CN117110249B - OCT imaging device with adjustable focal point and large focal depth and imaging method thereof - Google Patents
OCT imaging device with adjustable focal point and large focal depth and imaging method thereof Download PDFInfo
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Abstract
The invention provides an OCT imaging device and a method with adjustable focal point and large focal depth, wherein the OCT imaging device comprises a light source component which is respectively connected with a reference arm component and a sample arm component; the beam transformation component is arranged in the sample arm component and the reference arm component; the interference signal acquisition assembly is used for connecting the reference arm assembly, the sample arm assembly and the control assembly; the light source component, the K clock component and the control component are sequentially connected; the beam transformation assembly is used for shaping the Gaussian beam into a beam with a cubic phase, and the beam is focused by the imaging objective lens to form an Airy beam at an imaging focal plane. The invention provides an optical coherence tomography device and method with adjustable focal point based on large depth of field of Airy light beams, which takes Airy light with diffraction-free, self-healing and transverse self-acceleration characteristics as an imaging light beam of an optical coherence tomography system for the first time, improves the imaging focal depth of the traditional optical coherence tomography system, and improves the imaging quality of the system.
Description
Technical Field
The invention relates to the technical field of Optical Coherence Tomography (OCT), in particular to an OCT imaging device with adjustable focal point and large focal depth and an imaging method thereof.
Background
Optical Coherence Tomography (OCT) is a micron-scale tomographic imaging technique that utilizes coherence gates to achieve depth resolution, and it has now become a clinical standard of care for pathological diagnosis and therapy monitoring in a number of medical professions. For a typical OCT system, its axial resolution is primarily determined by the coherence length of the light source, which may be on the order of submicron. On the other hand, the lateral resolution of conventional OCT relies on a confocal gate focusing a gaussian beam, characterized by depth of focus, i.e., depth of focus (DOF). Specifically, there is a tradeoff between the beam waist diameter of the gaussian beam (which determines the lateral resolution of OCT) and the depth of focus (which limits the depth field of OCT imaging). Thus, OCT systems often sacrifice lateral resolution (tens of microns) to achieve depths of focus as long as several hundred microns to several millimeters in order to obtain deeper tissue imaging.
On the other hand, in practical applications, it is often necessary to adjust the focal position of the OCT system in order to obtain optimal imaging results. When the imaging depth is several millimeters, the depth of focus of the gaussian beam is short, so that even the focal point is adjusted, the imaging depth cannot be provided with better transverse resolution.
The application number is CN201820586790X, the patent name is liquid lens coherence tomography system and optical coherence tomography equipment, and the performance of realizing light beam focusing and zooming by using a liquid lens instead of a mechanical lens group is disclosed. However, it still uses gaussian beams, which have the disadvantage of a short focal depth. In addition, in high-speed OCT systems, the zoom speed of the liquid lens often cannot meet the scan speed of a-scan.
The patent application number is CN201710562810X, the patent name is an optical coherence tomography system for increasing the focal depth range, and the scheme for converting Gaussian beams into zero-order Bessel beams by using a circular ring Dammann grating is disclosed, so that the focal depth of the system is successfully expanded. However, since the bessel beam has many side lobes, the center beam of the bessel beam is mainly used in imaging, but only accounts for about 10-20% of the whole beam, so that the light intensity is wasted, and at the same time, the side lobes bring additional background light noise, so that the image contrast is reduced.
Disclosure of Invention
The invention aims at least solving the technical problems in the prior art, and particularly creatively provides an OCT imaging device with adjustable focal point and large focal depth, and an imaging method and an imaging system thereof.
In order to achieve the above object, the present invention provides an OCT imaging apparatus with adjustable focal point and large focal depth, which includes a light source assembly, a reference arm assembly, a sample arm assembly, a beam conversion assembly, a K clock assembly, an interference signal acquisition assembly, and a control assembly;
the light source assembly is respectively connected with the reference arm assembly and the sample arm assembly;
the beam transformation component is arranged in the sample arm component and the reference arm component;
the interference signal acquisition assembly is used for connecting the reference arm assembly, the sample arm assembly and the control assembly;
the light source component, the K clock component and the control component are connected in sequence;
the reference arm assembly comprises a fourth single mode fiber, a first fiber collimator, dispersion compensation glass, a second fiber collimator, a first polarization controller and a fifth single mode fiber;
the fourth single mode fiber, the first optical fiber collimator, the dispersion compensation glass, the second optical fiber collimator, the first polarization controller and the fifth single mode fiber are sequentially connected;
the sample arm assembly comprises a sixth single mode fiber, a seventh single mode fiber, a third optical fiber collimator, a fourth optical fiber collimator, a second polarization controller, a beam splitter, a two-dimensional scanning galvanometer, an imaging objective lens and a sample;
The sixth single-mode fiber, the third optical fiber collimator, the beam splitter, the two-dimensional scanning galvanometer, the imaging objective lens and the sample are sequentially connected;
the beam splitter, the fourth optical fiber collimator, the second polarization controller and the seventh single mode fiber are sequentially connected;
the beam splitter is used for collecting signal light returned from the sample;
the light beam conversion component comprises a polarizer, a first half-wave plate, a spatial light modulator, a first lens, a small hole and a second lens;
the polarizer, the first half-wave plate and the spatial light modulator are sequentially connected;
the first lens, the small hole and the second lens are connected in sequence;
the spatial light modulator is used for shaping Gaussian beams into beams with cubic phases, and the beams form Airy beams at an imaging focal plane after being focused by the imaging objective lens;
the polarizer is used for changing an incident Gaussian beam into a linearly polarized beam;
the first half wave plate is used for changing the polarization direction of the incident linearly polarized light beam to be parallel to the specific direction of the spatial light modulator;
the first lens, the small hole and the second lens are used for filtering zero-order light spots of the spatial light modulator;
at this time, it is: the sixth single-mode optical fiber, the third optical fiber collimator, the polarizer, the first half-wave plate, the spatial light modulator, the beam splitter, the first lens, the small hole, the second lens, the two-dimensional scanning galvanometer, the imaging objective lens and the sample are sequentially connected;
The beam splitter, the fourth optical fiber collimator, the second polarization controller and the seventh single mode optical fiber are sequentially connected.
In a preferred embodiment of the present invention, the sample arm assembly further includes a second half-wave plate and a polarizer, the beam splitter is replaced by a polarizing beam splitter, and the imaging objective is replaced by a 4F lens;
at this time, it is: the sixth single-mode optical fiber, the third optical fiber collimator, the polarizer, the first half-wave plate, the spatial light modulator, the first lens, the small hole, the second lens, the polarization beam splitter, the second half-wave plate, the polaroid, the two-dimensional scanning galvanometer, the 4F lens and the body to be measured are sequentially connected;
the polarization beam splitter, the fourth optical fiber collimator, the second polarization controller and the seventh single mode optical fiber are sequentially connected.
In a preferred embodiment of the present invention, the light source assembly includes a swept light source, an indicator light source, a first fiber coupler, a second fiber coupler, a first single mode fiber, a second single mode fiber, and a third single mode fiber;
the sweep frequency light source, the first single-mode fiber, the first optical fiber coupler, the second single-mode fiber and the second optical fiber coupler are sequentially connected;
the indicator light source, the third single-mode fiber and the second fiber coupler are sequentially connected.
In a preferred embodiment of the present invention, the first fiber coupler is a 1×2 fiber coupler;
the second optical fiber coupler is a 2×2 optical fiber coupler; the second optical fiber coupler divides light into two parts, and the two parts enter the reference arm assembly and the sample arm assembly respectively;
the indication lamp light source is a visible light source and is used for indicating an imaging position.
In a preferred embodiment of the present invention, the first fiber collimator and the second fiber collimator are optically coaxial.
In a preferred embodiment of the present invention, the front and rear focal planes of the imaging objective are located on the two-dimensional scanning galvanometer plane and the sample plane, respectively;
the beam splitter is a beam splitter with high reflectivity;
the front focal plane and the rear focal plane of the first lens are sequentially positioned on the plane of the spatial light modulator and the plane of the small hole;
the front focal plane of the second lens is positioned on the small hole plane;
the beam splitter is positioned between the spatial light modulator and the first lens and connects the light path of the sample arm assembly and the light path of the light beam conversion assembly.
In a preferred embodiment of the present invention, the K clock assembly includes an eighth single mode fiber, a ninth single mode fiber, a tenth single mode fiber, an eleventh single mode fiber, a twelfth single mode fiber, a thirteenth single mode fiber, a third fiber coupler, a fourth fiber coupler, a fifth fiber collimator, a sixth fiber collimator, and a first photodetector;
The eighth single-mode optical fiber is connected with the third optical fiber coupler;
the third optical fiber coupler, the tenth single-mode optical fiber, the fifth optical fiber collimator, the sixth optical fiber collimator, the eleventh single-mode optical fiber and the fourth optical fiber coupler are sequentially connected;
the third optical fiber coupler, the ninth single-mode optical fiber and the fourth optical fiber coupler are sequentially connected;
the fourth optical fiber coupler inputs interference signals to the first photoelectric detector through a twelfth single mode optical fiber and a thirteenth single mode optical fiber;
the K clock component is used for constructing an MZI interferometer, providing clock signals for the interference signal acquisition module and realizing the acquisition of interference signals according to the linear change of wave numbers;
the eighth single mode fiber connects the third fiber coupler and the first fiber coupler together, so that a part of light of the sweep frequency light source enters the light path of the K clock component.
In a preferred embodiment of the present invention, the fifth optical fiber collimator is fixed on the displacement stage, and the optical path difference between the fifth optical fiber collimator and the sixth optical fiber collimator is changed by moving the displacement stage, that is, the interference signal frequency of the interferometer is changed, so that the highest interference signal frequency that can be obtained by the interference signal acquisition assembly is changed.
In a preferred embodiment of the present invention, the third fiber coupler is a 1×2 fiber coupler;
the fourth optical fiber coupler is a 2×2 optical fiber coupler;
the first photoelectric detector is a photoelectric balance detector.
In a preferred embodiment of the present invention, the interference signal acquisition component includes a fifth optical fiber coupler, a second photodetector, a data acquisition card, a fourteenth single mode optical fiber, and a fifteenth single mode optical fiber;
the triggering signal of the acquisition card is provided by the synchronous output signal of the sweep frequency light source;
the fourteenth single-mode fiber and the fifteenth single-mode fiber connect the fifth optical fiber coupler and the second photoelectric detector together;
the fifth fiber coupler combines the reference arm signal from the fifth single mode fiber and the sample arm signal from the seventh single mode fiber and causes interference.
In a preferred embodiment of the present invention, the second photodetector is a photoelectric balance detector;
the fifth optical fiber coupler is a 2×2 optical fiber coupler with a ratio of 50:50.
In a preferred embodiment of the present invention, the control assembly includes a computer and a function generator;
The computer is used for controlling the working time sequence of the acquisition card, the function generator and the spatial light modulator, processing data and displaying results;
the function generator takes an interference signal generated by the K clock component as an external trigger clock, and then outputs a synchronous trigger signal 1, a control signal 2 and a control signal 3;
the trigger signal 1 is used for shaping an interference signal into a pulse signal and is used as an external clock signal of the acquisition card;
the control signal 2 and the control signal 3 are used for controlling the deflection of the two-dimensional scanning galvanometer.
In a preferred embodiment of the invention, the acquisition card and the computer are connected through a PCIe socket;
the spatial light modulator is connected with the computer through a DVI video line;
the electric signal is transmitted through the radio frequency coaxial cable.
In a preferred embodiment of the invention, a self-written acquisition control system and a signal processing program are arranged in the computer;
the acquisition control system and the signal processing program of the computer are written in the language C.
The invention also discloses an OCT imaging method with adjustable focal point and large focal depth, which comprises the following steps:
s1, placing a sample to be detected under an imaging objective lens and at a focal plane;
S2, enabling laser emitted by a sweep frequency light source to pass through a polarizer and a first half wave plate, enabling an incident Gaussian beam to be changed into linearly polarized light meeting a specific direction, then irradiating the linearly polarized light onto a spatial light modulator, loading a phase diagram with a cubic phase to the spatial light modulator through a computer, enabling a common Gaussian beam to be changed into a beam with a cubic phase distribution characteristic, removing zero-order light spots brought by the spatial light modulator through a spatial filtering system, and finally enabling the beam to be focused through an imaging objective lens and become an Airy beam at an imaging position;
s3, in order to achieve the best imaging effect, the focus position of the light beam focusing is required to be regulated, the focus position can be realized by changing the value of the cubic phase loaded by the spatial light modulator, namely, the focus position can be effectively changed in real time by directly transmitting different phase values to the spatial light modulator through a computer;
s4, after the focal position is adjusted, starting a data acquisition process, namely changing signals returned by the sample arm and the reference arm respectively into electric signals through the photoelectric detector, and then carrying out data acquisition by the acquisition card, so that the signal acquisition process of one data point is completed; then changing the deflection angles of the two-dimensional scanning galvanometer, so as to realize acquisition of A scanning data once every polarization of the galvanometer;
S5, after all data are acquired, a required B-Scan cross-section image or a three-dimensional image is obtained through data processing and reconstruction, or a two-dimensional plane image is obtained through a maximum projection method.
In summary, by adopting the technical scheme, the invention has the following effects:
(1) The invention provides an optical coherence tomography device and method with adjustable focal point based on large depth of field of Airy light beams, which takes Airy light with diffraction-free, self-healing and transverse self-acceleration characteristics as an imaging light beam of an optical coherence tomography system for the first time, improves the imaging focal depth of the traditional optical coherence tomography system, and improves the imaging quality of the system.
(2) The Airy beam utilized by the invention solves the problem that the Gaussian beam has a short focal depth after being focused by the objective lens due to the characteristic of easy divergence, and the contradiction of consistent transverse resolution from the surface of the sample to the inside of the sample can not be realized.
(3) Compared with the method based on Bei Ersai L light beam, the method for expanding focal depth by utilizing the Airy light beam is better, and because the Airy light beam has better diffraction-free characteristic than the Bessel light beam, the method based on the Airy light beam can realize longer focal depth; in addition, since the side lobe of the Airy beam is less than that of the Bessel beam, the Airy beam-based method has higher utilization rate of the beam and the obtained signal has higher signal-to-noise ratio.
(4) The invention provides a method for changing the focal position by utilizing the transverse self-acceleration characteristic of the Airy light beam for the first time, which can be realized simply and efficiently by loading different phases to a spatial light modulator through a computer without adding a zooming system like a liquid lens in the device, thereby achieving the advantage of simplifying the system.
(5) The invention provides the advantage of realizing adjustable focal length by skillfully designing the phase diagram of the Airy light beam for the first time. In addition, the focal point of the Airy light beam with large depth of field further lengthens the focal depth of the system imaging. The optical coherence tomography device and the method which can expand the focal depth and can adjust the focal length simultaneously get rid of the defects of short focal depth and small imaging depth, and have positive effects on expanding the application field of the optical coherence tomography technology. Is well suited for imaging of the entire retina and a large depth range of the choroid.
(6) Particularly, when the method is used for fundus OCT extended focal depth imaging, the lens effect of the eyeball is skillfully utilized, and a Gaussian beam with a cubic phase factor at the cornea can be changed into an Airy beam at the fundus after passing through the eyeball without an additional lens, so that the purpose of extending the focal depth is realized; the system light path is simplified, the system cost is reduced, and the system integration level is improved.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
The foregoing and/or additional aspects and advantages of the invention will become apparent and may be better understood from the following description of embodiments taken in conjunction with the accompanying drawings in which:
fig. 1 is a schematic structural diagram of embodiment 1.
Fig. 2 (a) is a one-dimensional ideal distribution pattern of light intensity of the eiy beam; (b) Is a one-dimensional finite energy actual Airy light beam intensity distribution law chart which is subjected to exponential decay.
Fig. 3 (a) is a sectional view of the light beam X-Y at a distance of 3cm from the imaging lens, fig. 3 (a) is a phase diagram loaded on the spatial light modulator, fig. 3 (b) is a sectional view of the light beam X-Y at a distance of 6cm from the imaging lens, and fig. 3 (c) is a sectional view of the light beam X-Y at a distance of 9cm from the imaging lens.
Fig. 4 is a schematic structural diagram of embodiment 2.
Reference numerals: 1 is a sweep frequency light source, 31 is an indicator light source, 2 is a first optical fiber coupler, 3 is a second optical fiber coupler, 201 is a first single-mode optical fiber, 203 is a second single-mode optical fiber, 301 is a third single-mode optical fiber, 302 is a four-mode optical fiber, 4 is a first optical fiber collimator, 5 is dispersion compensation glass, 6 is a second optical fiber collimator, 7 is a first polarization controller, 211 is a fifth single-mode optical fiber, 303 is a sixth single-mode optical fiber, 8 is a third optical fiber collimator, 9 is a polarizer, 10 is a first half-wave plate, 11 is a spatial light modulator, 12 is a beam splitter, 13 is a first lens, 14 is a small hole, 15 is a second lens, 16 is a two-dimensional scanning galvanometer, 17 is an imaging objective lens, 18 is a sample, 19 is a fourth optical fiber collimator, 20 is a second polarization controller, 212 is a seventh single-mode fiber, 21 is a fifth optical fiber coupler, 213 is a fourteenth single-mode fiber, 214 is a fifteenth single-mode fiber, 22 is a second photoelectric detector, 202 is an eighth single-mode fiber, 23 is a third optical fiber coupler, 231 is a ninth single-mode fiber, 232 is a tenth single-mode fiber, 24 is a fifth optical fiber collimator, 32 is a displacement table, 25 is a sixth optical fiber collimator, 262 is an eleventh single-mode fiber, 26 is a fourth optical fiber coupler, 263 is a twelfth single-mode fiber, 264 is a thirteenth single-mode fiber, 27 is a first photoelectric detector, 28 is a data acquisition card, 29 is a computer, 30 is a function generator, 121 is a polarization beam splitter, 122 is a second half-wave plate, 123 is a polarizing plate, 124 is a set of 4F lens, 401 first signal lines, and 402 second signal lines.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the invention.
Example 1
As shown in fig. 1, the schematic diagram of the OCT imaging device with adjustable focal depth includes a swept light source 1, an indicator light source 31, a first fiber coupler 2, a second fiber coupler 3, a first single-mode fiber 201, a second single-mode fiber 203, a third single-mode fiber 301, a fourth single-mode fiber 302, a first fiber collimator 4, a dispersion compensating glass 5, a second fiber collimator 6, a first polarization controller 7, a fifth single-mode fiber 211, a sixth single-mode fiber 303, a third fiber collimator 8, a polarizer 9, a first half-wave plate 10, a spatial light modulator 11, a beam splitter 12, a first lens 13, an aperture 14, a second lens 15, a two-dimensional scanning galvanometer 16, an imaging objective 17, a sample 18, a fourth fiber collimator 19, a second polarization controller 20, a seventh single-mode fiber 212, a fifth fiber coupler 21, a fourteenth single-mode fiber 213, a fifteenth single-mode fiber 214, a second photodetector 22, an eighth single-mode fiber 202, a third fiber coupler 23, a ninth single-mode fiber 231, a tenth single-mode fiber 232, a fifth fiber 24, a displacement stage 32, a sixth collimator 25, an eleventh fiber coupler 262, a twelfth single-mode fiber coupler 26, a thirteenth single-mode fiber coupler 28, and a thirteenth optical fiber coupler 28.
The third single-mode optical fiber 301 of the indicator light source 31 enters the imaging optical path, and has the functions of conveniently debugging the optical path system and indicating the imaging position. The swept optical source 1 is used as an imaging optical source of the optical coherence tomography system and enters the first optical fiber coupler 2 through the first single-mode optical fiber 201, and the first optical fiber coupler 2 divides the optical source into two parts, one part is used for imaging, and the other part is used for generating a K clock signal. The light beam used for imaging enters the second fiber coupler 3 through the second single mode fiber 203, and the second fiber coupler 3 splits the entered light beam into a reference arm portion and a sample arm portion. The light beam of the reference arm part passes through the fourth single mode fiber 302, the first fiber collimator 4, the dispersion compensating glass 5, the second fiber collimator 6, the first polarization controller 7 and the fifth single mode fiber 211 in this order after exiting from the second fiber coupler 3, wherein the dispersion compensating glass 5 is used for compensating the dispersion difference between the reference arm and the sample arm. The partial light beam of the sample arm passes through a sixth single mode fiber 303, a third fiber collimator 8, a polarizer 9, a first half wave plate 10, a spatial light modulator 11, a beam splitter 12, a first lens 13, a small hole 14, a second lens 15, a two-dimensional scanning galvanometer 16 and an imaging objective lens 17 in sequence after exiting from the second fiber coupler 3, and is converged in the sample 18.
The polarizer 9, the first half-wave plate 10, the spatial light modulator 11, the first lens 12, the small hole 13 and the second lens 14 form a beam shaping assembly; the polarizer 9 is used to change the incident gaussian beam into a linearly polarized beam; the first half-wave plate 10 is used for changing the polarization direction of the incident linearly polarized light beam to be parallel to the specific direction of the spatial light modulator; the spatial light modulator 11 is used to shape a gaussian beam into a beam with a cubic phase, which, after focusing by the imaging objective, forms an airy beam at the imaging focal plane. Here, the first lens 13, the aperture 14 and the second lens 15 are used to filter out the zero-order light spot of the spatial light modulator, the aperture 14 is located at the common focal plane of the first lens 13 and the second lens 15, and the front-back focal plane of the first lens 13 is located on the plane of the spatial light modulator 11 and on the plane of the aperture 14 in sequence. The signal light returned from the sample enters the fourth optical fiber collimator 19, the second polarization controller 20 and the seventh single mode fiber 212 through the beam splitter 12 with high reflectivity, finally, the interference occurs between the fifth optical fiber coupler 21 and the light beam of the reference arm, the interference light is divided into two parts by the fifth optical fiber coupler 21, and then enters the second photoelectric detector 22 through the fourteenth single mode fiber 213 and the fifteenth single mode fiber 214 to generate an interference electric signal S1, and the signal is input to the acquisition card 28 through a radio frequency coaxial cable. The external trigger signal of the acquisition card is provided by the synchronous trigger signal of the sweep frequency light source 1.
The light beam used for generating the K clock signal firstly enters the third optical fiber coupler 23 through the eighth single mode fiber 202, the third optical fiber coupler 23 divides the light into two parts, one light beam enters the fourth optical fiber coupler 26 through the ninth single mode fiber 231, the other light beam also enters the fourth optical fiber coupler 26 after sequentially passing through the tenth single mode fiber 232, the fifth optical fiber collimator 24 and the sixth optical fiber collimator 25, so that interference occurs in the coupler with the front light beam, the frequency of the interference signal is determined by the optical path difference before the two light beams, the frequency of the interference signal can be changed by adjusting the displacement table 32, the light beam after interference is equally divided into two parts by the fourth optical fiber coupler 26, and enters the first photoelectric detector 27 after passing through the twelfth single mode fiber 263 and the thirteenth single mode fiber 264 respectively, and at the moment, the first photoelectric detector 27 outputs the preliminary K clock signal. This preliminary K clock signal is then input in the form of a trigger other than the K clock signal to the function generator 30, which will then output the synchronized trigger signal 1, control signal 2 and control signal 3; the trigger signal 1 is formed by shaping a preliminary K clock signal into a pulse signal and is used as an external clock signal of the acquisition card; the control signals 2 and 3 are used to control the deflection of the two-dimensional scanning galvanometer.
The computer 29 is used to control the timing of the operation of the acquisition card, function generator and spatial light modulator, as well as to process the data and display the results. In addition, a self-written acquisition control system and signal processing program are provided in the computer 29.
The invention relates to a method for imaging by using an optical coherence tomography device with adjustable focal point and large focal depth, which comprises the following steps:
placing a sample to be measured under the imaging objective lens and at the focal plane;
the laser emitted by the sweep frequency light source passes through the polarizer and the first half wave plate, so that an incident Gaussian beam is changed into linearly polarized light meeting a specific direction, then the linearly polarized light irradiates the spatial light modulator, a phase diagram with a cubic phase is loaded on the spatial light modulator through a computer, so that a common Gaussian beam is changed into a beam with a cubic phase distribution characteristic, then a zero-order light spot brought by the spatial light modulator is removed by an emergent beam through a spatial filtering system, and finally the beam is focused by an imaging objective lens and becomes an Airy beam at an imaging position;
in order to achieve the best imaging effect, the focal position of the focusing of the light beam is required to be regulated, the focusing can be realized by changing the value of the cubic phase loaded by the spatial light modulator, namely, the position of the imaging focal point can be effectively changed in real time by directly transmitting different phase values to the spatial light modulator through a computer;
After the focal position is adjusted, starting a data acquisition process, namely changing signals returned by the sample arm and the reference arm respectively into electric signals through the photoelectric detector, and then acquiring data by the acquisition card, so that the signal acquisition process of one data point is completed; then changing the deflection angles of the two-dimensional scanning galvanometer, so as to realize acquisition of A scanning data once every polarization of the galvanometer;
after all data are acquired, the required B-Scan cross-sectional view or three-dimensional image is obtained through data processing and reconstruction, and a two-dimensional plane view can be obtained by using a maximum projection method.
The principle of the invention is as follows:
the Airy beam refers to a beam with a beam distribution rule meeting an Airy function, the Airy function is a solution of a Schrodinger one-dimensional paraxial wave equation in a free space, the physical meaning is a wave packet of particle dynamics motion characteristics,
（1）
wherein,AF() The function of the ai li is represented by,s=x/x 0 is a one-dimensional dimensionless transverse coordinate,xrepresenting the transverse directionThe spatial coordinates of the two-dimensional object are calculated,x 0 representing an arbitrary lateral dimension of the device,ξindicating the normalized transmission distance is indicated by the ratio,exprepresenting natural base numberse，iIs an imaginary unit.
At the position ofξAt the point of =0,φ(ξ,s)=AF(s) It is defined as the airy function. However, since the function is not integrable, i.e. the expression of the airy function has infinite energy, it is not possible to obtain experimentally. Therefore, the Airy function of infinite energy is multiplied by an exponential decay function, so that the Airy function is subjected to "toe-off" to limit the energy, thereby realizing an Airy beam in experiments, namely, an Airy beam with finite energy, with the following expression:
(2)
Wherein,ξ=z/k 0 x 0 2 for the normalized transmission distance, the transmission distance is,k 0 =2π/λis the number of waves to be used,k 0 the wave number is represented by a number of waves,λrepresenting wavelength, coefficientaIs an attenuation factor, and 0<a<<1。
Further, the wave packet expression of the Airy beam can be obtained as follows:
(3)
fourier transforming equation (3) can obtain the frequency spectrum of the eiri function, which is:
(4)
the spectrum of the improved Airy beam is composed of a cubic phase factor and a Gaussian phase factor. Therefore, the gaussian beam is incident on a spatial light modulator loaded with a cubic phase, and fourier transform is performed by a lens, so that the airy can be obtained. As shown in fig. 2, the one-dimensional ideal eiy beam intensity distribution is shown in fig. 2 (a), and the one-dimensional finite energy actual eiy beam intensity distribution with exponential decay is shown in fig. 2 (b). As can be seen from fig. 2 (a), the ideal eili beam does not spread in the transverse direction (X-axis) during propagation, and is a non-diffracted beam. In addition, its transverse profile moves along a parabolic path as the propagation distance increases. It can be seen from fig. 2 (b) that the one-dimensional finite energy eili beam does not spread in the transverse direction (X-axis) during propagation over a distance, and therefore has a greater depth of focus than the gaussian beam, which tends to diverge. The beams of (a) in fig. 2 and (b) in fig. 2 have the same lateral scale factor.
The two-dimensional Airy beam can be understood as the superposition of two one-dimensional Airy beams, so the expression is:
(5)
the phase diagram shown in fig. 3 is formed by splicing four attenuated two-dimensional Airy beams.
In addition, the characteristic of the Airy lateral self-acceleration, namely self-bending, refers to that when the Airy beam propagates, the beam profile of the Airy beam deviates from a parabolic track in the X-Y plane. The effect of this embodiment is shown in fig. 3, where (a) in fig. 3 is a cross-sectional view of the light beam X-Y at a distance of 3cm from the imaging lens, the inset in fig. 3 is a phase diagram loaded on the spatial light modulator, fig. 3 (b) is a cross-sectional view of the light beam X-Y at a distance of 6cm after the imaging objective lens, fig. 3 (c) is a cross-sectional view of the light beam X-Y at a distance of 9cm after the imaging objective lens, where it is apparent that the light beam is focused, where the light beam is focused is related to the focal length of the imaging lens and the parameters of the eiy beam, and the focal length of the imaging objective lens used in the experiment is 100mm. Therefore, by loading different phase diagrams to the spatial light modulator, airy beams with different parameters can be realized, and thus, the optical coherence tomography system with large depth of field and adjustable focus can be realized.
Example 2
As shown in fig. 4, when the optical coherence tomography device with a large depth of field and the optical coherence tomography device with an adjustable focal point is applied to fundus OCT, the device comprises a swept light source 1, an indicator light source 31, a first fiber coupler 2, a second fiber coupler 3, a first single mode fiber 201, a second single mode fiber 203, a third single mode fiber 301, a fourth single mode fiber 302, a first fiber collimator 4, a dispersion compensating glass 5, a second fiber collimator 6, a first polarization controller 7, a fifth single mode fiber 211, a sixth single mode fiber 303, a third fiber collimator 8, a polarizer 9, a first half-wave plate 10, a spatial light modulator 11, a first lens 13, a small hole 14, a second lens 15, a polarization beam splitter 121, a second half-wave plate 122, a polarizer 123, a two-dimensional scanning galvanometer 16, a 4F lens group 124, a fourth fiber collimator 19, a second polarization controller 20, a seventh single mode fiber 212, a fifth fiber coupler 21, a fourteenth single mode fiber 213, a fifteenth single mode fiber 214, a second photoelectric detector 22, an eighth single mode fiber 202, a third fiber coupler 23, a ninth single mode fiber 231, a tenth collimator 232, a tenth collimator 24, a eleventh single mode fiber 262, a thirteenth optical fiber coupler 29, a thirteenth optical fiber coupler 25, a thirteenth optical fiber function acquiring device, and a thirteenth optical fiber function of the fourth single mode fiber or a fourth collimator device is used as the optical coherence tomography device.
The third single-mode optical fiber 301 of the indicator light source 31 enters the imaging optical path, and has the functions of conveniently debugging the optical path system and indicating the imaging position. The swept optical source 1 is used as an imaging optical source of the optical coherence tomography system and enters the first optical fiber coupler 2 through the first single-mode optical fiber 201, and the first optical fiber coupler 2 divides the optical source into two parts, one part is used for imaging, and the other part is used for generating a K clock signal. The light beam used for imaging enters the second fiber coupler 3 through the second single mode fiber 203, and the second fiber coupler 3 splits the entered light beam into a reference arm portion and a sample arm portion. The light beam of the reference arm part passes through the fourth single mode fiber 302, the first fiber collimator 4, the dispersion compensating glass 5, the second fiber collimator 6, the first polarization controller 7 and the fifth single mode fiber 211 in this order after exiting from the second fiber coupler 3, wherein the dispersion compensating glass 5 is used for compensating the dispersion difference between the reference arm and the sample arm. The partial light beam of the sample arm passes through a sixth single mode fiber 303, a third fiber collimator 8, a polarizer 9, a first half wave plate 10, a spatial light modulator 11, a beam splitter 12, a first lens 13, a small hole 14, a second lens 15, a two-dimensional scanning galvanometer 16 and an imaging objective lens 17 in sequence after exiting from the second fiber coupler 3, and is converged in the sample 18.
The polarizer 9, the first half-wave plate 10, the spatial light modulator 11, the first lens 12, the small hole 13 and the second lens 14 form a beam shaping assembly; the polarizer 9 is used to change the incident gaussian beam into a linearly polarized beam; the first half-wave plate 10 is used for changing the polarization direction of the incident linearly polarized light beam to be parallel to the specific direction of the spatial light modulator; the spatial light modulator 11 is used to shape a gaussian beam into a beam with a cubic phase, which, after focusing by the imaging objective, forms an airy beam at the imaging focal plane. Here, the first lens 13, the aperture 14 and the second lens 15 are used to filter out the zero-order light spot of the spatial light modulator, the aperture 14 is located at the common focal plane of the first lens 13 and the second lens 15, and the front-back focal plane of the first lens 13 is located on the plane of the spatial light modulator 11 and on the plane of the aperture 14 in sequence. The P-ray transmission direction of the polarization beam splitter 121 is modulated so as to coincide with the vibration direction of the light beam emitted from the lens 15; the P light emitted from the polarization beam splitter 121 passes through the second half-wave plate 122, and the optical axis direction of the second half-wave plate 122 has an included angle of 22.5 degrees with the vibration direction of the incident P light; the light transmitting direction of the polarizing plate 123 is kept identical to the vibration direction of the light beam emitted from the second half-wave plate 122; the beam then passes through the two-dimensional scanning galvanometer 16 and the 4F lens group 124 in sequence, focusing on the fundus retina and choroid through the anterior ocular segment of the eye; the light beam is Gaussian light beam with cubic phase factor at cornea, and becomes Airy light beam at fundus through focusing function of eyeball self lens; the signal light returned from the fundus passes through the 4F lens group 124, the two-dimensional scanning galvanometer 16, and the polarizing plate 123 in this order, and when passing through the second half-wave plate 122, the vibration direction of the return light is deflected again by 22.5 °; when the light beam continues to be transmitted to the polarization beam splitter 121, the return light is totally reflected, then enters the fourth optical fiber collimator 19, the second polarization controller 20 and the seventh single mode fiber 212, finally, the fifth optical fiber coupler 21 interferes with the light beam of the reference arm, the interference light is equally divided into two parts by the fifth optical fiber coupler 21, then enters the second photodetector 22 through the fourteenth single mode fiber 213 and the fifteenth single mode fiber 214 to generate an interfered electric signal S1, and the signal is input to the acquisition card 28 through a radio frequency coaxial cable. The external trigger signal of the acquisition card is provided by the synchronous trigger signal of the sweep frequency light source 1.
In particular, the difference between the length of the fourteenth single-mode optical fiber 213 and the length of the fifteenth single-mode optical fiber 214 needs to be less than 1cm.
In particular, in example 2, the collection of the sample arm return light was performed by the polarizing beam splitter, and the recovery efficiency was higher and the system signal-to-noise ratio was higher, as compared with the method of collecting the sample arm return light by the ordinary beam splitter in example 1.
Particularly, when the device is used for fundus OCT imaging, the lens effect of the eyeball is skillfully utilized, a Gaussian beam with a cubic phase factor at the cornea can be changed into an Airy beam at the fundus after passing through the eyeball without an additional lens, and the purpose of expanding focal depth is realized; the system light path is simplified, the system cost is reduced, and the system integration level is improved.
The light beam used for generating the K clock signal firstly enters the third optical fiber coupler 23 through the eighth single mode fiber 202, the third optical fiber coupler 23 divides the light into two parts, one light beam enters the fourth optical fiber coupler 26 through the ninth single mode fiber 231, the other light beam also enters the fourth optical fiber coupler 26 after sequentially passing through the tenth single mode fiber 232, the fifth optical fiber collimator 24 and the sixth optical fiber collimator 25, so that interference occurs in the coupler with the front light beam, the frequency of the interference signal is determined by the optical path difference before the two light beams, the frequency of the interference signal can be changed by adjusting the displacement table 32, the light beam after interference is equally divided into two parts by the fourth optical fiber coupler 26, and enters the first photoelectric detector 27 after passing through the twelfth single mode fiber 263 and the thirteenth single mode fiber 264 respectively, and at the moment, the first photoelectric detector 27 outputs the preliminary K clock signal. This preliminary K clock signal is then input in the form of a trigger other than the K clock signal to the function generator 30, which will then output the synchronized trigger signal 1, control signal 2 and control signal 3; the trigger signal 1 is formed by shaping a preliminary K clock signal into a pulse signal and is used as an external clock signal of the acquisition card; the control signals 2 and 3 are used to control the deflection of the two-dimensional scanning galvanometer.
The computer 29 is used to control the timing of the operation of the acquisition card, function generator and spatial light modulator, as well as to process the data and display the results. In addition, a self-written acquisition control system and signal processing program are provided in the computer 29.
The preliminary K clock signal output from the first photodetector 27 is connected to the function generator 30 through a first signal line 401; the interfered electrical signal S1 output from the second photodetector 22 is connected to the data acquisition card 28 via the second signal line 402;
in particular, the lengths of the first signal line 401 and the second signal line 402 are adjustable to ensure that there is no phase difference between the external clock signal of the acquisition card and the interfering electrical signal S1.
Further, an adjustment method is as follows:
a glass sheet A1 is added between the sweep light source 1 and the first single-mode optical fiber 201, and the thickness is preferably 1mm;
disconnecting the ninth single mode fiber 231 such that there is no real K clock signal in the preliminary K clock signal;
performing the whole OCT imaging once so that both the preliminary K clock signal output by the first photodetector 27 and the interfered electrical signal S1 output by the second photodetector 22 contain the self-coherent signal of the glass sheet A1;
processing the interfered electric signal S1 and the self-coherent signal of the glass sheet A1 contained in the preliminary K clock signal respectively, and comparing the phase offset D0;
The lengths of the first signal line 401 and the second signal line 402 are adjusted so that the phase shift D0 tends to be 0, and the length error of the signal lines is less than 1cm.
While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: many changes, modifications, substitutions and variations may be made to the embodiments without departing from the spirit and principles of the invention, the scope of which is defined by the claims and their equivalents.
Claims (7)
1. The OCT imaging device with the adjustable focal point and large focal depth is characterized by comprising a light source assembly, a reference arm assembly, a sample arm assembly, a beam conversion assembly, a K clock assembly, an interference signal acquisition assembly and a control assembly;
the light source assembly is respectively connected with the reference arm assembly and the sample arm assembly;
the beam transformation component is arranged in the sample arm component and the reference arm component;
the interference signal acquisition assembly is used for connecting the reference arm assembly, the sample arm assembly and the control assembly;
the light source component, the K clock component and the control component are connected in sequence;
the reference arm assembly comprises a fourth single mode fiber, a first fiber collimator, dispersion compensation glass, a second fiber collimator, a first polarization controller and a fifth single mode fiber;
The fourth single mode fiber, the first optical fiber collimator, the dispersion compensation glass, the second optical fiber collimator, the first polarization controller and the fifth single mode fiber are sequentially connected;
the sample arm assembly comprises a sixth single mode fiber, a seventh single mode fiber, a third optical fiber collimator, a fourth optical fiber collimator, a second polarization controller, a beam splitter, a two-dimensional scanning galvanometer, an imaging objective lens and a sample;
the sixth single-mode fiber, the third optical fiber collimator, the beam splitter, the two-dimensional scanning galvanometer, the imaging objective lens and the sample are sequentially connected;
the beam splitter, the fourth optical fiber collimator, the second polarization controller and the seventh single mode fiber are sequentially connected;
the beam splitter is used for collecting signal light returned from the sample;
the light beam conversion component comprises a polarizer, a first half-wave plate, a spatial light modulator, a first lens, a small hole and a second lens;
the polarizer, the first half-wave plate and the spatial light modulator are sequentially connected;
the first lens, the small hole and the second lens are connected in sequence;
the spatial light modulator is used for shaping Gaussian beams into beams with cubic phases, and the beams form Airy beams at an imaging focal plane after being focused by the imaging objective lens;
The polarizer is used for changing an incident Gaussian beam into a linearly polarized beam;
the first half wave plate is used for changing the polarization direction of the incident linearly polarized light beam to be parallel to the specific direction of the spatial light modulator;
the first lens, the small hole and the second lens are used for filtering zero-order light spots of the spatial light modulator;
at this time, it is: the sixth single-mode optical fiber, the third optical fiber collimator, the polarizer, the first half-wave plate, the spatial light modulator, the beam splitter, the first lens, the small hole, the second lens, the two-dimensional scanning galvanometer, the imaging objective lens and the sample are sequentially connected;
the beam splitter, the fourth optical fiber collimator, the second polarization controller and the seventh single mode fiber are sequentially connected;
the light source assembly comprises a sweep frequency light source, an indicator light source, a first optical fiber coupler, a second optical fiber coupler, a first single mode optical fiber, a second single mode optical fiber and a third single mode optical fiber;
the sweep frequency light source, the first single-mode fiber, the first optical fiber coupler, the second single-mode fiber and the second optical fiber coupler are sequentially connected;
the indicator light source, the third single-mode fiber and the second fiber coupler are sequentially connected;
the K clock component comprises an eighth single-mode fiber, a ninth single-mode fiber, a tenth single-mode fiber, an eleventh single-mode fiber, a twelfth single-mode fiber, a thirteenth single-mode fiber, a third fiber coupler, a fourth fiber coupler, a fifth fiber collimator, a sixth fiber collimator and a first photoelectric detector;
The eighth single-mode optical fiber is connected with the third optical fiber coupler;
the third optical fiber coupler, the tenth single-mode optical fiber, the fifth optical fiber collimator, the sixth optical fiber collimator, the eleventh single-mode optical fiber and the fourth optical fiber coupler are sequentially connected;
the third optical fiber coupler, the ninth single-mode optical fiber and the fourth optical fiber coupler are sequentially connected;
the fourth optical fiber coupler inputs interference signals to the first photoelectric detector through a twelfth single mode optical fiber and a thirteenth single mode optical fiber;
the K clock component is used for constructing an MZI interferometer, providing clock signals for the interference signal acquisition module and realizing the acquisition of interference signals according to the linear change of wave numbers;
the eighth single mode fiber connects the third fiber coupler and the first fiber coupler together, so that part of light of the sweep frequency light source enters the light path of the K clock component;
the fifth optical fiber collimator is fixed on the displacement table, and the optical path difference between the fifth optical fiber collimator and the sixth optical fiber collimator is changed through the displacement table, namely, the interference signal frequency of the interferometer is changed, so that the highest interference signal frequency which can be obtained by the interference signal acquisition assembly is changed.
2. The OCT imaging apparatus of claim 1, wherein the sample arm assembly further comprises a second half-wave plate and a polarizer, the beam splitter is replaced with a polarizing beam splitter, and the imaging objective is replaced with a 4F lens;
at this time, it is: the sixth single-mode optical fiber, the third optical fiber collimator, the polarizer, the first half-wave plate, the spatial light modulator, the first lens, the small hole, the second lens, the polarization beam splitter, the second half-wave plate, the polaroid, the two-dimensional scanning galvanometer, the 4F lens and the body to be measured are sequentially connected; the body to be measured is an eyeball;
the polarization beam splitter, the fourth optical fiber collimator, the second polarization controller and the seventh single mode optical fiber are sequentially connected.
3. The OCT imaging apparatus of claim 1, wherein the interference signal acquisition assembly comprises a fifth fiber coupler, a second photodetector, a data acquisition card, a fourteenth single mode fiber, and a fifteenth single mode fiber;
the triggering signal of the acquisition card is provided by the synchronous output signal of the sweep frequency light source;
the fourteenth single-mode fiber and the fifteenth single-mode fiber connect the fifth optical fiber coupler and the second photoelectric detector together;
The fifth optical fiber coupler combines the reference arm signal from the fifth single-mode optical fiber and the sample arm signal from the seventh single-mode optical fiber together and makes the reference arm signal and the sample arm signal interfere;
the difference between the length of the fourteenth single-mode optical fiber and the length of the fifteenth single-mode optical fiber is smaller than 1cm;
the second photoelectric detector is a photoelectric balance detector;
the fifth optical fiber coupler is a 2×2 optical fiber coupler with a ratio of 50:50.
4. A large depth of focus adjustable OCT imaging apparatus according to claim 3, wherein the control assembly comprises a computer and a function generator;
the computer is used for controlling the working time sequence of the acquisition card, the function generator and the spatial light modulator, processing data and displaying results;
the function generator takes an interference signal generated by the K clock component as an external trigger clock, and then outputs a synchronous trigger signal 1, a control signal 2 and a control signal 3;
the trigger signal 1 is used for shaping an interference signal into a pulse signal and is used as an external clock signal of the acquisition card;
the control signal 2 and the control signal 3 are used for controlling the deflection of the two-dimensional scanning galvanometer.
5. The OCT imaging apparatus of claim 4, wherein the acquisition card and the computer are connected via a PCIe jack;
The spatial light modulator is connected with the computer through a DVI video line;
the electrical signal is transmitted through a radio frequency coaxial cable.
6. The large depth of focus adjustable OCT imaging apparatus of claim 4, wherein the preliminary K clock signal output by the first photodetector is connected to the function generator through a first signal line; the interfered electric signal S1 output by the second photoelectric detector is connected to the data acquisition card through a second signal line; the lengths of the first signal line and the second signal line are adjustable so as to ensure that no phase difference exists between an external clock signal of the acquisition card and an interfered electric signal S1;
the method for ensuring no phase difference between the external clock signal of the acquisition card and the interfered electric signal S1 comprises the following steps:
adding a glass sheet A1 between the sweep frequency light source and the first single-mode optical fiber;
disconnecting the ninth single mode fiber so that no real K clock signal exists in the preliminary K clock signal;
performing the whole OCT imaging once so that the primary K clock signal output by the first photoelectric detector and the interference electric signal S1 output by the second photoelectric detector both comprise self-coherent signals of the glass sheet A1;
processing the interfered electric signal S1 and the self-coherent signal of the glass sheet A1 contained in the preliminary K clock signal respectively, and comparing the phase offset D0;
The lengths of the first signal line and the second signal line are adjusted so that the phase offset D0 tends to 0, and the length error of the signal line is smaller than 1cm.
7. An imaging method of an OCT imaging apparatus with adjustable focus based on a large focal depth as claimed in claim 1, comprising the steps of:
s1, placing a sample to be detected under an imaging objective lens and at a focal plane;
s2, enabling laser emitted by a sweep frequency light source to pass through a polarizer and a first half wave plate, enabling an incident Gaussian beam to be changed into linearly polarized light meeting a specific direction, then irradiating the linearly polarized light onto a spatial light modulator, loading a phase diagram with a cubic phase to the spatial light modulator through a computer, enabling a common Gaussian beam to be changed into a beam with a cubic phase distribution characteristic, removing zero-order light spots brought by the spatial light modulator through a spatial filtering system, and finally enabling the beam to be focused through an imaging objective lens and become an Airy beam at an imaging position;
s3, in order to achieve the best imaging effect, the focus position of the light beam focusing is required to be regulated, the focus position can be realized by changing the value of the cubic phase loaded by the spatial light modulator, namely, the focus position can be effectively changed in real time by directly transmitting different phase values to the spatial light modulator through a computer;
S4, after the focal position is adjusted, starting a data acquisition process, namely changing signals returned by the sample arm and the reference arm respectively into electric signals through the photoelectric detector, and then carrying out data acquisition by the acquisition card, so that the signal acquisition process of one data point is completed; then changing the deflection angles of the two-dimensional scanning galvanometer, so as to realize acquisition of A scanning data once every polarization of the galvanometer;
s5, after all data are acquired, a required B-Scan cross-section image or a three-dimensional image is obtained through data processing and reconstruction, or a two-dimensional plane image is obtained through a maximum projection method.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110907451A (en) * | 2019-11-29 | 2020-03-24 | 南昌航空大学 | Ultra-deep OCT system device based on Airy beam and tissue transparentization technology |
| CN112587066A (en) * | 2020-12-16 | 2021-04-02 | 哈尔滨工业大学 | Scanning optical tomography endoscopic imaging system based on spatial attitude sensing |
| CN115096857A (en) * | 2022-06-10 | 2022-09-23 | 北京石油化工学院 | OCT imaging method and device based on Airy optical sheet line scanning |
| CN116519601A (en) * | 2023-03-24 | 2023-08-01 | 西安电子科技大学 | Photoacoustic microscopic imaging system and method based on Airy light beam combined sparse sampling |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9243885B2 (en) * | 2012-04-12 | 2016-01-26 | Axsun Technologies, LLC | Multi-speed OCT swept source with optimized k-clock |
| WO2018119222A1 (en) * | 2016-12-21 | 2018-06-28 | The Curators Of The University Of Missouri | Systems and methods for airy beam optical coherence tomography |
-
2023
- 2023-10-23 CN CN202311369724.9A patent/CN117110249B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110907451A (en) * | 2019-11-29 | 2020-03-24 | 南昌航空大学 | Ultra-deep OCT system device based on Airy beam and tissue transparentization technology |
| CN112587066A (en) * | 2020-12-16 | 2021-04-02 | 哈尔滨工业大学 | Scanning optical tomography endoscopic imaging system based on spatial attitude sensing |
| CN115096857A (en) * | 2022-06-10 | 2022-09-23 | 北京石油化工学院 | OCT imaging method and device based on Airy optical sheet line scanning |
| CN116519601A (en) * | 2023-03-24 | 2023-08-01 | 西安电子科技大学 | Photoacoustic microscopic imaging system and method based on Airy light beam combined sparse sampling |
Non-Patent Citations (1)
| Title |
|---|
| Hisashi Yamada et al..《Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XVII》.SPIE BIOS,2013,第8571卷第85710C-1~85710C-6页. * |
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