CN110873956B - Ultrahigh-speed orthogonal polarization imaging device and method - Google Patents
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Abstract
The invention discloses an ultrahigh-speed orthogonal polarization imaging device and method, wherein the imaging method comprises the following processes: the femtosecond laser is divided into two parts of orthogonal signal light and reference light after filtering, dispersion, gain and orthogonal polarization multiplexing, and the orthogonal polarization direction is along the fast and slow axes of the polarization-maintaining optical fiber; the signal light is scattered through a diffraction space, enters a space light imaging system, carries sample information and returns along a light path; the signal light loaded with sample information and the reference light are connected into an optical coherent receiver together to complete optical coherent detection, an optical signal is converted into an electric signal, the electric signal is sampled at high speed through high-speed analog-to-digital conversion and is converted into a digital signal to be output, and finally, the image is demodulated and restored by a computer. Compared with the traditional CCD imaging sensor, the invention can acquire the polarization information of the sample at the ultrahigh hundred MHz frame rate under the condition of ensuring the micron-scale imaging resolution, and the full digital acquisition based on the optical coherent receiver is beneficial to the later-stage real-time analysis and the image optimization processing.
Description
Technical Field
The invention belongs to the technical field of polarization microscopic imaging, particularly relates to an ultrafast polarization imaging technology, and more particularly relates to a femtosecond laser ultrahigh-speed orthogonal polarization imaging device and method based on optical coherent detection.
Background
Polarized light imaging is a very important imaging technique in the field of optical imaging, and can provide multidimensional information of intensity, phase and polarization. Particularly in the field of biomedical imaging, the polarized light imaging technology has the advantages of no need of invasion, low damage to samples and sensitivity to sub-wavelength structural change. The change of the polarization state of the light is closely related to the microstructure of the sample, so that the measurement of the polarization state of the light can obtain abundant structural information of the tissue sample. In addition to imaging static tissue structures, polarization imaging techniques are widely used for microscopic dynamic biomedical research. In order to better understand the real-time microscopic polarization-sensitive dynamic change process and realize the large-capacity tissue and even cell polarization research, it is necessary to improve the time resolution of the polarized light imaging technology.
Today's polarized light imaging technology has a slow image acquisition speed, wherein CCD and CMOS image sensors are the most widely used technologies in polarized light imaging systems today. In daily life, both imagers will typically only have a frame rate of 30 HZ. Although in the laboratory, a frame rate of several tens of KHZ can be obtained by reducing the number of pixels, the imaging quality is inevitably lowered. The pixel sensitivity and refresh frequency of such imagers are significantly limited with respect to each other. To ensure that the image is clearer, the corresponding picture refreshing frequency must be lower; conversely, if the refresh frequency of a picture is higher, the picture will be less sharp. This mutual limitation between sensitivity and frame rate also affects almost all polarized light imaging systems.
Therefore, an ultrafast polarized light imaging technology is urgently needed to be found to meet the requirements of experimental analysis work or actual production of modern polarized imaging.
Disclosure of Invention
The invention aims to solve the problem of imaging speed in the prior art, and provides a femtosecond laser ultra-high-speed orthogonal polarization microscopic imaging device and method based on optical coherent detection, which can greatly improve the imaging speed on the premise of ensuring micron-scale imaging resolution and can also acquire the polarization information of a sample.
The first purpose of the invention can be achieved by adopting the following technical scheme:
an ultra-high-speed orthogonal polarization imaging device comprises a femtosecond laser 1, a filter 2, a dispersion optical fiber 3, an optical fiber amplifier 4, a polarization controller 5, an optical fiber polarizer 6, a first polarization-preserving coupler 7, a specified-length polarization-preserving optical fiber 8, a polarization beam combiner 9, a second polarization-preserving coupler 10, a circulator 11, a laser collimating lens 12, lambda/4 space waves/13, a diffraction grating 14, a first microscope objective lens 15, a second microscope objective lens 16, a sample 17, a plane mirror 18, an optical fiber delay line 19, an optical coherent receiver 20, a high-speed analog-to-digital conversion module 21 and a computer 22, wherein lambda is the central wavelength of femtosecond laser.
The femtosecond laser 1, the filter 2, the dispersion optical fiber 3, the optical fiber amplifier 4, the polarization controller 5 and the optical fiber polarizer 6 are connected in turn through a single-mode optical fiber; the optical fiber polarizer 6 is connected with the first polarization maintaining coupler 7 through a polarization maintaining optical fiber, the first polarization maintaining coupler 7 comprises two output branches, one branch is directly connected with one branch of the polarization beam combiner 9 through the polarization maintaining optical fiber, the other branch is connected with the other branch of the polarization beam combiner 9 through a section of polarization maintaining optical fiber 8 with a specified length, the output of the polarization beam combiner 9 is connected with the second polarization maintaining coupler 10 through the polarization maintaining optical fiber, and the second polarization maintaining coupler 10 divides the optical path into a signal optical path and a reference optical path; the signal light path is firstly connected with the circulator 11, then, the output port of the circulator 11 is connected with the laser collimating lens 12 through the polarization maintaining optical fiber, the light in the optical fiber is converted into space light, the space light path is sequentially provided with the lambda/4 space wave plate 13, the diffraction grating 14, the first microscope objective 15, the second microscope objective 16, the sample 17 and the plane mirror 18, the signal light loaded with sample information is finally reflected back to the circulator 11 through the space light path, and is guided into the signal light input port of the optical coherent receiver 20 through the polarization maintaining optical fiber by the circulator 11; the reference optical path output by the second polarization-maintaining coupler 10 is first connected to the optical fiber delay line 19, and then is connected to the reference optical input port of the optical coherent receiver 20 through the polarization-maintaining optical fiber; finally, the optical coherent receiver 20 performs coherent detection on the orthogonally polarized light, obtains polarization and phase information of two orthogonal directions of the sample 17 at the same time, converts an optical signal into an electrical signal, samples the electrical signal at a high speed by the high-speed analog-to-digital conversion module 21 and converts the electrical signal into a digital signal for output, and finally demodulates and restores the image by the computer 22.
Further, the laser collimating lens 12, the λ/4 space wave plate 13, the diffraction grating 14, the first micro-objective lens 15, the second micro-objective lens 16 and the plane mirror 18 are space optical devices made of quartz glass.
Further, the femtosecond laser 1 has a center wavelength in the C band, a pulse repetition frequency of 100MHz, and a pulse duration of several hundred femtoseconds.
Further, the dispersion amount of the dispersion fiber 3 is equivalent to 20km of single-mode fiber, and the pulse is widened to nanosecond level.
Further, the diffraction grating 14 is a 600 lines per millimeter grating, which is a polarization insensitive optical element.
Furthermore, the specified length of the polarization-maintaining fiber 8 is used for delaying the pulse, and the length thereof is required to enable the total length of the upper branch fiber connected with the first polarization-maintaining coupler 7 and the polarization beam combiner 9 to be longer than the lower branch by L meters, wherein the length L is v/(2f), where v is the propagation speed of light in the fiber, and f is the repetition frequency of the output laser of the femtosecond laser 1.
The second purpose of the invention can be achieved by adopting the following technical scheme:
an ultra-high speed orthogonal polarization imaging method, said imaging method comprising:
s1, a femtosecond laser preprocessing step, wherein the femtosecond laser 1 generates broadband pulse light, the filter 2 filters the laser emitted by the femtosecond laser 1, the central wavelength of 1550nm and the appropriate spectral width are selected, the dispersion optical fiber 3 widens the filtered laser in the time domain through the group velocity dispersion effect, and the optical fiber amplifier 4 amplifies the power of the dispersed filtered laser;
s2, an orthogonal double-polarization generating step, namely, the preprocessed laser pulse is combined by a polarization controller 5 and an optical fiber polarizer 6 to ensure the linear polarization state of the pulse, then the linear polarization pulse is divided into two parts by a first polarization-preserving coupler 7, the pulse on the upper arm is divided by a section of polarization-preserving fiber 8 with a specified length for delaying to ensure that the pulses on the upper arm and the lower arm are not overlapped after being combined, the linear polarization pulses on the two arms are combined by a polarization beam combiner 9, the combined pulse is two orthogonal polarization pulses along the fast and slow axes of the polarization-preserving fiber, and then the combined pulse is divided into two parts by a second polarization-preserving coupler 10 to be signal light and reference light;
s3, a signal light information loading step, wherein the signal light is firstly guided into a space light imaging system through a circulator 11 and a laser collimating lens 12, then the signal light is converted into parallel space light through the laser collimating lens 12, a lambda/4 space wave plate 13 and a diffraction grating 14 in sequence, then the parallel space light is dispersed in space, then the sample information loading is completed by focusing the parallel space light on a sample 17 through a first microscope objective 15 and a second microscope objective 16, and finally the information carrying two orthogonal polarization directions of the sample 17 is reflected back to an optical fiber loop through a plane mirror 18; the reference light branch enters an optical coherent receiver 20 after passing through an optical fiber delay line 19;
s4, optical coherent detection and image restoration, wherein the signal light loaded with sample information and the reference light are connected into the optical coherent receiver 20, the optical coherent receiver 20 performs coherent detection on the orthogonal polarized light, obtains the polarization and phase information of the two orthogonal directions of the sample, converts the optical signal into an electric signal, samples the electric signal at high speed by the high-speed analog-to-digital conversion module 21 and converts the electric signal into a digital signal for output, and finally, the computer 22 demodulates and restores the image.
Compared with two image controllers of CCD and CMOS which are widely applied in daily life, the invention has the following advantages and effects:
1) under the frame rate of a great hundred MHz magnitude, the resolution of an imaged picture can still be ensured to be in a micron magnitude, and the device can also be used for observing near real-time polarization sensitive microscopic change;
2) the invention can obtain the full digital information about the shot sample, and is very beneficial to analyzing the digital information in real time according to the sample and carrying out various optimization treatments on the recovered image.
Drawings
FIG. 1 is a schematic structural diagram of an ultra-high-speed orthogonal polarization imaging device disclosed by the invention,
the drawings illustrate the following: 1- - -a femtosecond laser, 2- - -a filter, 3- - -a dispersion optical fiber, 4- - -an optical fiber amplifier, 5- - -a polarization controller, 6- - -an optical fiber polarizer, 7- - -a polarization maintaining coupler, 8- - -a polarization maintaining optical fiber with a specified length, 9- - -a polarization beam combiner, 10- - -a polarization maintaining coupler, 11- - -a circulator, 12- - -a laser collimating lens, 13- - -a lambda/4 space wave plate, 14- - -a diffraction grating, 15- - -a first micro objective lens, 16- - -a second micro objective lens, 17- - -a sample, 18- - -a plane reflector, 19- - -an optical coherent receiver, 20-optical fiber delay line, 21-high speed analog-to-digital conversion module, 22-computer.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Examples
The invention relates to a time domain broadening imaging technology based on dispersive Fourier transform, which is invented and widely researched as a high-speed microscopic imaging technology possibly applied to microscopic real-time observation.
In this embodiment, as shown in fig. 1, a femtosecond laser ultra-high-speed orthogonal polarization imaging device based on optical coherent detection includes:
the device comprises a femtosecond laser 1, a filter 2, a dispersion optical fiber 3, an optical fiber amplifier 4, a polarization controller 5 and an optical fiber polarizer 6 which are connected in sequence through a single-mode optical fiber; the first polarization-maintaining coupler 7 is connected with the optical fiber polarizer 6 through a polarization-maintaining optical fiber, the first polarization-maintaining coupler 7 comprises two output branches, one branch is directly connected to one branch of the polarization beam combiner 9 through the polarization-maintaining optical fiber, the other branch is connected to the other branch of the polarization beam combiner 9 through a section of specified-length polarization-maintaining optical fiber 8, the output of the polarization beam combiner 9 is connected with the second polarization-maintaining coupler 10 through the polarization-maintaining optical fiber, and the second polarization-maintaining coupler 10 divides the optical path into a signal optical path and a reference optical path; the signal light path is firstly connected with a circulator 11, the output port of the circulator 11 is connected with a laser collimating lens 12 through a polarization maintaining optical fiber, the light in the optical fiber is converted into space light, a lambda/4 space wave plate 13, a diffraction grating 14, a first micro objective 15, a second micro objective 16, a sample 17 and a plane mirror 18 are sequentially arranged on the space light path, the signal light loaded with sample information is finally reflected back to the circulator 11 through the space light path, and is guided into a signal light input port of an optical coherent receiver 20 through the polarization maintaining optical fiber by the circulator 11; the reference optical path output by the second polarization maintaining coupler 10 is connected to the optical fiber delay line 19, and then is connected to the reference optical input port of the optical coherent receiver 20 through the polarization maintaining optical fiber; finally, the photoelectric optical signal output by the optical coherent receiver 20 is connected to the high-speed analog-to-digital conversion module 21, and the digital signal after analog-to-digital conversion is finally sent to the computer 22 through the ethernet or the USB.
The laser collimating lens 12, the lambda/4 space wave plate 13, the diffraction grating 14, the first micro objective lens 15, the second micro objective lens 16 and the plane mirror 18 are space optical devices made of quartz glass.
The femtosecond laser 1 has a center wavelength in the C band, a pulse repetition frequency of 100MHz, and a pulse duration of several hundred femtoseconds.
The dispersion amount of the dispersion fiber 3 is equivalent to 20km of single-mode fiber, and the pulse can be widened to nanosecond level.
The diffraction grating 14 is a 600 lines per millimeter grating, which is a polarization insensitive optical element.
The process of loading the sample information by light through the diffraction grating is that after one beam of parallel light is scattered by the diffraction grating, the light with different frequencies irradiates different positions on the sample to carry the information on different positions of the sample.
Example two
In this embodiment, based on the disclosed femtosecond laser ultra-high-speed orthogonal polarization imaging device based on optical coherent detection, an ultra-high-speed orthogonal polarization imaging method is disclosed, which includes the following steps:
s1, preprocessing the femtosecond laser, wherein the femtosecond laser 1 generates broadband pulse light, the filter 2 filters the laser emitted by the femtosecond laser 1, the central wavelength is 1550nm and the appropriate spectral width are selected, the dispersion optical fiber 3 widens the filtered laser in the time domain through the group velocity dispersion effect, and the optical fiber amplifier 4 amplifies the power of the filtered laser after dispersion.
S2, orthogonal double polarization generating, wherein the preprocessed laser pulse is combined by a polarization controller 5 and an optical fiber polarizer 6 to ensure the linear polarization state of the pulse, then the linear polarization pulse is divided into two parts by a first polarization-preserving coupler 7, the pulse on the upper arm is divided into two parts by a section of polarization-preserving fiber 8 with a specified length for delaying to ensure that the pulses on the upper arm and the lower arm are not overlapped after being combined, the linear polarization pulses on the two arms are combined by a polarization beam combiner 9, the combined pulse is just two orthogonal polarization pulses along the fast and slow axes of the polarization-preserving fiber, and then the combined pulse is divided into two parts by a second polarization-preserving coupler 10 to be signal light and reference light.
S3, a signal light information loading step, wherein the signal light is guided into a space light imaging system through a circulator 11 and a laser collimating lens 12, then the signal light is converted into parallel space light through the laser collimating lens 12, a lambda/4 space wave plate 13 and a diffraction grating 14 in sequence, then the parallel space light is dispersed in space, then the sample information loading is completed by focusing the parallel space light on a sample 17 through a first microscope objective 15 and a second microscope objective 16, and finally the information carrying two orthogonal polarization directions of the sample 17 is reflected back to an optical fiber loop through a plane mirror 18; and the reference light branch enters the optical coherent receiver after passing through the optical fiber delay line.
S4, optical coherent detection and image restoration, wherein the signal light loaded with sample information and the reference light are connected into the optical coherent receiver 20, the optical coherent receiver 20 performs coherent detection on the orthogonal polarized light, obtains the polarization and phase information of the two orthogonal directions of the sample, converts the optical signal into an electric signal, samples the electric signal at high speed by the high-speed analog-to-digital conversion module 21 and converts the electric signal into a digital signal for output, and finally, the computer demodulates and restores the original image.
Due to the combination of the device of ultra-high-speed imaging, the imaging method can obtain ultra-high hundred MHz imaging frame rate.
The high-speed analog-to-digital conversion module 21 may further calculate and solve a jones matrix and a mueller matrix distribution image of the sample based on polarization and phase information in the orthogonal direction of the sample, and may further calculate and solve polarization parameters such as dichroism, phase delay, scattering depolarization, and the like of the sample based on the mueller matrix.
More specifically, as shown in fig. 1, the femtosecond laser high-speed polarization microscopic imaging method based on optical coherent detection comprises four steps.
Firstly, the pretreatment step of femtosecond laser: the filter 2 filters the laser emitted from the femtosecond laser 1, and selects a center wavelength of 1550nm and a suitable spectral width. The dispersion optical fiber 3 and the optical fiber amplifier 4 complete proper gain dispersion on the filtered laser and widen the femtosecond pulse to nanosecond level.
Secondly, the generation step of orthogonal double polarization: the pre-treated laser pulse is passed through a combination of a polarization controller 5 and a fiber polarizer 6 to ensure the linear polarization state of the pulse. Then the linear polarization pulse is divided into two parts by a first polarization-maintaining coupler 7, the pulse of the upper arm is enabled not to be overlapped after the pulse of the upper arm and the pulse of the lower arm are combined by a section of polarization-maintaining fiber 8 with a specified length for delay, the linear polarization pulse of the two arms is combined by a polarization beam combiner 9, and the combined pulse is just two orthogonal polarization pulses along the fast and slow axes of the polarization-maintaining fiber. And then divided into signal light and reference light by the second polarization maintaining coupler 10.
The length of the specified length of polarization maintaining fiber 8 for delay is determined according to the period calculation of the femtosecond laser. The length of the polarization maintaining fiber 8 is specified to be such that the total length of the upper branch fiber connected with the polarization beam combiner 9 by the first polarization maintaining coupler 7 is longer than the lower branch by L meters, and the length L is equal to v/(2f), wherein v is the propagation speed of light in the fiber, and f is the repetition frequency of the output laser of the femtosecond laser.
Thirdly, loading information of the signal light: the signal light is guided into the space light imaging system through the circulator 11 and the laser collimating lens 12. The lambda/4 space wave plate 13 can ensure that the incident space light pulse light keeps the orthogonal linear polarization state. The diffraction grating 14 can sequentially spread the spatial light according to the wavelength, then focus on the sample 17 through the first microscope objective 15 and the second microscope objective 16, and finally reflect the signal light loaded with the sample information back to the optical fiber through the plane mirror 18.
Fourthly, optical coherent detection and image restoration steps: the signal light loaded with information returns to the optical fiber loop again through the circulator 11 and is accessed to the optical coherent receiver 20; the reference light split by the second polarization maintaining coupler 10 passes through the fiber delay line 19 and then is connected to the optical coherent receiver 20, so as to complete the optical path matching of the two paths of light and the optical detection of coherent information. The high-speed analog-to-digital sampling module 21 is used for collecting data, and then the computer 22 stores the collected coherent data and demodulates the coherent data by an algorithm to recover the polarization-related information image of the sample.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.
Claims (7)
1. The ultra-high-speed orthogonal polarization imaging device is characterized by comprising a femtosecond laser (1), a filter (2), a dispersion optical fiber (3), an optical fiber amplifier (4), a polarization controller (5), an optical fiber polarizer (6), a first polarization maintaining coupler (7), a specified-length polarization maintaining optical fiber (8), a polarization beam combiner (9), a second polarization maintaining coupler (10), a circulator (11), a laser collimating lens (12), a lambda/4 space wave plate (13), a diffraction grating (14), a first microscope objective (15), a second microscope objective (16), a sample (17), a plane mirror (18), an optical fiber delay line (19), an optical coherent receiver (20), a high-speed analog-to-digital conversion module (21) and a computer (22), wherein lambda is the central wavelength of femtosecond laser;
the femtosecond laser (1), the filter (2), the dispersion optical fiber (3), the optical fiber amplifier (4), the polarization controller (5) and the optical fiber polarizer (6) are connected in turn through a single-mode optical fiber; the optical fiber polarizer (6) is connected with the first polarization maintaining coupler (7) through a polarization maintaining optical fiber, the first polarization maintaining coupler (7) comprises two output branches, one branch is directly connected with one branch of the polarization beam combiner (9) through the polarization maintaining optical fiber, the other branch is connected with the other branch of the polarization beam combiner (9) through a section of specified length of polarization maintaining optical fiber (8), the output of the polarization beam combiner (9) is connected with the second polarization maintaining coupler (10) through the polarization maintaining optical fiber, and the second polarization maintaining coupler (10) divides the optical path into a signal optical path and a reference optical path; the signal light path is firstly connected with the circulator (11), then, the output port of the circulator (11) is connected with a laser collimating lens (12) through a polarization-maintaining optical fiber to convert the light in the optical fiber into space light, the space light path is sequentially provided with the lambda/4 space wave plate (13), a diffraction grating (14), a first microscope objective (15), a second microscope objective (16), a sample (17) and a plane mirror (18), the signal light loaded with sample information is finally reflected back to the circulator (11) through the space light path, and is guided into a signal light input port of the optical coherent receiver (20) through the polarization-maintaining optical fiber by the circulator (11); the reference light path output by the second polarization-maintaining coupler (10) is firstly connected with an optical fiber delay line (19) and then is connected to a reference light input port of the optical coherent receiver (20) through a polarization-maintaining optical fiber; and finally, the optical coherent receiver (20) performs coherent detection on the orthogonal polarized light, obtains polarization and phase information of two orthogonal directions of the sample (17), converts an optical signal into an electric signal, samples the electric signal at high speed by a high-speed analog-to-digital conversion module (21) and converts the electric signal into a digital signal for output, and finally demodulates and restores the image by a computer (22).
2. The ultra-high speed orthogonal polarization imaging device according to claim 1, wherein the laser collimating lens (12), the λ/4 space wave plate (13), the diffraction grating (14), the first micro-objective (15), the second micro-objective (16) and the plane mirror (18) are quartz glass space optics.
3. An ultra-high speed orthogonal polarization imaging device according to claim 1, wherein the femtosecond laser (1) has a center wavelength in the C-band, a pulse repetition frequency of 100MHz, and a pulse duration of several hundred femtoseconds.
4. An ultra-high speed orthogonal polarization imaging device according to claim 1, wherein the dispersion amount of said dispersion fiber (3) is equivalent to 20km single mode fiber, and pulse broadening is in the order of nanoseconds.
5. An ultra-high speed orthogonal polarization imaging device according to claim 1, wherein said diffraction grating (14) is a 600 lines per mm grating, such grating being a polarization insensitive optical element.
6. An ultra-high speed orthogonal polarization imaging device according to claim 1, wherein the specified length of the polarization maintaining fiber (8) is used for delaying pulses, and the length thereof is such that the total length of the upper branch fiber connected to the first polarization maintaining coupler (7) and the polarization beam combiner (9) is longer than the lower branch by L meters, and the length L is v/(2f), where v is the propagation speed of light in the fiber and f is the repetition rate of the laser light output from the femtosecond laser (1).
7. An ultra-high speed orthogonal polarization imaging method, comprising:
s1, a femtosecond laser preprocessing step, wherein a femtosecond laser (1) generates broadband pulse light, a filter (2) filters the laser emitted by the femtosecond laser (1), the central wavelength of 1550nm and a proper spectrum width are selected, a dispersion optical fiber (3) widens the filtered laser in a time domain through a group velocity dispersion effect, and an optical fiber amplifier (4) amplifies the power of the filtered laser after dispersion;
s2, an orthogonal double-polarization generating step, namely, the preprocessed laser pulse is combined by a polarization controller (5) and an optical fiber polarizer (6) to ensure the linear polarization state of the pulse, then the linear polarization pulse is divided into two parts by a first polarization-preserving coupler (7), the pulse of the upper arm is combined by a section of polarization-preserving fiber (8) with a specified length for delaying to ensure that the pulses of the upper arm and the lower arm are not overlapped, the linear polarization pulses of the two arms are combined by a polarization beam combiner (9), the combined pulse is two orthogonal polarization pulses along the fast and slow axes of the polarization-preserving fiber, and then the combined pulse is divided into two parts by a second polarization-preserving coupler (10) to be signal light and reference light;
s3, a signal light information loading step, wherein the signal light is guided into a space light imaging system through a circulator (11) and a laser collimating lens (12), then the signal light is converted into parallel space light through the laser collimating lens (12), a lambda/4 space wave plate (13) and a diffraction grating (14) in sequence, then the parallel space light is dispersed in space, then a first microscope objective (15) and a second microscope objective (16) are focused on a sample (17) to complete the loading of sample information, and finally the information carrying two orthogonal polarization directions of the sample (17) is reflected back to an optical fiber loop through a plane mirror (18); the reference light branch enters an optical coherent receiver (20) after passing through an optical fiber delay line (19);
s4, optical coherent detection and image restoration, wherein signal light loaded with sample information and reference light are connected into an optical coherent receiver (20), the optical coherent receiver (20) performs coherent detection on orthogonal polarized light, polarization and phase information of two orthogonal directions of a sample are obtained simultaneously, an optical signal is converted into an electric signal, the electric signal is sampled at high speed through a high-speed analog-to-digital conversion module (21) and is converted into a digital signal to be output, and finally the computer (22) demodulates and restores the image.
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