CN104165582B - Phase shift point-diffraction interference detection device and method based on reflecting grating - Google Patents
Phase shift point-diffraction interference detection device and method based on reflecting grating Download PDFInfo
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Abstract
The invention belongs to the technical field of optical interference detection and particularly relates to a phase shift point-diffraction interference detection device and method based on a reflecting grating. The phase shift point-diffraction interference detection device based on the reflecting grating comprises a light source, a collimation and beam expanding system, a window, an object to be detected, a first lens, an unpolarized splitting prism, the reflecting grating, a small-hole reflector, a second lens and an image sensor. A light beam emitted by the light source enters the collimation and beam expanding system, the outgoing beam subjected to collimation and beam expanding of the collimation and beam expanding system enters the first lens through the window and the object to be detected, and the light beam subjected to focusing of the first lens is divided into a bundle of reference light and a bundle of object light by the unpolarized splitting prism. The reference light irradiates to the small-hole reflector, and the object light irradiates to the reflecting grating. The phase shift point-diffraction interference detection device based on the reflecting grating is low in system complexity and cost, simple in structure, flexible and convenient to operate and free of special optical elements of a polarizer group and the like.
Description
Technical field
The invention belongs to optical interference detection technique field is and in particular to a kind of phase shift point diffraction based on reflecting grating is done
Relate to detection means and detection method.
Background technology
Optical interference detection method is because of its noncontact, resolving power is high, sample need not be done with the unique features such as special handling, by
It is widely used in the detection fields such as optical surface, deformation and thickness.Current optical interference detection structure can be divided into separation light
Road and altogether two kinds of light path：Separate light path interferometer, such as Twyman Green Interferometer, Mach-Zehnder interferometer etc. are because reference beam
Interfered by different paths with measuring beam, easily affected by extraneous vibration, temperature fluctuation etc..Interfere compared to separating light path
Instrument, because reference beam and measuring beam are interfered through identical optical path, it is to external world for interference with common path instrument
Vibration, temperature fluctuation etc. are insensitive, have the advantages that strong antijamming capability, receive much concern in field of optical interference detection.Light altogether
A kind of interferometer typical structure in road is point-diffraction interferometer, but the point-diffraction interferometer quantitative measurement capability of early stage is poor, in order to
Make up this shortcoming, Chinese scholars have made a lot of Beneficials.
Israel scholar N.T.Shaked proposes a kind of reflective off axis point diffraction microinterferometer (Shaked N.T.
“Quantitative phase microscopy of biological samples using a portable
Interferometer, " Opt.Lett., 37 (11), 2016-2018 (2012) .), introduce in a standard 4f optical system
Unpolarized Amici prism produces two-beam, by using reflective pinhole filter to wherein light beam, thus forming reference light, separately
Light beam is converged with reference light once again by unpolarized Amici prism after being reflected by a reflector.The method only need to gather a width and interfere
Figure just can obtain quantitative phase information, and measurement efficiency is high, but because using from axle construction, sacrifices spatial bandwidth and the sky of camera
Between ability in sampling, and then limit system space resolving power, and be easily lost the high-frequency information of testing sample.
" a kind of reflection type point diffraction is from axle simultaneous phase-shifting interference checking device and detection side for patent 201310206690.1
Method " is passed through to introduce the light splitting synchronized orthogonal phase-shifting technique based on polarization splitting prism, is gathered by single exposure and is just obtaining two width
Hand over phase shift, while ensureing measurement efficiency, improve systematic survey resolving power, but system complex, the utilization ratio of visual field of camera
Low.
Xi'an ray machine Guo Rongli etc. propose a kind of coaxial microinterferometer of reflection type point diffraction (R.Guo, B.Yao,
P.Gao,J.Min,J.Zheng,T.Ye.“Reflective Point-diffraction microscopic
interferometer with long term stability.”COL 2011,9(12):120002.), polarized by introducing
Phase-shifting technique, exposure collection four width phase shifting interferences in chronological order, utilization ratio of visual field is high, but because using at least 4 polarizations
Phase shift realized by element, and system complexity is high.
Content of the invention
It is an object of the invention to provide a kind of phase shift point-diffraction interference detection means based on reflecting grating.
The present invention also aims to providing a kind of phase shift point-diffraction interference detection method based on reflecting grating.
The object of the present invention is achieved like this：
Based on the phase shift point-diffraction interference detection means of reflecting grating, including light source, collimating and beam expanding system, window, to be measured
Object, the first lens, unpolarized Amici prism, reflecting grating, aperture reflecting mirror, the second lens, imageing sensor, light source is launched
Light beam collimated beam-expanding system collimator and extender after outgoing beam be incident to the first lens, warp after window, object under test
Light beam after first lens focuss is divided into a branch of reference light and a branch of object light by unpolarized Amici prism；Reference light is radiated at aperture
On reflecting mirror, object light is radiated in reflecting grating；Through the object light of reflection with after reference light again passes by unpolarized Amici prism
After merging into light beam, generate interferogram after the second lens, collected in computer by imageing sensor simultaneously.
Aperture reflecting mirror is located on the focal plane of the first lens, and described reflecting grating is located at the focal plane of the second lens
On.
Reflecting grating can carry out horizontal minute movement to produce phase shift.
+ 1 order of diffraction light of reflecting grating is used for generating interferogram.
The a diameter of d of reflector space of aperture reflecting mirrorp≤1.22λf1/ D, wherein, λ is optical source wavelength, f1For the first lens
Focal length, D be window diameter.
Microcobjective and correction object lens can also be sequentially placed between object under test and the first lens.
Based on the phase shift point-diffraction interference detection method of reflecting grating, comprise the steps：
(1) adjust light source, make the light beam that light source is launched sequentially pass through collimating and beam expanding system, window, object under test, first saturating
Form object light and the reference light of focusing, object light and reference light are respectively by reflecting grating and aperture back after mirror and unpolarized Amici prism
Penetrate after mirror reflects jointly through unpolarized Amici prism and the second lens forming interferogram, meter is transferred to by imageing sensor collection
In calculation machine；
(2) reflecting grating is driven serial lateral displacement Δ=(k-1) d/N of generation, the interferogram of imageing sensor collection
Series of phase shift δ will be introduced intok=(k-1) 2 π/N, its corresponding intensity distributions is
Wherein, k=1,2 ..., N, O are object light optical field distribution, and R is reference light optical field distribution,For object under test
PHASE DISTRIBUTION；
Using the PHASE DISTRIBUTION that method of least square can obtain object under test it is
The beneficial effects of the present invention is：
1. reflection type point diffraction interference technique is combined by the present invention with reflecting grating phase shift technology, by the serial phase of collection
Move interferogram and complete phase recovery to be measured, ensure system rejection to disturbance ability and resolving power and image sensor field of view utilization rate
On the basis of, improve Phase shift precision, simplify the complexity of phase shift；
2. apparatus of the present invention system complexity is low, and structure is simple, flexible and convenient operation, and low cost is it is not necessary to polarizer group
Deng special optical element；
3. pass through to introduce microcobjective, the method can be applicable in micrometering.
Brief description
Fig. 1 is the principle schematic of the phase shift point-diffraction interference detection means based on reflecting grating；
Fig. 2 is the principle schematic of the phase shift point diffraction micro-interference detection means based on reflecting grating；
Fig. 3 (a) is the first width phase shifting interference of computer acquisition；
Fig. 3 (b) is the second width phase shifting interference of computer acquisition；
Fig. 3 (c) is the 3rd width phase shifting interference of computer acquisition；
Fig. 3 (d) is the 4th width phase shifting interference of computer acquisition；
Fig. 4 is the PHASE DISTRIBUTION according to object under testRecover the PHASE DISTRIBUTION of the object under test of acquisition.
Specific embodiment
Below in conjunction with the accompanying drawings the present invention is described further.
Phase shift point-diffraction interference detection means based on reflecting grating of the present invention, it includes light source, collimator and extender system
System, window, object under test, the first lens, unpolarized Amici prism, reflecting grating, aperture reflecting mirror, the second lens, image pass
Sensor,
The light beam collimated beam-expanding system collimator and extender of light source transmitting, then outgoing beam is after window, object under test
It is incident to the first lens, the light beam after the first lens focuss is divided into a branch of reference light and a branch of thing by unpolarized Amici prism
Light；Reference light is radiated on aperture reflecting mirror, and object light is radiated in reflecting grating；Object light and reference light warp again through reflection
After merging into light beam after crossing unpolarized Amici prism, generate interferogram after the second lens, adopted by imageing sensor simultaneously
Collect in computer.
Aperture reflecting mirror is located on the focal plane of the first lens, and reflecting grating is located on the focal plane of the second lens.
Reflecting grating can carry out horizontal minute movement to produce phase shift.
+ 1 order of diffraction light of reflecting grating is used for generating interferogram.
The a diameter of d of reflector space of aperture reflecting mirrorp≤1.22λf1/ D, wherein, λ is optical source wavelength, f1For the first lens
Focal length, D be window diameter.
Microcobjective can also be sequentially placed between object under test and the first lens and correction object lens are used for micrometering.
Based on the interference detection method of above-mentioned interference detection means, it to realize process as follows：
1., adjust light source, make the light beam that light source is launched sequentially pass through collimating and beam expanding system, window, object under test, first saturating
Form object light and the reference light of focusing, this object light and reference light are respectively by reflecting grating and aperture after mirror and unpolarized Amici prism
Jointly through unpolarized Amici prism and the second lens forming interferogram after reflecting mirror reflection, it is transferred to by imageing sensor collection
In computer；
2., assume that reflecting grating is driven serial lateral displacement Δ=(k-1) d/N of generation, it is dry that imageing sensor gathers
Relate to figure and will be introduced into series of phase shift δk=(k-1) 2 π/N, its corresponding intensity distributions is
Wherein, k=1,2 ..., N, O are object light optical field distribution, and R is reference light optical field distribution,For object under test
PHASE DISTRIBUTION.
Using the PHASE DISTRIBUTION that method of least square can obtain object under test it is
The specific embodiment of the present invention is described, the phase shift based on reflecting grating described in present embodiment with reference to Fig. 1
Point-diffraction interference detection means, it includes light source 1, collimating and beam expanding system 2, window 3, object under test 4, the first lens 5, unpolarized
Amici prism 6, reflecting grating 7, aperture reflecting mirror 8, the second lens 9, imageing sensor 10.Wherein, light source 1 adopts wavelength
The He-Ne laser instrument of 632.8nm, or be other monochromatic visible light sources, wavelength can be optional as needed.First lens 5 and
The focal length of two lens 9 is identical, is f1=f2=250mm.Aperture reflecting mirror 8 is located on the focal plane of the first lens 5, reflected light
Grid 7 are located on the focal plane of the second lens 9.The cycle d of reflecting grating 7 is 54.72um, and it can carry out horizontal minute movement to produce
Raw phase shift.The a diameter of d of reflector space of aperture reflecting mirror 8p≤1.22λf1/ D (D is window diameter).Object under test 4 and first is saturating
Microcobjective and correction object lens can also be sequentially placed between mirror 5.
Using the phase shift point-diffraction interference detection means based on reflecting grating described above, the detection method of the present invention
Specific embodiment is as follows：
First, adjust whole optical system before detecting, open light source 1, the collimated beam-expanding system of light beam 2 of this light source transmitting
Outgoing beam after collimator and extender is incident to the first lens 5 after window 3, object under test 4, after focusing on through the first lens 5
Light beam is divided into a branch of object light and a branch of reference light by unpolarized Amici prism 6, and reference light is radiated on aperture reflecting mirror 8, object light
It is radiated in reflecting grating 7, pass sequentially through after unpolarized Amici prism 6 merges into again through the object light of reflection and reference light
Generate interferogram after second lens 9 and imageing sensor 10 is gathered and collects in computer；
Record the first width interferogram I1Afterwards, reflecting grating 7, each micro-displacement during three translation reflecting gratings are translated
Amount is d/4 (d is the cycle of reflecting grating), and i.e. in three translation motion, object light moves introduced phase shift by reflecting grating
It is respectively pi/2, π, 3 pi/2s, and record interferogram successively.So, four width interferogram I are just obtained by four exposures1、I2、I3With
I4Phase recovery for determinand.Phase place to be measured is calculated by below equation：
Between each interference pattern that this embodiment has needed for extraordinary stability, phase recovery phase shift accurately, and
Because recovery algorithms are simple, the complexity of system reduce further.
Claims (2)
1. a kind of phase shift point-diffraction interference detection means based on reflecting grating, including light source (1), collimating and beam expanding system (2), window
Mouthful (3), object under test (4), the first lens (5), unpolarized Amici prism (6), reflecting grating (7), aperture reflecting mirror (8), the
Two lens (9), imageing sensor (10) it is characterised in that：The collimated beam-expanding system of light beam (2) collimation that light source (1) is launched expands
Outgoing beam after bundle is incident to the first lens (5) after window (3), object under test (4), after focusing on through the first lens (5)
Light beam a branch of reference light and a branch of object light are divided into by unpolarized Amici prism (6)；Reference light is radiated at aperture reflecting mirror (8)
On, object light is radiated in reflecting grating (7)；Through the object light of reflection with after reference light again passes by unpolarized Amici prism (6)
After merging into light beam, generate interferogram after the second lens (9), computer is collected by imageing sensor (10) simultaneously
In；
Described aperture reflecting mirror (8) is located on the focal plane of the first lens (5), and it is saturating that described reflecting grating (7) is located at second
On the focal plane of mirror (9)；
Described reflecting grating (7) can carry out horizontal minute movement to produce phase shift；
+ 1 order of diffraction light of described reflecting grating (7) is used for generating interferogram；
The a diameter of d of reflector space of described aperture reflecting mirrorp≤1.22λf1/ D, wherein, λ is light source (1) wavelength, f1Saturating for first
The focal length of mirror (5), D is the diameter of window (3)；
It is sequentially placed microcobjective (11) and correction object lens (12) between described object under test (4) and the first lens (5).
2. a kind of phase shift point-diffraction interference detection method based on reflecting grating is it is characterised in that comprise the steps：
(1) adjust light source, make light source launch light beam sequentially pass through collimating and beam expanding system, window, object under test, the first lens and
Form object light and the reference light of focusing, object light and reference light are respectively by reflecting grating and aperture reflecting mirror after unpolarized Amici prism
Jointly through unpolarized Amici prism and the second lens forming interferogram after reflection, computer is transferred to by imageing sensor collection
In；
(2) reflecting grating is driven serial lateral displacement Δ=(k-1) d/N of generation, and the interferogram of imageing sensor collection will be by
Introduce series of phase shift δk=(k-1) 2 π/N, its corresponding intensity distributions is
Wherein, k=1,2 ..., N, O are object light optical field distribution, and R is reference light optical field distribution,Phase place for object under test is divided
Cloth；
Using the PHASE DISTRIBUTION that method of least square can obtain object under test it is
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| CN108088368A (en) * | 2018-01-08 | 2018-05-29 | 哈尔滨工程大学 | Reflective off-axis digital holography apparatus and method based on light splitting pupil |
| JP6969453B2 (en) * | 2018-03-12 | 2021-11-24 | オムロン株式会社 | Optical measuring device |
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| US5822066A (en) * | 1997-02-26 | 1998-10-13 | Ultratech Stepper, Inc. | Point diffraction interferometer and pin mirror for use therewith |
| US6559953B1 (en) * | 2000-05-16 | 2003-05-06 | Intel Corporation | Point diffraction interferometric mask inspection tool and method |
| US6573997B1 (en) * | 2000-07-17 | 2003-06-03 | The Regents Of California | Hybrid shearing and phase-shifting point diffraction interferometer |
| CN2599524Y (en) * | 2003-02-14 | 2004-01-14 | 中国科学院上海光学精密机械研究所 | Dot diffraction interferometer for detecting surface shape |
| JP2006017485A (en) * | 2004-06-30 | 2006-01-19 | Nikon Corp | Device and method for measuring surface shape, manufacturing method of projection optical system, projection optical system, and projection exposing device |
| CN101183042B (en) * | 2007-12-13 | 2011-10-12 | 上海微电子装备有限公司 | Point diffraction interferometer |
| CN102798341A (en) * | 2012-07-23 | 2012-11-28 | 中国科学院长春光学精密机械与物理研究所 | Method used for improving measuring accuracy of point-diffraction interferometer |
| CN103245285B (en) * | 2013-04-22 | 2015-12-02 | 哈尔滨工程大学 | A kind of reflection type point diffraction carrier synchronization movable phase interfere pick-up unit and detection method |
| CN103322912B (en) * | 2013-05-29 | 2016-01-27 | 哈尔滨工程大学 | A kind of reflection type point diffraction is from axle simultaneous phase-shifting interference checking device and detection method |
| CN204177342U (en) * | 2014-08-28 | 2015-02-25 | 哈尔滨工程大学 | A kind of phase shift point diffraction interference pick-up unit based on reflection grating |
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