Optical needle generation method for OCT system, spatial light modulator, detection arm optical path, and OCT system

Abstract

The present invention relates to the field of optical detection technology, and specifically provides an optical needle generation method, a spatial light modulator, a detection arm optical path, and an OCT system for an OCT system. The method sets the number of focal points on the optical axis according to the target optical needle parameters, and optimizes the focal point position and interval; then generates a phase diagram of the target optical needle, and loads the phase diagram through a spatial light modulator. After the light beam is modulated by the spatial light modulator, the target optical needle can be generated. Compared with the traditional quartz optical diffraction element-based method, which has the disadvantage of having a fixed number of focal points and phase distribution and only being applicable to fixed parameter light beam adjustment, the present invention uses a spatial light modulator to modulate the generated optical needle, and can dynamically adjust the number of focal points and focal depth length by adjusting the spatial light modulator, thereby realizing dynamic modulation of the optical needle. The present invention further applies this method to a spatial light modulator, and for the first time uses a spatial light modulator in a detection arm optical path and an OCT system to modulate the detection beam.

Description

Technical Field

[0001] The present invention belongs to the field of optical detection technology, and in particular relates to an optical needle generation method, a spatial light modulator, a detection arm optical path, and an OCT system for an OCT system. Background Art

[0002] As a non-invasive, high-resolution biomedical imaging method, optical coherence tomography (OCT) technology has broad application prospects in a variety of fields, including biological imaging, surface profiling, film thickness measurement, multilayer film inspection, and sub-surface damage detection. In these applications, precise modulation and control of the optical beam is one of the key factors in achieving high-precision detection and imaging.

[0003] Optical needles are primarily classified into two types: one is a Bessel beam with a low degree of homogenization, and the other is a needle-shaped beam with a high degree of homogenization. Currently, designs exist for optical needle modulation using diffraction optical elements (DOEs). These designs employ a specific DOE based on the desired beam parameters, achieving beam shaping through the customized DOE. However, this DOE-based modulation approach has significant limitations. First, the DOE can only modulate optical needles with fixed parameters; once the beam length and width are determined, these parameters cannot be changed. Furthermore, adjusting different optical needles requires designing and customizing different DOEs, limiting flexible control. Furthermore, DOE production costs are relatively high, with pixel sizes typically ranging from 1 to 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 correspondingly greater manufacturing errors, significantly limiting the flexibility and cost-effectiveness of DOEs in practical applications. Summary of the Invention

[0004] In light of this, the present invention aims to provide a method for generating an optical needle for an OCT system. This method utilizes a spatial light modulator (SLM) to replace the quartz optical diffraction element used in conventional OCT systems. By performing phase modulation at each focal point of the optical needle and forming a phase map of the target optical needle, the SLM is used to load the phase map, achieving optical needle generation. The present invention further provides a SLM, a detector arm optical path, and an OCT system.

[0005] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0006] The present invention provides, in a first aspect, a method for generating an optical needle for an OCT system, comprising:

[0007] The number of focal points on the optical axis is set according to the target optical needle parameters, the focal position and interval are initialized, and the focal position and interval are optimized so that the light intensity distribution from the first focus to the last focus meets the light intensity distribution curve preset by the target optical needle;

[0008] The phase to be modulated corresponding to each focus is obtained through spatial multiplexing, and a phase map of the target optical needle is formed. The phase map is loaded using a spatial light modulator, and the target optical needle is formed after the light beam passes through the spatial light modulator.

[0009] Preferably, the preset light intensity distribution curve is an axial light intensity uniform distribution curve.

[0010] Preferably, when initializing the focus positions and spacings, the focus points are set equidistantly or non-equidistantly.

[0011] 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.

[0012] 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:

[0013] ;

[0014] 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.

[0015] Preferably, the optimization objective function of the genetic algorithm is:

[0016] ;

[0017] in, Indicates the uniformity of light intensity distribution from the first focus to the last focus. The optimization goal is Approaching 0, Indicates the maximum light intensity between the first focus and the last focus. Indicates the minimum light intensity between the first focus and the last focus.

[0018] Preferably, the adjustable parameters of the target optical needle include beam length, width and light intensity distribution.

[0019] A second aspect of the present invention provides a spatial light modulator that adopts an optical needle generation method for an OCT system.

[0020] The third aspect of the present invention provides a detection arm optical path, comprising:

[0021] a collimating lens, used for collimating the detection light;

[0022] a polarizer for processing the probe light into linearly polarized light;

[0023] a spatial light modulator that dynamically adjusts the light beam based on an input phase pattern;

[0024] The galvanometer is used to change the propagation direction of the detection light and perform scanning detection on the sample.

[0025] A fourth aspect of the present invention provides an OCT system, comprising: a light source, a spectrometer, a reference arm optical path, a detection arm optical path, and a spectrometer.

[0026] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0027] This invention replaces traditional optical diffraction elements (DOEs) with spatial light modulators (SLMs), optimizes the focal position and spacing, and then uses spatial multiplexing to obtain the phase modulation corresponding to each focal point. This SLM then uses the SLM to load a phase pattern. When generating optical needles with different parameters, different phase patterns can be loaded through the SLM, enabling flexible modulation of the optical needles to meet different needs. Compared to DOE modulation, SLMs offer advantages such as reusability and the ability to dynamically load phase patterns. They can easily adjust parameters such as the length, width, and light intensity distribution of the optical needle, overcoming the limitations of DOE modulation, which often have fixed parameters and high costs. This significantly improves the adaptability and flexibility of OCT systems in different application scenarios, reduces equipment costs, and provides strong support for the widespread application of OCT technology in biological imaging, surface shape detection, film thickness detection, multilayer film detection, and sub-surface damage detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] 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:

[0029] Figure 1 is a flow chart of a method for generating an optical needle for an OCT system according to an embodiment of the present invention;

[0030] Figure 2 is a schematic diagram of light intensity distribution of an optical needle provided according to an embodiment of the present invention;

[0031] Figure 3 is a graph showing the axial light intensity distribution of an optical needle provided according to an embodiment of the present invention;

[0032] Figure 4 is a diagram of an optical path of a detector arm for an OCT system provided according to an embodiment of the present invention;

[0033] Figure 5 2 is an optical path diagram of an OCT system provided according to an embodiment of the present invention.

[0034] Reference numerals include:

[0035] Spatial light modulator 1, collimating lens 2, polarizer 3, first galvanometer 4, second galvanometer 5, focusing lens 6, sample 7;

[0036] First lens f1, second lens f2, third lens f3;

[0037] Light source 10 , spectrometer 20 , reference arm optical path 30 , and spectrometer 40 . DETAILED DESCRIPTION

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0043] Example 1: Please refer to Figure 1 In Example 1 of the present invention, a method for generating an optical needle for an OCT system is provided, which is used to generate an optical needle with uniform axial light intensity. OCT technology based on optical needles has wide applications in biological imaging, surface shape detection, film thickness detection, multilayer film detection, sub-surface damage detection, and other fields. The optical needle generation method specifically includes the following steps:

[0044] S1: First, determine the optical parameters of the target optical needle to be modulated based on actual application requirements, such as the length, width, and light intensity distribution of the target optical needle. In OCT systems, a uniform light intensity distribution along the axial direction of the optical needle is generally required. In this embodiment, the preset light intensity distribution curve of the target optical needle is a uniform axial light intensity distribution curve.

[0045] The number of focal points on the optical axis can be set according to parameters such as the length, width, and light intensity distribution of the target optical needle. Generally speaking, the longer the optical needle is, the more focal points it requires. Longer optical needles need to maintain specific light intensity distribution characteristics within a longer optical axis range, so more focal points need to be set on the optical axis to finely control the shape and energy distribution of the light beam. For example, when the OCT system performs deep detection imaging of biological tissue, in order to ensure that clear and uniform images can be obtained throughout the entire imaging depth range, it is necessary to generate an optical needle with a longer length, and thus it is necessary to set more focal points on the optical axis to achieve stable focusing and energy regulation of the light beam over a long distance. Generally, the length of the optical needle and the number of focal points are required to meet the following conditions:

[0046] ;

[0047] in, represents the Rayleigh length of the objective lens of the OCT system, represents the length of the optical needle, M represents the number of focal points, It is a preset value used to limit the maximum distance between adjacent focal points to ensure that the beam does not expand too much between the focal points.

[0048] Similarly, the width of the optical needle will also affect the number of focal points on the optical axis. The width of the light beam will affect the focusing accuracy and energy distribution. Therefore, the number of focal points will be adjusted to ensure that the optical needle has good focusing performance and uniform energy distribution in both the axial and radial directions.

[0049] After setting the number of focal points, the positions of the focal points and the intervals between adjacent focal points are initialized, that is, the positions of all focal points and the intervals between adjacent focal points are randomized, that is, the focal points can be set equidistantly or unequally. Generally, it is preferred to set the focal points equidistantly.

[0050] S2: After the focus is initialized, the focus position and interval are optimized using an optimization algorithm so that the light intensity distribution from the first focus to the last focus in the axial direction meets the preset light intensity distribution curve of the target optical needle, that is, the light intensity from the first focus to the last focus is uniformly distributed.

[0051] In an embodiment of the present invention, the initialized number, position, and interval of the focal points are input into MATLAB, and the focal position and interval are optimized using a genetic algorithm in MATLAB. The optimization objective function of the genetic algorithm is:

[0052] ;

[0053] in, Indicates the uniformity of light intensity distribution from the first focus to the last focus. The optimization goal is Approaching 0, Indicates the maximum light intensity between the first focus and the last focus. Indicates the minimum light intensity between the first focus and the last focus.

[0054] Furthermore, the optimization method is not limited to the genetic algorithm in MATLAB. Dodging optimization can also be achieved using other languages. The basic processing process of the genetic algorithm is:

[0055] A set of initial solutions are randomly selected as initial conditions to form an initial population, that is, the position of the focus and the interval between adjacent focuses are initialized.

[0056] The evaluation function is set as the standard for measuring the quality of individuals. In the implementation of the present invention, energy uniformity is used. As the evaluation criterion, it is used to evaluate the quality of the current solution.

[0057] Restrictions are placed near the allowed position range of each focus, and the focus position is determined by random selection, so that some individuals are selected from the current population as parent candidates for subsequent operations. The selection process tends to select individuals with higher evaluation function values ​​to guide the algorithm towards a better solution.

[0058] 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 uniformity between them, compare the calculated results with the evaluation criteria, and determine whether and how to crossover based on the comparison to generate new individuals.

[0059] The position of each focal point is randomly changed to simulate the mutation process in biological evolution, preventing the algorithm from falling into a local optimal solution. By introducing new genes into the population through mutation operations, the diversity of the population is further enhanced, allowing the algorithm to escape the local optimal solution and continue to search for the global optimal solution.

[0060] Set the termination condition, when the light intensity uniformity When the value is less than a preset threshold (for example, 0.05, which means that the light intensity uniformity reaches more than 95%), it is considered that a solution that meets the requirements has been found, the calculation process is stopped, and the optimal solution or approximate optimal solution at this time is output.

[0061] S3: Based on the optimized focal position and spacing, spatial multiplexing is used to generate phase modulation information corresponding to each focal point, i.e., the phase to be modulated, thereby forming a phase map of the target optical needle. Phase modulation can precisely control the beam characteristics at each focal point. The spatial multiplexing process involves generating a phase mask with densely spaced focal points through spatial multiplexing along the axial direction. Specifically, the phase mask is divided into multiple groups, each responsible for generating a focal point at a specific axial position. Multiple focal points are generated simultaneously on the optical axis, each corresponding to different phase information. By mapping the phase modulation information of each focal point to the corresponding position in the phase map, a complete phase map of the target optical needle can be generated.

[0062] S4: Using a spatial light modulator to load the phase pattern of the target optical needle, the spatial light modulator performs modulation according to the phase pattern of the target optical needle. After the light beam passes through the spatial light modulator loaded with the phase pattern, the target optical needle can be formed.

[0063] When an optical needle with different optical parameters needs to be generated, the focal position and interval can be directly regenerated and optimized to generate a new phase map. The new phase map can be loaded using a spatial light modulator. After the light beam passes through the spatial light modulator, the modulation change can be achieved to generate a new optical needle.

[0064] The modulation generation of the optical needle by the above method has the advantages of reusability and dynamic loading of phase patterns. It can easily adjust the parameters of the optical needle and overcome the limitations of traditional DOE modulation.

[0065] In a preferred embodiment, the spatial light modulator utilizes a liquid crystal spatial light modulator (LCSLM). After obtaining the phase map of the target optical needle in step S3, the phase values ​​in 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 ​​in 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 in 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 an optical needle with a specific phase distribution. This ensures that the generated optical needle meets the stringent requirements of OCT systems in various application scenarios. This method can achieve flexible control of the optical needle length, diameter and axial intensity distribution, thereby significantly improving the imaging quality and detection accuracy of the OCT system.

[0066] Specifically, the liquid crystal spatial light modulator is mainly composed of a liquid crystal layer, a transparent electrode, a polarizer, a substrate and other parts. Among them, the liquid crystal layer is a thin film composed of liquid crystal molecules. The liquid crystal molecules have long rod-like or disc-like shapes and have anisotropic and polarizable properties. The transparent electrode is used to apply voltage to control the orientation of the liquid crystal molecules. The polarizer is used to polarize the incident light, and the substrate is usually made of glass or plastic and other materials to play a supporting and protective role. When light is irradiated on the liquid crystal spatial light modulator, the deflection angle and arrangement direction of the liquid crystal molecules are controlled by adjusting the applied voltage, thereby changing the optical properties of the liquid crystal, which in turn causes the phase, amplitude or polarization state of the light to change, thereby achieving spatial modulation of the light wave.

[0067] The long axis direction of the liquid crystal molecules corresponds to the extraordinary light, and its refractive index is , and the short axis direction corresponds to ordinary light, whose refractive index is The effective refractive index of liquid crystal molecules The phase delay of light is related to the wavelength of the incident light. and the thickness of the liquid crystal layer Relatedly, by controlling the deflection angle and effective refractive index of liquid crystal molecules, the phase of the light wave can be precisely modulated, thereby realizing the phase modulation function.

[0068] The effective refractive index of liquid crystal molecules for:

[0069] ;

[0070] in, Indicates the position of liquid crystal molecules in the liquid crystal layer y The deflection angle at y Indicates the thickness direction along the liquid crystal layer.

[0071] Phase delay of light for:

[0072] .

[0073] 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 target optical needle through step S3, 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 displaced, the optical path of the light after being reflected from the micromirrors to the subsequent optical system will change, thereby achieving phase modulation. The relationship between the axial height of the micromirrors and the phase is:

[0074] ;

[0075] 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.

[0076] like Figure 2 As shown, the inner portion of the axial light intensity of the target optical needle generated by the above method. Figure 3 is the normalized light intensity distribution curve of the target optical needle. Figure 2 and Figure 3 It can be seen that after the light beam passes through the spatial light modulator, the light intensity distribution of the generated target optical needle conforms to the preset light intensity uniform distribution curve.

[0077] Example 2: In Example 2 of the present invention, a liquid crystal spatial light modulator is provided. On the basis of the existing liquid crystal spatial light modulator, a phase map generation module is added. The optical needle generation method for the OCT system in Example 1 is used to generate a phase map. The phase map is input into the liquid crystal spatial light modulator to realize light beam modulation.

[0078] Example 3: Figure 4As shown, in Example 3 of the present invention, a detection arm optical path is provided, specifically comprising: a collimating lens 2, a polarizer 3, a spatial light modulator 1, and a second galvanometer 5, arranged in sequence along the transmission direction of the detection light. The spatial light modulator 1 is a liquid crystal spatial light modulator. The detection light first passes through the collimating lens 2, which collimates the detection light into a parallel beam. After the beam is collimated, it is transmitted through the polarizer 3, which is a linear polarizer. The polarizer 3 processes the detection light into linearly polarized light. Linearly polarized light can reduce the interference of scattered light and stray light during the detection of the sample 7. Furthermore, linearly polarized light has a clear polarization direction and phase relationship, which facilitates maintaining a stable interference signal during the interference process of the OCT system.

[0079] After passing through polarizer 3, the probe light is directed toward first galvanometer 4, which adjusts the direction of the probe light. This galvanometer guides the probe light to spatial light modulator 1, which modulates the probe light to form a target optical needle. After being modulated by spatial light modulator 1, the target optical needle is directed toward second galvanometer 5, a fast-deflecting mirror. This second galvanometer 5 directs the target optical needle toward focusing lens 6, which focuses the target optical needle onto sample 7, achieving coherent tomography of sample 7. Adjusting the second galvanometer 5 dynamically controls the direction of the target optical needle, enabling two-dimensional dynamic scanning of sample 7.

[0080] In addition, a 4f system can be set up in the propagation optical path to scale the probe light. Specifically, a first lens f1 is set between the polarizer 3 and the first galvanometer 4. A shared second lens f2 is set up in the optical path to the spatial light modulator 1 and the optical path emitted by the spatial light modulator 1. That is, the probe light emitted to the spatial light modulator 1 and the target optical needle modulated by the spatial light modulator 1 and emitted by the spatial light modulator 1 to the second galvanometer 5 both pass through the second lens f2. A third lens f3 is set up in the optical path from the target optical needle through the second lens f2 to the second galvanometer 5. The first lens f1 and the second lens f2 form a 4f system for amplifying the beam diameter, adjusting the diameter of the probe light beam to match the target surface size of the spatial light modulator 1 to achieve a better modulation effect. The second lens f2 and the third lens f3 form another 4f system for reducing the beam diameter, so that the size of the second galvanometer 5 matches the entrance pupil of the focusing lens 6 (i.e., the scanning objective lens). In the embodiment of the present invention, since the effective modulation angle of the spatial light modulator 1 is relatively small, typically between ±5°, the second lens f2 can be shared in terms of aperture. This shared design can also make the optical path more compact.

[0081] Example 4: Figure 5As shown, in Example 4 of the present invention, an OCT system is provided, comprising: a detection arm optical path as in Example 3, as well as a light source 10, a spectrometer 20, a reference arm optical path 30, and a spectrometer 40. The process of coherent tomography is as follows: the light source 10 emits coherent light, which is then split into detection light and reference light after passing through the spectrometer 40. The reference light is incident on the reference arm optical path 30, and the detection light is incident on the detection arm optical path. After being modulated by the spatial light modulator 1 in the detection arm optical path, an optical needle is formed. The optical needle is incident on the sample 7. The optical needle is reflected at different depths of the sample 7. The reflected light at different depths interferes with the reference light processed by the reference arm optical path to generate an interference signal. The interference signal is incident on the spectrometer 20. The spectrometer 20 analyzes the Fourier transform of the interference light spectral signal to obtain depth information, thereby achieving coherent tomography. When detection imaging at different depths is required, detection imaging at different depths can be achieved by adjusting the phase map loaded by the spatial light modulator 1 and the optical parameters of the generated optical needle.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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 an optical needle for an OCT system, characterized in that: include: Setting the number of focal points on the optical axis according to the target optical needle parameters, initializing the focal position and interval, and optimizing the focal position and interval so that the light intensity distribution from the first focus to the last focus meets the light intensity distribution curve preset by the target optical needle; The phase to be modulated corresponding to each focus is acquired through spatial multiplexing, and a phase diagram of the target optical needle is formed. The phase diagram is loaded by a spatial light modulator, and the target optical needle is formed after the light beam passes through the spatial light modulator.

2. The optical needle generation method for an OCT system according to claim 1, characterized in that: The preset light intensity distribution curve is an axial light intensity uniform distribution curve.

3. The optical needle generation method for an OCT system according to claim 1, wherein: When initializing the focus positions and spacing, the focus points are set to be equidistant or non-equidistant.

4. The optical needle generation method for an OCT system according to claim 1, wherein: 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.

5. The optical needle generation method for an OCT system according to claim 1, wherein: 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.

6. The optical needle generation method for an OCT system according to claim 4, characterized in that: The optimization objective function of the genetic algorithm is: ； in, Indicates the uniformity of light intensity distribution from the first focus to the last focus. The optimization goal is Approaching 0, Indicates the maximum light intensity between the first focus and the last focus. Indicates the minimum light intensity between the first focus and the last focus.

7. The optical needle generation method for an OCT system according to claim 1, wherein: The adjustable parameters of the target optical needle include beam length, width and light intensity distribution.

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