A common-path phase-shift interferometer based on single grating multiplexing

Abstract

The present invention provides a common-path phase-shift interference device based on single grating multiplexing, comprising: a microscopic imaging module, which performs transmission illumination on a sample; a phase modulation module, which comprises a non-polarizing cube beam splitter, a Ronchi grating, a diffraction beam filter assembly and a phase-type spatial light modulator, wherein the Ronchi grating diffracts a light beam transmitted through the non-polarizing cube beam splitter into multiple orders, and after passing through the diffraction beam filter assembly, the zero-order diffraction beam and the first-order diffraction beam are processed by the phase-type spatial light modulator and return to the Ronchi grating to diffract again to produce multiple orders; an interference imaging module, which receives the light beam reflected by the non-polarizing cube beam splitter and generates an interference image. The present invention significantly reduces the length of the optical structure and the system complexity through a single grating multiplexing design, and simplifies the filtering process in conjunction with the phase-type spatial light modulator, avoids phase shift errors, and significantly improves the imaging speed.

Description

Technical Field

[0001] The invention belongs to the technical field of common-path phase-shift interference, and in particular relates to a common-path phase-shift interference device based on single grating multiplexing. Background Art

[0002] Quantitative phase imaging technology has become an important tool for studying transparent samples such as cells because of its non-contact, non-destructive, and label-free measurement method. The phase imaging device based on the common path structure can effectively reduce the influence of external environmental disturbances because its object light and reference light propagate along the same path, and has good temporal stability. Therefore, the common path phase shift interferometer is suitable for stably obtaining high-resolution, large-field quantitative phase images of biological samples.

[0003] In order to simplify the phase recovery process, common-path phase shift devices based on dual-beam interference are widely used in the prior art. However, these technical methods have strict requirements on sample placement and adjustment. Devices using a dual-grating structure can reduce the requirements for sample placement and adjustment. However, the dual-grating structure's method of achieving phase shift by mechanically moving the second grating is prone to phase shift errors and limits the imaging speed, and the optical system is highly complex. Summary of the invention

[0004] The present invention provides a common-path phase-shift interferometer based on single grating multiplexing, aiming to solve the problems that the current common-path phase-shift double-grating structure method of achieving phase shift by mechanically moving the second grating is prone to error and limits the imaging speed, and the optical system is highly complex.

[0005] The present invention is implemented as follows: a common-path phase-shift interferometer based on single grating multiplexing, comprising:

[0006] A microscopic imaging module, the microscopic imaging module comprising an illumination component, a filtering polarization component and an optical calibration component; the filtering polarization component processes the light beam generated by the illumination component and then irradiates the light beam onto the biological sample, and the optical calibration component receives and images the light beam that passes through the biological sample;

[0007] A phase modulation module, the phase modulation module comprising a non-polarizing cubic beam splitter, a Ronchi grating, a diffraction beam filter assembly and a phase-type spatial light modulator; the non-polarizing cubic beam splitter allows the output beam of the microscopic imaging module to be transmitted into the phase modulation module and at the same time allows the output beam of the phase modulation module to be reflected into a subsequent interference imaging module; the Ronchi grating diffracts the beam into multiple orders; after being processed by the diffraction beam filter assembly, the zero-order diffraction beam and the first-order diffraction beam that meet the requirements reach the phase-type spatial light modulator; after being processed by the phase-type spatial light modulator, the zero-order diffraction beam and the first-order diffraction beam return to the Ronchi grating to diffract again to generate multiple orders and reach the non-polarizing cubic beam splitter;

[0008] The interference imaging module includes a magnifying imaging system and a sCOMS camera; the non-polarizing cube beam splitter reflects multiple diffraction beams formed by the zero-order diffraction beam and the first-order diffraction beam on the Ronchi grating to the magnifying imaging system, and the interference image is received by the sCOMS camera at the rear end of the magnifying imaging system.

[0009] Preferably, the lighting assembly comprises a laser, a first lens and a second lens; the first lens and the second lens collimate and expand the light beam emitted by the laser;

[0010] The filtering polarization component includes a pinhole filter and a first polarizer, and the pinhole filter and the first polarizer perform low-pass filtering on the light beam output by the lighting component and adjust its polarization state to a horizontal direction;

[0011] The optical calibration component includes an objective lens, a third lens and a first aperture. The light beam transmitted through the sample is magnified by the objective lens and reaches the third lens and the first aperture. After being collimated by the third lens and the light path of the first aperture is adjusted, the light beam enters the phase modulation module.

[0012] The diffraction beam filtering assembly includes a fourth lens, a second aperture and a second polarizer;

[0013] The diffracted light beams of different orders formed by the Ronchi grating are focused by the fourth lens; the second aperture filters the diffracted light beams of different orders and only allows the zero-order diffracted light beam and the first-order diffracted light beam to pass through; the polarization state of the zero-order diffracted light beam is adjusted to be 45° with the horizontal direction after passing through the second polarizer; the focal points of the zero-order diffracted light beam and the first-order diffracted light beam are located in the modulation plane of the phase-type spatial light modulator;

[0014] The e-axis of the phase-type spatial light modulator is along the horizontal direction. The phase-type spatial light modulator does not apply a phase delay to the low-frequency component of the zero-order diffraction beam (the area within the dotted line of the focus of the zero-order diffraction beam), and applies a phase delay of π to the high-frequency component of the zero-order diffraction beam (the area outside the dotted line of the focus of the zero-order diffraction beam).

[0015] The phase-type spatial light modulator sequentially applies a phase delay of nπ / 2 to all components of the first-order diffracted light beam, where n=0, 1, 2, 3.

[0016] After the zero-order diffracted light beam is reflected by the modulation plane of the phase-type spatial light modulator, the low-frequency component polarization state remains unchanged and can return through the second polarizer, while the high-frequency component polarization state changes by 90° and cannot return through the second polarizer. After the high-frequency component is filtered out, the zero-order diffracted light beam becomes the reference light beam R;

[0017] After being reflected by the modulation plane of the phase-type spatial light modulator, the first-order diffraction beam is given a phase delay and becomes the object beam O.

[0018] When the reference beam R and the object beam O pass through the Ronchi grating for the second time, the first-order diffraction beam R1 of R and the zero-order diffraction beam O0 of O propagate in the same direction through the non-polarization cube beam splitter to reach the interference imaging module.

[0019] The phase-type spatial light modulator sequentially loads four grayscales in the focal area of ​​the first-order diffraction beam, applies phase delays of 0π, π / 2, π, and 3 / 2π to O0, and the sCOMS camera sequentially receives four coaxial interference images of R1 and O0:

[0020]

[0021] Where: n=0, 1, 2, 3;

[0022] The phase distribution of biological samples can be calculated using the traditional four-step phase shift algorithm:

[0023]

[0024] Preferably, the magnifying imaging system comprises a fifth lens, a third aperture, a third polarizer and a sixth lens, the third aperture filters the diffracted light beams of R and O and only allows O0 and R1 to pass, and the third polarizer adjusts O0 and R1 to the same polarization state while balancing the light intensity.

[0025] The positions of the components are as follows: the Ronchi grating is located at the output image plane of the microscopic imaging module and at the front focal plane of the fourth lens; the modulation plane of the phase-type spatial light modulator is located at the back focal plane of the fourth lens; the fold line distance between the Ronchi grating and the fifth lens along the optical axis is the focal length of the fifth lens; the sCOMS camera is located at the back focal plane of the sixth lens.

[0026] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0027] 1. The common-path phase-shift interferometer based on single grating multiplexing provided by the present invention forms a compact common-path phase-shift structure through a single grating multiplexing design. Compared with the double grating structure of the existing object parameter common-path phase-shift digital holographic microscopy device, it significantly reduces the length of the optical structure and the system complexity, and has extremely strong anti-disturbance.

[0028] 2. The common-path phase-shift interferometer based on single grating multiplexing provided by the present invention utilizes a phase-type spatial light modulator to replace the traditional pinhole filter to perform low-pass filtering on one of the sample fields, and simultaneously applies a phase shift operation to the other sample field, thereby simplifying the filtering process, avoiding phase shift errors, and significantly improving the imaging speed. It can stably obtain high-resolution, large-field-of-view quantitative phase images of transparent biological samples without labeling. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of a common-path phase-shifting interferometer based on single grating multiplexing provided by the present invention.

[0030] Description of reference numerals:

[0031] 1. Laser; 2. First lens; 3. Pinhole filter; 4. Second lens; 5. First polarizer; 6. Observed sample; 7. Objective lens; 8. Third lens; 9. First aperture;

[0032] 10. Non-polarizing cube beam splitter; 11. Ronchi grating; 12. Fourth lens; 13. Second aperture; 14. Second polarizer; 15. Phase-type spatial light modulator;

[0033] 16. Fifth lens; 17. Third aperture; 18. Third polarizer; 19. Sixth lens; 20. sCOMS camera. DETAILED DESCRIPTION

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by technicians in the technical field of this application; the terms used in the specification of the application herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, not to describe a specific order.

[0035] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0036] The embodiment of the present invention provides a common-path phase-shift interferometer based on single grating multiplexing, such as Figure 1 As shown, the common-path phase-shift interferometer based on single grating multiplexing includes:

[0037] A microscopic imaging module, the microscopic imaging module comprising an illumination component, a filtering polarization component and an optical calibration component, the filtering polarization component processes the light beam generated by the illumination component and then irradiates the light beam onto the biological sample, and the optical calibration component receives and images the light beam that passes through the biological sample;

[0038] A phase modulation module, the phase modulation module includes a non-polarizing cube beam splitter 10, a Ronchi grating 11, a lens 12, a second aperture 13, a second polarizer 14 and a phase-type spatial light modulator 15,

[0039] The non-polarizing cubic beam splitter 10 allows the output beam of the microscopic imaging module to be transmitted into the phase modulation module, and at the same time, allows the output beam of the phase modulation module to be reflected into the subsequent interference imaging module. The Ronchi grating 11 is located at the output image plane of the microscopic imaging module, and diffracts the output beam of the microscopic imaging module into multiple orders. The different order diffraction beams formed by the Ronchi grating 11 are focused by the lens 12; and the second aperture 13 filters the different order diffraction beams, and only allows the zero-order diffraction beam and the first-order diffraction beam to pass through; the polarization state of the zero-order diffraction beam is adjusted to 45° with the horizontal direction after passing through the second polarizer 14, and the zero-order diffraction beam and the first-order diffraction beam that meet the requirements after processing reach the phase-type spatial light modulator 15;

[0040] The e-axis of the phase-type spatial light modulator 15 is along the horizontal direction, and the zero-order diffraction beam and the first-order diffraction beam are modulated by the phase-type spatial light modulator 15 to form a reference beam R and an object beam O; the reference beam R and the object beam O are reflected and then pass through the lens 12 and the second aperture 13 to reach the Ronchi grating 11 for the second time, diffract again to generate multiple orders, and reach the non-polarization cube beam splitter 10;

[0041] The interference imaging module includes a magnifying imaging system and a sCOMS camera 20; the non-polarizing cube beam splitter 10 reflects multiple diffraction beams of different orders formed by the zero-order diffraction beam and the first-order diffraction beam on the Ronchi grating 11 to the magnifying imaging system, and the interference image is received by the sCOMS camera 20 at the rear end of the magnifying imaging system.

[0042] In this embodiment, the phase-type spatial light modulator 15 does not apply a phase delay to the low-frequency component of the zero-order diffraction beam (the area within the dotted line of the focus of the zero-order diffraction beam), and applies a phase delay of π to the high-frequency component of the zero-order diffraction beam (the area outside the dotted line of the focus of the zero-order diffraction beam); after the zero-order diffraction beam is reflected by the modulation plane of the phase-type spatial light modulator 15, the low-frequency component polarization state is unchanged and can be returned through the second polarizer 14, and the high-frequency component polarization state changes by 90° and cannot be returned through the second polarizer 14, and the zero-order diffraction beam is filtered out of sample information by a low-pass filter to become a reference beam R; the phase-type spatial light modulator 15 applies a phase delay of nπ / 2 to all components of the first-order diffraction beam in sequence, where n=0, 1, 2, and 3; after the first-order diffraction beam is reflected by the modulation plane of the phase-type spatial light modulator 15, it becomes an object beam O;

[0043] When the reference beam R and the object beam O pass through the Ronchi grating 11 for the second time, the first-order diffraction beam R1 of R and the zero-order diffraction beam O0 of O propagate in the same direction to reach the interference imaging module;

[0044] The present invention has strong anti-disturbance, high spatial resolution, and simple implementation method, and can stably obtain high-resolution, large-field quantitative phase images of transparent biological samples without labeling. Compared with the dual-grating structure of the existing object-parameter common-path phase-shifting digital holographic microscopy device, the present invention significantly reduces the length of the optical structure and the system complexity through a single grating multiplexing design, and finally forms a compact common-path phase-shifting device; and uses a phase-type spatial light modulator to replace the traditional pinhole filter to perform low-pass filtering on one of the sample fields, while applying a phase shift operation to the other sample field, simplifying the filtering process, avoiding phase shift errors, and significantly improving the imaging speed.

[0045] As a preferred implementation in this embodiment, the lighting assembly includes a laser 1, a first lens 2 and a second lens 4; the first lens 2 and the second lens 4 collimate and expand the light beam emitted by the laser 1;

[0046] The filtering polarization component includes a pinhole filter 3 and a first polarizer 5; the pinhole filter 3 performs low-pass filtering on the illumination beam to make its intensity distribution uniform, and the first polarizer 5 adjusts the illumination beam to a horizontal polarization state;

[0047] The optical calibration component includes an objective lens 7, a third lens 8 and a first aperture 9; the light beam irradiated on the sample by the filtering polarization component and transmitted through the sample is magnified by the objective lens 7 and reaches the third lens 8 and the first aperture 9, the third lens 8 re-collimates the light beam, and the first aperture 9 adjusts the diameter of the light beam to a suitable size and then sends it to the phase modulation module;

[0048] As a preferred implementation in this embodiment, the magnified imaging system includes a fifth lens 16, a third aperture 17, a third polarizer 18 and a sixth lens 19. The reference beam R1 and the object beam O0 reflected from the non-polarizing cube beam splitter 10 sequentially pass through the fifth lens 16, the third aperture 17, the third polarizer 18 and the sixth lens 19, and finally reach the sCMOS camera 20;

[0049] The fifth lens 16 and the sixth lens 19 form a 4f system for magnified imaging; the third aperture 17 blocks other light beams except O0 and R1; the third polarizer 18 is used to adjust O0 and R1 to the same polarization state and balance the light intensity so that the coaxial interference image of O0 and R1 has the best contrast;

[0050] In this embodiment, the phase-type spatial light modulator 15 sequentially loads four grayscales in the focal area of ​​the first-order diffraction beam, applies phase delays of 0π, π / 2, π and 3 / 2π to O0 respectively, and the sCMOS camera 20 sequentially receives four coaxial interference images of R1 and O0:

[0051]

[0052] Where: n=0, 1, 2, 3;

[0053] The phase distribution of sample 6 can be calculated using the traditional four-step phase shift algorithm:

[0054]

[0055] It should be noted that, for the above-mentioned embodiments, for the sake of simplicity, they are all described as a series of action combinations, but those skilled in the art should know that the present invention is not limited by the described order of actions, because according to the present invention, some steps may be performed in other orders or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present invention.

[0056] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the scope of protection of the invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on these embodiments, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in this field can still combine, add, delete or make other adjustments to the features in the various embodiments of the present invention according to the circumstances without conflict, without making creative work, so as to obtain different other technical solutions that do not deviate from the concept of the present invention in essence, and these technical solutions also belong to the scope of protection of the present invention.

Claims

1. A common-path phase-shift interferometer based on single grating multiplexing, applied to quantitative phase imaging of biological samples, characterized in that: include: A microscopic imaging module, the microscopic imaging module comprising an illumination component, a filtering polarization component and an optical calibration component, the filtering polarization component processes the light beam generated by the illumination component and then irradiates the light beam onto the biological sample, and the optical calibration component receives and images the light beam that passes through the biological sample; A phase modulation module, the phase modulation module comprising a non-polarizing cubic beam splitter (10), a Ronchi grating (11), a diffraction beam filtering component and a phase-type spatial light modulator (15), the diffraction beam filtering component comprising a fourth lens (12), a second aperture (13) and a second polarizer (14), the Ronchi grating (11) being located at an output image plane of a microscopic imaging module and at a front focal plane of the fourth lens (12); the modulation plane of the phase-type spatial light modulator (15) being located at a rear focal plane of the fourth lens (12); The non-polarizing cubic beam splitter (10) allows the output light beam of the microscopic imaging module to be transmitted into the phase modulation module. The output light beam of the microscopic imaging module passes through the Ronchi grating (11) to form different order diffraction light beams, which are focused by the fourth lens (12). The second aperture (13) filters the different order diffraction light beams, allowing only the zero-order diffraction light beam and the first-order diffraction light beam to pass through. The polarization state of the zero-order diffraction light beam is adjusted to be 45 degrees with respect to the horizontal direction after passing through the second polarizer (14). After being processed by the diffraction light beam filtering component, the zero-order diffraction light beam and the first-order diffraction light beam that meet the requirements reach the phase-type spatial light modulator (15). The e-axis of the phase-type spatial light modulator (15) is along the horizontal direction. The phase-type spatial light modulator (15) does not apply a phase delay to the low-frequency component of the zero-order diffraction light beam, and applies a phase delay of π to the high-frequency component of the zero-order diffraction light beam. The phase-type spatial light modulator (15) sequentially applies a phase delay of nπ / 2 to all components of the first-order diffraction light beam, where n=0, 1, 2, and 3. After the zero-order diffraction light beam is reflected by the modulation plane of the phase-type spatial light modulator (15), the low-frequency component polarization state is unchanged and returns through the second polarizer (14), while the high-frequency component polarization state changes by 90° and cannot return through the second polarizer (14). After the high-frequency component is filtered, the zero-order diffraction light beam becomes a reference light beam R. After the first-order diffraction light beam is reflected by the modulation of the phase-type spatial light modulator (15), a phase delay is applied to it and it becomes an object light beam O. An interference imaging module comprises an amplifying imaging system and a sCMOS camera (20); the reference beam R and the object beam O pass through a Ronchi grating (11) for a second time and are diffracted again to generate multiple orders and reach a non-polarizing cubic beam splitter (10); the non-polarizing cubic beam splitter (10) forms multiple orders of diffraction beams from a zero-order diffraction beam and a first-order diffraction beam on the Ronchi grating (11) and reflects the diffraction beams to the amplifying imaging system; the first-order diffraction beam R1 of R and the zero-order diffraction beam O0 of O propagate in the same direction and reach the interference imaging module, and an interference image is generated by the sCMOS camera (20) at the rear end of the amplifying imaging system.

2. A common-path phase-shift interferometer based on single grating multiplexing as claimed in claim 1, characterized in that: The phase-type spatial light modulator (15) sequentially loads four grayscales in the focal region of the first-order diffraction beam, applies phase delays of 0π, π / 2, π and 3 / 2π to O0 respectively, and the sCMOS camera (20) sequentially receives four coaxial interference images of R1 and O0: Where: n=0, 1, 2, 3; The phase distribution of the biological sample (6) is calculated using the traditional four-step phase shift algorithm: 。 3. A common-path phase-shift interferometer based on single grating multiplexing as claimed in claim 1, characterized in that: The lighting assembly comprises a laser (1), a first lens (2) and a second lens (4); the first lens (2) and the second lens (4) collimate and expand the light beam emitted by the laser (1); The filtering polarization component comprises a pinhole filter (3) and a first polarizer (5), wherein the pinhole filter (3) and the first polarizer (5) perform low-pass filtering on the light beam output by the lighting component and adjust the polarization state thereof to a horizontal direction; The optical calibration component comprises an objective lens (7), a third lens (8) and a first aperture (9). The light beam irradiated on the sample through the filtering polarization component and transmitted through the sample is magnified by the objective lens (7) and reaches the third lens (8) and the first aperture (9). After being collimated by the third lens (8) and the light path adjusted by the first aperture (9), the light beam is sent to the phase modulation module.

4. A common-path phase-shift interferometer based on single grating multiplexing as claimed in claim 3, characterized in that: The magnifying imaging system comprises a fifth lens (16), a third aperture (17), a third polarizing plate (18) and a sixth lens (19); the third aperture (17) and the third polarizing plate (18) perform filtering and polarization processing on the diffracted light beams of R and O to obtain O0 and R1.

5. A common-path phase-shift interferometer based on single grating multiplexing as claimed in claim 4, characterized in that: The fold line distance between the Ronchi grating (11) and the fifth lens (16) along the optical axis is the focal length of the fifth lens, and the sCMOS camera (20) is located at the rear focal plane of the sixth lens.

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