Generation method of linear light intensity optical needle and OCT (Optical Coherence Tomography) system

Abstract

The invention relates to the technical field of coherence tomography, in particular to a linear light intensity optical needle generation method and an OCT system, the ideal slope of a light intensity distribution curve of a linear light intensity optical needle is determined according to the length of the linear light intensity optical needle and the light intensity of the head and tail focus positions, the positions and intervals of all focuses are optimized, and the linear light intensity optical needle generation method is obtained. The method comprises the following steps of: determining a linear light intensity optical needle with a plurality of focuses until the linearity of the linear light intensity optical needle formed by the focuses approaches to an ideal slope, determining a phase corresponding to each focus, generating a corresponding phase diagram, loading the phase diagram by utilizing a spatial light modulator, and modulating a light beam passing through the spatial light modulator into the linear light intensity optical needle. The linear light intensity optical needle is applied to an OCT system for coherence tomography. According to the invention, not only is the repeatability of optical needle modulation realized through the spatial light modulator, but also the linear light intensity optical needle is designed for the problem of material absorption, so that the problems of fewer deep detection reflected light signals and poorer imaging definition caused by material absorption in the prior art are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of coherent tomography, and in particular relates to a method for generating a linear light intensity optical needle and an OCT system. Background Art

[0002] In the field of optical inspection, optical coherence tomography (OCT) technology, due to its non-invasive and high-resolution characteristics, is widely used in a variety of important fields, including biological imaging, surface inspection, film thickness inspection, multilayer film inspection, and sub-surface damage detection. In these applications, precise modulation and control of the light beam plays a key role in achieving high-precision inspection and imaging.

[0003] In optical coherence tomography (OCT), uniform light probes are currently used to capture depth information of the sample under test. To generate uniform light probes, previous studies have proposed using a diffraction element (DOE) to modulate the optical probe. A specific DOE is designed based on the desired beam parameters, and beam shaping is achieved through the customized DOE. However, DOE modulation can only modulate optical probes with fixed parameters; once the beam length and width are determined, parameters such as the length and width cannot be changed. To generate different optical probes, a new DOE must be designed and customized. Furthermore, the pixel size of a DOE is generally in the range of 1-10 μm. Smaller pixel sizes increase production costs, and process limitations also limit the size of the DOE. Furthermore, smaller pixel sizes increase production complexity and introduce greater manufacturing errors. These factors significantly limit the flexibility and cost-effectiveness of DOEs in practical applications.

[0004] In addition, during the actual detection process, due to the influence of material absorption, the energy of the light beam will gradually attenuate as it penetrates the material, and less energy will be returned from deep inside, resulting in unclear deep imaging. This energy attenuation problem is caused by the material's absorption characteristics of the light beam. When the light beam passes through the material, the atoms or molecules in the material will absorb the energy in the light beam, causing the energy of the light beam to gradually weaken. As the penetration depth of the light beam increases, this energy attenuation phenomenon becomes more and more obvious, resulting in insufficient energy returned from deep inside the material, which in turn affects the quality of deep imaging. This problem of unclear deep imaging seriously affects the detection of depth information, and currently no technical solution has been proposed to solve the above-mentioned energy attenuation problem. Summary of the Invention

[0005] In view of this, the present invention aims to provide a method for generating a linear light intensity optical needle and an OCT system, which utilizes a spatial light modulator instead of a quartz optical diffraction element for optical needle modulation, thereby overcoming the limitations of fixed DOE modulation parameters and high cost, and improving the traditional uniform light optical needle. By optimizing the design of the linear light intensity optical needle, the light intensity distribution of the optical needle increases linearly with the increase of the detection depth or distance, thereby offsetting the energy attenuation problem caused by material absorption, and effectively improving the clarity and resolution of deep imaging.

[0006] To achieve the above object, the technical solution created by the present invention is implemented as follows: The present invention provides a method for generating a linear light intensity optical needle, comprising: Determine the number M and length of the focal points of the optical needle to be generated, and set the ideal slope of the linear light intensity distribution curve of the optical needle to be generated ; Generate M focal points, optimize the positions and intervals of the M focal points, so that the linearity and ideal slope of the linear light intensity optical needle formed by the optimized M focal points meet preset conditions; The phase corresponding to each focus is determined according to the optimized positions and intervals of the M focuses, and a phase map of the linear light intensity optical needle is formed, and the phase map is loaded using a spatial light modulator.

[0007] Preferably, the ideal slope The setup process includes: Set the first focus of the linear optical needle to be generated Light intensity at the location and the Mth focus Light intensity at the location , combined with the length L of the linear light intensity optical needle to be generated, the ideal light intensity distribution curve of the linear light intensity optical needle to be generated is: ; in, Indicates the The ideal light intensity at each focal point, Indicates the first focus and the The distance of the focal point, Indicates the first focus of the linear optical needle to be generated The light intensity at the location, , Represents the Mth focus of the linear optical needle to be generated The light intensity at the location.

[0008] Preferably, the preset conditions are: After optimization, the sum of the differences between the actual light intensity at the positions of the M focal points and the ideal light intensity is less than the set first threshold.

[0009] Preferably, the sum of the differences between the actual light intensity at the M focal points and the ideal light intensity after optimization is for: ; in, The first linear light intensity optical needle generated by the M focal points after optimization is represented by The actual light intensity at the focal point.

[0010] Preferably, the preset conditions are: After optimization, the maximum difference between the actual light intensity and the ideal light intensity in the M focal points is less than a set second threshold.

[0011] Preferably, the preset conditions are: After optimization, a standard deviation or variance of the actual light intensity at the positions of the M focal points relative to the ideal light intensity is less than a set third threshold.

[0012] Preferably, the spatial light modulator is a liquid crystal spatial light modulator, and the phase map is loaded by the liquid crystal spatial light modulator, including: normalizing the phase value of the phase map to the modulatable phase range of the liquid crystal spatial light modulator, and converting the phase value of the phase map into a corresponding grayscale value based on the correspondence between the grayscale value of the liquid crystal spatial light modulator and the phase delay in the phase map, generating a grayscale map, and the liquid crystal spatial light modulator performs liquid crystal modulation according to the grayscale map.

[0013] Preferably, the spatial light modulator is a digital micromirror device, and the phase image is loaded using the digital micromirror device, including: converting the phase value of the phase image into the axial height of a micromirror in the digital micromirror device, and performing phase modulation using the digital micromirror device, wherein the relationship between the axial height and the phase of the micromirror is: ; in, Indicates the phase difference between the current focus phase and the initial focus phase, represents the optical path difference, Indicates the central wavelength of the light beam.

[0014] Preferably, the phase diagram generation process is: A phase mask for generating a phase map is set, where the phase mask is divided into a plurality of cells, M cells are divided into a sub-unit, and phases corresponding to the optimized M focal points are respectively set in the M cells of each sub-unit to form a phase map.

[0015] Another aspect of the present invention provides an OCT system, comprising: a light source, a spectrometer, a reference arm, and a detection arm; Among them, the detection arm includes: a collimating lens, a semi-transparent and semi-reflective mirror, a spatial light modulator and a sample to be measured. The spatial light modulator uses a linear light intensity optical needle generation method to modulate the detection beam to generate a linear light intensity optical needle for imaging detection.

[0016] Compared with the prior art, the present invention can achieve the following beneficial effects: The present invention uses a spatial light modulator to replace the traditional optical diffraction element (DOE) modulation to generate optical needles, overcoming the limitations of DOE modulation parameters, high cost, and pixel size limited by the preparation process. The spatial light modulator has the advantages of reusability and dynamic loading of phase patterns. It can flexibly adjust parameters such as the length, width, and light intensity distribution of the optical needle, thereby improving the flexibility of optical needle modulation and its application in different application scenarios of OCT systems. In addition, the traditional DOE modulation method requires the preparation of a specific DOE when generating optical needles with different parameters, and also requires assembly and replacement, which is not conducive to coherent tomography detection.

[0017] In addition, the present invention optimizes the design to address the problems of the sample to be tested absorbing the detection light energy during coherent tomography, resulting in too low detection light intensity and too little sample information carried by the reflected light signal. Since the detection light energy attenuation becomes more obvious with the increase of the detection light penetration depth, the present invention adopts linear light intensity distribution as the modulation target according to the detection requirements. By enhancing the light intensity at a deeper detection position, the detection light energy received by the sample to be tested is offset, resulting in the problem of detection light energy attenuation. This design not only compensates for the problem of too weak detection light energy at a deeper position, but also avoids the problem of energy process in shallow detection, thereby ensuring that both deep and shallow imaging of the sample to be tested have high clarity and resolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings: Figure 1 is a flow chart of a method for generating a linear light intensity optical needle according to an embodiment of the present invention; Figure 2 is an ideal light intensity distribution curve diagram of a linear light intensity optical needle to be generated according to an embodiment of the present invention; Figure 3 Schematic diagram of the optical path of an OCT system according to an embodiment of the present invention.

[0019] The reference numerals include: Light source 1, spectrometer 2, beam splitter 3, reference arm 4, detection arm 5; Collimating mirror 51 , semi-transparent mirror 52 , spatial light modulator 53 , galvanometer mirror 54 , focusing mirror 55 , and sample to be measured 56 . DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation to the present invention. Similar elements in different embodiments use associated similar element numbers. In the following embodiments, many detailed descriptions are intended to enable the present invention to be better understood. However, those skilled in the art can easily recognize that some of the features can be omitted in different situations, or can be replaced by other elements, materials, or methods. In some cases, some operations related to the present invention are not shown or described in the specification. This is to avoid the core part of the present invention being overwhelmed by too much description. For those skilled in the art, it is not necessary to describe these related operations in detail. They can fully understand the related operations based on the description in the specification and the general technical knowledge in the art.

[0021] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other to form various implementation methods. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various orders in the description and the drawings are only for the purpose of clearly describing a certain embodiment and are not intended to be a required order, unless otherwise specified that a certain order must be followed.

[0022] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0023] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art can understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0024] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0025] See also Figure 1 In one embodiment of the present invention, a method for generating a linear intensity optical needle is provided. This method utilizes a spatial light modulator (SLM) instead of a DOE to modulate the OCT light source. Based on the principle that light intensity attenuates more severely as the detection depth increases, the method generates a linear intensity optical needle whose light intensity increases linearly with distance. The method specifically includes the following steps: S1: First, determine the optical parameters of the linear light intensity optical needle to be modulated based on actual detection requirements, including the length, number of focal points, and light intensity distribution of the linear light intensity optical needle to be generated. In this embodiment of the present invention, the length of the linear light intensity optical needle is set to L, and the number of focal points of the linear light intensity optical needle to be generated is set to M.

[0026] like Figure 2 As shown, the first focus is set according to the detection depth and the absorption rate of the sample to be tested to the light intensity energy. The light intensity at the location is , the first focus The light intensity at the location is , the Mth focus The light intensity at the location is Among them, the first focus The focal point closest to the incident direction of the light beam among the M focal points corresponds to the shallowest layer of the sample to be tested. Combined with the length L of the linear light intensity optical needle to be generated, the ideal light intensity distribution curve of the linear light intensity optical needle to be generated can be calculated as: ; in, Indicates the The ideal light intensity at each focal point, Indicates the first focus and the The distance of the focal point, Indicates the first focus of the linear optical needle to be generated The light intensity at the location, represents the ideal slope of the linear light intensity distribution curve of the linear light intensity optical needle to be generated, , Represents the Mth focus of the linear optical needle to be generated The light intensity at the location.

[0027] S2: Determine the optical axis of the linear optical needle to be generated, generate M focal points on the optical axis, and initialize the position and interval of each focal point. The initialization method can be to choose to distribute the intervals of all focal points equally or to randomly distribute the intervals of all focal points. In addition, it should be noted that the first focal point Light intensity at the location and the Mth focus Light intensity at the location By optimizing the position of the focal point and the interval between adjacent focal points, the light intensity distribution curve of the generated linear optical needle is made close to the ideal light intensity distribution curve.

[0028] In the embodiment of the present invention, in order to realize the above-mentioned optimization design, the optimization objective function is first set, that is, the linearity of the linear light intensity optical needle generated after optimization. Approaching the ideal slope ,Right now Since it is difficult to achieve linearity of the linear light intensity optical needle during the optimization process Completely equal to the ideal slope , so the preset conditions are set. When the linear light intensity of the optical needle formed by the M focal points is optimized, the linearity With the ideal slope If the preset conditions are met, it can be considered that the positions and intervals of the M focal points are optimized successfully, and the actually generated linear light intensity optical needle meets the design requirements and is approximately an ideal linear light intensity optical needle.

[0029] Specifically, the embodiment of the present invention designs the following three preset conditions, among which the three preset conditions can individually determine whether the positions and intervals of the M focal points are optimized, or can be combined with each other. The optimization is considered to be completed only when the linear light intensity optical needle generated after optimization satisfies the following two or three preset conditions at the same time.

[0030] Preset condition 1: The sum of the differences between the actual light intensity at the M focal points after optimization and the ideal light intensity is less than the set first threshold. This preset condition requires calculating the actual light intensity at each focal point after optimization. ,in Indicates any focus. And calculate the actual light intensity and the ideal light intensity obtained by calculating the ideal light intensity distribution curve of the linear light intensity optical needle to be generated The difference between the actual light intensity and the ideal light intensity of all focal points is summed to obtain the total difference for: .

[0031] Set a first threshold ,when When the linear light intensity optical needle is considered to be linear Approaching the ideal slope , the positions and intervals of the M focal points are optimized.

[0032] Furthermore, the preset condition can also be further converted into the average difference, that is, the average difference is calculated , The smaller the value, the better the linearity. The closer to the ideal slope , and the optimization end time is also determined by setting a threshold.

[0033] Preset condition 2: The maximum difference between the actual light intensity and the ideal light intensity in the M focal points after optimization is less than the set second threshold. This preset condition requires calculating the actual light intensity at each focal point after optimization. , and calculate the actual light intensity at each focal position and the ideal light intensity obtained by calculating the ideal light intensity distribution curve of the linear light intensity optical needle to be generated The difference between the two values is calculated and the maximum difference among all the differences is obtained. , The smaller it is, the closer the generated linear light intensity optical needle is to the linear light intensity distribution.

[0034] Similarly, set a second threshold ,when When the linear light intensity optical needle is considered to be linear Approaching the ideal slope , the positions and intervals of the M focal points are optimized.

[0035] Preset condition three: After optimization, the standard deviation or variance of the actual light intensity at the M focal points relative to the ideal light intensity is less than the set third threshold. This preset condition requires calculating the actual light intensity at each focal point after optimization. , and calculate the actual light intensity at each focal position and the ideal light intensity obtained by calculating the ideal light intensity distribution curve of the linear light intensity optical needle to be generated The difference, and further calculate the variance or standard deviation : .

[0036] variance and standard deviation The smaller it is, the closer the generated linear light intensity optical needle is to the linear light intensity distribution.

[0037] Similarly, set a third threshold ,when When the linear light intensity optical needle is considered to be linear Approaching the ideal slope , the position and spacing of M focal points are optimized. For example, the calculation and judgment principle of variance is similar to that of standard deviation. same.

[0038] According to actual needs, any one, two, or three of the three preset conditions are used as the optimization objective function of the focus position and interval to optimize the position and interval of the M focus points. In the embodiment of the present invention, the focus position and interval are optimized using a genetic algorithm in MATLAB. The optimization principle and process of the genetic algorithm are as follows: The initialized number, position, and spacing of the focal points are input into MATLAB. A set of initial data is randomly selected as initial conditions to form the initial population. The initial data includes the initial position of each focal point and the initial spacing between adjacent focal points. The light intensity of each focal point in the initial population is obtained, with the light intensity of the first and Mth focal points being constant values. The difference between the actual and ideal light intensity is used as an evaluation function to measure the quality of each individual. Restrictions are placed around the allowed position range of each focal point, and the focal positions are determined through random selection. This allows the selection of a subset of focal points from the current population as parent candidates for subsequent operations. The selection process tends to favor individuals with higher evaluation function values, meaning those with smaller differences between the actual and ideal light intensities, guiding the algorithm towards more optimal solutions.

[0039] A crossover operation is performed between every two or several individuals (the number is less than the number of focal points). The specific operation is to calculate the light intensity slope between them and compare the calculated result with the ideal slope. Based on the comparison, it is determined whether and how to crossover to generate new individuals.

[0040] The position of each focus is randomly altered, simulating the mutation process in biological evolution and preventing the algorithm from becoming trapped in a local optimum. By introducing mutation, new genes are introduced into the population, further enhancing population diversity and enabling the algorithm to escape local optima and continue searching for a global optimal solution. The generated focus data is used to form an optical needle. When the generated optical needle meets the aforementioned pre-defined conditions, the solution is considered to have been found, the genetic optimization process is terminated, and the positions and spacing of the M focuses at that point are output.

[0041] S3: Based on the positions and intervals of the M focal points obtained by the above optimization, the phase modulation information corresponding to each focal point is determined by spatial multiplexing, and a phase map of the linear light intensity optical needle is generated. The process of generating the phase map by spatial multiplexing is as follows: Set a phase mask for generating a phase map, divide the phase mask into a grid, including multiple cells, each cell can be considered to correspond to a pixel in the subsequent imaging. Then divide the sub-units according to the number of focal spots, divide M cells into a sub-unit, and map the phases corresponding to the optimized M focal spots in the M cells of each sub-unit to form a phase map. For example, when M=9, then The cell is regarded as a sub-unit. Assume that the pixel size of the spatial modulator is , then we can form sub-units. A cell in each sub-unit corresponds to a phase and is responsible for modulating a focus. All cells with the same phase modulate together to form a focus, so the number of pixels corresponding to one focus is .

[0042] A spatial light modulator is used to load the phase diagram of a linear light intensity optical needle. The spatial light modulator performs modulation based on the phase diagram of the linear light intensity optical needle. After the light beam passes through the spatial light modulator with the loaded phase diagram, a linear light intensity optical needle is formed. When it is necessary to generate an optical needle with different optical parameters, the light intensity distribution curve of the optical needle can be directly redesigned, the focal position and interval can be re-optimized, a new phase diagram can be generated, and the new phase diagram can be loaded using the spatial light modulator. After the light beam passes through the spatial light modulator, the modulation change can be achieved, and a new optical needle can be generated. The modulation generation of the optical needle using the above method has the advantages of reusability and dynamic loading of phase patterns. It can also easily adjust the parameters of the optical needle, overcoming the limitations of traditional DOE modulation.

[0043] In a preferred embodiment, the spatial light modulator utilizes a liquid crystal spatial light modulator (LCSLM). After obtaining a phase map of a linear intensity optical needle, the phase values of the phase map are normalized to the modulatable phase range of the LCSLM. This prevents the phase values in the phase map from exceeding the range that the LCSLM can handle. This normalization ensures that each phase value is appropriately scaled to the operating range of the LCSLM, thereby ensuring modulation accuracy and effectiveness. Based on the correspondence between the grayscale values of the LCSLM and the phase delays in the phase map, the phase values of the phase map are converted to corresponding grayscale values to generate a grayscale map. This grayscale map serves as an instruction for the LCSLM, precisely defining the orientation of the liquid crystal molecules at each position within the LCSLM to achieve precise modulation of the light beam phase. The LCSLM adjusts the orientation of the liquid crystal molecules based on the grayscale map, modulating the input light beam into a linear intensity optical needle.

[0044] As a preferred embodiment, the spatial light modulator uses a digital micromirror device (DMD), which is composed of many tiny micromirrors that can rotate rapidly. After obtaining the phase diagram of the linear light intensity optical needle, the 4f system is used to adjust the optical focal relationship between the object plane and the image plane to achieve phase modulation. The phase is changed by changing the vertical axis displacement distance between adjacent micromirrors. That is, the phase value of the phase diagram is converted into the axial height of the micromirrors in the digital micromirror device. When the axial height of the micromirrors is shifted, the optical path of light after reflection from the micromirrors to the subsequent optical system is changed, thereby achieving phase modulation. The relationship between the axial height of the micromirrors and the phase is: ; in, Indicates the phase difference between the current focus phase and the initial focus phase, It represents the optical path difference caused by the change of the micro-mirror axial height distribution, that is, the optical path difference between the micro-mirror axial height and the initial focus position after the micro-mirror axial height changes. Indicates the central wavelength of the light beam, that is, the wavelength of the incident light.

[0045] Based on the above-mentioned method for generating linear light intensity optical needles, the present invention applies it in the OCT system. To solve the problem of light intensity attenuation during coherent tomography, a linear light intensity optical needle is generated as the detection light to perform imaging detection on the sample to be tested, ensuring that clear imaging can be obtained in both deep and shallow layers. Specifically, Figure 3 As shown, the OCT system includes: a light source 1, a spectrometer 2, a spectrometer 3, a reference arm 4, and a detection arm 5, wherein the light source 1 emits coherent light, which is split into detection light and reference light after passing through the spectrometer 3. The reference light is incident on the reference arm 4, and the detection light is incident on the detection arm 5. After being modulated by the spatial light modulator 53 in the detection arm 5, a linear light intensity optical needle is formed, which is incident on the sample to be tested 56. The linear light intensity optical needle is reflected at different depths of tissue in the sample to be tested 56, and the reflected light at different depths interferes with the reference light processed by the reference arm 4 to generate an interference signal. The interference signal is incident on the spectrometer 2, and the spectrometer 2 analyzes the Fourier transform of the interference light spectrum signal to obtain depth information and realize coherent tomography.

[0046] The detection arm 4 includes a collimator 51, a semi-transparent and semi-reflective mirror 52, a spatial light modulator 53, a galvanometer 54, a focusing mirror 55, and a sample to be measured 56. After the probe light is split by the beam splitter 3, it is first collimated by the collimator 51. The collimated probe light is then input into the semi-transparent and semi-reflective mirror 52, where the transmitted portion continues to propagate and enters the spatial light modulator 53. The spatial light modulator 53 is loaded with a phase map obtained using the method for generating linear light intensity optical needles. After the probe light is irradiated by the spatial light modulator 53, the spatial light modulator 53 modulates the probe light into a linear light intensity optical needle and reflects the linear light intensity optical needle toward the semi-transparent and semi-reflective mirror 52. At this time, a portion of the linear light intensity optical needle is reflected toward the galvanometer 54, which then reflects the linear light intensity optical needle toward the focusing mirror 55. After being processed by the focusing mirror 55, the linear light intensity optical needle is irradiated onto the sample to be measured 56. The linear light intensity optical needle reflects at different depths in the tissue of the sample 56 to be measured. The reflected light at different depths interferes with the reference light processed by the reference arm 3, generating an interference signal, which is incident on the spectrometer 2. The placement angle of the galvanometer 54 can be rotated. By controlling the spatial angle of the galvanometer 54, coherent tomography imaging of different regions of the sample 56 to be measured can be achieved.

[0047] Because the probe light of the present invention is modulated by the spatial light modulator 53 to form a linear light intensity optical needle, and the light intensity of the linear light intensity optical needle increases with the depth of the incident sample 56, this linear light intensity can effectively compensate for the problem of light intensity energy attenuation caused by light absorption by the sample 56. This ensures that the light signal intensities reflected from tissues at different depths are relatively close, avoiding the problem of low light intensity reflected from deep tissues when conventional uniform light optical needles probe the sample 56, resulting in reduced imaging contrast and the inability to obtain clear, high-resolution images.

[0048] In short, the above description is only a preferred embodiment of this specification and is not intended to limit the scope of protection of this specification. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this specification shall be included in the scope of protection of this specification.

[0049] The systems, devices, modules, or units described in one or more of the above embodiments may be implemented by a computer chip or entity, or by a product having a certain function. A typical implementation device is a computer. Specifically, the computer may be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smartphone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

[0050] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0051] The various embodiments in this specification are described in a progressive manner. Similar parts between the various embodiments can be referred to in conjunction with each other. Each embodiment focuses on the differences between the other embodiments. In particular, the system embodiments are generally similar to the method embodiments, so the description is relatively simple. For relevant parts, refer to the description of the method embodiments.

[0052] The foregoing description of this specification describes specific embodiments. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims can be performed in an order different from that described in the embodiments and still achieve the desired results. Furthermore, the processes depicted in the accompanying drawings do not necessarily require the specific order shown or the sequential order to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

Claims

1. A method for generating a linear light intensity optical needle, characterized in that: include: Determine the number M and length of the focal points of the optical needle to be generated, and set the ideal slope of the linear light intensity distribution curve of the optical needle to be generated ; Generating M focal points, and optimizing the positions and intervals of the M focal points so that the linearity of the linear light intensity optical needle formed by the optimized M focal points and the ideal slope meet preset conditions; The phase corresponding to each focus is determined according to the optimized positions and intervals of the M focuses, and a phase diagram of the linear light intensity optical needle is formed, and the phase diagram is loaded by a spatial light modulator.

2. The method for generating a linear light intensity optical needle according to claim 1, characterized in that: The ideal slope The setup process includes: Set the first focus of the linear optical needle to be generated Light intensity at the location and the Mth focus Light intensity at the location , combined with the length L of the linear light intensity optical needle to be generated, the ideal light intensity distribution curve of the linear light intensity optical needle to be generated is: ； in, Indicates the The ideal light intensity at each focal point, Indicates the first focus and the The distance of the focal point, Indicates the first focus of the linear optical needle to be generated The light intensity at the location, , Represents the Mth focus of the linear optical needle to be generated The light intensity at the location.

3. The method for generating a linear light intensity optical needle according to claim 2, characterized in that: The preset conditions are: After optimization, the sum of the differences between the actual light intensity at the positions of the M focal points and the ideal light intensity is less than the set first threshold.

4. The method for generating a linear light intensity optical needle according to claim 2, characterized in that: The sum of the differences between the actual light intensity at the M focal points after optimization and the ideal light intensity for: ； in, The first linear light intensity optical needle generated by the M focal points after optimization is represented by The actual light intensity at the focal point.

5. The method for generating a linear light intensity optical needle according to claim 2, characterized in that: The preset conditions are: After optimization, the maximum difference between the actual light intensity and the ideal light intensity in the M focal points is less than a set second threshold.

6. The method for generating a linear light intensity optical needle according to claim 2, characterized in that: The preset conditions are: After optimization, a standard deviation or variance of the actual light intensity at the positions of the M focal points relative to the ideal light intensity is less than a set third threshold.

7. The method for generating a linear light intensity optical needle according to claim 1, characterized in that: The spatial light modulator is a liquid crystal spatial light modulator, and the phase map is loaded using the liquid crystal spatial light modulator. The method includes normalizing the phase values of the phase map to within the modulatable phase range of the liquid crystal spatial light modulator, and converting the phase values of the phase map into corresponding grayscale values based on the correspondence between the grayscale values of the liquid crystal spatial light modulator and the phase delay in the phase map to generate a grayscale map. The liquid crystal spatial light modulator performs liquid crystal modulation according to the grayscale map.

8. The method for generating a linear light intensity optical needle according to claim 1, characterized in that: The spatial light modulator is a digital micromirror device, and the phase map is loaded using the digital micromirror device, including: converting the phase value of the phase map into the axial height of a micromirror in the digital micromirror device, and performing phase modulation using the digital micromirror device, wherein the relationship between the axial height and the phase of the micromirror is: ； in, Indicates the phase difference between the current focus phase and the initial focus phase, represents the optical path difference, Indicates the central wavelength of the light beam.

9. The method for generating a linear light intensity optical needle according to claim 1, characterized in that: The generation process of the phase diagram is: A phase mask for generating the phase map is set, the phase mask is divided into a plurality of cells, M cells are divided into a sub-unit, and phases corresponding to the optimized M focal points are respectively set in the M cells of each sub-unit to form the phase map.

10. An OCT system, characterized in that: include: Light source, spectrometer, reference arm, and detection arm; Wherein, the detection arm includes: a collimating lens, a semi-transparent and semi-reflective mirror, a spatial light modulator and a sample to be tested. The spatial light modulator uses the method for generating a linear light intensity optical needle as described in any one of claims 1 to 9 to modulate the detection beam to generate a linear light intensity optical needle for imaging detection.

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