CA2284602C - Interferometer tunable in a non-mechanical manner by a pancharatnam phase - Google Patents
Interferometer tunable in a non-mechanical manner by a pancharatnam phase Download PDFInfo
- Publication number
- CA2284602C CA2284602C CA002284602A CA2284602A CA2284602C CA 2284602 C CA2284602 C CA 2284602C CA 002284602 A CA002284602 A CA 002284602A CA 2284602 A CA2284602 A CA 2284602A CA 2284602 C CA2284602 C CA 2284602C
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- Prior art keywords
- interferometer
- analyzer
- reference surface
- test specimen
- polarization
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B9/00—Measuring instruments characterised by the use of optical techniques
- G01B9/02—Interferometers
- G01B9/02055—Reduction or prevention of errors; Testing; Calibration
- G01B9/02056—Passive reduction of errors
- G01B9/02057—Passive reduction of errors by using common path configuration, i.e. reference and object path almost entirely overlapping
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B9/00—Measuring instruments characterised by the use of optical techniques
- G01B9/02—Interferometers
- G01B9/02001—Interferometers characterised by controlling or generating intrinsic radiation properties
- G01B9/02011—Interferometers characterised by controlling or generating intrinsic radiation properties using temporal polarization variation
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B2290/00—Aspects of interferometers not specifically covered by any group under G01B9/02
- G01B2290/70—Using polarization in the interferometer
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Instruments For Measurement Of Length By Optical Means (AREA)
- Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
- Spectrometry And Color Measurement (AREA)
Abstract
The object of the invention is to create an improved interferometer which does not require a drive mechanism for moving a reference surface or test specimen in order to tune the interferometer and which can be tuned in virtually vibration-free manner, thereby preventing measuring errors. For this purpose, the interferometer (10) comprises at least one light source, a reference surface (40), a test specimen (50) and at least one beam splitter (30). For vibration-free tuning, the interferometer (10) further contains an apparatus (60, 70) for the polarization of the.interference beams such that, at the output of the interferometer (10), they have different polarization states with respect to each other; and an analyzer (80), disposed at the output of the interferometer (10), with a polarization state variable in predetermined manner, said analyzer (80) - depending on its polarization state - introducing a defined Pancharatnam phase into the interference beams for tuning the interferometer (10).
Description
Interferometer The invention relates to an interferometer, in particular for the measurement of optical surfaces.
A conventional two-beam interferometer is used to measure optical surfaces in that it generates at the output an interference fringe pattern of the optical surface and supplies said pattern, for example, to a video camera for further processing. The light reflected by the optical surface, known also as a test wave field, contains aberrations because of lens errors and surface roughnesses at the surface being measured, said aberrations being imaged by the interference fringe pattern. The local position of the deviations of the interference fringe pattern from an ideal fringe pattern (e. g. parallel fringes) correlates with the local position of the aberration in the test wave field and thus with the deviations of the optical test surface, for example, with respect to an ideally flat surface. Such a displacement of the interference fringe pattern because of aberrations may have a considerably adverse effect on the measuring sensitivity, because the fringe deformation, e.g.
in the pattern maxima and minima, is not able to image the deformation of the test wave field as accurately as in the regions with high intensity gradients. Therefore, it is desirable to be able to displace the interference fringe pattern in a defined manner in order to improve the measuring accuracy. For this purpose, the reference surface or the test specimen itself has hitherto been moved or tilted in order to introduce an additional phase gradient into the interference beams and thus into the interference fringe pattern. In this manner it is also possible to obtain unambiguous information about the aberration of the test wave field, this subsequently allowing the elimination of errors e.g. in a flat test surface. However, the movement of large and heavy test specimens or reference surfaces introduces further inaccuracies into the interferometer.
Embodiments of the invention, therefore, create an improved interferometer which does not require a drive mechanism for moving a reference surface or test specimen in order to tune the interferometer and which can be tuned in virtually vibration-free manner, thereby preventing measuring errors.
Accordingly, in one aspect of the present invention, there is provided a tunable interferometer, in particular for the measurement of optical surfaces, comprising: at least one light source, a reference surface and a test specimen and at least one beam splitter, an apparatus for the polarization of the interference beams such that, at the output of the interferometer, they have different polarization states with respect to each other;
and an analyzer, disposed at the output of the interferometer, with a polarization state variable in predetermined manner for tuning the interferometer, the analyzer being physically separate from the interferometer.
In some embodiments, the interferometer is a two-beam interferometer; and linearly polarized light is present at the input of the interferometer; and the polarization apparatus comprises a first ~/4 retardation plate, associated with the reference surface or with the test specimen, and a second ~/4 retardation plate, positioned before the analyzer.
In some embodiments, the analyzer is a rotatable linear analyzer.
2a In some embodiments, the analyzer comprises an electrically tunable liquid crystal element with a linear polarizer.
A conventional two-beam interferometer is used to measure optical surfaces in that it generates at the output an interference fringe pattern of the optical surface and supplies said pattern, for example, to a video camera for further processing. The light reflected by the optical surface, known also as a test wave field, contains aberrations because of lens errors and surface roughnesses at the surface being measured, said aberrations being imaged by the interference fringe pattern. The local position of the deviations of the interference fringe pattern from an ideal fringe pattern (e. g. parallel fringes) correlates with the local position of the aberration in the test wave field and thus with the deviations of the optical test surface, for example, with respect to an ideally flat surface. Such a displacement of the interference fringe pattern because of aberrations may have a considerably adverse effect on the measuring sensitivity, because the fringe deformation, e.g.
in the pattern maxima and minima, is not able to image the deformation of the test wave field as accurately as in the regions with high intensity gradients. Therefore, it is desirable to be able to displace the interference fringe pattern in a defined manner in order to improve the measuring accuracy. For this purpose, the reference surface or the test specimen itself has hitherto been moved or tilted in order to introduce an additional phase gradient into the interference beams and thus into the interference fringe pattern. In this manner it is also possible to obtain unambiguous information about the aberration of the test wave field, this subsequently allowing the elimination of errors e.g. in a flat test surface. However, the movement of large and heavy test specimens or reference surfaces introduces further inaccuracies into the interferometer.
Embodiments of the invention, therefore, create an improved interferometer which does not require a drive mechanism for moving a reference surface or test specimen in order to tune the interferometer and which can be tuned in virtually vibration-free manner, thereby preventing measuring errors.
Accordingly, in one aspect of the present invention, there is provided a tunable interferometer, in particular for the measurement of optical surfaces, comprising: at least one light source, a reference surface and a test specimen and at least one beam splitter, an apparatus for the polarization of the interference beams such that, at the output of the interferometer, they have different polarization states with respect to each other;
and an analyzer, disposed at the output of the interferometer, with a polarization state variable in predetermined manner for tuning the interferometer, the analyzer being physically separate from the interferometer.
In some embodiments, the interferometer is a two-beam interferometer; and linearly polarized light is present at the input of the interferometer; and the polarization apparatus comprises a first ~/4 retardation plate, associated with the reference surface or with the test specimen, and a second ~/4 retardation plate, positioned before the analyzer.
In some embodiments, the analyzer is a rotatable linear analyzer.
2a In some embodiments, the analyzer comprises an electrically tunable liquid crystal element with a linear polarizer.
In some embodiments, the analyzer is physically separate from the interferometer.
The principal idea behind the invention consists in making available a tunable interferometer without it being necessary for the reference surface or test specimen to be moved in order to tune the interferometer. Usually, the tuning of an interferometer means changing the optical path of one of the arms of the interferometer by moving or tilting the reference surface or test specimen, this introducing a defined phase into the interferometer. In contrast thereto, tuning in the sense of the invention means that a defined phase, the so-called Pancharatnam phase, is introduced into the interferometer, there being, however, no change in the relative position between the reference surface and the test specimen. The phenomenon of the Pancharatnam phase is known and is described in detail in the paper "Pancharatnams Phase in Polarisation Optics", published in Advanced Electromagnetism, T. Barratt et al., Editors Singapore, pages 357-375 by W. Dultz et al.
The interferometer comprises at least one light source, a reference surface and a test specimen as well as at least one beam splitter. The interferometer further contains an apparatus for the polarization of the interference beams such that, at the output of the interferometer, they have different polarization states.
Disposed at the output of the interferometer is an analyzer with a polarization state variable in predetermined manner for tuning the interferometer. Depending on the polarization state of the analyzer, an additional phase, the so-called Pancharatnam phase, is introduced into the interference beams of different polarizations, the result being that the interference fringe pattern, imaging the test specimen, is displaced by a predetermined distance.
The principal idea behind the invention consists in making available a tunable interferometer without it being necessary for the reference surface or test specimen to be moved in order to tune the interferometer. Usually, the tuning of an interferometer means changing the optical path of one of the arms of the interferometer by moving or tilting the reference surface or test specimen, this introducing a defined phase into the interferometer. In contrast thereto, tuning in the sense of the invention means that a defined phase, the so-called Pancharatnam phase, is introduced into the interferometer, there being, however, no change in the relative position between the reference surface and the test specimen. The phenomenon of the Pancharatnam phase is known and is described in detail in the paper "Pancharatnams Phase in Polarisation Optics", published in Advanced Electromagnetism, T. Barratt et al., Editors Singapore, pages 357-375 by W. Dultz et al.
The interferometer comprises at least one light source, a reference surface and a test specimen as well as at least one beam splitter. The interferometer further contains an apparatus for the polarization of the interference beams such that, at the output of the interferometer, they have different polarization states.
Disposed at the output of the interferometer is an analyzer with a polarization state variable in predetermined manner for tuning the interferometer. Depending on the polarization state of the analyzer, an additional phase, the so-called Pancharatnam phase, is introduced into the interference beams of different polarizations, the result being that the interference fringe pattern, imaging the test specimen, is displaced by a predetermined distance.
A linear relationship between the degree of displacement of the fringe pattern and the position of the analyzer is obtained if, in a two-beam interferometer, the interference beams are polarized orthogonally with respect to each other. This is achieved in that, first, a linearly polarized light, preferably laser light, is present at the input of the interferometer, and in that the polarization apparatus comprises a first ~/4 retardation plate, associated with the reference surface or with the test specimen, and a second ~/4 retardation plate, positioned before the analyzer.
The first retardation plate ensures that the light beams reflected by the reference surface and by the test specimen are polarized orthogonally with respect to each other. The second retardation plate converts the two beams into a left-circularly polarized beam and a right-circularly polarized beam.
The analyzer may be a rotatable linear analyzer or an electrically tunable liquid-crystal element with a linear polarizer.
In order to afford the interferometer additional protection against vibration during tuning, the interferometer and the analyzer may be physically separate, i.e. even installed in different locations.
Herein below, the invention is described in greater detail with reference to an example embodiment in connection with the drawing.
The drawing shows a two-beam interferometer 10 at the input of which is a linearly polarized laser light which has previously passed through a linear polarizer 20. The linear polarizer 20 is followed by a known beam splitter 30 which splits the incident light into at least two components. In the present example, a reference surface 40 is placed in the optical path which passes the beam splitter 30. With respect to the light beam which passes 5 through the beam splitter 30, there is an optical test specimen 50 after the reference surface 40. Let it be assumed that the reference surface 40 is a flat glass plate of such properties that it transmits 950 of the incident light and reflects 50 of the incident light back to the beam splitter 30. In the present example, the test specimen 50 is likewise represented by a glass plate which, in turn, reflects 50 of the incident light and transmits 95o thereof.
Disposed between the reference surface 40 and the test specimen 50 is a ~/4 plate 60, referred to below, for the sake of simplicity, as retardation plate 60. Let it be emphasized that the described relative position between the reference surface 40, the retardation plate 60 and the test specimen serves merely as an example. A second ~/4 plate 70, referred to below, for the sake of simplicity, as retardation plate 70, is disposed in the interferometer 10 in such a manner that the light beams reflected by the reference surface 40 and the test specimen 50 and deflected by the beam splitter 30 are able to pass through the retardation plate 70. A rotatable linear analyzer 80 is positioned after the retardation plate 70, with the result that the interference beams which pass through the retardation plate 70 strike the analyzer 80. The analyzer 80 is followed, for example, by a video camera (not shown) which records the interference fringe pattern supplied by the interferometer 10 at the output.
In the following, the operating principle for tuning the interferometer 10 is described in greater detail.
Let it be emphasized once again that conventional interferometers are tuned in that the reference surface 40 or the test specimen 50 has to be moved or tilted. However, the interferometer 10 according to the invention can be tuned without it being necessary to move the reference surface 40 or the test specimen. In other words, the relative position between the reference surface 40 and the test specimen 50 remains unchanged. This is achieved by the invention in that the interference beams - i.e. the beams reflected by the reference surface 40 and the test surface 50 - have different polarization states. Let it be assumed that the light passing the linear polarizer 20 is polarized in the direction of the arrow, i.e. vertically.
The vertically polarized light strikes the beam splitter 30 and half of it, for example, is reflected to the outside, the other half passing through the beam splitter 30. The vertically polarized light first strikes the reference surface 40, on which 50 of the light is reflected. The proportion that penetrates the reference surface 50 passes through the retardation plate 60, as a result of which the vertically polarized light undergoes right-circular polarization. If this light strikes the test surface 50, the reflected light is left-circularly polarized. The light reflected from the test surface 50 passes the retardation plate 60 again. Having again passed the retardation plate 60, the light once again has a linear polarization which, however, is orthogonal with respect to the polarization of the light reflected from the reference surface 40. The two reflected interference beams with polarizations orthogonal with respect to each other strike, in turn, the beam splitter 30, which deflects half of the light intensity to the retardation plate 70. In the retardation plate 70, the two interference beams undergo circular polarization, one of the beams being right-circularly polarized and the other left-circularly polarized. Owing to this polarization state of the interference beams and the rotatable linear analyzer 80, there is a linear relationship between the displacement of the interference fringe pattern at the output of the interferometer 10 and the rotation angle of the linear analyzer 80. In order to tune the interferometer 10, the linear analyzer 80 is simply rotated in a predetermined manner, as a result of which the so-called Pancharatnam phase is introduced into the interferometer 10, said Pancharatnam phase causing the linear displacement of the interference fringe pattern. The rotation angle by which the linear analyzer 80 has to be rotated in order to cause a predetermined displacement of the interference fringe pattern can be accurately determined if use is made of the Poincare sphere, which is known. The polarization states of the interference beams are on the poles of the Poincare sphere, the linear analyzer 80 moving on the equator when it is rotated. The phase which is in this manner inserted into the interferometer 10 is y=~ ~(A, R, L, P) when ~ is the spherical excess of the spherical lune A, R, P, L, A on the Poincare sphere. Therein, A is the linear polarization state of the light at the input of the interferometer 10.
R and L, respectively, stand for the right- and left-circular polarization states of the two interference beams.
The right- R and left- L circular polarization states of the two interference beams are achieved, as already mentioned, by the retardation plates 60 and 70. The right- and left-circularly polarized light (R, L) is, as already mentioned, present at the output of the retardation plate 70. With the aid of the rotatable linear analyzer 10, the Pancharatnam phase y, which is proportional to the rotation angle of the analyzer 80, is introduced between the left- and right-circularly polarized beams at the output of the interferometer. Through the defined rotation of the analyzer 80, the Pancharatnam phase is changed in predetermined manner and the interference fringes, recorded by the video camera, are displaced as if the reference surface 40 or the test surface 50 had been displaced.
Instead of a rotatable linear analyzer 80 it is possible to employ a known electrically tunable liquid-crystal element with a linear polarizes. Particularly preferred is an electrically rotatable ~/2 retardation plate of the kind producible using modern liquid-crystal techniques. With such retardation plates which operate very quickly, the axial orientation is rotated with the electric voltage.
The interferometer 10 can be tuned with all processes in which the two beams are differently polarized.
However, the tuning is only linear, i.e. predictable, if the polarizations of the beams reflected from the reference surface 40 and the test specimen 50 are orthogonal and if the analyzer moves on the symmetrically intermediate great circle on the Poincare sphere.
The first retardation plate ensures that the light beams reflected by the reference surface and by the test specimen are polarized orthogonally with respect to each other. The second retardation plate converts the two beams into a left-circularly polarized beam and a right-circularly polarized beam.
The analyzer may be a rotatable linear analyzer or an electrically tunable liquid-crystal element with a linear polarizer.
In order to afford the interferometer additional protection against vibration during tuning, the interferometer and the analyzer may be physically separate, i.e. even installed in different locations.
Herein below, the invention is described in greater detail with reference to an example embodiment in connection with the drawing.
The drawing shows a two-beam interferometer 10 at the input of which is a linearly polarized laser light which has previously passed through a linear polarizer 20. The linear polarizer 20 is followed by a known beam splitter 30 which splits the incident light into at least two components. In the present example, a reference surface 40 is placed in the optical path which passes the beam splitter 30. With respect to the light beam which passes 5 through the beam splitter 30, there is an optical test specimen 50 after the reference surface 40. Let it be assumed that the reference surface 40 is a flat glass plate of such properties that it transmits 950 of the incident light and reflects 50 of the incident light back to the beam splitter 30. In the present example, the test specimen 50 is likewise represented by a glass plate which, in turn, reflects 50 of the incident light and transmits 95o thereof.
Disposed between the reference surface 40 and the test specimen 50 is a ~/4 plate 60, referred to below, for the sake of simplicity, as retardation plate 60. Let it be emphasized that the described relative position between the reference surface 40, the retardation plate 60 and the test specimen serves merely as an example. A second ~/4 plate 70, referred to below, for the sake of simplicity, as retardation plate 70, is disposed in the interferometer 10 in such a manner that the light beams reflected by the reference surface 40 and the test specimen 50 and deflected by the beam splitter 30 are able to pass through the retardation plate 70. A rotatable linear analyzer 80 is positioned after the retardation plate 70, with the result that the interference beams which pass through the retardation plate 70 strike the analyzer 80. The analyzer 80 is followed, for example, by a video camera (not shown) which records the interference fringe pattern supplied by the interferometer 10 at the output.
In the following, the operating principle for tuning the interferometer 10 is described in greater detail.
Let it be emphasized once again that conventional interferometers are tuned in that the reference surface 40 or the test specimen 50 has to be moved or tilted. However, the interferometer 10 according to the invention can be tuned without it being necessary to move the reference surface 40 or the test specimen. In other words, the relative position between the reference surface 40 and the test specimen 50 remains unchanged. This is achieved by the invention in that the interference beams - i.e. the beams reflected by the reference surface 40 and the test surface 50 - have different polarization states. Let it be assumed that the light passing the linear polarizer 20 is polarized in the direction of the arrow, i.e. vertically.
The vertically polarized light strikes the beam splitter 30 and half of it, for example, is reflected to the outside, the other half passing through the beam splitter 30. The vertically polarized light first strikes the reference surface 40, on which 50 of the light is reflected. The proportion that penetrates the reference surface 50 passes through the retardation plate 60, as a result of which the vertically polarized light undergoes right-circular polarization. If this light strikes the test surface 50, the reflected light is left-circularly polarized. The light reflected from the test surface 50 passes the retardation plate 60 again. Having again passed the retardation plate 60, the light once again has a linear polarization which, however, is orthogonal with respect to the polarization of the light reflected from the reference surface 40. The two reflected interference beams with polarizations orthogonal with respect to each other strike, in turn, the beam splitter 30, which deflects half of the light intensity to the retardation plate 70. In the retardation plate 70, the two interference beams undergo circular polarization, one of the beams being right-circularly polarized and the other left-circularly polarized. Owing to this polarization state of the interference beams and the rotatable linear analyzer 80, there is a linear relationship between the displacement of the interference fringe pattern at the output of the interferometer 10 and the rotation angle of the linear analyzer 80. In order to tune the interferometer 10, the linear analyzer 80 is simply rotated in a predetermined manner, as a result of which the so-called Pancharatnam phase is introduced into the interferometer 10, said Pancharatnam phase causing the linear displacement of the interference fringe pattern. The rotation angle by which the linear analyzer 80 has to be rotated in order to cause a predetermined displacement of the interference fringe pattern can be accurately determined if use is made of the Poincare sphere, which is known. The polarization states of the interference beams are on the poles of the Poincare sphere, the linear analyzer 80 moving on the equator when it is rotated. The phase which is in this manner inserted into the interferometer 10 is y=~ ~(A, R, L, P) when ~ is the spherical excess of the spherical lune A, R, P, L, A on the Poincare sphere. Therein, A is the linear polarization state of the light at the input of the interferometer 10.
R and L, respectively, stand for the right- and left-circular polarization states of the two interference beams.
The right- R and left- L circular polarization states of the two interference beams are achieved, as already mentioned, by the retardation plates 60 and 70. The right- and left-circularly polarized light (R, L) is, as already mentioned, present at the output of the retardation plate 70. With the aid of the rotatable linear analyzer 10, the Pancharatnam phase y, which is proportional to the rotation angle of the analyzer 80, is introduced between the left- and right-circularly polarized beams at the output of the interferometer. Through the defined rotation of the analyzer 80, the Pancharatnam phase is changed in predetermined manner and the interference fringes, recorded by the video camera, are displaced as if the reference surface 40 or the test surface 50 had been displaced.
Instead of a rotatable linear analyzer 80 it is possible to employ a known electrically tunable liquid-crystal element with a linear polarizes. Particularly preferred is an electrically rotatable ~/2 retardation plate of the kind producible using modern liquid-crystal techniques. With such retardation plates which operate very quickly, the axial orientation is rotated with the electric voltage.
The interferometer 10 can be tuned with all processes in which the two beams are differently polarized.
However, the tuning is only linear, i.e. predictable, if the polarizations of the beams reflected from the reference surface 40 and the test specimen 50 are orthogonal and if the analyzer moves on the symmetrically intermediate great circle on the Poincare sphere.
Claims (4)
1. A tunable interferometer, in particular for the measurement of optical surfaces, comprising:
at least one light source, a reference surface and a test specimen and at least one beam splitter, an apparatus for the polarization of the interference beams such that, at the output of the interferometer, they have different polarization states with respect to each other;
and an analyzer, disposed at the output of the interferometer, with a polarization state variable in predetermined manner for tuning the interferometer, the analyzer being physically separate from the interferometer.
at least one light source, a reference surface and a test specimen and at least one beam splitter, an apparatus for the polarization of the interference beams such that, at the output of the interferometer, they have different polarization states with respect to each other;
and an analyzer, disposed at the output of the interferometer, with a polarization state variable in predetermined manner for tuning the interferometer, the analyzer being physically separate from the interferometer.
2. The interferometer according to claim 1, wherein the interferometer is a two-beam interferometer; and linearly polarized light is present at the input of the interferometer; and the polarization apparatus comprises a first .lambda./4 retardation plate, associated with the reference surface or with the test specimen, and a second .lambda./4 retardation plate, positioned before the analyzer.
3. The interferometer according to claim 1 or 2, wherein the analyzer is a rotatable linear analyzer.
4. The interferometer according to claim 1 or 2, wherein the analyzer comprises an electrically tunable liquid-crystal element with a linear polarizer.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19720246A DE19720246C2 (en) | 1997-05-15 | 1997-05-15 | Tunable interferometer |
| DE19720246.2 | 1997-05-15 | ||
| PCT/EP1998/002494 WO1998051992A1 (en) | 1997-05-15 | 1998-04-28 | Interferometer tunable in a non-mechanical manner by a pancharatnam phase |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2284602A1 CA2284602A1 (en) | 1998-11-19 |
| CA2284602C true CA2284602C (en) | 2006-11-07 |
Family
ID=7829453
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002284602A Expired - Fee Related CA2284602C (en) | 1997-05-15 | 1998-04-28 | Interferometer tunable in a non-mechanical manner by a pancharatnam phase |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0981717B1 (en) |
| AT (1) | ATE246341T1 (en) |
| AU (1) | AU736850B2 (en) |
| CA (1) | CA2284602C (en) |
| DE (2) | DE19720246C2 (en) |
| WO (1) | WO1998051992A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE10037652A1 (en) * | 2000-07-31 | 2002-02-14 | Deutsche Telekom Ag | Process for transferring moment of momentum to double refracting object made of mercury halide and/or Kevlar comprises changing polarizing state of light as polarized light passes through object |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3635552A (en) * | 1970-04-14 | 1972-01-18 | Philips Corp | Optical interferometer |
| US3873207A (en) * | 1973-03-09 | 1975-03-25 | Xerox Corp | Polarizing interferometer |
| JPH03195907A (en) * | 1989-12-25 | 1991-08-27 | Matsushita Electric Works Ltd | Fizeau interferometer for polarized light |
| IL100655A (en) * | 1991-02-08 | 1994-11-28 | Hughes Aircraft Co | Interferometric laser profilometer |
| DE69206654T2 (en) * | 1991-03-26 | 1996-07-11 | Hamamatsu Photonics Kk | Optical voltage detector |
| US5627666A (en) * | 1994-07-27 | 1997-05-06 | Board Of Regents Of The University Of Colorado | Liquid crystal phase modulator using cholesteric circular polarizers |
-
1997
- 1997-05-15 DE DE19720246A patent/DE19720246C2/en not_active Expired - Fee Related
-
1998
- 1998-04-28 DE DE59809161T patent/DE59809161D1/en not_active Expired - Lifetime
- 1998-04-28 WO PCT/EP1998/002494 patent/WO1998051992A1/en active IP Right Grant
- 1998-04-28 EP EP98924229A patent/EP0981717B1/en not_active Expired - Lifetime
- 1998-04-28 CA CA002284602A patent/CA2284602C/en not_active Expired - Fee Related
- 1998-04-28 AT AT98924229T patent/ATE246341T1/en not_active IP Right Cessation
- 1998-04-28 AU AU76499/98A patent/AU736850B2/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| DE19720246A1 (en) | 1998-11-19 |
| EP0981717B1 (en) | 2003-07-30 |
| AU736850B2 (en) | 2001-08-02 |
| WO1998051992A1 (en) | 1998-11-19 |
| ATE246341T1 (en) | 2003-08-15 |
| AU7649998A (en) | 1998-12-08 |
| DE19720246C2 (en) | 1999-04-15 |
| DE59809161D1 (en) | 2003-09-04 |
| CA2284602A1 (en) | 1998-11-19 |
| EP0981717A1 (en) | 2000-03-01 |
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