CN105674875B - A kind of full filed low frequency heterodyne point-diffraction interferometer - Google Patents
A kind of full filed low frequency heterodyne point-diffraction interferometer Download PDFInfo
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- CN105674875B CN105674875B CN201610006912.9A CN201610006912A CN105674875B CN 105674875 B CN105674875 B CN 105674875B CN 201610006912 A CN201610006912 A CN 201610006912A CN 105674875 B CN105674875 B CN 105674875B
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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
- G01B9/02094—Speckle interferometers, i.e. for detecting changes in speckle pattern
- G01B9/02096—Speckle interferometers, i.e. for detecting changes in speckle pattern detecting a contour or curvature
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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
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
- G01B11/2441—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures using interferometry
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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
- G01B9/02001—Interferometers characterised by controlling or generating intrinsic radiation properties
- G01B9/0201—Interferometers characterised by controlling or generating intrinsic radiation properties using temporal phase variation
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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
- G01B9/02015—Interferometers characterised by the beam path configuration
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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
- G01B9/02075—Reduction or prevention of errors; Testing; Calibration of particular errors
- G01B9/02076—Caused by motion
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Abstract
The invention discloses a kind of full filed low frequency heterodyne point-diffraction interferometers, and using acousto-optic frequency shifters difference interference phase shift, effectively avoiding interference with instrument, there are movement parts, measurement accuracy further increases, anti-interference is good, and development difficulty can be reduced with cost, and advantage same compared to Mechanical Driven becomes apparent from.Meanwhile being generated respectively using two optical fiber and measuring light and reference light, rather than with a part for emergent light, optical fiber point-diffraction light is combined to be easy to get, the advantages of being adjusted flexibly compares typical optical fiber point-diffraction interferometer system, and can improve measured value pore diameter range.In addition, the conjunction beam that diffractometry light and reference light are realized by the way of the optical fiber head and light splitting plain film mutually gluing of grinding angle, is closed beam and realizes that the wavefront for avoiding focused light spot is interfered by diffraction bore edges by the lateral surface of semi-transparent semi-reflecting plain film, and it is easy to implement, it is of low cost.
Description
Technical field
The present invention relates to optical image technology field more particularly to a kind of full filed low frequency heterodyne point-diffraction interferometers.
Background technology
Using deep-UV lithography machine projection exposure system therefor as the advanced optical equipment of representative, processing, optics to optical element
The integrated of system proposes great challenge.Interferometer integrates indispensable as high-precision optical element processing and optical system
Core detection device, accuracy of detection require to be continuously improved.
The surface characterization test method used in traditional optical processing includes Hartmann sensor method, knife-edge method and consistency profiles
Deng.These methods, which are respectively present non-digitalization, needs the different disadvantage of subjective interpretation or contact damage part to be measured etc., and is difficult to reach
It is simple method for measuring to higher measurement accuracy.
Interference detection method is just used before a century, belongs to non-contact measurement, and with wide range, highly sensitive
The features such as degree, high-precision, is widely used when high-precision detects, and principle is the reference planes conduct of light beam irradiation standard
Reference light, another Shu Guangzhao penetrate tested surface and return with face shape information as light is measured, due to hot spot difference when two-beam is interfered
Position phase difference generates optical path difference to generate the interference fringe of bending, you can judges that the face shape of tested surface rises and falls.Until
Bruning in 1974 et al. proposes Phase-Shifting Interferometry, and locking phase Detection Techniques in Communication Theory are introduced into optical interference
In art so that the precision of interference detection spherical surface shape greatly improves.Its basic principle is to move member to be measured by four steps or multistep
Part, to change the difference of the position between test waves and reference wave, light intensity also changes correspondingly, to obtain a series of equation.Finally,
The position that element under test (or system) is obtained by solving equation group is mutually worth.Phase-Shifting Interferometry is quite ripe, is examined in optics
Survey field has irreplaceable status.
The development of high-precision interference detection method can be divided by interferometer structure and feature：Tai Man-Green's type interferometer,
Striking rope type interferometer and point-diffraction interferometer etc..
Traditional spherical interference detection method is all that the reference spherical surface acquisition with higher surface figure accuracy is referred to using one
Corrugated, and then be compared with the detection corrugated containing tested surface shape information, thus obtain tested surface graphic data.Thus standard mirror
The surface figure accuracy of the upper plane of reference directly limits the accuracy of detection achieved by conventional interference system, and point-diffraction interferometer
The appearance and development of (Point Diffraction Interferometer, abbreviation PDI) have well solved the problem.Point spreads out
The basic thought for penetrating spherical interference detection technique is that ideal spherical wave is obtained using diffraction principle, and will be before diffracted wave
For a part as wavefront is referred to, another part can realize the high-precision detection of spherical surface shape as detection wavefront.Using point
Diffraction principle obtains ideal spherical face wavefront, avoids in conventional interference detecting system and system is examined due to standard mirror surface-shaped error
The limitation of precision is surveyed, thus the resolution ratio of diffraction limit performance can be reached, and makes accuracy of detection that there is preferable reproducibility.
It is different according to the acquisition modes before diffracted wave, a diffractive spherical interference detection method can be divided into optical fiber point-diffraction and interfere detection method
With pin hole point-diffraction interference detection method.
Typical optical fiber point-diffraction interference system is as shown in Figure 1, it generates point diffraction light using optical fiber, by short-coherence light source
The light sent out closes beam after the reflection of pyramid mirror and is coupled into optical fiber respectively after being divided into two bundles, light beam is made as another beam of light is measured
Pyramid mirror for reference light, reference light carries out mechanical phase shift by Piezoelectric Ceramic.The light cone one being emitted from the optical fiber other end
Divide and be pointed into measured lens, fiber end face reflection is focused on after return, overlaps interference with another part of outgoing light cone, form interference
Figure is matched since the coherence length of laser is short by the light path of front end, and measuring light itself can not do with the light returned from measured lens
Relate to, it is avoided that crosstalk.Interference pattern by recording respectively after mechanical phase shift, so as to calculate the face type of measured lens.However,
Since using high-precision Mechanical Moving, as phase-moving method, precision is still not high enough, of high cost, development difficulty is big, especially
Measurement to heavy caliber face shape, precision machinery drive precision to reduce, and measurement accuracy also decreases；In addition, using fiber exit
A part for light cone is as light is measured, so measurable minute surface range is by larger limitation.
Typical pin hole point diffraction interferometer system is as shown in Fig. 2, it is high-precision as point opening diffracting generation using small pin hole
Reference light is spent, and takes a part of of outgoing light cone and measurement light irradiation is used as to be tested minute surface, the plating semi-transparent semi-reflecting film at aperture,
The light of focusing returns to after aperture and overlaps interference with light cone another part through reflecting, and is pushed using piezoelectric ceramics and is tested minute surface progress machine
Tool phase shift measures.However, the mechanical phase shift of Piezoelectric Driving is not suitable for bigbore measured target mirror, the difficult accurate driving of piezoelectric ceramics
The prodigious object of quality；In addition, if the hot spot that tested minute surface is assembled is larger, returns at aperture and be easy by aperture edge
The interference of diffraction changes Wave-front phase distribution, reduces measurement accuracy, and small diffraction aperture complex manufacturing technology, of high cost.
Invention content
The object of the present invention is to provide a kind of full filed low frequency heterodyne point-diffraction interferometers, have higher measurement accuracy,
And interference free performance is preferable；Meanwhile development difficulty and cost are relatively low, particularly with the measurement of heavy caliber face shape, compared to machinery
Same advantage is driven to become apparent from.
The purpose of the present invention is what is be achieved through the following technical solutions：
A kind of full filed low frequency heterodyne point-diffraction interferometer, including：Laser, first and second half-wave plate, polarization spectro
Mirror, first and second acousto-optic frequency shifters, first and second fibre-coupled mirrors, first and second single-mode polarization maintaining fiber, light splitting plain film,
Imaging lens, planar array detector；Wherein：
It is orthogonal that the laser of the laser emitting by the first half-wave plate with polarization spectroscope is divided into polarization direction
Two-beam；
Wherein light beam passes sequentially through the second half-wave plate, the first acousto-optic frequency shifters, the first fibre-coupled mirrors and the first single mode
Polarization maintaining optical fibre enters light splitting plain film, and as with reference to light directive imaging lens；
Another light beam time enters light splitting by the second acousto-optic frequency shifters, the second fibre-coupled mirrors and the second single-mode polarization maintaining fiber
Plain film, and as measuring illumination to measured lens；The measurement light for injecting measured lens is emitted by measured lens to light splitting plain film, then through light splitting
Plain film reflection vertical divergence is overlapped to other direction with reference light；
Two-beam after coincidence generates interference, and interference pattern is obtained on planar array detector after imaged camera lens.
Further, further include：Light splitting piece, monitoring camera lens and supervision camera；
The light splitting piece setting goes out the light beam after a part overlaps between light splitting plain film and imaging lens, for beam splitting,
Monitored camera lens injects supervision camera again.
Further, first and second single-mode polarization maintaining fiber lift one's head be angle be i end face, and with described point
Optical plane is glued together；
If the beam direction that the end face that angle is i is projected and light splitting plane are at 45 °, then：
Wherein, n indicates the refractive index of light splitting plane.
Further, the interference signal S (t) of the variations of t at any time of some acquisition is expressed as on planar array detector：
Wherein, E indicates the light intensity of two-beam, ν1With ν2It indicates respectively after first and second acousto-optic frequency shifters frequency modulation
Beam frequencies, R are the coarse relief volume of measured lens, and c is the light velocity, and L is more relative to reference light when measuring light toward measured lens surface
The light path walked.
A kind of full filed low frequency heterodyne point-diffraction interferometer, including：Laser, half-wave plate, polarization spectroscope, first and
Two acousto-optic frequency shifters, first and second fibre-coupled mirrors, first and second single-mode polarization maintaining fiber, light splitting plain film, imaging lens, face
Array detector；Wherein：
The laser of the laser emitting is divided into the orthogonal two-beam in polarization direction by wave plate with polarization spectroscope；
Wherein light beam passes sequentially through the first acousto-optic frequency shifters, the first fibre-coupled mirrors and the first single-mode polarization maintaining fiber and enters
It is divided plain film, and as with reference to light directive imaging lens；
Another light beam time enters light splitting by the second acousto-optic frequency shifters, the second fibre-coupled mirrors and the second single-mode polarization maintaining fiber
Plain film, and as measuring illumination to measured lens；The measurement light for injecting measured lens is emitted by measured lens to light splitting plain film, then through light splitting
Plain film reflection vertical divergence is overlapped to other direction with reference light；
Two-beam after coincidence generates interference, and interference pattern is obtained on planar array detector after imaged camera lens.
Further, further include：Light splitting piece, monitoring camera lens and supervision camera；
The light splitting piece setting goes out the light beam after a part overlaps between light splitting plain film and imaging lens, for beam splitting,
Monitored camera lens injects supervision camera again.
Further, first and second single-mode polarization maintaining fiber lift one's head it is orthogonal and be separated by a distance placement simultaneously
With the light splitting plain film close to；
The light splitting plain film is ultra-thin light splitting plain film, and thickness is less than 1mm.
Further, the interference signal S (t) of the variations of t at any time of some acquisition is expressed as on planar array detector：
Wherein, E indicates the light intensity of two-beam, ν1With ν2It indicates respectively after first and second acousto-optic frequency shifters frequency modulation
Beam frequencies, R are the coarse relief volume of measured lens, and c is the light velocity, and L is more relative to reference light when measuring light toward measured lens surface
The light path walked.
As seen from the above technical solution provided by the invention, it using acousto-optic frequency shifters difference interference phase shift, effectively keeps away
Exempt from interferometer there are movement parts, measurement accuracy further increases, and anti-interference is good, and development difficulty can be reduced with cost, phase
Advantage more same than Mechanical Driven becomes apparent from.In addition, continuous using low frequency differences difference interference and planar array detector progress full filed
Acquisition, the information content of acquisition is more rich, is more advantageous to accurate resolving phase；To the face type of heavy caliber, long-focus curved reflector
It measures, due to measuring optical length, is particularly susceptible to the factors such as vibrations, air-flow and interferes, outside the full filed low frequency that the present invention uses
Poor interferometer scheme has the ability of the factors interference such as vibration-inhibition, air-flow, in conjunction with the light path that the present invention designs, particularly suitable for
Heavy caliber, long-focus curved reflector face type dynamic measure.Meanwhile it being generated respectively using two optical fiber and measuring light and reference
Light, rather than with a part for emergent light, the advantages of optical fiber point-diffraction light is easy to get, is adjusted flexibly is combined, compared to typical case
Optical fiber point-diffraction interferometer system, and measured value pore diameter range can be improved.In addition, using grinding angle optical fiber head with
The glued mode of light splitting plain film phase realizes the conjunction beam of diffractometry light and reference light, closes lateral surface of the beam by semi-transparent semi-reflecting plain film
It realizes, the wavefront for avoiding focused light spot is interfered by diffraction bore edges, and easy to implement, of low cost.
Description of the drawings
In order to illustrate the technical solution of the embodiments of the present invention more clearly, required use in being described below to embodiment
Attached drawing be briefly described, it should be apparent that, drawings in the following description are only some embodiments of the invention, for this
For the those of ordinary skill in field, without creative efforts, other are can also be obtained according to these attached drawings
Attached drawing.
Fig. 1 is the typical optical fiber point-diffraction interference system schematic diagram that background of invention provides；
Fig. 2 is the typical pin hole point diffraction interferometer system schematic diagram that background of invention provides；
Fig. 3 is a kind of structural schematic diagram of full filed low frequency heterodyne point-diffraction interferometer provided in an embodiment of the present invention；
Fig. 4 is the signal form schematic diagram of planar array detector provided in an embodiment of the present invention acquisition；
Fig. 5 is the structural schematic diagram of another full filed low frequency heterodyne point-diffraction interferometer provided in an embodiment of the present invention.
Specific implementation mode
With reference to the attached drawing in the embodiment of the present invention, technical solution in the embodiment of the present invention carries out clear, complete
Ground describes, it is clear that described embodiments are only a part of the embodiments of the present invention, instead of all the embodiments.Based on this
The embodiment of invention, every other implementation obtained by those of ordinary skill in the art without making creative efforts
Example, belongs to protection scope of the present invention.
Fig. 3 is a kind of structural schematic diagram of full filed low frequency heterodyne point-diffraction interferometer provided in an embodiment of the present invention.Such as
Shown in Fig. 3, include mainly：
A kind of full filed low frequency heterodyne point-diffraction interferometer, which is characterized in that including：Laser, first and second half-wave
Piece, polarization spectroscope, first and second acousto-optic frequency shifters, first and second fibre-coupled mirrors, first and second single mode polarization-maintaining light
Fine, light splitting plain film, imaging lens, planar array detector；Wherein：
It is orthogonal that the laser of the laser emitting by the first half-wave plate with polarization spectroscope is divided into polarization direction
Two-beam；Meanwhile it can arbitrarily adjust the splitting ratio of two-beam by rotating the first half-wave plate；
Wherein light beam passes sequentially through the second half-wave plate, the first acousto-optic frequency shifters, the first fibre-coupled mirrors and the first single mode
Polarization maintaining optical fibre enters light splitting plain film, and as with reference to light directive imaging lens；
Another light beam time enters light splitting by the second acousto-optic frequency shifters, the second fibre-coupled mirrors and the second single-mode polarization maintaining fiber
Plain film, and as measuring illumination to measured lens；The measurement light for injecting measured lens is emitted by measured lens to light splitting plain film, then through light splitting
Plain film reflection vertical divergence is overlapped to other direction with reference light；
Two-beam after coincidence generates interference, and interference pattern is obtained on planar array detector after imaged camera lens.
Further, further include：Light splitting piece, monitoring camera lens and supervision camera；
The light splitting piece setting goes out the light beam after a part overlaps between light splitting plain film and imaging lens, for beam splitting,
Monitored camera lens injects supervision camera again；For the adjustment of auxiliary optical path and interference pattern.
Further, lifting one's head for first and second single-mode polarization maintaining fiber is end face (in such as Fig. 1 that angle is i
First and second angle optical fiber head), and it is glued together with the light splitting plane；
If the beam direction that the end face that angle is i is projected and light splitting plane are at 45 °, then：
Wherein, n indicates the refractive index of light splitting plane.
In the embodiment of the present invention, first and second acousto-optic frequency shifters can change laser frequency, two acousto-optic frequency shifters
Shift frequency amount is different, and difference frequency can be the low difference frequency of several hertz or tens hertz magnitudes, and array detector camera is using tens of or hundreds of
Hertz magnitude sample frequency, therefore can accurately detect the beat signal of heterodyne.The t at any time a little acquired on planar array detector
The interference signal S (t) of variation is expressed as：
Wherein, E indicates the light intensity of two-beam, ν1With ν2It indicates respectively after first and second acousto-optic frequency shifters frequency modulation
Beam frequencies, R are the coarse relief volume of measured lens, and c is the light velocity, and L is more relative to reference light when measuring light toward measured lens surface
The light path walked.
Due to the presence of beat frequency, interference fringe can be with ν1-ν2Frequency scanning get up, planar array detector some correspondence wait for
A point on survey face, one group of face battle array photo of detector camera continuous acquisition, as one group of data cube, corresponding identical every bit
Value extract as a cosine periodic signal, the as form of S (t), as shown in Figure 4.It is different it can be seen from signal form
Point causes the signal phase that corresponding points detect on camera different since the R values of coarse fluctuating are different.Using Fourier analysis or its
Its data processing method can resolve the phase for often pointing out signal, combine and carry out the meters such as denoising, phase unwrapping solution, the recovery of face type
It can be obtained the relief volume on surface to be measured after calculation, that is, realize the measurement of full filed heterodyne opposite type.
Nearly all Mechanical Driven is used to carry out phase shift for the prior art, reaches that high-precision difficulty is big, and vulnerability to jamming difference is really
Fixed, said program of the present invention uses acousto-optic frequency shifters difference interference phase shift, and effectively avoiding interference with instrument, there are movement parts, measurement accuracy
It further increases, anti-interference is good, and development difficulty can be reduced with cost.Advantage same compared to Mechanical Driven becomes apparent from.
In addition, carrying out full filed continuous acquisition using low frequency differences difference interference and planar array detector, the information content of acquisition is more
It is abundant, it is more advantageous to accurate resolving phase.To the surface type measurement of heavy caliber, long-focus curved reflector, due to measuring optical length,
It is particularly susceptible to the interference of the factors such as vibrations, air-flow, the full filed low frequency heterodyne ineterferometer scheme that the present invention uses, which has, to be inhibited
The ability of the factors such as vibrations, air-flow interference, it is anti-particularly suitable for heavy caliber, long-focus curved surface in conjunction with the light path that the present invention designs
The dynamic for penetrating the face type of mirror measures.
Meanwhile being generated respectively using two optical fiber and measuring light and reference light, rather than with a part for emergent light, it combines
The advantages of optical fiber point-diffraction light is easy to get, is adjusted flexibly is compared typical optical fiber point-diffraction interferometer system, and can be improved
Measured value pore diameter range.
In addition, realizing diffractometry light and reference by the way of the optical fiber head and light splitting plain film mutually gluing of grinding angle
The conjunction beam of light closes beam and is realized by the lateral surface of semi-transparent semi-reflecting plain film, avoids the wavefront of focused light spot by diffraction bore edges
Interference.And it is easy to implement, it is of low cost.
The embodiment of the present invention also provides a kind of full filed low frequency heterodyne point-diffraction interferometer, as shown in figure 5, it is mainly wrapped
It includes：Laser, half-wave plate, polarization spectroscope, first and second acousto-optic frequency shifters, first and second fibre-coupled mirrors, first with
Second single-mode polarization maintaining fiber, light splitting plain film, imaging lens, planar array detector；Wherein：
The laser of the laser emitting is divided into the orthogonal two-beam in polarization direction by wave plate with polarization spectroscope；
Wherein light beam passes sequentially through the first acousto-optic frequency shifters, the first fibre-coupled mirrors and the first single-mode polarization maintaining fiber and enters
It is divided plain film, and as with reference to light directive imaging lens；
Another light beam time enters light splitting by the second acousto-optic frequency shifters, the second fibre-coupled mirrors and the second single-mode polarization maintaining fiber
Plain film, and as measuring illumination to measured lens；The measurement light for injecting measured lens is emitted by measured lens to light splitting plain film, then through light splitting
Plain film reflection vertical divergence is overlapped to other direction with reference light；
Two-beam after coincidence generates interference, and interference pattern is obtained on planar array detector after imaged camera lens.
Further, further include：Light splitting piece, monitoring camera lens and supervision camera；
The light splitting piece setting goes out the light beam after a part overlaps between light splitting plain film and imaging lens, for beam splitting,
Monitored camera lens injects supervision camera again.
In the embodiment of the present invention, first and second single-mode polarization maintaining fiber is lifted one's head orthogonal and is separated by a distance
It places and with the plain film that is divided close to (the first optical fiber head and the second optical fiber head as shown in Figure 5)；The light splitting plain film is
Ultra-thin light splitting plain film, thickness are less than 1mm.Light of the measurement light through ultra-thin light splitting plain film reflection can be allow to keep away based on this structure
Reference light fiber end face is opened without generating veiling glare crosstalk.
In addition, the interference signal S (t) of the variations of t at any time of some acquisition is expressed as on planar array detector：
Wherein, E indicates the light intensity of two-beam, ν1With ν2It indicates respectively after first and second acousto-optic frequency shifters frequency modulation
Beam frequencies, R are the coarse relief volume of measured lens, and c is the light velocity, and L is more relative to reference light when measuring light toward measured lens surface
The light path walked.
The full filed low frequency of full filed low frequency heterodyne point-diffraction interferometer provided in an embodiment of the present invention and previous embodiment
Heterodyne point-diffraction interferometer principle is almost the same, and the specific description that can be found in above, details are not described herein again.
The foregoing is only a preferred embodiment of the present invention, but scope of protection of the present invention is not limited thereto,
Any one skilled in the art is in the technical scope of present disclosure, the change or replacement that can be readily occurred in,
It should be covered by the protection scope of the present invention.Therefore, protection scope of the present invention should be with the protection model of claims
Subject to enclosing.
Claims (6)
1. a kind of full filed low frequency heterodyne point-diffraction interferometer, which is characterized in that including：Laser, first and second half-wave plate,
Polarization spectroscope, first and second acousto-optic frequency shifters, first and second fibre-coupled mirrors, first and second single-mode polarization maintaining fiber,
It is divided plain film, imaging lens, planar array detector；Wherein：
The laser of the laser emitting is divided into orthogonal two beam in polarization direction by the first half-wave plate with polarization spectroscope
Light；
Wherein light beam passes sequentially through the second half-wave plate, the first acousto-optic frequency shifters, the first fibre-coupled mirrors and the first single mode polarization-maintaining
Optical fiber enters light splitting plain film, and as with reference to light directive imaging lens；
Another light beam time enters light splitting by the second acousto-optic frequency shifters, the second fibre-coupled mirrors and the second single-mode polarization maintaining fiber puts down
Piece, and as measuring illumination to measured lens；The measurement light for injecting measured lens is emitted by measured lens to light splitting plain film, then flat through being divided
Piece reflection vertical divergence is overlapped to other direction with reference light；
Two-beam after coincidence generates interference, and interference pattern is obtained on planar array detector after imaged camera lens；
Lifting one's head for first and second single-mode polarization maintaining fiber is end face that angle is i, and is glued at the light splitting plane
Together；
If the beam direction that the end face that angle is i is projected and light splitting plane are at 45 °, then：
Wherein, n indicates the refractive index of light splitting plane.
2. a kind of full filed low frequency heterodyne point-diffraction interferometer according to claim 1, which is characterized in that further include：Point
Mating plate, monitoring camera lens and supervision camera；
The light splitting piece setting goes out the light beam after a part overlaps between light splitting plain film and imaging lens, for beam splitting, then passes through
Monitor that camera lens injects supervision camera.
3. a kind of full filed low frequency heterodyne point-diffraction interferometer according to claim 1, which is characterized in that planar array detector
The interference signal S (t) of the variations of t at any time of upper some acquisition is expressed as：
Wherein, E indicates the light intensity of two-beam, ν1With ν2The light beam after first and second acousto-optic frequency shifters frequency modulation is indicated respectively
Frequency, R are the coarse relief volume of measured lens, and c is the light velocity, and L measures light and walked relative to reference light toward when measured lens surface more
Light path.
4. a kind of full filed low frequency heterodyne point-diffraction interferometer, which is characterized in that including：Laser, half-wave plate, polarization spectro
Mirror, first and second acousto-optic frequency shifters, first and second fibre-coupled mirrors, first and second single-mode polarization maintaining fiber, light splitting plain film,
Imaging lens, planar array detector；Wherein：
The laser of the laser emitting is divided into the orthogonal two-beam in polarization direction by wave plate with polarization spectroscope；
Wherein light beam passes sequentially through the first acousto-optic frequency shifters, the first fibre-coupled mirrors and the first single-mode polarization maintaining fiber and enters light splitting
Plain film, and as with reference to light directive imaging lens；
Another light beam time enters light splitting by the second acousto-optic frequency shifters, the second fibre-coupled mirrors and the second single-mode polarization maintaining fiber puts down
Piece, and as measuring illumination to measured lens；The measurement light for injecting measured lens is emitted by measured lens to light splitting plain film, then flat through being divided
Piece reflection vertical divergence is overlapped to other direction with reference light；
Two-beam after coincidence generates interference, and interference pattern is obtained on planar array detector after imaged camera lens；
First and second single-mode polarization maintaining fiber lifts one's head orthogonal and is separated by a distance placement and is put down with the light splitting
Piece close to；
The light splitting plain film is ultra-thin light splitting plain film, and thickness is less than 1mm.
5. a kind of full filed low frequency heterodyne point-diffraction interferometer according to claim 4, which is characterized in that further include：Point
Mating plate, monitoring camera lens and supervision camera；
The light splitting piece setting goes out the light beam after a part overlaps between light splitting plain film and imaging lens, for beam splitting, then passes through
Monitor that camera lens injects supervision camera.
6. a kind of full filed low frequency heterodyne point-diffraction interferometer according to claim 4, which is characterized in that planar array detector
The interference signal S (t) of the variations of t at any time of upper some acquisition is expressed as：
Wherein, E indicates the light intensity of two-beam, ν1With ν2The light beam after first and second acousto-optic frequency shifters frequency modulation is indicated respectively
Frequency, R are the coarse relief volume of measured lens, and c is the light velocity, and L measures light and walked relative to reference light toward when measured lens surface more
Light path.
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| CN110109139A (en) * | 2019-05-16 | 2019-08-09 | 电子科技大学 | A kind of high-resolution imaging system and method based on heterodyne detection of laser |
| CN110926360B (en) * | 2019-11-18 | 2021-09-21 | 中国科学院光电研究院 | Device for measuring free-form surface by full-field external differential phase shift |
| CN110849593B (en) * | 2019-11-22 | 2021-06-01 | 中国科学院长春光学精密机械与物理研究所 | Measuring equipment for measuring wave aberration of optical system based on heterodyne interference of acousto-optic modulator |
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| WO1993022637A1 (en) * | 1992-05-05 | 1993-11-11 | Tabarelli, Werner | Interferometer |
| CN203025420U (en) * | 2013-01-05 | 2013-06-26 | 山东建筑大学 | Optical fiber beam combiner |
| CN104296678B (en) * | 2014-09-29 | 2017-02-22 | 中国科学院光电研究院 | Heterodyne interferometer based on phase shift of low-frequency-difference acousto-optic frequency shifter |
| CN104296676B (en) * | 2014-09-29 | 2017-04-26 | 中国科学院光电研究院 | Heterodyne point diffraction interferometer based on phase shift of low-frequency-difference acousto-optic frequency shifter |
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