Active-passive integrated micro-distance measuring device and automatic focusing device comprising same

Abstract

The application provides a kind of active and passive integrated micro distance measuring device and automatic focusing device comprising it, belong to microscopic imaging technical field, to solve the problem of existing focusing device active focusing failure, passive focusing slow. Wherein, first beam splitter and third beam splitter are sequentially arranged on the light path of incident light beam emitted by infrared generator, third beam splitter is configured to reflect incident light beam to the sample to be measured and can produce reverse reflected light beam on the surface of the sample to be measured, and third beam splitter can transmit visible light beam to complete passive ranging;Linear array detector is arranged on the reflection light path of reflected light beam at first beam splitter, for receiving returned near-infrared light and judging defocus direction according to its imaging position on linear array detector. The application is fast and anti-interference in active focusing, passive correction has high precision, and the structure is compact and compatible with ocular lens.

Description

Technical Field

[0001] This application belongs to the field of microscopic imaging technology, specifically relating to an integrated active and passive microscopic ranging device and an autofocus device including the same. Background Technology

[0002] During microscopic imaging, due to the extremely small depth of field of the objective lens, typically only on the order of μm, defocusing can easily occur when the platform moves or the sample surface has height variations, resulting in blurred images. Microscopic autofocus technology is crucial for ensuring image quality and is currently mainly divided into two categories: active autofocus and passive autofocus. Both methods have their advantages but also significant drawbacks.

[0003] Active focusing technology uses active light sources (such as infrared lasers or near-infrared light) or auxiliary devices like ultrasound to emit detection signals to the sample. It then directly measures the distance between the objective lens and the sample based on the reflected signals, thereby driving the focusing mechanism to achieve focus. This method offers fast focusing speed, quickly determining the defocus direction and achieving focus without requiring multiple adjustments to the stage. However, the focusing effect of active focusing is significantly affected by factors such as the sample surface condition, reflectivity, ambient lighting, and interfering objects. In scenarios with low reflectivity, high transparency, or multi-layered reflective interfaces, the quality of the reflected signal deteriorates, and focusing may even fail.

[0004] Passive autofocus technology does not emit additional detection signals. It directly utilizes sample images acquired by the camera and scans along the Z-axis using image sharpness evaluation functions (such as gradient, entropy, or frequency domain energy) to find the sharpness peak position, thus belonging to direct autofocus. It boasts high focusing accuracy and a relatively simple hardware structure. However, passive autofocus has significant drawbacks: its focusing speed is slow, and it cannot directly determine whether the defocus is positive or negative. It requires multiple up-and-down movements of the stage along the Z-axis to obtain the sharpness change trend and thus determine the positive or negative defocus direction. This process is time-consuming and cannot meet the continuous focusing requirements of high-throughput real-time imaging or dynamic samples.

[0005] Therefore, there is an urgent need for an autofocus device for microscopes that can compensate for the shortcomings of active and passive focusing. Summary of the Invention

[0006] In view of this, this application provides an integrated active and passive microscopic rangefinder and an autofocus device including the same, to solve the problems of easy failure of active focusing and slow passive focusing speed of existing focusing devices.

[0007] To solve the above problems, the technical solution adopted in this application is as follows: In a first aspect, this application proposes an integrated active and passive microscopic ranging device, comprising an infrared generator, a first beam splitter, a third beam splitter, and a linear array detector; the first and third beam splitters are sequentially disposed on the optical path of the incident beam emitted by the infrared generator, the third beam splitter is configured to reflect the incident beam to the sample to be tested and generate a reverse reflected beam on the surface of the sample to be tested, and the third beam splitter can transmit visible light to complete passive focusing detection; the linear array detector is disposed on the reflected optical path of the reflected beam at the first beam splitter, and is used to receive the returned near-infrared light and determine whether it is in focus and the direction of defocusing based on its imaging position on the linear array detector.

[0008] Preferably, the ranging device further includes a second beam splitter and an area array detector; the second beam splitter is disposed between the first beam splitter and the third beam splitter, and is located in the optical path of the incident beam; the area array detector is disposed in the reflected optical path of the visible light after being reflected from the specimen at the second beam splitter, and is used to receive the returned visible light to achieve passive focusing detection.

[0009] Preferably, the first beam splitter is a near-infrared semi-transparent and semi-reflective mirror; and / or, the second beam splitter is a near-infrared transmitting and visible light reflecting mirror; and / or, the third beam splitter is a near-infrared reflecting mirror, with most visible light transmitting and a small portion of visible light reflecting.

[0010] Preferably, the ranging device further includes an aperture stop, which is disposed in the optical path between the infrared generator and the first beam splitter to block part of the incident light.

[0011] Preferably, the ranging device further includes a collimating lens, which is disposed in the optical path between the infrared generator and the first beam splitter to collimate the incident beam into parallel light.

[0012] Preferably, the ranging device further includes a sleeve lens, which is disposed on the exit path of the visible light beam passing through the third beam splitter.

[0013] Preferably, the system further includes a first lens and a second lens, wherein the first lens is disposed after the third beam splitter and between the sleeve lens and the eyepiece; and the second lens is disposed between the third beam splitter and the microscope stage.

[0014] Preferably, the ranging device further includes a light trap, which is disposed in the transmission light path of the third beam splitter to absorb or block light transmitted through the third beam splitter.

[0015] Secondly, this application also proposes an autofocus device, including the rangefinder device described in the first aspect and an actuator for adjusting the distance, wherein the actuator drives the objective lens or the stage to focus based on the detection results of the eyepiece, the linear array detector and / or the area array detector.

[0016] Thirdly, this application also proposes a microscope, including an objective lens, a stage, an eyepiece, and the autofocusing device described in the second aspect; the incident light beam reflected by the third beam splitter of the ranging device is incident on the sample to be tested through the objective lens; the visible light beam transmitted through the third beam splitter is incident on the eyepiece.

[0017] In summary, due to the adoption of the above technical solution, the beneficial effects of this application are: The ranging device of this application features an active focusing component unaffected by sample contrast, enabling rapid defocus direction determination on low-reflectivity, transparent samples, thus improving focusing speed compared to purely passive methods. Simultaneously, by retaining the passive focusing optical path, it can utilize image data from the area array detector for precise focus verification and closed-loop correction, effectively overcoming ranging errors in active focusing at multi-layered interfaces or in low-reflectivity scenarios. Furthermore, the design of the third beam splitter transmitting visible light to the eyepiece allows the entire device to be compatible with conventional microscopic observation without increasing the optical path length, resulting in a compact structure that is easily integrated into existing microscope systems. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is a schematic diagram of the microscope provided in the embodiments of this application; Figure 2 A top-view schematic diagram of the internal structure of the ranging device provided in the embodiments of this application; Figure 3 A bottom-view schematic diagram of the internal structure of the ranging device provided in the embodiments of this application; Figure 4 This is a schematic diagram illustrating the working principle of the internal structure of the ranging device provided in the embodiments of this application.

[0019] Among them, 100 is the microscope; 110 is the eyepiece; 120 is the stage; 130 is the actuator; and 140 is the objective lens. 200. Ranging device; 210. Infrared generator; 220. Aperture; 230. Collimating lens; 240. Linear array detector; 250. Area array detector; 260. Sleeve lens; 271. First beam splitter; 272. Second beam splitter; 273. Third beam splitter; 281. First lens; 282. Second lens; 290. Optical trap; 300, Incident beam; 400, Reflected beam; 410, Reflected beam; 420, First reflection beam; 430, Second reflection beam; 500, Visible beam. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. The components of the embodiments of this application described and shown in the accompanying drawings can be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0023] It should be noted that similar labels 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.

[0024] In this application, unless otherwise expressly specified and limited, "above" or "below" a second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of a second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" a second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature. The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and do not limit the number of objects; for example, a first object can be one or more. Furthermore, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0025] Existing microscopic autofocus technologies are mainly divided into two categories: active focusing and passive focusing. Each type has its advantages but also significant drawbacks. Active focusing technology uses an active light source (such as infrared laser or near-infrared light) or auxiliary devices like ultrasound to emit a detection signal to the sample. It then directly measures the distance between the objective lens and the sample based on the reflected signal, thereby driving the focusing mechanism to achieve focus. This method offers fast focusing speed, quickly determining the defocus direction and achieving focus without multiple stage adjustments. However, the focusing effect of active focusing is significantly affected by factors such as the sample surface condition, reflectivity, ambient light, and interfering objects. In scenarios with low reflectivity, high transparency, or multi-layered reflective interfaces, the quality of the reflected signal deteriorates, and focusing may even fail. Passive focusing technology, on the other hand, does not emit additional detection signals. It directly utilizes the sample image acquired by the camera, using an image sharpness evaluation function (such as gradient, entropy, or frequency domain energy) to scan in a step-by-step manner along the Z-axis to find the sharpness peak position. This is a direct focusing method. It offers high focusing accuracy and a relatively simple hardware structure. However, passive focusing has obvious drawbacks: the focusing speed is slow, and it cannot directly determine whether the current defocus is positive or negative. It requires moving the stage up and down along the Z-axis multiple times to obtain the trend of sharpness change, so as to complete the determination of the positive or negative defocus direction. This process consumes a lot of time and is difficult to meet the continuous focusing requirements of high-throughput real-time imaging or dynamic samples.

[0026] The ranging device of this application features an active focusing component unaffected by sample contrast, enabling rapid defocus direction determination on low-reflectivity, transparent samples, thus improving focusing speed compared to purely passive methods. Simultaneously, by retaining the passive focusing optical path, it can utilize image data from the area array detector for precise focus verification and closed-loop correction, effectively overcoming ranging errors in active focusing at multi-layered interfaces or in low-reflectivity scenarios. Furthermore, the design of the third beam splitter transmitting visible light to the eyepiece allows the entire device to be compatible with conventional microscopic observation without increasing the optical path length, resulting in a compact structure that is easily integrated into existing microscope systems.

[0027] The following is in conjunction with the appendix Figures 1 to 4 The technical solutions provided in this application will be described in detail through specific embodiments and application scenarios.

[0028] Firstly, such as Figures 2-4 As shown, this application proposes an integrated active and passive microscopic ranging device 200. The ranging device 200 includes an infrared generator 210, a first beam splitter 271, a third beam splitter 273, and a linear array detector 240. The first beam splitter 271 and the third beam splitter 273 are sequentially disposed on the optical path of the incident beam 300 emitted by the infrared generator 210. The third beam splitter 273 is configured to reflect the incident beam 300 to the sample to be tested and can generate a reverse reflected beam 400 on the surface of the sample to be tested. The third beam splitter 273 can transmit a visible beam 500 to complete passive focusing detection. The linear array detector 240 is disposed on the reflected optical path of the reflected beam at the first beam splitter 271 and is used to receive the returned near-infrared light and determine whether it is in focus and the direction of defocusing based on its imaging position on the linear array detector 240.

[0029] Specifically, the infrared generator 210 can employ a near-infrared laser diode with a wavelength of 850nm to emit a well-collimated incident beam 300. A first beam splitter 271 and a third beam splitter 273 are sequentially arranged along the propagation direction of the incident beam 300. The first beam splitter 271 is a near-infrared semi-transparent mirror with a transmittance to reflectance ratio of 50:50. The third beam splitter 273 is a dichroic mirror with a reflectance greater than 90% for 850nm near-infrared light, while exhibiting high transmittance (e.g., >85%) in the visible light band (400-700nm) and retaining approximately 5-10% of the visible light reflection component. The third beam splitter 273 is configured to reflect and bend most of the near-infrared light in the incident beam 300 by 90°, and then converge it to the surface of the sample under test through the objective lens 140. At the same time, the third beam splitter 273 allows most of the visible light imaging beam 500 from the sample to pass through, thereby passing through the ranging device 200 and entering the eyepiece 110 or imaging detector to provide image information for passive ranging.

[0030] The linear array detector 240 can be a 2048-pixel linear CCD or linear CMOS sensor, which is positioned on the reflected light path of the reflected beam 400 at the first beam splitter 271. The reflected beam 400 refers to the portion of the incident near-infrared light that, after being reflected by the sample, returns along its original path, passes again through the third beam splitter 273 and the second beam splitter 272 (if configured), reaches the first beam splitter 271, and is reflected by it to the linear array detector 240.

[0031] When the ranging device 200 is in operation, the infrared generator 210 continuously emits 850nm near-infrared laser light. The incident beam 300 passes sequentially through the first beam splitter 271, the second beam splitter 272 (if any), and then reaches the third beam splitter 273. It is reflected by the third beam splitter 273 and focused onto the surface of the sample to be measured by the objective lens 140. The reflected light from the sample surface forms a reflected beam 400, which returns along the original optical path in reverse, passes through the objective lens 140, the third beam splitter 273, and the second beam splitter 272 (if any), and finally reaches the first beam splitter 271. Since the first beam splitter 271 is a semi-transparent and semi-reflective mirror, 50% of the energy in the reflected beam 400 is reflected onto the photosensitive surface of the linear array detector 240. By monitoring the imaging position of the light spot on the linear array detector 240: when the light spot is located at the center of the detector, it indicates that the sample is exactly on the focal plane of the objective lens; when the light spot shifts to the left, it indicates that the sample is above the focal plane (positive defocus); when the light spot shifts to the right, it indicates that the sample is below the focal plane (negative defocus). Thus, the linear array detector 240 can output the defocus direction and defocus amount signals in real time.

[0032] Simultaneously, the third beam splitter 273 transmits most of the visible light imaging beam 500 from the sample. This visible light can be directly observed by the human eye through the sleeve lens 260 into the eyepiece 110, or it can be guided to the area array detector 250 by another beam splitting (e.g., using a small portion of visible light reflected by the second beam splitter 272) for passive image sharpness evaluation focusing. This achieves parallel operation of active and passive ranging.

[0033] The ranging device 200 of this embodiment, whose active focusing part is unaffected by sample contrast, can quickly determine the defocus direction on low-reflectivity, transparent samples, and the focusing speed can be improved compared to a purely passive method. Simultaneously, because the passive focusing optical path is retained, image data from the area array detector 250 can be used for precise focus verification and closed-loop correction, effectively overcoming the ranging errors of active focusing in multi-layer interfaces or low-reflectivity scenarios. Furthermore, the design of the third beam splitter 273 transmitting visible light to the eyepiece 110 allows the entire device to be compatible with conventional microscopic observation without increasing the additional optical path length, resulting in a compact structure that is easy to integrate into existing microscope systems.

[0034] In some embodiments, the ranging device 200 further includes a second beam splitter 272 and an area array detector 250. The second beam splitter 272 is disposed between the first beam splitter 271 and the third beam splitter 273, located in the optical path of the incident beam 300; the area array detector 250 is disposed in the reflected optical path of the visible light returning after reflection from the specimen at the second beam splitter 272. Specifically, the second beam splitter 272 is a flat beam splitter, with a near-infrared anti-reflection coating and a visible light reflective coating coated on the side facing the incident beam 300. The visible light reflected beam from the sample is transmitted through the third beam splitter 273, reaches the second beam splitter 272, and is reflected by it to the area array detector 250. The area array detector 250 uses a CMOS image sensor with more than 5 megapixels to acquire sample images in real time at a frame rate of 30fps to achieve passive focusing detection. This configuration allows active and passive ranging to work in parallel: the active component quickly provides the defocus direction, while the passive component provides accurate focus verification and image feedback. The two complement each other, improving the robustness and accuracy of the focusing system.

[0035] In some embodiments, the first beam splitter 271 is a near-infrared semi-transparent and semi-reflective mirror; the second beam splitter 272 is a near-infrared transmitting and visible light reflecting mirror; and the third beam splitter 273 is a near-infrared reflecting mirror, with most visible light transmitted and a small portion of visible light reflected. Specific parameters are as follows: the first beam splitter 271 has a transmittance / reflectance ratio of 50:50 for 850nm near-infrared light; the second beam splitter 272 has a transmittance of >95% for 850nm near-infrared light and a reflectance of >90% for 400-700nm visible light; the third beam splitter 273 has a reflectance of >98% for 850nm near-infrared light, a total transmittance of 90% for visible light, and retains a 10% reflection component. This combination of beam splitting characteristics achieves effective separation of the optical path: most of the near-infrared light is guided to the sample and returns to the linear array detector, while the visible light mainly enters the eyepiece and the area array detector, with no crosstalk between them, while ensuring the weak reflection signal required for passive focusing.

[0036] In some embodiments, the ranging device 200 further includes an aperture stop 220. The aperture stop 220 is disposed in the optical path between the infrared generator 210 and the first beam splitter 271, specifically a variable aperture stop with an aperture range of 0.5 mm to 3 mm. By adjusting the opening size of the aperture stop 220, the edge portion of the infrared laser beam can be blocked, allowing only the central portion with uniform intensity to pass through, thereby reducing side lobes and stray light of the laser beam and improving the signal-to-noise ratio of the light spot on the linear array detector 240. This aperture stop can also be used for beam shaping, matching the diameter of the light spot incident on the sample to the diffraction limit of the objective lens, thus improving the ranging resolution.

[0037] In some embodiments, the ranging device 200 further includes a collimating lens 230. The collimating lens 230 is disposed in the optical path between the infrared generator 210 and the first beam splitter 271, specifically a molded aspherical lens with a focal length of 10 mm and a numerical aperture of 0.25. The near-infrared laser emitted by the infrared generator 210 first passes through the collimating lens 230, where it is converted into a parallel beam with a small divergence angle before being incident on the subsequent beam splitter. The collimated parallel light ensures that the spot size remains essentially unchanged throughout the optical path transmission, avoiding edge cutting and energy loss of the beam splitter due to divergence. Simultaneously, it ensures that the spot returning after sample reflection can be accurately imaged on the linear array detector 240, improving the linearity of defocus detection.

[0038] In some embodiments, the rangefinder 200 further includes a sleeve lens 260. The sleeve lens 260 is positioned in the exit path of the visible beam 500 through the third beam splitter 273, specifically between the third beam splitter 273 and the eyepiece 110, and forms an infinity-corrected optical system with the objective lens 140. The sleeve lens 260 has a focal length of 200mm, converging the infinity-image beam from the objective lens 140 to the front focal plane of the eyepiece 110, allowing the observer to obtain a clear microscopic image. This design ensures that the optical insertion of the rangefinder 200 does not affect the original infinity optical path structure of the microscope, allowing the user to directly install this rangefinder module without replacing the eyepiece or objective lens.

[0039] In some embodiments, a first lens 281 and a second lens 282 are also included. The first lens 281 is located after the third beam splitter 273 and between the sleeve lens 260 and the eyepiece 110. Specifically, it is a positive lens with a focal length of 30mm. It is used to converge the intermediate image plane emitted from the sleeve lens 260 to the eyepiece 110 a second time to compensate for the optical path difference introduced by the third beam splitter 273 and ensure the sharpness of the field of view edges. The second lens 282 is located between the third beam splitter 273 and the stage 120 of the microscope 100. Specifically, it is a compensating lens and is installed in the threaded interface at the front end of the objective lens 140. It is used to correct the axial chromatic aberration caused by the difference in wavelength between near-infrared light and visible light, so that the focal plane of active ranging is consistent with the focal plane of passive imaging. Through the first lens 281 and the second lens 282, the image quality of the observation optical path and the ranging optical path can be optimized simultaneously to achieve what is in focus.

[0040] In some embodiments, the ranging device 200 further includes a light trap 290. The light trap 290 is disposed in the transmission light path of the third beam splitter 273, specifically a cylindrical absorber made of black anodized aluminum with threaded matting texture on its inner wall. Its main function is to absorb near-infrared residual light and stray light transmitted through the third beam splitter 273, preventing these rays from undergoing secondary reflection inside the lens barrel and returning along their original path to the linear array detector 240, thus preventing false defocus signals. The light trap 290 also blocks dust from entering the optical system, extending the detector's lifespan. In actual operation, the light trap 290 makes the end of the transmission light path a complete light trap, significantly improving the signal-to-noise ratio and stability of active ranging.

[0041] Secondly, this application also proposes an autofocus device. This autofocus device includes a ranging device 200 as described in any of the above embodiments and an actuator 130 for adjusting the distance. The actuator 130 can be a piezoelectric ceramic driver or a combination of a stepper motor and a ball screw, with its drive end connected to the objective lens 140 or the stage 120. During operation, the actuator 130 adjusts the axial distance between the objective lens 140 and the sample in real time based on the defocus direction signal output by the linear array detector 240 and the data output by the area array detector 250, until the light spot on the linear array detector 240 is centered and the image sharpness of the area array detector 250 reaches its peak. This autofocus device integrates the rapid orientation capability of active ranging and the high-precision confirmation capability of passive ranging, achieving millisecond-level response and sub-micron-level focusing accuracy.

[0042] Thirdly, this application also proposes a microscope 100. The microscope 100 includes an objective lens 140, a stage 120, an eyepiece 110, and the aforementioned autofocus device. In specific assembly, the incident light beam 300 reflected by the third beam splitter 273 of the ranging device 200 is incident on the sample to be measured through the objective lens 140 for active ranging; the visible light beam 500 transmitted through the third beam splitter 273 is incident on the eyepiece 110 for human observation or passive imaging. Simultaneously, the actuator 130 in the autofocus device drives the objective lens 140 or the stage 120 according to the output signal of the ranging device, achieving fully automatic and rapid focusing. This microscope can be upgraded to an integrated active and passive autofocus microscope by directly adding this ranging module and actuator without changing the main structure of a traditional microscope, making it particularly suitable for scenarios such as digital pathological scanning, long-term live cell imaging, and automated semiconductor detection.

[0043] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0044] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0045] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0046] Furthermore, it should be noted that the scope of the methods and apparatus in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. In addition, features described with reference to certain examples may be combined in other examples.

Claims

1. A combined active and passive microscopic ranging device, characterized in that, The ranging device (200) includes an infrared generator (210), a first beam splitter (271), a third beam splitter (273), and a linear array detector (240); the first beam splitter (271) and the third beam splitter (273) are sequentially arranged in the optical path of the incident beam (300) emitted by the infrared generator (210); the third beam splitter (273) is configured to reflect the incident beam (300) to the sample to be tested and can generate a reverse reflected beam on the surface of the sample to be tested; and the third beam splitter (273) can transmit visible light (500) to complete passive focusing detection. The linear array detector (240) is positioned on the reflected light path of the reflected beam at the first beam splitter (271) to receive the returned near-infrared light and determine whether it is in focus and the direction of defocusing based on its imaging position on the linear array detector (240).

2. The active-passive integrated micro-range measuring device according to claim 1, characterized in that, The ranging device (200) further includes a second beam splitter (272) and an area array detector (250); the second beam splitter (272) is disposed between the first beam splitter (271) and the third beam splitter (273) and is located in the optical path of the incident beam (300); the area array detector (250) is disposed in the reflected optical path of the visible light after being reflected from the specimen at the second beam splitter (272) and is used to receive the returned visible light to achieve passive focusing detection.

3. The active-passive integrated micro-range measuring device according to claim 2, characterized in that, The first beam splitter (271) is a near-infrared semi-transparent and semi-reflective mirror; and / or, the second beam splitter (272) is a near-infrared transmitting and visible light reflecting mirror; and / or, the third beam splitter (273) is a near-infrared reflecting, mostly visible light transmitting and a small portion of visible light reflecting mirror.

4. The active-passive integrated micro-range measuring device according to claim 1, characterized in that, The ranging device (200) also includes an aperture (220), which is disposed in the optical path between the infrared generator (210) and the first beam splitter (271) to block part of the incident light.

5. The active-passive integrated micro-range measuring device according to claim 1, characterized in that, The ranging device (200) further includes a collimating lens (230), which is disposed in the optical path between the infrared generator (210) and the first beam splitter (271) to collimate the incident beam (300) into parallel light.

6. The active-passive integrated micro-range measuring device according to claim 1, characterized in that, The ranging device (200) also includes a sleeve lens (260), which is disposed on the exit path of the visible light beam (500) through the third beam splitter (273).

7. The active-passive integrated micro-range measuring device according to claim 6, characterized in that, It also includes a first lens (281) and a second lens (282). The first lens (281) is located after the third beam splitter (273) and between the sleeve lens (260) and the eyepiece (110). The second lens (282) is located between the third beam splitter (273) and the microscope stage (120).

8. The active-passive integrated micro-range measuring device according to claim 1, characterized in that, The ranging device (200) also includes a light trap (290), which is disposed in the transmission light path of the third beam splitter (273) and is used to absorb or block the light transmitted through the third beam splitter (273).

9. An automatic focusing device, characterized in that, The device includes a ranging device (200) according to any one of claims 1 to 8 and an actuator (130) for adjusting distance, the actuator (130) driving the objective lens (140) or the stage (120) to focus based on the detection results of the eyepiece (110), the linear array detector (240) and / or the area array detector (250).

10. A microscope, characterized in that, The device includes an objective lens (140), a stage (120), an eyepiece (110), and an autofocus device as described in claim 9; the incident light beam (300) reflected by the third beam splitter (273) of the ranging device (200) is incident on the sample to be tested through the objective lens (140); the visible light beam (500) transmitted through the third beam splitter (273) is incident on the eyepiece (110).

Images