded so that the beam arrives normal to the surface of the object and returns into the circuit loop by means of an auxiliary semi-reflecting beam-splitter, the afocal system, being of the reflecting type formed by a single lens, and the said reflecting object, being placed in the first focus of the lens, the transparent means, whether refracting or diffracting, being placed in the second focus of the reflecting system lens between the separator and the auxiliary separator.

Claim 12

An interferometer according to claim 10, wherein, when the object surface is spherical, whether concave or convex, the transparent means is placed at a point where beams perpendicular to the surface of said object cut the optical axis.

Claim 13

An interferometer according to claim 10, further comprising adjustment means for displacement of the transparent means in its plane along two mutually perpendicular directions.

Claim 14

An interferometer according to claim 10, further comprising a parallel-plane plate in the beam path and inclinable in two mutually perpendicular directions to accomplish minor compensation.

Claim 15

An interferometer according to claim 1, particularly intended for microscopy of objects, characterized in that it includes mirrors in the path of the beam for introducing an odd number of beam reflections into the incidence plane of the beam splitter and for introducing an odd number of beam reflections into a plane perpendicular to said incidence plane, and further comprising: A. an afocal system interposed in the circuit, the object to be studied being placed within the afocal system, and B. the self-conjugated point, where the transparent means is placed, being located in the middle of the loop path as measured beginning with the beam-splitter and returning to it, deduction being made from this distance of four times the lens focal length of the afocal system, and C. further comprising an observation glass placed outside of the interferometer for observing the images.

Claim 16

An interferometer according to claim 14, wherein the object is opaque and reflecting and wherein the beam path is folded so that the beam arrives normal to the surface of the object and returns into the beam path circuit by means of an auxiliary semi-reflecting beam splitter, the afocal system being of the reflecting type formed by a single lens, and the said reflecting object being placed in the first focus of the lens, the distance between the second lens focus and the transparent means via the auxiliary beam splitter being constant and independent of the focal length of the reflecting afocal system lens.

Claim 17

An interferometer according to claim 15, further comprising a series of objectives of different focal length, wherein the coherence adjustments are effected by the axial displacement of the transparent means corresponding to the variation of the position of the image focus of the objective being used.

Claim 18

An interferometer according to claim 1, wherein the transparent means is a symmetrical lens.

Claim 19

An interferometer according to claim 1, wherein the transparent means is diffracting and is formed of an optical fiber block.

Claim 20

An interferometer according to claim 1, wherein the transparent means is a diffracting means and consists of an optical fiber block.

Claim 21

An interferometer according to claim 19, further comprising means for subjecting the diffracting means to low-amplitude motion in its plane.

Claim 22

An interferometer according to claim 1, wherein the effective opening of the transparent means is limited by a diaphragm with an adjustable opening.

Claim 23

An interferometer according to claim 1, further comprising: A. an auxiliary beam splitter for folding the beam path between the auxiliary beam splitter and said object, B. an auxiliary device working in polarized light, composed of a parallel polarizer and analyzer, the polarizer operating on the light beam from the beam source before it reaches the first beam splitter and the analyzer operating upon a recombined beam from the first beam splitter, C. a birefracting quarter-wave plate lambda /4 inserted between the surface of the object and the auxiliary beam splitter, and D. a birefracting half-wave plate lambda /2 inserted in the path of the split beam outside of the space separating the object from the auxiliary beam splitter, the two wave plates lambda /4 and lambda /2 being oriented so that their slow axes are crossed and oriented at 45* with respect to the direction of the vibration transmitted by the polarizer and the analyser.