CN117760559A - Single exposure quantitative differential interference imaging device and method - Google Patents
Single exposure quantitative differential interference imaging device and method Download PDFInfo
- Publication number
- CN117760559A CN117760559A CN202311572745.0A CN202311572745A CN117760559A CN 117760559 A CN117760559 A CN 117760559A CN 202311572745 A CN202311572745 A CN 202311572745A CN 117760559 A CN117760559 A CN 117760559A
- Authority
- CN
- China
- Prior art keywords
- light
- interference
- differential interference
- lens
- imaging
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000003384 imaging method Methods 0.000 title claims abstract description 202
- 238000000034 method Methods 0.000 title claims abstract description 33
- 238000001228 spectrum Methods 0.000 claims abstract description 76
- 238000005286 illumination Methods 0.000 claims description 66
- 230000003287 optical effect Effects 0.000 claims description 49
- 230000010287 polarization Effects 0.000 claims description 33
- 238000011084 recovery Methods 0.000 claims description 21
- 230000005540 biological transmission Effects 0.000 claims description 18
- 238000010008 shearing Methods 0.000 claims description 15
- 238000006073 displacement reaction Methods 0.000 claims description 6
- 238000011144 upstream manufacturing Methods 0.000 claims description 5
- 239000004973 liquid crystal related substance Substances 0.000 claims description 3
- 230000035945 sensitivity Effects 0.000 abstract description 8
- 230000010363 phase shift Effects 0.000 description 9
- 238000005516 engineering process Methods 0.000 description 8
- 230000001427 coherent effect Effects 0.000 description 7
- 230000008569 process Effects 0.000 description 6
- 238000004364 calculation method Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000005070 sampling Methods 0.000 description 4
- 238000012546 transfer Methods 0.000 description 3
- 230000003044 adaptive effect Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000000386 microscopy Methods 0.000 description 2
- 230000001902 propagating effect Effects 0.000 description 2
- 230000003595 spectral effect Effects 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- 230000001131 transforming effect Effects 0.000 description 2
- 238000002834 transmittance Methods 0.000 description 2
- 101150095130 URAD gene Proteins 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 238000001444 catalytic combustion detection Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000008713 feedback mechanism Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 238000001093 holography Methods 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000002135 phase contrast microscopy Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000002123 temporal effect Effects 0.000 description 1
Landscapes
- Microscoopes, Condenser (AREA)
Abstract
The invention provides a single exposure quantitative differential interference imaging device, which comprises a differential interference imaging component, a first light wave and a second light wave which pass through an object, and an interference light which is formed by overlapping the first light wave and the second light wave and contains object gradient information and is formed by interference; the full light field camera comprises a first beam splitter and a detector, wherein the first beam splitter is arranged to split the interference light into first interference light and second interference light, the detector collects the first interference light to obtain differential interference image plane intensity, and collects a Fourier transform result of the second interference light to obtain differential interference space Fourier spectrum intensity; and an image operation processor which reconstructs amplitude and phase information of the object from the differential interference image plane intensity and the differential interference spatial Fourier spectrum intensity. The invention also provides a corresponding method. The imaging device provided by the invention simultaneously solves the problems of low time resolution, low phase sensitivity and the like of the existing phase imaging, and realizes real-time imaging.
Description
Technical Field
The invention belongs to the field of differential interference imaging, and particularly relates to a single exposure quantitative differential interference imaging device and method.
Background
The phase information of the object often plays a more important role in the imaging process relative to the intensity information of the object. However, in actual imaging, the imaging detector only detects the intensity information of the image, and the corresponding phase information is lost, so that the imaging loses important phase information in the image. In order to recover the phase information of the image, the phase imaging method has been developed in many years, and mainly comprises the following categories:
the first type is an interferometric phase recovery technique, represented by Zernike phase contrast microscopy, differential interference microscopy (DIC), digital Holography (DHM). This type of technique forms an interference pattern in the image by introducing an additional beam of reference light, or splitting the illumination light into two beams of light of different polarizations. The wave front amplitude and phase information of the extract can be quantitatively extracted from the interference pattern by the phase shift method and other techniques, so that the clear imaging of the object is realized. The method has high phase sensitivity, but quantitative techniques such as a phase shift method and the like need to carry out multi-frame acquisition, and the time resolution of imaging can be reduced.
The second type is iterative phase recovery technique, represented by Coherent Diffraction Imaging (CDI) and fourier stack imaging (FPM). The technology obtains amplitude and phase information through projection iterative operation recovery, and realizes imaging of objects. The CDI technology irradiates a sample through coherent light, light diffracted by the sample reaches a far field, spatial Fourier spectrum intensity distribution of the object is formed in the far field, and the spatial Fourier spectrum intensity distribution is collected to serve as constraint. The FPM technique is collected by a microscopic imaging system by illuminating the sample from different angles. The light of each angle corresponds to a real image plane intensity distribution carrying different Fourier spectrum information, and the redundant real image plane intensities are detected for reconstruction. The convergence and reconstruction uniqueness of the algorithm of the method is seriously dependent on the prior information (such as the size of the object) of the object, and the practical application is limited, and the time resolution of imaging is reduced by the multi-frame redundancy acquisition technology.
At present, the inventor groups earlier developed a full light field camera imaging technology, which is based on an iterative phase recovery technology, by collecting intensity information of a real image surface and a Fourier surface, and using inherent properties of a microscopic system as constraint conditions, phase recovery of an object can be realized by single exposure, so that the time resolution of optical phase microscopic imaging is improved, the imaging capability of real-time imaging is achieved, and a core patent (application number: 202111548124. X) has been filed. However, as a non-interference method, the iterative phase recovery technique has to be improved in phase sensitivity.
Existing phase imaging techniques cannot meet the requirements of reconstruction uniqueness, high phase sensitivity, and high temporal resolution at the same time.
Therefore, it is highly desirable to provide a novel differential interference imaging device integrating the interference phase recovery technique and the full-field camera imaging technique, so as to solve the problems of low time resolution, low phase sensitivity and the like of the existing phase imaging at the same time, and realize real-time imaging.
Disclosure of Invention
The invention aims to provide a single exposure quantitative differential interference imaging device and a method, which are used for simultaneously solving the problems of low time resolution, low phase sensitivity and the like of the existing phase imaging and realizing real-time imaging.
In order to achieve the above object, the present invention provides a single exposure quantitative differential interference imaging device comprising: a differential interference imaging assembly configured to generate a first object light wave and a second object light wave having a lateral differential shear generated after passing through an object, and output interference light including object gradient information formed by interference superposition of the first object light wave and the second object light wave with each other; the full light field camera comprises a first beam splitter and a detector, wherein the first beam splitter is arranged to split the interference light into first interference light and second interference light, and the detector is arranged to acquire the first interference light to obtain differential interference image plane intensity and acquire a Fourier transform result of the second interference light to obtain differential interference space Fourier spectrum intensity; and an image operation processor connected with the detector and configured to reconstruct the amplitude and phase information of the object based on the differential interference image plane intensity and the differential interference spatial Fourier spectrum intensity.
The differential interference imaging assembly comprises an illumination light source, a polarizer, a birefringent beam splitting prism, a collecting lens, a sample stage, an objective lens, a birefringent beam combining prism, an analyzer and a lens barrel lens which are sequentially arranged along the beam propagation direction; the double refraction beam splitting prism is used for splitting linearly polarized light into two beams of first linearly polarized illumination light with an included angle in the transmission direction and a polarization direction being a first direction and second linearly polarized illumination light with a polarization direction being a second direction; the condenser deflects the transmission directions of the first linear polarized illumination light and the second linear polarized illumination light to be parallel to each other and irradiate an object with a certain transverse shearing, and generates a first object light wave and a second object light wave passing through the object; the double refraction beam combining prism is arranged to combine the first object light wave and the second object light wave into a beam with the same transmission direction and without transverse offset; after passing through the analyzer, the first object light wave and the second object light wave interfere with each other to form interference light; the tube lens and the objective lens form a 4f system.
A phase shifting element is arranged between the birefringent beam combining prism and the lens barrel lens and is used for adjusting the initial phase difference of the first object light wave and the second object light wave; the phase shifting element is one of a combination of a 1/4 wave plate and the analyzer, a liquid crystal phase shifter, a Corrugation compensation plate and a spatial light modulator; the double-refraction beam splitting prism and the double-refraction beam combining prism comprise one of a Nomarski prism and a Wollaston prism.
The differential interference imaging assembly comprises an illumination light source, a condenser, a sample stage, an objective lens, a first imaging lens, a second imaging lens, a spatial light modulator and a lens barrel lens which are sequentially arranged along the propagation direction of a light beam; the objective lens and the first imaging lens form a 4f system, and the focal plane of the first imaging lens and the spatial light modulator are respectively positioned on the focal planes of two sides of the second imaging lens; the spatial light modulator is arranged to simultaneously load two gratings to split the object light into a first object light wave and a second object light wave with included angles in the transmission direction; the first object light wave and the second object light wave form an imaging image plane at a focal plane behind the first object light wave and the second object light wave after being transformed by the lens barrel lens, the first object light wave and the second object light wave are enabled to be parallel and have lateral displacement to be overlapped on the imaging image plane in an interference mode to form interference light, and the lateral interval and the initial phase difference of the first object light wave and the second object light wave are changed by controlling the period and the initial phase difference of the two gratings.
And a diaphragm is arranged at the downstream of the tube lens and is used for selecting +1 diffraction from two gratings loaded by the spatial light modulator.
The differential interference imaging assembly is a transmissive or reflective imaging assembly; in the reflective imaging component, the condenser lens and the objective lens are realized by the same objective lens, and the differential interference imaging component further comprises a first beam splitter; in a transmissive imaging assembly, the condenser lens and the objective lens are two distinct optical elements.
The differential interference imaging assembly is a transmissive or reflective imaging assembly; in the reflective imaging component, a condenser and an objective lens are realized by the same objective lens, the birefringent beam splitting prism and the birefringent beam combining prism are realized by the same birefringent prism, and the differential interference imaging component further comprises a first beam splitting lens; in a transmissive imaging assembly, the condenser and objective lens are two different optical elements, and the birefringent beam splitting prism and the birefringent beam combining prism are two different optical elements.
The full light field camera comprises a first beam splitter for splitting interference light to form a first light path and a second light path, a first detector positioned on the first light path to form a differential interference image plane intensity acquisition system, and a Fourier transform lens and a second detector which are sequentially arranged along the second light path to form a differential interference space Fourier spectrum intensity acquisition system, wherein the first detector and the second detector are connected with the image operation processor; the included angle between the first light path and the second light path is larger than the divergence angle of the interference light; the first beam splitter is arranged at any position downstream of the objective lens and upstream of the first detector and the second detector.
The full light field camera comprises a first beam splitter for splitting interference light to form a first light path and a second light path, a detector positioned on the first light path to form a differential interference image surface intensity acquisition system, a first reflecting mirror, a Fourier transform lens, a second reflecting mirror, a third reflecting mirror and the detector, wherein the first reflecting mirror, the Fourier transform lens, the second reflecting mirror, the third reflecting mirror and the detector are sequentially arranged on the second light path to form a differential interference space Fourier spectrum intensity acquisition system, a first area of the detector is positioned on the first light path, a second area of the detector is positioned on the second light path, and the detector is connected with the image operation processor.
In another aspect, the invention provides a single exposure quantitative differential interference imaging method comprising:
s1: providing the single exposure quantitative differential interference imaging device, and synchronously acquiring the differential interference image plane intensity and the differential interference space Fourier spectrum intensity by using a full light field camera;
s2: executing a full light field phase recovery algorithm by using an image operation processor, and calculating and reconstructing the acquired differential interference image plane intensity and differential interference space Fourier spectrum intensity by combining an interference model forming a transverse sheared object gradient in a differential interference system and constraint conditions in a single exposure quantitative differential interference imaging device to obtain the amplitude and phase of an object;
The full light field phase recovery algorithm is an iterative phase recovery method; the constraints include at least one of a double-sided constraint, an objective-induced field-of-view limited constraint, and a spectrum limited constraint.
The single exposure quantitative differential interference imaging device integrates the differential interference imaging technology and the full light field camera imaging technology, and only needs to add some common optical elements in the traditional imaging system, and has simple design, compact structure and lower cost. The differential interference imaging component divides illumination light into two beams to irradiate on a sample through the beam splitting prism, and interference occurs after the beams are combined at different positions of the sample, so that phase sensitivity is improved. The full light field camera technology adopts double-sided constraint Fourier iterative phase recovery, does not need multi-angle illumination and strict object priori, and can uniquely recover phase information only by single exposure. Therefore, the method has the advantages of good reconstruction uniqueness, high time resolution, high phase sensitivity and the like.
In addition, the existing iterative phase imaging method often needs more than 2 times of nyquist sampling rate to recover the phase. According to the full light field camera module in the single exposure quantitative differential interference imaging device, the object signals are subjected to light splitting treatment by the aid of the beam splitter in the full light field camera, so that the intensity signals of the real image plane and the Fourier plane are collected simultaneously, enough information solving phases can be obtained through double-sided constraint of the real image plane and the Fourier plane, phase recovery is carried out, phase object reconstruction imaging can be achieved under the condition of approaching one time of Nyquist sampling, and the full light field camera has a lower sampling rate compared with a traditional mode. The real image surface and fourier surface signal acquisition realized through lens transformation not only forms double-sided intensity constraint, but also introduces prior constraint (analytic constraint of the real image surface caused by lens fourier surface transformation property, band-limited constraint of the fourier surface caused by object lens cutting-off of the fourier surface, limited constraint caused by object size imaging on the real image surface, and the like) into an imaging system.
Therefore, the single exposure quantitative differential interference imaging device has the advantages of effectively reducing the sampling requirement of a detector, having a compact structure, improving the imaging information acquisition efficiency and the like, and providing a powerful imaging means for unmarked real-time biological phase imaging.
Drawings
Fig. 1 is a schematic structural diagram of a transmission type single exposure quantitative differential interference imaging device based on Nomarski prisms according to a first embodiment of the present invention.
Fig. 2 is a schematic structural diagram of a reflective single exposure quantitative differential interference imaging device based on Nomarski prisms according to a second embodiment of the present invention.
Fig. 3 is a schematic structural diagram of a reflective single exposure quantitative differential interference imaging device based on a spatial light modulator according to a third embodiment of the present invention.
Fig. 4 is a schematic structural diagram of a detector spatially multiplexed reflective single exposure quantitative differential interference imaging device in accordance with a fourth embodiment of the present invention.
Detailed Description
Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
First embodiment: transmission type single exposure quantitative differential interference imaging device and method based on Nomarski prism
As shown in fig. 1, a transmission type single exposure quantitative differential interference imaging device based on Nomarski prism according to a first embodiment of the present invention includes a differential interference imaging assembly, a full light field camera, and an image operation processor 30 connected in sequence. Wherein the differential interference imaging assembly is configured to generate first and second object light waves having a lateral differential shear generated after passing through the object, the first and second object light waves being capable of interfering with each other to form interference light, the interference light comprising object gradient information, whereby the differential interference imaging assembly is configured to output the interference light. The full-light field camera includes a first beam splitter configured to split interference light from the differential interference imaging assembly into first and second interference light and a detector configured to collect the first interference light to obtain a differential interference image plane intensity and to collect a fourier transform result of the second interference light to obtain a differential interference spatial fourier spectrum intensity. The image processor 30 is arranged to reconstruct the amplitude and phase information of the object from the differential interference image plane intensities and the differential interference spatial fourier spectrum intensities.
The differential interference imaging assembly comprises an illumination light source 11, a polarizer 12, a birefringent beam splitting prism 13, a condenser 14, a sample stage 15, an objective lens 16, a birefringent beam combining prism 17, a phase shifting element 18 and a tube lens 19 which are sequentially arranged along the propagation direction of a light beam.
In this embodiment, the phase shifting element 18 is composed of a 1/4 wave plate 181 and an analyzer 182, and the polarization directions of the polarizer 12 and the analyzer 182 are both located in a plane perpendicular to the propagation direction of the light beam. The polarizer 12 employs a linear polarizer to perform a polarizing function, thereby forming coherent light or linearly polarized light of known coherence.
The birefringent prism 13 is configured to split linearly polarized illumination light into two linearly polarized illumination light beams having a first polarization direction and a second polarization direction, the first polarization direction and the second polarization direction being at an angle to each other. The first direction and the second direction are both positioned on a plane perpendicular to the propagation direction of the light beam, are perpendicular to each other, and are not overlapped with the polarization directions of the polarizer and the analyzer.
Assuming that the polarization directions of the split first and second linearly polarized illumination light are the x-direction and the y-direction, respectively, the polarization directions of the polarizers should be in the xy plane, but not the x-or y-direction in order to ensure that the intensities of the light beams polarized in the x-direction and the y-direction are not 0.
The sample stage 15 is provided with an object, the birefringent beam splitting prism 13 and the object are respectively placed on the focal planes at two sides of the condenser 14, and the birefringent beam combining prism 17 and the object are respectively placed at the focal planes at two sides of the objective lens 16. Thereby, the condenser lens 14 deflects the first and second linearly polarized illumination lights emitted from the birefringent prism 13 into illumination lights having transmission directions parallel to each other and having a certain lateral shearing so as to irradiate different lateral positions of the object, and generates a first object light wave and a second object light wave passing through the object. Thus, the first and second object light waves interfere with each other to form a uniform transmission direction but with a lateral offset, and after passing through the analyzer 182, the first and second object light waves interfere with each other to form interference light. Wherein the angle between the first object light wave and the second object light wave is called the shear angle; after passing through the condenser lens 14, the lateral spacing of the first object light wave and the second object light wave in the object plane is referred to as the shearing distance. The objective lens 16 is arranged to focus the first object light wave and the second object light wave on the birefringent beam combining prism 17.
The birefringent beam combining prism 17 is configured to combine the first object light wave and the second object light wave into interference light having a uniform transmission direction and no lateral offset. In this embodiment, the two beams of light having the polarization directions perpendicular to each other and combined by the birefringent combining prism 17 are spatially superimposed, but the polarization states are not identical, and interference superposition is not performed. Accordingly, an analyzer 182 is required to cause the combined first and second object light waves to interfere with each other to form interference light. The analyzer 182 is used to adjust the polarization direction of the first object light wave and the second object light wave.
Meanwhile, in this embodiment, after the first object light wave and the second object light wave are interfered and overlapped with each other, the first object light wave and the second object light wave are affected by the phase gradient of the object, and a phase shifter 18 is required to adjust the first object light wave, the second object light wave and the initial phase difference, so as to adjust the contrast of the differential interference image plane intensity and the differential interference space fourier spectrum intensity. The final calculation will be affected by the contrast of the collected image and the user can adjust to the optimal phase shift (i.e. to the maximum contrast) or set an adaptive adjustment as desired.
Thus, by the arrangement of the phase shifting element 18, an adaptive matching of the sample can be achieved, and an optimal reconstruction according to the object gradient and the frequency spectrum can be achieved. Specifically, in the process of acquiring an image, the parameters of the phase shifting element 18 are continuously changed to change the initial phase difference, and the contrast of the differential interference image plane intensity and the differential interference spatial fourier spectrum intensity at the time of analyzing the different initial phase differences is acquired in real time. The contrast of the differential interference image plane intensity is optimal, and the contrast value is the maximum. The contrast of the differential interference space Fourier spectrum intensity is optimal, and is optimal when the contrast value is calculated to be the maximum by setting the most interesting spectrum area according to the needs of a user on the premise that the contrast of the object spectrum area in the band limit is not 0. And stopping adjusting when the contrast ratio of the differential interference image plane intensity and the differential interference space Fourier spectrum intensity is simultaneously optimal, recording the differential interference image plane intensity and the differential interference space Fourier spectrum intensity, and sending the differential interference image plane intensity and the differential interference space Fourier spectrum intensity to an image operation processor for later reconstruction process. If the two contrasts are not optimally at the same initial phase difference, then the phase shifting element 18 trades off for choosing any position between the two contrasts.
In this embodiment, the phase shift element 18 employs a 1/4 wave plate 181 and an analyzer 182, and the analyzer 182 allows components of the first object wave and the second object wave in the direction of the polarization to pass through and overlap each other to interfere with each other. Meanwhile, the combination of the analyzer 182 and the 1/4 wave plate forms a phase shifter, when the analyzer rotates by theta (rad), the phase shift of the initial phase difference is 2 theta (rad), and the analyzer not only plays the role of realizing interference of the analyzer, but also forms a phase shift element together with the 1/4 wave plate.
In the present embodiment, the initial setting of the optical axis direction of the polarizer 12 and the analyzer 182 is 45 degrees from the x-axis; the fast axis direction of the 1/4 wave plate is set as the x axis. The polarizer and the 1/4 wave plate are set so that the values of the polarizer and the 1/4 wave plate are not changed. The initial phase difference of the first object light wave and the second object light wave is adjusted by rotating the optical axis angle of the analyzer. When the analyzer optical axis is rotated by θ (rad) (θ relative to the initial setting), the initial phase difference of the first object light wave and the second object light wave increases by 2θ (rad). In this arrangement, the initial phase difference between the first object light wave and the second object light wave is twice as much as the relationship between the initial phase difference and the optical axis angle of the analyzer.
However, this embodiment discloses only one of the phase shifting elements, and the phase shifting element 18 may be replaced by other phase shifting elements, such as a liquid crystal phase shifter, a schlempe compensation plate, a spatial light modulator, etc. It should be noted that the analyzer is only a part of the phase shifting element 18 in the case of using a 1/4 wave plate, and serves as both a phase shifting and a subsequent polarization analyzing function. For other phase shifters, the analyzer only has the subsequent polarization analysis function and does not belong to the phase shifter.
In this embodiment, the birefringent beam splitting prism 13 and the birefringent beam combining prism 17 are Nomarski prisms. In other embodiments, the birefringent beam splitting prism 13 and the birefringent beam combining prism 17 include, but are not limited to, nomarski prism, wollaston prism, etc., which are made of birefringent materials, and can split a beam of light into two beams of birefringent prisms with perpendicular polarization directions and included angles between transmission directions generally in the urad order.
The tube lens 19 and the objective lens 16 constitute a 4f system such that the interference light formed by the phase shift element 18 forms a differential interference image surface real image at the focal plane of the tube lens 19. The differential interference image surface real image comprises gradient information distribution of the object along the shearing direction.
The coherent light source or the partial coherent light source with known coherence is arranged as linearly polarized light after passing through the polarizer, and is split into first linearly polarized illumination light with a certain included angle and a second linearly polarized illumination light with a certain polarization direction in a first direction and a second direction respectively after passing through the birefringent beam splitting prism, and the first linearly polarized illumination light and the second linearly polarized illumination light are irradiated on a sample in parallel and with a transverse shearing offset after passing through the condenser; two beams of first object light waves with transverse shearing offset and linear polarization along a first direction and second object light waves with linear polarization along a second direction are collected by an objective lens 16, and are combined into interference light with consistent transmission direction and no transverse offset after being combined by a birefringent beam combining prism 17; then, after passing through the phase shifting element 18 and the tube lens 19, the components of the first object light wave and the second object light wave along the polarization direction of the analyzer form interference superposition, and a differential interference image surface real image is formed at the focal plane of the tube lens 19, which contains gradient information distribution of the object along the shearing direction.
In this embodiment, the illumination light source 11 is a laser light source, and its output wavelength is 532nm; the collecting lens 14 was 0.8NA, and the shearing distance of the collecting lens 14 and the birefringent prism 13 was 72nm. The focal length of the condenser lens 14 is 1.8mm in accordance with the objective lens 16. The shearing angle of the birefringent beam splitting prism 13 and the birefringent beam combining prism 17 is 40 mrad. The objective lens 16 is 100 x, 0.8NA, focal length f obj =1.8mm; the focal length of the tube lens 19 is 200mm.
Thus, a coordinate system xyz is established, the z direction is the outgoing direction of the illumination light source 411 and is the vertical direction, the x direction and the y direction are the horizontal directions perpendicular to each other, the illumination light source 11 emits 532nm laser light, the laser light becomes linearly polarized light after passing through the polarizer, and the polarization direction is in the xy plane and forms 45 degrees with the x direction. After passing through the polarizer 12 with the crystal principal optical axis in the xy plane, the laser beam is divided into two beams of first linearly polarized illumination light with the polarization direction x and second linearly polarized illumination light with the polarization direction y, and after passing through the condenser lens 14, the first linearly polarized illumination light and the second linearly polarized illumination light are irradiatedIs incident on an object placed on the sample stage 15, the object function is t (x, y) =a (x, y) e iΦ(x,y) T (x, y) represents the object function, a (x, y) represents the amplitude of the object, in the transmissive embodiment, the transmittance is represented, Φ (x, y) represents the phase of the object, that is, the optical phase change of the light beam after passing through the object, x, y are the space coordinates of the object plane, and it is sufficient that the size of the object and the size of the detector correspond to the size of the object plane. The first and second linearly polarized illumination light are separated by 2Δx=72 μm in the x-direction on the object, and the object areas illuminated by the first and second linearly polarized illumination light are denoted as t (x- Δx, y) and t (x+Δx, y), respectively. After the reflected light and scattered light signals (i.e., the first object light wave and the second object light wave) from the differently illuminated object regions are collected by the objective lens, the first object light wave and the second object light wave are combined by the birefringent beam combining prism 17, and the first object light wave and the second object light wave are completely coincident in spatial position. The superimposed optical signals are subjected to interference superposition by a phase shifter 18 and a tube lens 19 placed at a distance of 200mm from the objective lens to form interference light.
The full-light field camera comprises a first beam splitter 21 for splitting interference light to form a first light path and a second light path, a first detector 22 positioned on the first light path to form a differential interference image plane intensity acquisition system, and a Fourier transform lens 23 and a second detector 24 which are sequentially arranged along the second light path to form a differential interference space Fourier spectrum intensity acquisition system, wherein the first detector 22 and the second detector 24 are connected with the image operation processor 30.
In the present embodiment, the included angle α of the first interference light and the second interference light is 90 degrees. In the actual arrangement, assuming that the divergence angles of the first interference light and the second interference light are β degrees, α > β. That is, the angle between the first interference light and the second interference light (i.e., the angle between the first optical path and the second optical path) is larger than the divergence angle of the interference light. Otherwise, the two light beams have a certain coincidence on the detection surface, but the invention needs to make the two light beams enter the first detector and the second detector completely and respectively.
In the present embodiment, the focal length of the fourier transform lens 23 is 100mm. The first detector 22 and the second detector 24 are two-dimensional detectors, specifically 2048×2048 sCMOS, and the pixel size is 6.45 μm×6.45 μm.
Thus, the interference light is split into the first interference light and the second interference light by the first beam splitter, and the components of the first interference light and the second interference light are completely coincident. The included angle between the first interference light and the second interference light after beam splitting is set to 90 degrees. Wherein the first interference light is collected by a first detector 22 placed at a distance of 200mm with respect to the tube lens 19 to obtain a differential interference image plane intensity I (x, y); the second interference light is collected by a second detector 24 placed at a distance of 100mm from the Fourier transform lens 23 after passing through the Fourier transform lens 23 placed at a distance of 300mm from the tube lens 19 to obtain differential interference space Fourier spectrum intensity I (k) x ,k y ). Wherein by rotating the angle of the analyzer 182 of the phase shifting element 18, the initial phase difference of the analyzer 182 can be changed, thereby changing the contrast of the differential interference image plane intensity and the differential interference spatial fourier spectrum intensity.
In this embodiment, the first optical path is a straight-through optical path of the first beam splitter 21, and the second optical path is a reflection optical path of the first beam splitter 21, so that the first detector 22 is located at the focal plane of the tube lens 19, so that the differential interference image plane intensity can be directly acquired, and the reflection position of the focal plane of the tube lens 19 relative to the reflection plane of the first beam splitter 21 and the second detector 24 are located on the focal planes on both sides of the fourier transform lens 23, so that the differential interference spatial fourier spectrum intensity can be acquired.
In other embodiments, the first optical path may be a reflection optical path of the first beam splitter 21, and the second optical path is a straight-through optical path of the first beam splitter 21, and accordingly, the first detector 22 is located at a reflection position of a focal plane of the tube lens 19 relative to a reflection plane of the first beam splitter 21, so that the differential interference image plane intensity can be directly acquired, and the focal plane of the tube lens 19 and the second detector 24 are located on two focal planes of the fourier transform lens 23, respectively, so that the differential interference spatial fourier spectrum intensity can be acquired.
In the present embodiment, the first beam splitter 21 is provided between the first detector 22 and the tube lens 19 for splitting the interference light into a first interference light propagating along the first optical path and a second interference light propagating along the second optical path, and therefore, the first interference light enters the differential interference image plane intensity acquisition system and the second interference light enters the differential interference spatial fourier spectrum intensity acquisition system. Unlike the birefringent beam splitting prism in the differential interference component, the first interference light and the second interference light have an included angle greater than their divergence angle, and thus can be completely separated.
In other embodiments, the first beam splitter 21 may also be disposed at any position downstream of the objective lens, upstream of the first detector 22 and the second detector 24. When the first beam splitter 21 is placed between the objective lens 16 and the tube lens 19, the full-field camera also includes the first beam splitter 21, a first detector 22 on a first optical path downstream of the first beam splitter 21, a fourier transform lens 23 and a second detector 24 on a second optical path downstream of the first beam splitter 21, and both the first detector 22 and the second detector 24 are connected to the image arithmetic processor 30. The difference is that the tube lens 19 in the differential interference imaging assembly includes a first tube lens located upstream of the first detector 22 on the first optical path and a second tube lens located upstream of the fourier transform lens 23 on the second optical path.
The beam splitter 21 splits the interference light into a first interference light and a second interference light, wherein the first interference light is collected by the first array detector on the first imaging plane via the first tube lens to obtain a differential interference image plane intensity I (x, y), and the second interference light is collected by the second detector via the second tube lens and the fourier transform lens to obtain a differential interference space fourier spectrum intensity I (k) x ,k y ) The method comprises the steps of carrying out a first treatment on the surface of the The second barrel lens to objective lens distance is equal to the first barrel lens to objective lens distance.
Based on the single exposure quantitative differential interference imaging device, the single exposure quantitative differential interference imaging method comprises the following steps:
step S1: providing the single exposure quantitative differential interference imaging device, and synchronously acquiring the differential interference image plane intensity and the differential interference space Fourier spectrum intensity by using a full light field camera;
step S2: the image operation processor 30 is utilized to execute a full light field phase recovery algorithm, and the acquired differential interference image plane intensity and differential interference space Fourier spectrum intensity are calculated and reconstructed by combining an interference model forming a transverse shearing object gradient in a differential interference system and constraint conditions in a single exposure quantitative differential interference imaging device to obtain the amplitude and phase of an object;
Wherein, the interference model of the object gradient forming the transverse shear in the differential interference system is as follows:
t N (x,y)
＝t(x+Δx,y)exp(-jθ 0 )-t(x-Δx,y)exp(jθ 0 )；T N (k x ,k y )
＝2j·T(k x ,k y )·sin(k x ·Δx-θ 0 )，
wherein t (x, y) is an object function, t N (x, y) is the effective matter function of actual imaging in the differential interference system, t N (x, y)/Δx is the object gradient; t and T N Respectively their fourier transforms. θ 0 The initial phase difference is the shearing distance of the Δx object plane. See in particular equation (7-8) of [ s.b. mehta, and C.J.R.Sheppard, opt.Express 16,19462-19479 (2008) ].
The full light field phase recovery algorithm is an iterative phase recovery method including, but not limited to, an iterative projection phase recovery algorithm. Constraints in the single exposure quantitative differential interference imaging device include, but are not limited to, double sided constraints, field-of-view limited constraints introduced by the objective lens, spectrum limited constraints, and the like.
In this embodiment, the projection iterative phase recovery algorithm specifically includes the following steps:
step S21: based on the differential interference image plane intensity I (x, y) and the differential interference space Fourier spectrum intensity I (k) x ,k y ) Obtaining the image plane amplitude distributionAnd Fourier plane amplitude distribution +.>
Step S22: determining complex amplitude distribution of an image plane and a spatial Fourier spectrum plane of the interference field according to the image plane amplitude distribution and the Fourier plane amplitude distribution;
The step S22 specifically includes:
step S221: randomly endowing the acquired image plane amplitude distribution |f (x, y) | with a phase valueObtaining an initial image plane amplitude distribution +.>And is used as the current image plane amplitude distribution;
step S222: for the current image plane amplitude distribution (e.g) Fourier transforming to obtain the current spatial fourier spectrum (e.g +.>)；
Step S223: the acquired spatial Fourier spectrum amplitude distribution |F (k x ,k y ) Substitution of this spatial fourier spectrum yields the current modified spatial fourier spectrum (e.g.) And applying a spatial fourier spectrum bounded constraint;
where the bounded constraint is a band-limited constraint, determined by the numerical aperture of the objective lens, the fourier spectrum replaces the amplitude with pixels in a band-limited range, and pixels outside the band-limited range are set to 0 or a feedback mechanism such as in the HIO algorithm is applied to approach 0.
Step S224: performing inverse Fourier transform on the current modified spatial Fourier spectrum to obtain a current phaseCorrected image plane amplitude distribution (e.g)；
Step S225: the phase portion of the current phase-corrected image plane amplitude distribution is used as a new phase portion, the acquired image plane amplitude distribution |f (x, y) | is used as an amplitude portion, and a field-of-view bounded beam is applied to obtain a new image plane amplitude distribution (for example, to obtain )；
Step S226: taking the new image plane amplitude distribution as the current image plane amplitude distribution, and repeating the steps S222-S225 until the algorithm converges, namely that the space Fourier spectrum plane complex amplitude distribution obtained after the kth repeated iteration meets the formula |F (k) (k x ,k y )|＝|F (k-1) (k x ,k y ) I, execute step S227;
step S227: taking the current image plane amplitude distribution and the current space Fourier spectrum as the complex amplitude distribution of the image plane of the interference field obtained by recoveryComplex amplitude distribution with spatial fourier spectral plane
Step S23: determining the amplitude and phase distribution of the object according to the complex amplitude distribution of the image plane and the space Fourier spectrum plane of the interference field;
the step S23 specifically includes:
step S231: filtering the interference field on the Fourier spectrum plane to obtain the Fourier spectrum T (k) x ,k y )；
Wherein the fourier spectrum T (k x ,k y ) The method comprises the following steps:
wherein H (k) x ,k y ) Transfer function, P (k), of differential interference microscopy system x ,k y ) The transfer function of the bright field microscope system is determined by an objective lens, t (x, y) is an object function, and the transfer function is a representation method for simultaneously representing the transmittance and the phase of an object; h (k) x ,k y )＝jsin(k x ·Δx-θ 0 )P(k x ,k y )；P(k x ,k y ) Is NA.f obj Na is the numerical aperture of the objective lens, f obj Is the focal length of the objective lens.
Step S232: fourier spectrum T (k) of object x ,k y ) The inverse fourier transform is performed to obtain an object function t (x, y), and then to obtain the amplitude a (x, y) and the phase Φ (x, y) of the object.
Second embodiment: reflection type single exposure quantitative differential interference imaging device based on Nomarski prism
Fig. 2 shows a Nomarski prism-based reflective single exposure quantitative differential interference imaging device according to a second embodiment of the present invention, which is similar to the first embodiment of the present invention, including a differential interference imaging assembly, a full light field camera, and an image operation processor 230 connected in sequence. Wherein the differential interference imaging assembly is configured to generate first and second object light waves that pass through the object, the first and second object light waves being configured to interfere with each other to form interference light, whereby the differential interference imaging assembly is configured to output the interference light. The full-light field camera includes a first beam splitter configured to split interference light from the differential interference imaging assembly into first and second interference light and a detector configured to collect the first interference light to obtain a differential interference image plane intensity and to collect a fourier transform result of the second interference light to obtain a differential interference spatial fourier spectrum intensity. The image processor 230 is configured to reconstruct the amplitude and phase information of the object from the differential interference image plane intensities and the differential interference spatial fourier spectrum intensities.
The differential interference imaging assembly comprises an illumination light source 211, a polarizer 212, a second beam splitter 213, a sample stage 216, an objective lens 215, a birefringent prism 214, the second beam splitter 213, a phase shifting element 217 and a barrel lens 218, which are sequentially arranged on a first optical axis along the propagation direction of a light beam. The phase shifting element 217 is comprised of a 1/4 wave plate 2171 and an analyzer 2172.
The structure of the full-field camera is identical to that of the full-field camera in the first embodiment of the present invention, and the full-field camera includes a first beam splitter 211 for splitting the interference light to form a first optical path and a second optical path, a first detector 222 located on the first optical path to form a differential interference image plane intensity acquisition system, and a fourier transform lens 223 and a second detector 224 sequentially located along the second optical path to form a differential interference spatial fourier spectrum intensity acquisition system, where the first detector 222 and the second detector 224 are connected to the image operation processor 230.
That is, unlike the first embodiment of the present invention in which the differential interference imaging assembly is a transmissive imaging assembly, in this embodiment the differential interference imaging assembly is a reflective imaging assembly in which the condenser lens and the objective lens are implemented by the same objective lens 215 and the birefringent beam combining prism and the birefringent beam splitting prism are implemented by the same birefringent prism 214.
Therefore, in the differential interference imaging assembly, the light beam emitted from the illumination light source 211 sequentially passes through the illumination light source 211, the polarizer 212 and the second beam splitter 213, and then sequentially passes through the birefringent prism 214 (serving as a birefringent beam splitter prism), the objective lens 215 (serving as a condenser), and the object on the sample stage 216 after being reflected by the second beam splitter 213, and then sequentially passes through the objective lens 215, the birefringent prism 214 (serving as a birefringent beam combining prism), the second beam splitter 213, the phase shifting element 217 and the barrel lens 218, and the operation principle of each optical element of the differential interference imaging assembly is the same as that of each optical element of the differential interference imaging assembly in the first embodiment.
In the present embodiment, the illumination light source 211 is a laser light source, and its output is the sameThe wavelength of the light is 532nm; the shearing angle of the Nomarski prism employed by the birefringent prism 214 is 40 mrad; the objective lens is 100X, 0.8NA, and the focal length f of the objective lens obj =1.8mm; the tube lens 218 has a focal length of 200mm; the focal length of the fourier transform lens 223 is 100mm; the first detector 222 and the second detector 224 are each 2048×2048 sCMOS, and the pixel size is 6.45 μm×6.45 μm.
Thus, in the single exposure quantitative differential interference imaging device of the present invention, a coordinate system xyz is established, the x direction is the emission direction of the illumination light source, the z direction is the vertical direction, the illumination light source 211 emits 532nm laser light, the laser light passes through the polarizer 212 and becomes linearly polarized light, and the polarization direction of the linearly polarized light is in the xy plane and forms 45 ° with the x direction. After passing through the birefringent prism 214 with the principal optical axis of the crystal in the xy plane, the laser beam is split into two beams of first linearly polarized illumination light with the polarization direction x and second linearly polarized illumination light with the polarization direction y, and the included angle between the propagation directions of the first linearly polarized illumination light and the second linearly polarized illumination light is 40 mu rad. The first linear polarized illumination light and the second linear polarized illumination light irradiate on an object placed on the sample stage after passing through the objective lens, and the object function is t (x, y) =a (x, y) e iΦ(x,y) The first and second linearly polarized illumination light are separated by 2Δx=72 μm in the x-direction on the object, and the object areas illuminated by the first and second linearly polarized illumination light are denoted as t (x- Δx, y) and t (x+Δx, y), respectively. After the reflected light and scattered light signals (i.e., the first object light wave and the second object light wave) from the differently illuminated object regions are collected by the objective lens, the beams are combined by the birefringent prism 214, and the first object light wave and the second object light wave are completely coincident in spatial position. The overlapped first object light wave and second object light wave are interfered and overlapped to form interference light after passing through a phase shift element 217 and a tube lens 218 placed at a position 200mm apart from the objective lens. The interference light is split into a first interference light and a second interference light by a beam splitter. Wherein the first interference light is collected by a first detector 222 placed at a distance of 200mm relative to the tube lens 218 to obtain a differential interference image plane intensity I (x, y); the second interference light passes through the Fourier transform lens 223 disposed at a distance of 300mm from the tube lens 218, and is then reflected by the lensThe second detector 224 with a distance of 100mm of the transforming lens 223 is collected to obtain the differential interference space fourier spectrum intensity I (k) x ,k y ). Wherein by rotating the angle of the analyzer of phase shifting element 217, the initial phase difference of the analyzer can be changed, thereby changing the contrast of the differential interference image plane intensity and the differential interference spatial fourier spectrum intensity.
The calculation process of the image arithmetic processor 230 is the same as that of the first embodiment.
Third embodiment: reflection type single exposure quantitative differential interference imaging device based on spatial light modulator
Referring to FIG. 3, a reflective single exposure quantitative differential interference imaging device based on a spatial light modulator according to a third embodiment of the present invention comprises a differential interference imaging assembly, a full light field camera and an image operation processor 330 connected in sequence. Wherein the differential interference imaging assembly is configured to generate first and second object light waves that pass through the object, the first and second object light waves being configured to interfere with each other to form interference light, whereby the differential interference imaging assembly is configured to output the interference light. The full-light field camera includes a first beam splitter configured to split interference light from the differential interference imaging assembly into first and second interference light and a detector configured to collect the first interference light to obtain a differential interference image plane intensity and to collect a fourier transform result of the second interference light to obtain a differential interference spatial fourier spectrum intensity. The image processor 330 is configured to reconstruct the amplitude and phase information of the object from the differential interference image plane intensities and the differential interference spatial fourier spectrum intensities.
In this embodiment, the differential interference imaging assembly is a reflective imaging assembly, so the differential interference imaging assembly includes an illumination light source 311, a second beam splitter 312, a sample stage 314, an objective lens 313, the second beam splitter 312, a first imaging lens 315, a second imaging lens 316, and a spatial light modulator 317 (SLM) sequentially disposed on a first optical axis along a propagation direction of a light beam, and a barrel lens 318 located downstream of an optical path of the spatial light modulator 317. The objective lens 313 and the first imaging lens 315 constitute a 4f system.
A spatial light modulator 317 (SLM) is configured to simultaneously load two gratings to split an object light into a first object light wave and a second object light wave having an included angle in a transmission direction, where the first object light wave and the second object light wave form an imaging image plane at a focal plane behind the first object light wave and the second object light wave after being transformed by a lens barrel lens 318, and enable the first object light wave and the second object light wave to form interference light in parallel and with lateral displacement on the imaging image plane by interference superposition; and the transverse interval and the initial phase difference of the first object light wave and the second object light wave are changed by controlling the period and the initial phase difference of the two gratings.
The focal plane of the first imaging lens 315 (i.e., the first imaging plane) and the spatial light modulator 317 are located on the focal planes of both sides of the second imaging lens 316, respectively. Thus, the spatial light modulator 317 is disposed on the fourier plane in which the focal plane of the second imaging lens 316 is located. The second imaging lens 316 is a position that performs a fourier transform such that the spatial light modulator 317 is located in the spectral space, the tube lens 318 is arranged to perform a fourier transform such that the focal plane behind the tube lens 318 is the image plane, and such that the two angled first and second object light waves become parallel, laterally displaced first and second object light waves.
The first object light wave and the second object light wave form a displacement less than the diffraction limit at the second imaging plane (i.e., the focal plane behind tube lens 318). In this embodiment, a stop 319 is disposed downstream of the tube lens 318 and is used to select +1 diffraction from the dual gratings loaded by the spatial light modulator. The first object light wave and the second object light wave are partially overlapped, so that they can be interfered with each other.
The spatial light modulator 317, tube lens 318, and stop 319 operate as follows: establishing an xyz coordinate system, wherein the x direction is the emergent direction of an illumination light source, the z direction is the vertical direction, the spatial light modulator 317 is arranged on a Fourier spectrum surface to simultaneously load two sine (or cosine) gratings with periods of d1 and d2 along the x direction, the light beam is diffracted after passing through the spatial light modulator 317, and the included angles between 0-order diffraction light and +1-order diffraction light are respectivelyAnd->After focusing with the tube lens 318 with a focal length L, two +1-order diffracted light beams are retained by the diaphragm, and the displacement generated on the image plane is approximately equal toThe imaging system is at a magnification of M, so the shearing amount of the coded object plane along the x direction is
Wherein, to load grating 1 (i.e. cosine grating with period d 1), the loading signal of the spatial light modulator is To load grating 2 (i.e. the cosine grating with period d 2), the loading signal of the spatial light modulator is +.>The invention is to make double grating modulation at the same time and make the initial phase difference be theta 0 The spatial light modulator is loaded with a signal of +.>Calculated T (k) x ) As a complex function, both amplitude and phase are included, but modulation is typically performed using a phase-type spatial light modulator. Thus, the phase distribution arg [ T (k) x )]Taking T (k) x ) Is a phase of (a) of (b).
At this time, two +1-level light are taken as a first object light wave and a second object light wave, and the included angle between the first object light wave and the second object light wave isInitial phase difference of θ 0 The method comprises the steps of carrying out a first treatment on the surface of the After focusing by tube lens 318 with a lens focal length L (lens L3 in FIG. 3), the lens becomes parallel at the second imaging plane (i.e., the focal plane behind tube lens 318) with a lateral spacing of +.>Initial phase difference θ 0 Is provided, and a second object light wave and a first object light wave of the same are provided. Because the imaging plane and the object plane are in an imaging relation of M times of magnification, the effect is equivalent to the transverse interval from the object plane>Initial phase difference θ 0 Is provided, and a second object light wave and a first object light wave of the same are provided.
In the present embodiment, the differential interference imaging assembly is a reflective imaging assembly in which the condenser lens and the objective lens are implemented by the same objective lens 313, and the second beam splitter 312 is disposed between the illumination light source 311 and the condenser lens and between the objective lens and the first imaging lens 315.
Therefore, in the differential interference imaging assembly, the light beam emitted from the illumination light source 311 sequentially passes through the illumination light source 311, the second beam splitter 312, the object 313 (as a condenser), and the object on the sample stage 314 after being reflected by the second beam splitter 312, and then sequentially passes through the object 313, the second beam splitter 312, the first imaging lens 315, the second imaging lens 316, the spatial light modulator 317, and the barrel lens 318. The objective lens 313 and the first imaging lens 315 constitute a 4f system.
In other embodiments, where the differential interference imaging assembly is a transmissive imaging assembly, the differential interference imaging assembly does not require the provision of a second beam splitter 312, including an illumination source 311, a condenser, a sample stage 314, an objective lens 313, a first imaging lens 315, a second imaging lens 316, a spatial light modulator 317, and a tube lens 318, disposed in that order along the direction of propagation of the beam.
Thus, the coherent light source or the partial coherent light source with known coherence irradiates the sample after passing through the condenser, and the object light emitted by the object is collected by a 4f system consisting of an objective lens and a tube lens and then imaged in real image on a first imaging surface at the focal plane of the first imaging lens 315; then a Fourier transform is realized after the first lens is passed, and a spatial light modulator is placed on the Fourier surface; the grating pattern encoded spatial light modulator splits the object light into a first object light wave and a second object light wave having a transmission direction with an included angle to form interference light, which is transmitted by the tube lens 318 in parallel with a lateral shearing offset to the second imaging plane for interference, and then enters the full light field camera for collection. The spatial light modulator 317 may realize the adjustment of the initial phase difference between the first object light wave and the second object light wave while realizing the object light beam splitting.
The full-light field camera comprises a first beam splitter 321 for splitting the interference light to form a first light path and a second light path, a first detector 322 positioned on the first light path to form a differential interference image plane intensity acquisition system, and a Fourier transform lens 323 and a second detector 324 sequentially arranged along the second light path to form a differential interference space Fourier spectrum intensity acquisition system, wherein the first detector 322 and the second detector 324 are connected with the image operation processor 330.
In this embodiment, the first optical path is a reflection optical path of the first beam splitter 321, the second optical path is a straight-through optical path of the first beam splitter 321, and accordingly, the first detector 322 is located at a reflection position of a focal plane of the barrel lens 318 relative to a reflection plane of the first beam splitter 21, so that the differential interference image plane intensity can be directly acquired, and the focal plane of the barrel lens 318 and the second detector 324 are located on two focal planes of the fourier transform lens 323, respectively, so that the differential interference spatial fourier spectrum intensity can be acquired.
In the present embodiment, the output wavelength of the laser light source is 532nm; the objective lens is 100X, 0.9NA, and the focal length f of the objective lens obj =1.8mm; the focal length f1 of the first imaging lens 315 is 200mm; the focal length f2 of the second imaging lens 316 is 150mm; the spatial light modulator 317 has a size of 1920×1080, a resolution of 8.0 μm×8.0 μm, and periods d1, d2 of the two gratings loaded are d1=40 μm, d2=39.9 μm, respectively; the focal length f3 of the tube lens 318 is 100mm; the focal length f4 of the fourier transform lens 323 is 100mm; first detector 322 and second detector 324 are each 2048×2048 CCDs, and the pixel size is 6.45 μm×6.45 μm sCMOS.
Thus, the laser emits 532nm laser light, and after passing through the objective lens, the object placed on the sample stage is irradiated with t (x, y) =a (x, y) ·exp [ j·Φ (x, y) ]. After being collected by the objective lens, the reflected and scattered light signals from the object reach a spatial light modulator 317 at a fourier spatial spectrum plane at a position 150mm from the second imaging lens 316 via a first imaging lens 315 placed at a position 200mm from the objective lens, a second imaging lens 316 at a position 350mm from the first imaging lens 315. The first imaging plane is between the first imaging lens 315 and the second imaging lens 316, and is both the focal plane of the first imaging lens 315 and the focal plane of the second imaging lens 316. The object light transmitted through the object is modulated by the spatial light modulator 317 and split into a first object light wave and a second object light wave, and the first object light wave and the second object light wave have an included angle of 1.26mrad, and interfere with each other to form interference light. The interference light is split into first interference light and second interference light by the first beam splitter 321 after passing through the tube lens 318 placed at a position 100mm from the spatial light modulator 317. The first interference light and the second interference light are preferably perpendicular to each other. For example, the first interference light passing through the first beam splitter 321 includes components of the first object light wave and the second object light wave, where the first object light wave and the second object light wave are spaced apart by 1.26mrad×100 mm=126 μm on the detector 1, but the radii of the two light beams are almost in the mm order, so that they interfere in the overlapping region. Whereas at the location of the second detector 324, the components of the first and second object waves of the second interference light enter the second detector 324 at different angles, but with the lateral positions being coincident, the first and second object waves being coincident to interfere.
Wherein the first interference light is collected by a first detector 322 placed 100mm from the tube lens 318 to obtain a differential interference image plane intensity I (x, y), which is the superposition of the first object light wave t (x- Δx, y) and the second object light wave t (x- Δx, y) from the object, 2 Δx being 50nm; the second interference light signal is transmitted by a second detector positioned 100mm from the position of the Fourier transform lens 323324 to obtain the differential interference space fourier spectrum intensity I (k) x ,k y ) Wherein the fourier transform lens 323 is placed 200mm from the tube lens 318.
The calculation process of the image operation processor 330 is the same as that of the first embodiment.
Fourth embodiment: single exposure quantitative differential interference imaging device based on detector spatial multiplexing
As shown in fig. 4, a single exposure quantitative differential interference imaging device based on detector spatial multiplexing according to a fourth embodiment of the present invention includes a differential interference imaging assembly, a full light field camera, and an image operation processor 430 connected in sequence. Wherein the differential interference imaging assembly is configured to generate first and second object light waves that pass through the object, the first and second object light waves being configured to interfere with each other to form interference light, whereby the differential interference imaging assembly is configured to output the interference light. The full-light field camera includes a first beam splitter configured to split interference light from the differential interference imaging assembly into first and second interference light and a detector configured to collect the first interference light to obtain a differential interference image plane intensity and to collect a fourier transform result of the second interference light to obtain a differential interference spatial fourier spectrum intensity. The image processor 430 is configured to reconstruct the amplitude and phase information of the object from the differential interference image plane intensities and the differential interference spatial fourier spectrum intensities.
The structure of the differential interference imaging assembly is identical to that of the differential interference imaging assembly of the second embodiment of the present invention, and the differential interference imaging assembly comprises an illumination light source 411, a polarizer 412, a second beam splitter 413, a sample stage 416, an objective lens 415, a birefringent prism 414, the second beam splitter 413, a phase shifting element 417 and a barrel lens 418, which are sequentially arranged on the first optical axis along the propagation direction of the light beam. The phase shifting element 417 is composed of a 1/4 wave plate 4171 and an analyzer 4172.
That is, in the present embodiment, the differential interference imaging assembly is a reflective imaging assembly in which the condenser lens and the objective lens are implemented by the same objective lens 415, and the birefringent beam combining prism and the birefringent beam splitting prism are implemented by the same birefringent prism 414.
Therefore, in the differential interference imaging assembly, the light beam emitted from the illumination light source 411 sequentially passes through the illumination light source 411, the polarizer 412 and the second beam splitter 413, and then sequentially passes through the birefringent prism 414 (as a birefringent beam splitter prism), the objective lens 415 (as a condenser lens), and the object on the sample stage 416 after being reflected by the second beam splitter 413, and then sequentially passes through the objective lens 415, the birefringent prism 414 (as a birefringent beam combining prism), the second beam splitter 413, the phase shifting element 417 and the barrel lens 418, and the operation principle of each optical element of the differential interference imaging assembly is the same as that of each optical element of the differential interference imaging assembly in the second embodiment.
In this embodiment, the full-light field camera also includes a detector for acquiring the differential interference image plane intensity and a detector for acquiring the differential interference spatial fourier spectrum intensity, which are different from other embodiments in that in this embodiment, the detector for acquiring the differential interference image plane intensity and the detector for acquiring the differential interference spatial fourier spectrum intensity are realized by a single detector spatial multiplexing.
Specifically, the full-light field camera includes a first beam splitter 421 for splitting the interference light to form a first light path and a second light path, a detector 422 located on the first light path to form a differential interference image plane intensity acquisition system, and a first mirror 423, a fourier transform lens 424, a second mirror 425, a third mirror 426 and the detector 422 sequentially located on the second light path to form a differential interference spatial fourier spectrum intensity acquisition system, where a first area of the detector 422 is located on the first light path and a second area of the detector 422 is located on the second light path. The detector 422 is connected to an image processor 430.
The spatial multiplexing of the detector 422 includes, but is not limited to, up-down type or side-to-side type, and thus, the first region and the second region of the detector 422 may be in up-down relationship or side-to-side relationship.
The third reflector 426 is shaped to match the second region of the detector so as to reflect only signal light from the differential interference spatial fourier spectrum intensity acquisition system. The third mirror 426 includes, but is not limited to, a D-type mirror. The third mirror 426 is rotatable to adjust the angle and displacement of the first interference light in the first optical path to further enable spatial multiplexing of the detector.
In this embodiment, the specific structure of the differential interference imaging device is the same as that of embodiment 2, and is a reflective system. The illumination light source 411 is a laser light source, and its output wavelength is 532nm; birefringent prism 414 is a Nomarski prism and birefringent prism 414 has a shear angle of 40 μrad; objective 415 is 100×,0.8NA, focal length f obj =1.8mm; the focal length of the tube lens 418 is 200mm; the focal length of the fourier transform lens 424 is 100mm. Detector 422 is 2048×2048 sCMOS with pixel dimensions of 6.45 μm×6.45 μm. The third mirror 426 in the full-field camera is rotatable in the xz plane, so that the angle and lateral position of the reflected light path can be adjusted, and further the spatial multiplexing of the detector is realized.
Therefore, a coordinate system xyz is established, the x direction is the emergent direction of the illumination light source, the y direction is the vertical direction, the laser emits 532nm laser light which propagates along the x direction, the laser light becomes linearly polarized light after passing through the polarizer, and the polarization direction is in the xy plane and forms an angle of 45 degrees with the x direction. After passing through the birefringent prism 414, the laser beam is split into two beams of first linear polarized illumination light with the polarization direction x and second linear polarized illumination light with the polarization direction y, and the included angle between the propagation directions of the first linear polarized illumination light and the second linear polarized illumination light is 40 mu rad. After passing through the objective lens, the first linearly polarized illumination light and the second linearly polarized illumination light are irradiated on an object placed on the sample stage with t (x, y) =a (x, y) e iΦ(x,y) The object regions illuminated by the first and second linearly polarized illumination light are denoted t (x- Δx, y) and t (x+Δx, y), respectively, at a distance of 2Δx=72 μm in the x-direction on the object. The reflected light and scattered light signals (i.e., the first object light wave and the second object light wave) from the differently illuminated object regions are collected by the objective lens and then by the birefringent prism 414And combining the beams, wherein the first object light wave and the second object light wave are completely overlapped in space position, and interference superposition is carried out to form interference light. The superimposed interference light passes through a phase shift element 417 and a tube lens 418 placed at a distance of 200mm from the objective lens, and is split into first interference light and second interference light by a first beam splitter 421. The included angle between the first interference light and the second interference light after being split by the first beam splitter is set to 90 degrees.
Wherein the first interference light is collected by a first area of the upper half of the detector to obtain differential interference image plane intensity I (x, y); the second interference light is reflected by the third mirror 426 after passing through the mirror 1, the Fourier transform lens 424 placed at a position 300mm from the barrel lens 418, and the second mirror 425, and is collected by the second region of the lower half of the detector placed at a position 100mm from the Fourier transform lens 424, to obtain differential interference space Fourier spectrum intensity I (k) x ,k y ). By rotating the angle of the analyzer of the phase shifting element 417, the direct initial phase difference of the first object light wave and the second object light wave can be changed, thereby adjusting the contrast of the differential interference image plane intensity and the differential interference spatial fourier spectrum intensity.
The calculation process of the image operation processor 430 is the same as that of the first embodiment.
The above-mentioned embodiments of the present invention are only preferred embodiments of the present invention, and are not intended to limit the scope of the present invention, and various changes can be made in the above-mentioned embodiments of the present invention. All simple, equivalent changes and modifications made in accordance with the claims and the specification of this application fall within the scope of the patent claims. The present invention is not described in detail in the conventional art.
Claims (10)
1. A single exposure quantitative differential interference imaging device, comprising:
a differential interference imaging assembly configured to generate a first object light wave and a second object light wave having a lateral differential shear generated after passing through an object, and output interference light including object gradient information formed by interference superposition of the first object light wave and the second object light wave with each other;
the full light field camera comprises a first beam splitter and a detector, wherein the first beam splitter is arranged to split the interference light into first interference light and second interference light, and the detector is arranged to acquire the first interference light to obtain differential interference image plane intensity and acquire a Fourier transform result of the second interference light to obtain differential interference space Fourier spectrum intensity; and
And the image operation processor is connected with the detector and is used for reconstructing the amplitude and phase information of the object according to the differential interference image plane intensity and the differential interference space Fourier spectrum intensity.
2. The single exposure quantitative differential interference imaging device of claim 1, wherein the differential interference imaging assembly comprises an illumination source, a polarizer, a birefringent beam splitting prism, a condenser, a sample stage, an objective lens, a birefringent beam combining prism, an analyzer and a barrel lens, which are arranged in sequence along the beam propagation direction;
the double refraction beam splitting prism is used for splitting linearly polarized light into two beams of first linearly polarized illumination light with an included angle in the transmission direction and a polarization direction being a first direction and second linearly polarized illumination light with a polarization direction being a second direction; the condenser deflects the transmission directions of the first linear polarized illumination light and the second linear polarized illumination light to be parallel to each other and irradiate an object with a certain transverse shearing, and generates a first object light wave and a second object light wave passing through the object; the double refraction beam combining prism is arranged to combine the first object light wave and the second object light wave into a beam with the same transmission direction and without transverse offset; after passing through the analyzer, the first object light wave and the second object light wave interfere with each other to form interference light; the tube lens and the objective lens form a 4f system.
3. The single exposure quantitative differential interference imaging device according to claim 2, wherein a phase shifting element is arranged between the birefringent beam combining prism and the tube lens, and the phase shifting element is used for adjusting the initial phase difference of the first object light wave and the second object light wave;
the phase shifting element is one of a combination of a 1/4 wave plate and the analyzer, a liquid crystal phase shifter, a Corrugation compensation plate and a spatial light modulator; the double-refraction beam splitting prism and the double-refraction beam combining prism comprise one of a Nomarski prism and a Wollaston prism.
4. The single exposure quantitative differential interference imaging device of claim 1, wherein the differential interference imaging assembly comprises an illumination source, a condenser, a sample stage, an objective lens, a first imaging lens, a second imaging lens, a spatial light modulator, and a tube lens, which are sequentially arranged along a propagation direction of a light beam;
the objective lens and the first imaging lens form a 4f system, and the focal plane of the first imaging lens and the spatial light modulator are respectively positioned on the focal planes of two sides of the second imaging lens; the spatial light modulator is arranged to simultaneously load two gratings to split the object light into a first object light wave and a second object light wave with included angles in the transmission direction; the first object light wave and the second object light wave form an imaging image plane at a focal plane behind the first object light wave and the second object light wave after being transformed by the lens barrel lens, the first object light wave and the second object light wave are enabled to be parallel and have lateral displacement to be overlapped on the imaging image plane in an interference mode to form interference light, and the lateral interval and the initial phase difference of the first object light wave and the second object light wave are changed by controlling the period and the initial phase difference of the two gratings.
5. The single exposure quantitative differential interference imaging device of claim 4, wherein a stop is provided downstream of the tube lens for selecting +1 diffraction order from both gratings loaded by the spatial light modulator.
6. The single exposure quantitative differential interference imaging device of claim 4, wherein the differential interference imaging assembly is a transmissive or reflective imaging assembly; in the reflective imaging component, the condenser lens and the objective lens are realized by the same objective lens, and the differential interference imaging component further comprises a first beam splitter; in a transmissive imaging assembly, the condenser lens and the objective lens are two distinct optical elements.
7. The single exposure quantitative differential interference imaging device of claim 2, wherein the differential interference imaging assembly is a transmissive or reflective imaging assembly; in the reflective imaging component, a condenser and an objective lens are realized by the same objective lens, the birefringent beam splitting prism and the birefringent beam combining prism are realized by the same birefringent prism, and the differential interference imaging component further comprises a first beam splitting lens; in a transmissive imaging assembly, the condenser and objective lens are two different optical elements, and the birefringent beam splitting prism and the birefringent beam combining prism are two different optical elements.
8. The single exposure quantitative differential interference imaging device of claim 1, wherein the full light field camera comprises a first beam splitter splitting the interference light to form a first light path and a second light path, a first detector positioned on the first light path to form a differential interference image plane intensity acquisition system, and a fourier transform lens and a second detector sequentially positioned along the second light path to form a differential interference spatial fourier spectrum intensity acquisition system, the first detector and the second detector being coupled to the image operation processor; the included angle between the first light path and the second light path is larger than the divergence angle of the interference light; the first beam splitter is arranged at any position downstream of the objective lens and upstream of the first detector and the second detector.
9. The single exposure quantitative differential interference imaging device of claim 1 wherein the full light field camera comprises a first beam splitter splitting the interference light to form a first light path and a second light path, a detector positioned on the first light path to form a differential interference image plane intensity acquisition system, and a first mirror, a fourier transform lens, a second mirror, a third mirror, and the detector positioned in sequence on the second light path to form a differential interference spatial fourier spectrum intensity acquisition system, the first region of the detector positioned on the first light path and the second region of the detector positioned on the second light path, the detector coupled to the image processor.
10. A single exposure quantitative differential interference imaging method, comprising:
step S1: providing a single exposure quantitative differential interference imaging device according to any one of claims 1-9, synchronously acquiring differential interference image plane intensity and differential interference spatial fourier spectrum intensity by using a full light field camera;
step S2: executing a full light field phase recovery algorithm by using an image operation processor, and calculating and reconstructing the acquired differential interference image plane intensity and differential interference space Fourier spectrum intensity by combining an interference model forming a transverse sheared object gradient in a differential interference system and constraint conditions in a single exposure quantitative differential interference imaging device to obtain the amplitude and phase of an object;
the full light field phase recovery algorithm is an iterative phase recovery method; the constraints include at least one of a double-sided constraint, an objective-induced field-of-view limited constraint, and a spectrum limited constraint.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311572745.0A CN117760559A (en) | 2023-11-23 | 2023-11-23 | Single exposure quantitative differential interference imaging device and method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311572745.0A CN117760559A (en) | 2023-11-23 | 2023-11-23 | Single exposure quantitative differential interference imaging device and method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117760559A true CN117760559A (en) | 2024-03-26 |
Family
ID=90324654
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311572745.0A Pending CN117760559A (en) | 2023-11-23 | 2023-11-23 | Single exposure quantitative differential interference imaging device and method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117760559A (en) |
-
2023
- 2023-11-23 CN CN202311572745.0A patent/CN117760559A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN108303020B (en) | Double-channel phase shift phase measurement microscope combining digital holography and differential interference | |
| US10613478B2 (en) | Imaging method of structured illumination digital holography | |
| CN110058393B (en) | Phase microscopic imaging device and method based on structured light illumination | |
| EP2084488B1 (en) | Optical devices based on internal conical diffraction | |
| EP3102982B1 (en) | Digital holographic device | |
| WO2011072175A2 (en) | Method and system for fast three-dimensional structured-illumination-microscopy imaging | |
| CN105241374A (en) | Dual wavelength common-channel quadrature carrier frequency digital holographic detection apparatus and detection method | |
| CN112798564B (en) | Random optical reconstruction and structured light illumination composite super-resolution imaging system | |
| CN110108201B (en) | High-precision off-axis digital holographic microscopic device with dual transmission and reflection modes and imaging method | |
| WO2023221400A1 (en) | Super-resolution single-objective light-sheet optical microscopy system and imaging system comprising same | |
| CN116448728A (en) | Dual-beam field interference light sheet microscopic imaging method and device based on galvanometer scanning | |
| US11947098B2 (en) | Multi-focal light-sheet structured illumination fluorescence microscopy system | |
| CN113758901B (en) | Diffraction tomography microscopic imaging system and method | |
| CN117760559A (en) | Single exposure quantitative differential interference imaging device and method | |
| CN116465868A (en) | Crystal lattice light sheet microscopic imaging method and device based on galvanometer scanning | |
| KR102052414B1 (en) | Reflection phase microscopy | |
| US11365961B2 (en) | Polarization holographic microscope system and sample image acquisition method using the same | |
| KR101789441B1 (en) | Holographic microscope system | |
| CN114374779A (en) | Full-light-field imaging camera, imaging method thereof and full-light-field imaging device | |
| CN108593114B (en) | Method and light path for efficiently and synchronously measuring polarization state and phase of any light beam | |
| JPS60181877A (en) | Optical correlator | |
| Huang et al. | Non-interferometric accurate phase imaging via linear-convergence iterative optimization | |
| Wang et al. | Off-axis differential interference contrast (DIC) microscopy enabled by polarization gratings pair and synthetic aperture technology for integrational and sectional quantitative phase imaging | |
| RU2758003C1 (en) | Method for registration of holographic images of objects | |
| CN114544552B (en) | Method for improving surface plasma resonance holographic microscopy image quality |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |