Focus drift compensation system, optical system and focus drift compensation method

Abstract

The application provides a focus drift compensation system, an optical system and a focus drift compensation method. The compensation system comprises: a flat mirror arranged between lenses of an optical system to be compensated; a temperature detector configured to detect the temperature of the flat mirror; and a temperature regulating module arranged on a first surface of the flat mirror and configured to compensate for the temperature of the flat mirror.

Description

Technical Field

[0001] This application relates to the field of laser technology, and more specifically, to a focus drift compensation system, an optical system, and a focus drift compensation method. Background Technology

[0002] As laser power increases, in addition to thermal expansion and deformation, the refractive index of optical lens materials also changes with temperature, causing thermal lensing effects, including focus shift and altered energy distribution due to thermal aberrations. Existing thermal lensing compensation methods require large amounts of data processing, have extremely high responsiveness requirements, and are therefore very costly to compensate for focus drift. Summary of the Invention

[0003] The purpose of this application is to provide a focus drift compensation system, an optical system, and a focus drift compensation method that can achieve focus drift compensation with a relatively simple structure and a small amount of data processing.

[0004] In a first aspect, this application provides a focus drift compensation system, comprising: a planar mirror for being disposed between lenses of an optical system to be compensated; a temperature detector for detecting the temperature of the planar mirror; and a temperature control module disposed on a first surface of the planar mirror for compensating the temperature of the planar mirror.

[0005] In the above embodiments, a plano mirror and a temperature control module can be set up. The temperature control module can perform thermal control on the plano mirror. Based on the adjustment of the temperature of the plano mirror, the focus drift of the optical system to be compensated can be compensated.

[0006] In an optional embodiment, the temperature control module is used to heat the planar mirror within a first defined range on the first surface of the planar mirror, and the edge of the first defined range does not extend beyond the edge of the planar mirror.

[0007] In the above embodiments, by performing temperature compensation on the first defined range, thermal aberration compensation characteristics can be achieved, which helps to correct the energy distribution of the final focused beam and improve beam convergence.

[0008] In an optional embodiment, the temperature control module is arranged within a first defined range on the first surface of the plano mirror, and the edge of the first defined range does not extend beyond the edge of the plano mirror.

[0009] In an optional implementation, the distance between the edge of the first defined range and the edge of the plano mirror is not less than a specified value, the specified value being no greater than half the longest diameter of the plano mirror.

[0010] In the above embodiments, the temperature control module can be applied to the central region of the plano mirror. The temperature control module adjusts the temperature of the central region of the plano mirror, and during the heating process, the temperature compensation center is higher than the edge. This corresponds to the fact that the center temperature of the lens of the conventional laser processing optical system, which is to be compensated, is higher than the edge temperature due to the Gaussian or Gaussian beam of the laser, is the same as that of the optical system to be compensated. Therefore, it can have a certain degree of thermal aberration compensation characteristics, which helps to correct the energy distribution of the final focused beam and improve the beam convergence.

[0011] In an optional implementation, the temperature control module includes a semiconductor cooler.

[0012] In an optional embodiment, the temperature detector is used to detect the temperature of a second defined range of the mirror surface of the plano mirror, the edge of the second defined range not exceeding the edge of the mirror surface of the plano mirror.

[0013] In the above embodiments, by detecting the temperature within the second defined range, the focus drift compensation can be better achieved based on the temperature within the second defined range, which can also realize the thermal aberration compensation characteristics, help correct the energy distribution of the final focused beam, and improve the beam convergence.

[0014] In an optional embodiment, the reflector is made of a material with a coefficient of thermal expansion greater than the thermal expansion threshold, a reflectivity greater than the reflection threshold, and a light absorption rate lower than the absorption threshold.

[0015] In the above embodiments, based on the large thermal expansion coefficient of the plano mirror, the temperature control module applies different temperatures to the plano mirror in real time to achieve temperature adjustment and control of the reflective surface of the plano mirror, so as to better adjust the focal length of the mirror from infinity to finite focal length by means of the micro-convex deformation of the mirror surface due to thermal expansion.

[0016] In an optional implementation, the focus drift compensation system includes multiple temperature sensors; Each temperature sensor is used to detect the temperature of each lens in the optical system to be compensated and one lens in the plano mirror; The temperature control module is also used to determine the adjustment temperature based on the temperatures of each lens of the optical system to be compensated and the temperature of the plano mirror detected by each of the temperature detectors, so as to use the adjustment temperature to compensate for the temperature of the plano mirror.

[0017] In the above embodiments, the adjustment temperature of the plano mirror can be calculated based on the real-time temperature detected by the temperature detector. With less computation, the temperature of the plano mirror can be adjusted more accurately and quickly, thereby enabling the compensation of focus drift of the optical system to be compensated.

[0018] Secondly, this application provides an optical system, including: a lens group and the focus drift compensation system described in the foregoing embodiments; the plano mirror is disposed between two of the lenses in the lens group.

[0019] In an optional embodiment, the lens group includes: a collimation protection lens, a collimation lens, a focusing lens, and a focusing protection lens; wherein, the plano mirror is disposed between the collimation lens and the focusing lens; the collimation protection lens is disposed on the side of the collimation lens away from the plano mirror; and the focusing protection lens is disposed on the side of the focusing lens away from the plano mirror.

[0020] In an optional embodiment, it further includes: a plurality of heat insulation components; the heat insulation components are disposed between the lens group and the individual lenses included in the plano mirror.

[0021] In the above embodiments, heat insulation components can also be provided between the lenses of the lens group to reduce the influence between the lenses.

[0022] In an optional implementation, multiple temperature sensors are also included; The number of temperature detectors is not less than the total number of lenses in the lens group and the mirror; each temperature detector is used to detect the temperature of one of the lenses.

[0023] Thirdly, this application provides a focus drift compensation method, applied to the focus drift compensation system of any one of the foregoing embodiments or the optical system described in any one of the foregoing embodiments, the method comprising: compensating the temperature of the mirror by means of the temperature control module of the focus drift compensation system.

[0024] In an optional implementation, the temperature control module determines the adjustment temperature based on the temperatures of each lens in the optical system to be compensated and the determined temperature of the plano mirror; the temperature control module then compensates for the temperature of the plano mirror based on the adjustment temperature.

[0025] In an optional implementation, the temperature adjustment is determined by the following formula: DF=M 2 *[k1*(T1-T0)+k2*(T2-T0)]+k3*(T3-T0)+k4*(T4-T0); T5 = -DF / k5 + T0; Where k1, k2, k3, and k4 represent the focus drift temperature conversion coefficients of the collimating protective lens, collimating lens, focusing lens, and focusing protective lens of the optical system to be compensated, respectively; k5 represents the focus drift temperature conversion coefficient of the mirror; T1, T2, T3, and T4 represent the real-time temperatures of the collimating protective lens, collimating lens, focusing lens, and focusing protective lens of the optical system to be compensated, respectively; T0 represents the initial reference temperature; T5 represents the adjustment temperature; and M represents the focal length ratio of the focusing lens to the collimating lens. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the focus drift compensation system provided in the embodiments of this application; Figure 2 A schematic diagram of the optical system provided in the embodiments of this application; Figure 3 A flowchart of the focus drift compensation method provided in the embodiments of this application.

[0028] Icons: 110-Mirror; 120-Temperature control module; 130-Temperature detector; S1-First side of the mirror; 210-Collimation protection lens; 220-Collimation lens; 230-Focusing lens; 240-Focusing protection lens; Lp-Optical path. Detailed Implementation

[0029] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0030] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this application, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0031] Fiber optic lasers typically have wavelengths between 400µm and 1100nm, with typical examples including blue light (445nm), green light (532nm), semiconductor light (970nm), and fiber light (1064nm). Commonly used laser processing head lens materials include quartz and sapphire, with quartz being the most prevalent. As laser power increases, in addition to thermal expansion and deformation, the refractive index of optical lens materials also changes with temperature, causing a thermal lensing effect. This thermal lensing effect may include focus drift and altered energy distribution due to thermal aberration.

[0032] Currently, common methods for compensating for thermal lensing effects include: the first method is to detect the curves of laser processing head changes with power and time using a focus drift detection instrument, and then supplement the control system with an algorithm through curve fitting for control compensation; the second method is to set a beam splitting spot detection module in the focused beam segment to detect the real-time spot size, and then compensate through the control system; the third method is to visually detect the processing width of the spot and adjust the focus position in real time to achieve a quantitative width.

[0033] The first method mentioned above is insufficient in compensating for differences in different batches and models of lenses, as well as for different laser parameters such as different divergence angles. The fitted curve also has limitations, requiring additional compensation strategies for users to compensate themselves, which carries uncontrollable risks. The second method mentioned above requires gradual compensation under unknown laser parameters. At the same time, the focus drift caused by the newly added beam splitter and the protective mirror at the end of the optical path cannot be detected, which also carries uncontrollable risks. The third method mentioned above requires real-time processing of detection graphic information, with a relatively large data processing volume and extremely high responsiveness requirements. Consequently, the cost of compensating for the required focus drift is relatively high.

[0034] Based on the above analysis, this application provides a focus drift compensation system, an optical system, and a focus drift compensation method. By applying different temperatures to the plano mirror in real time through a temperature control module, the temperature of the plano mirror's reflective surface is adjusted and controlled, so as to achieve the purpose of changing the focal length of the mirror from infinity to a finite focal length by causing the mirror surface to expand and deform slightly due to heat.

[0035] Please see Figure 1 This is a schematic diagram of a focus drift compensation system provided in an embodiment of this application. The focus drift compensation system may include a plano mirror 110, a temperature control module 120, and a temperature detector 130.

[0036] In this embodiment, the planar mirror 110 is disposed between the lenses of the optical system to be compensated, and the temperature control module 120 can be disposed on the first surface S1 of the planar mirror.

[0037] Temperature detector 130 is used to detect the temperature of the plano mirror 110 and the lens of the optical system to be compensated.

[0038] The planar mirror 110 can be a reflector, and the first surface can be the surface through which the light path Lp will not pass. For example... Figure 1 As shown, the first surface can be Figure 1 The first face S1 is shown.

[0039] Optionally, the temperature detector 130 can be used to detect the temperature within a defined area of ​​the plan-up mirror 110. For example, this defined area may be the central region of the lens. Taking a circular lens as an example, the defined area may be a circle with the center of the lens as its center and half the radius of the lens as its radius.

[0040] The temperature control module 120 can be used to compensate for the temperature of the mirror 110.

[0041] For example, the temperature control module 120 gradually adjusts based on the temperature feedback of the mirror 110 detected by the temperature detector 130 to compensate for the focus drift of the optical system to be compensated.

[0042] For example, when using the temperature control module 120 to adjust the temperature of the mirror 110, the temperature of the mirror 110 detected by the temperature detector 130 can be obtained according to a set time frequency. Based on the temperature feedback from the temperature detector 130, the temperature of the mirror 110 can be adjusted to compensate for the focus drift of the optical system to be compensated.

[0043] Optionally, the temperature control module 120 can also compensate for the temperature of the plano mirror 110 by adjusting the temperature. For example, the adjusted temperature can be a preset temperature; or it can be calculated based on the temperature of the lens of the optical system to be compensated and the temperature of the plano mirror 110.

[0044] Optionally, the focus drift compensation system includes multiple temperature detectors 130; each temperature detector 130 is used to detect the temperature of each lens of the optical system to be compensated and one lens of the plano mirror 110.

[0045] In this embodiment, the number of temperature detectors 130 can vary depending on the optical system to be compensated. One temperature detector 130 can be set for each lens, allowing for one-to-one temperature detection of each lens. This also makes the determined adjustment temperature more accurate.

[0046] Optionally, the number of temperature sensors 130 is one greater than the number of lenses in the optical system to be compensated; of course, the number of temperature sensors 130 can also be greater than the number of lenses in the optical system to be compensated. More temperature sensors 130 can serve as backup temperature sensors.

[0047] The temperature control module 120 is also used to determine the adjustment temperature based on the temperature of each lens of the optical system to be compensated and the temperature of the plano mirror detected by each temperature detector 130, so as to use the adjustment temperature to compensate the temperature of the plano mirror.

[0048] For example, each time temperature compensation is required for the mirror 110, the real-time temperature of each lens of the optical system to be compensated and the real-time temperature of the mirror 110 can be obtained by the temperature detector 130, and the adjustment temperature can be determined based on the real-time temperature of each lens.

[0049] Optionally, the adjustment temperature can be determined based on the temperature of each lens and the focal drift temperature conversion coefficient of each lens. Each lens has its own specific focal drift temperature conversion coefficient, which can be determined after the lenses of the optical system and the mirror are determined.

[0050] In this embodiment, the temperature control module 120 can obtain the temperature of each lens detected by each temperature detector 130, and then determine the adjustment temperature based on the obtained temperature and the focus drift temperature conversion coefficient of each lens.

[0051] Taking an optical system to be compensated that includes collimating protection lens 210, collimating lens 220, focusing lens 230, and focusing protection lens 240 as an example, the adjustment temperature determined by the temperatures of each lens in the optical system to be compensated and the temperature of the planar mirror 110 can be calculated using the following formula: DF=M 2 *[k1*(T1-T0)+k2*(T2-T0)]+k3*(T3-T0)+k4*(T4-T0); T5 = -DF / k5 + T0; Wherein, k1, k2, k3, and k4 represent the focus drift temperature conversion coefficients of the collimating protection lens 210, collimating lens 220, focusing lens 230, and focusing protection lens 240 of the optical system to be compensated, respectively; k5 represents the focus drift temperature conversion coefficient of the planar mirror 110; T1, T2, T3, and T4 represent the real-time temperatures of the collimating protection lens 210, collimating lens 220, focusing lens 230, and focusing protection lens 240 of the optical system to be compensated, respectively; T0 represents the initial reference temperature; T5 represents the adjustment temperature; and M represents the focal length ratio of the focusing lens 230 to the collimating lens 220.

[0052] In the example above, the temperature of the mirror can be adjusted to T5, which can compensate for the focus drift of the optical system to be compensated.

[0053] The above example only uses the collimating protection lens 210, collimating lens 220, focusing lens 230, and focusing protection lens 240 included in the optical system to be compensated. In actual use, the optical system to be compensated may contain more or fewer lenses. Different lenses have different focal drift temperature conversion coefficients.

[0054] By applying different temperatures to the plano-mirror 110 in real time, the temperature of the reflective surface of the plano-mirror 110 can be adjusted and controlled, achieving micro-convex deformation of the mirror surface due to thermal expansion. This allows the focal length of the plano-mirror 110 to vary from infinity to a finite focal length. When used in a conventional laser processing optical system, a temperature detector 130 determines the temperature rise of each lens during laser transmission, thus obtaining the focal drift of the lens. The temperature of the plano-mirror 110 is then used to compensate for the focal drift, achieving real-time reset of the focal drift in the conventional laser processing optical system and effectively ensuring the stability of the optical system during laser processing.

[0055] Considering that focus calibration is more important in the area of ​​the relative center of the lens, the temperature control module 120 can be used to heat the plano mirror 110 within a first defined range of the first surface S1 of the plano mirror 110, and the edge of the first defined range does not extend beyond the edge of the plano mirror 110.

[0056] To facilitate heating only within the first defined range, the temperature control module 120 can be arranged within the first defined range of the first surface S1 of the plano mirror 110, and the edge of the first defined range does not extend beyond the edge of the plano mirror 110.

[0057] The above-described configuration allows the temperature control module 120 to operate more accurately within the first defined range of the first surface S1 of the plano mirror, thereby achieving more accurate correction of focus drift. Furthermore, by performing temperature compensation on the plano mirror 110 in the relatively central region, thermal aberration compensation characteristics can be achieved, which helps to correct the energy distribution of the final focused beam and improve beam convergence.

[0058] Optionally, the distance between the edge of the first defined range and the edge of the plano mirror 110 is not less than a specified value, the specified value being no greater than half the longest diameter of the plano mirror 110.

[0059] Optionally, the first defined range may be the central region of the first surface S1 of the plano mirror. The area of ​​the central region may be half the area of ​​the first surface S1 of the plano mirror. The area of ​​the central region may be less than half the area of ​​the first surface S1 of the plano mirror.

[0060] Taking the mirror 110 as a circular lens as an example, the central area of ​​the first surface can be represented as the area with the center of the mirror 110 as the center and a radius not greater than half the radius of the mirror 110.

[0061] Of course, the mirror 110 can also be a lens of other shapes. The shape of the first defined range varies depending on the shape of the mirror 110. Optionally, when the mirror 110 is a lens of other shapes, the first defined range does not extend beyond the edge of the mirror 110, and the area of ​​the first defined range is not greater than half the area of ​​the mirror 110.

[0062] The above settings allow the temperature applied by the temperature control module 120 to the plano mirror 110 to be distributed in the central region of the plano mirror 110, thereby achieving a temperature distribution that is higher in the center than at the edge, in order to compensate for the focus drift caused by each lens of the optical system.

[0063] Optionally, the reflective mirror 110 is made of a material with a coefficient of thermal expansion greater than the thermal expansion threshold, a reflectivity greater than the reflection threshold, and a light absorption rate lower than the absorption threshold.

[0064] For example, the thermal expansion threshold, reflection threshold, and absorption threshold can all be set as needed. The thermal expansion threshold, reflection threshold, and absorption threshold can be set to relatively large values, which can reduce the situation where the plano-mirror 110 expands violently when heated, and can also reduce the light absorption caused during the heating process of the plano-mirror 110.

[0065] Optionally, the planar mirror 110 may have an extremely high melting point and a large thermal conductivity coefficient. For example, the material of the planar mirror 110 may be a high-purity metal, alloy material, etc.

[0066] The temperature control module 120 has a rapid temperature adjustment function. Optionally, the temperature control module 120 includes a thermoelectric cooler (TEC).

[0067] Considering that the focal point of the lens is mainly affected by the central area of ​​the lens, temperature adjustments are primarily made to the central area. Therefore, the temperature sensor 130 can be used to detect the temperature of a second defined range on the surface of the plano mirror 110. The edge of this second defined range does not extend beyond the edge of the plano mirror's surface.

[0068] Optionally, the temperature sensor 130 can be used to detect the temperature of a second defined range on the first surface of the plano mirror. The temperature sensor 130 can also be used to detect the temperature of a second defined range on the second surface of the plano mirror opposite to the first surface.

[0069] Optionally, the temperature sensor 130 can be connected to the mirror 110, for example, it can be connected to the frame of the mirror 110.

[0070] For example, the angle formed between the temperature detector 130 and the mirror surface of the plano mirror 110 can be set so that the temperature detector 130 can also be used to detect the temperature of the mirror surface of the plano mirror within a second defined range.

[0071] Optionally, the temperature detector 130 can also be a handheld temperature detector. When it is necessary to detect the temperature of the mirror, the temperature of the mirror surface of the mirror 110 within a second defined range can be detected by the handheld temperature detector.

[0072] By detecting the temperature within the second defined range, it is possible to achieve a temperature compensation lens with a center temperature higher than the edge temperature during the heating process. This corresponds to the center temperature being higher than the edge temperature caused by a Gaussian-like beam. Therefore, it can have a certain degree of thermal aberration compensation characteristics, which helps to correct the energy distribution of the final focused beam and improve beam convergence.

[0073] Taking the mirror 110 as a circular lens as an example, the second defined range can represent a region with the center of the mirror 110 as the center and a radius not greater than half the radius of the mirror 110.

[0074] Taking the mirror 110 as an elliptical lens as an example, the second defined range can represent an area with the focal point of the mirror 110 as the focal point and an area not greater than half the area of ​​the mirror 110.

[0075] Of course, the mirror 110 can also be a lens of other shapes. The shape of the second defined range varies depending on the shape of the mirror 110. Optionally, when the mirror 110 is a lens of other shapes, the second defined range does not extend beyond the edge of the mirror 110, and the area of ​​the second defined range is not greater than half the area of ​​the mirror surface of the mirror 110.

[0076] Through the above implementation, the temperature of the plano-mirror 110 can be adjusted by the temperature control module 120 to compensate for the focus, thereby achieving real-time reset of the focus drift in conventional laser processing optical systems and effectively ensuring the stability of the optical system to be compensated. Furthermore, by heating a first defined area of ​​the plano-mirror 110 to adjust the focus drift, temperature control over a small area can be achieved, allowing for more accurate reset of the focus drift.

[0077] like Figure 2 As shown in the illustration, this application also provides an optical system comprising: a lens group and a focus drift compensation system. A plano mirror 110 is disposed between two lenses in the lens group.

[0078] exist Figure 2 In the example shown, the lens group of the optical system may include: collimation protection lens 210, collimation lens 220, focusing lens 230, and focusing protection lens 240.

[0079] The planar mirror 110 is disposed between the collimating mirror 220 and the focusing mirror 230; the collimating protection mirror 210 is disposed on the side of the collimating mirror 220 away from the planar mirror 110; and the focusing protection mirror 240 is disposed on the side of the focusing mirror 230 away from the planar mirror 110.

[0080] Each lens in this lens group can have a small coefficient of thermal expansion and a positive temperature coefficient of refractive index. Optionally, the material of each lens in this lens group can be, but is not limited to, quartz or sapphire.

[0081] In this embodiment, the focal position of the optical system shortens as the lens temperature increases.

[0082] The optical system may also include multiple temperature sensors. The number of temperature sensors 130 is not less than the total number of lenses in the lens group and the plano mirror. Optionally, the number of temperature sensors 130 is the same as the total number of lenses in the lens group and the plano mirror; each temperature sensor is used to detect the temperature of one of the lenses. Optionally, the number of temperature sensors 130 is greater than the total number of lenses in the lens group and the plano mirror 110; each temperature sensor is used to detect the temperature of one of the lenses. The extra temperature sensors can serve as backup temperature sensors, which can be activated if any temperature sensor fails.

[0083] Optionally, the temperature detector 130 for each lens can be used to detect the third defined range of the mirror surface of each lens, and the edge of the third defined range does not extend beyond the edge of the lens.

[0084] by Figure 2 Taking the example shown, the optical system may also include five temperature sensors. These five temperature sensors are used to detect the temperatures of the plano mirror 110, collimating protection mirror 210, collimating mirror 220, focusing mirror 230, and focusing protection mirror 240, respectively.

[0085] Optionally, the temperature sensor 130 can be connected to each lens, for example, it can be connected to the frame of the lens. Optionally, the temperature sensor can also be a handheld temperature sensor, which can be used to detect the temperature of the lens surface within a third defined range when it is necessary to detect the temperature of the lens.

[0086] For example, the angle formed between the temperature detector 130 and the mirror surface of the lens can be set so that the temperature detector 130 can also be used to detect the temperature of the mirror surface of each lens within a third defined range.

[0087] Taking a circular lens as an example, the third limiting range can represent a region with the center of the lens as the center and a radius not greater than half the radius of the lens.

[0088] The shape of the third defined range varies depending on the shape of the lens. Optionally, when the lens is of other shapes, the third defined range does not extend beyond the edges of each lens, and the area of ​​the third defined range is not greater than half the area of ​​the mirror surface of each lens.

[0089] Optionally, the optical system may also include multiple heat-insulating components. The heat-insulating components are disposed between the lens group and the individual lenses included in the plano mirror 110.

[0090] The thermal insulation component can be an insulating part or a part with poor thermal conductivity. For example, the thermal insulation component can serve as a connection structure between lenses.

[0091] In this embodiment, the collimating protection lens 210, collimating lens 220, focusing lens 230, and focusing protection lens 240 each have their own specific focus drift temperature conversion coefficient.

[0092] In one example, the collimating protective lens 210, collimating lens 220, focusing lens 230, and focusing protective lens 240 can all be made of quartz material, while the plane mirror 110 can be made of oxygen-free copper metal material, and the focal length ratio of the focusing lens 230 to the collimating lens 220 can be M.

[0093] In practical processing, the diverging beam from the fiber output point passes sequentially through collimating protection mirror 210 and collimating mirror 220 to obtain a collimated beam. This collimated beam is then reflected by plane mirror 110, focused by focusing mirror 230, and finally converged to a single point by focusing protection mirror 240. During laser emission, the collimating protection mirror 210, collimating mirror 220, focusing mirror 230, and focusing protection mirror 240 are heated, causing their temperatures to rise and ultimately resulting in focus drift in the optical system. When focus drift compensation is needed, it can be achieved by heating plane mirror 110.

[0094] Based on the aforementioned optical system, and taking advantage of the large coefficient of thermal expansion, extremely high melting point, and large thermal conductivity of the plano-mirror 110, the temperature control module 120 applies different temperatures to the plano-mirror 110 in real time to adjust and control the temperature of the reflective surface of the plano-mirror 110. This achieves the purpose of the mirror surface expanding slightly and deforming due to heat, thereby changing the focal length of the mirror surface from infinity to a finite focal length. Through this temperature control, the temperature of the plano-mirror 110 compensates for the focal point, realizing the real-time reset of the focal point drift of the optical system, thereby improving the stability of the optical system during the manufacturing process.

[0095] Please see Figure 3 This is a flowchart of the focus drift compensation method provided in the embodiments of this application. It is applied to the focus drift compensation or optical system of the aforementioned embodiments. The following will describe... Figure 3 The specific process shown will be explained in detail.

[0096] Step 310: The temperature of the mirror is compensated by the temperature control module of the focus drift compensation system.

[0097] Optionally, step 310 may include steps 311 and 312.

[0098] Step 311: The temperature is adjusted by the temperature control module based on the temperature of each lens and the determination of the mirror in the optical system to be compensated.

[0099] When it is necessary to compensate for the temperature of a plano mirror, the real-time temperature of each lens in the optical system to be compensated, as well as the plano mirror, can be obtained.

[0100] Step 312: The temperature of the mirror is adjusted by the temperature control module to compensate for the temperature of the mirror.

[0101] By compensating for the temperature of the mirror, the focus drift of the optical system to be compensated can be achieved.

[0102] In this embodiment, the focal drift of each lens in the optical system can be calculated by the focal drift temperature conversion coefficient of each lens and the position of each lens in the optical path. The sum of the focal drift of each lens is the focal drift of the optical system.

[0103] For example, the adjustment temperature is determined based on the temperature of each lens in the optical system to be compensated using the following formula: DF=M 2 *[k1*(T1-T0)+k2*(T2-T0)]+k3*(T3-T0)+k4*(T4-T0); T5 = -DF / k5 + T0; Wherein, k1, k2, k3, and k4 represent the focus drift temperature conversion coefficients of the collimating protection lens 210, collimating lens 220, focusing lens 230, and focusing protection lens 240 of the optical system to be compensated, respectively; k5 represents the focus drift temperature conversion coefficient of the planar mirror 110; T1, T2, T3, and T4 represent the real-time temperatures of the collimating protection lens 210, collimating lens 220, focusing lens 230, and focusing protection lens 240 of the optical system to be compensated, respectively; T0 represents the initial reference temperature; T5 represents the adjustment temperature; and M represents the focal length ratio of the focusing lens 230 to the collimating lens 220.

[0104] In the above example, the focal drift temperature conversion coefficients of collimating protective lens 210, collimating lens 220, focusing lens 230, focusing protective lens 240 and mirror 110 are k1, k2, k3, k4 and k5 respectively, where the focal drift temperature conversion coefficient is related to the lens material, infrared temperature measurement area, etc.

[0105] Optionally, multiple sets of parameters can be fitted by detecting the focus drift and the temperature of each lens through lasers with different output powers, so as to calculate and determine the focus drift temperature conversion coefficient of each lens.

[0106] The method of this embodiment is applied to the aforementioned focus drift compensation or optical system. For details regarding the operation of the components involved in this method, please refer to the description in the foregoing embodiments, which will not be repeated here.

[0107] The method provided in this application uses temperature detection and temperature compensation as a closed loop. Based on the temperature control of the mirror 110, the optical system is used to compensate for focus drift. This processing method is simple and easy to implement and is not affected by the parameters of the optical system. At the same time, since the temperature control module 120 adjusts the temperature of the central area of ​​the mirror 110, the temperature compensation center is higher than the edge during the heating process. This corresponds to the center temperature being higher than the edge temperature caused by the Gaussian beam. Therefore, it can have a certain degree of thermal aberration compensation characteristics, which helps to correct the energy distribution of the final focused beam and improve the beam convergence.

[0108] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application. It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0109] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A focus drift compensation system, characterized in that, include: A planar mirror is used to be placed between the lenses of an optical system that needs to be compensated. A temperature detector is used to detect the temperature of the planar mirror. A temperature control module is installed on the first surface of the mirror to compensate for the temperature of the mirror. The focus drift compensation system includes multiple temperature sensors; Each temperature sensor is used to detect the temperature of each lens in the optical system to be compensated and one lens in the plano mirror; The temperature control module is also used to determine an adjustment temperature based on the temperatures of each lens of the optical system to be compensated and the temperature of the mirror detected by each of the temperature detectors, so as to use the adjustment temperature to compensate for the temperature of the mirror. The adjusted temperature is determined by the following formula: DF=M 2 *[k1*(T1-T0)+k2*(T2-T0)]+k3*(T3-T0)+k4*(T4-T0); T5 = -DF / k5 + T0; Where k1, k2, k3, and k4 represent the focus drift temperature conversion coefficients of the collimating protective lens, collimating lens, focusing lens, and focusing protective lens of the optical system to be compensated, respectively; k5 represents the focus drift temperature conversion coefficient of the mirror; T1, T2, T3, and T4 represent the real-time temperatures of the collimating protective lens, collimating lens, focusing lens, and focusing protective lens of the optical system to be compensated, respectively; T0 represents the initial reference temperature; T5 represents the adjustment temperature; and M represents the focal length ratio of the focusing lens to the collimating lens.

2. The focus drift compensation system according to claim 1, characterized in that, The temperature control module is used to heat the mirror within a first defined range on the first surface of the mirror, and the edge of the first defined range does not extend beyond the edge of the mirror.

3. The focus drift compensation system according to claim 2, characterized in that, The temperature control module is arranged within the first defined range of the first surface of the planar mirror.

4. The focus drift compensation system according to claim 3, characterized in that, The distance between the edge of the first defined range and the edge of the plano mirror is not less than a specified value, which is not greater than half the longest diameter of the plano mirror.

5. The focus drift compensation system according to claim 1, characterized in that, The temperature control module includes a semiconductor cooler.

6. The focus drift compensation system according to claim 1, characterized in that, The temperature detector is used to detect the temperature of a second defined range of the mirror surface of the plano mirror, wherein the edge of the second defined range does not extend beyond the edge of the mirror surface of the plano mirror.

7. The focus drift compensation system according to any one of claims 1-6, characterized in that, The reflective mirror is made of a material with a coefficient of thermal expansion greater than the thermal expansion threshold, a reflectivity greater than the reflection threshold, and a light absorption rate lower than the absorption threshold.

8. An optical system, characterized in that, include: The lens assembly and the focus drift compensation system according to any one of claims 1-6; The reflective mirror is positioned between two of the lenses in the lens group; The focus drift compensation system includes multiple temperature detectors; The number of temperature detectors is not less than the total number of lenses in the lens group and the mirror; each temperature detector is used to detect the temperature of one of the lenses.

9. The optical system according to claim 8, characterized in that, The lens group includes: a collimation protection lens, a collimation lens, a focusing lens, and a focusing protection lens; The planar mirror is disposed between the collimating mirror and the focusing mirror; The collimation protection mirror is located on the side of the collimation mirror away from the plane mirror; The focusing protection lens is located on the side of the focusing lens away from the mirror.

10. The optical system according to claim 8, characterized in that, Also includes: Multiple insulation components; The heat insulation component is disposed between the lens group and the individual lenses contained in the plano mirror.

11. A focus drift compensation method, characterized in that, The method, applied to the focus drift compensation system of any one of claims 1-7 or the optical system of any one of claims 8-10, comprises: The temperature control module adjusts the temperature based on the temperature of each lens in the optical system to be compensated and the temperature of the plano mirror. The temperature control module compensates for the temperature of the reflective mirror according to the adjusted temperature; the adjusted temperature is determined by the following formula: DF=M 2 *[k1*(T1-T0)+k2*(T2-T0)]+k3*(T3-T0)+k4*(T4-T0); T5 = -DF / k5 + T0; Where k1, k2, k3, and k4 represent the focus drift temperature conversion coefficients of the collimating protective lens, collimating lens, focusing lens, and focusing protective lens of the optical system to be compensated, respectively; k5 represents the focus drift temperature conversion coefficient of the mirror; T1, T2, T3, and T4 represent the real-time temperatures of the collimating protective lens, collimating lens, focusing lens, and focusing protective lens of the optical system to be compensated, respectively; T0 represents the initial reference temperature; T5 represents the adjustment temperature; and M represents the focal length ratio of the focusing lens to the collimating lens.

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