Microscopic auto-focusing device based on laser spot and electronic equipment

Abstract

The utility model discloses a kind of microscopic automatic focusing device and electronic equipment based on laser spot, it is related to automatic focusing field.The microscopic automatic focusing device includes: one or more than two optical rotators, be set in objective lens group or between objective lens group and measured object, for once or multiple rotation polarization direction of all linear polarization detection light received by automatic focusing sensor, to distinguish from polarization direction of all or part objective lens group surface reflected light;First polarizer, set in the front side of automatic focusing sensor, only for eliminating all or part of the reflected light outside the linear polarization detection light.Based on the above setting, the polarization direction of linear polarization detection light is changed by optical rotator, so that it is different from the polarization direction of reflected light directly reflected from objective lens surface to automatic focusing sensor, based on this, all or part of reflected light is eliminated using first polarizer, reduce the stray light generated by internal lens of objective lens group reflection.

Description

Technical Field

[0001] This utility model belongs to the field of autofocus, and in particular relates to a microscopic autofocus device and electronic device based on laser spot. Background Technology

[0002] Active autofocus technology based on laser spot adds an object distance sensing optical path to the conventional imaging optical path. It projects a laser beam of a specific shape onto the surface of the object being measured. By analyzing the shape of the laser spot returning from the surface of the object being measured, the defocus amount of the lens is calculated, and the movement of the focusing system is controlled according to the defocus amount to achieve the effect of autofocus.

[0003] The light beam used for defocus sensing needs to be converged onto the surface of the object being measured through the objective lens. To effectively separate the defocus sensing beam from the imaging beam, a certain wavelength interval is required between them, resulting in the defocus sensing beam generally being outside the high-transmittance wavelength range of the objective lens. For example, the high-transmittance range of conventional visible light microscope objectives is 400-700 nm, while the wavelength of the defocus sensing beam is 785 nm. Therefore, some light energy inevitably returns directly to the autofocus sensor due to reflection from the internal lenses of the objective lens assembly, forming stray light. When the defocus distance is large, or the surface reflectivity of the object being measured is very low, the intensity of the light signal used for distance sensing returning from the object's surface is close to the intensity of the stray light. In this case, the stray light interferes with the calculation of the defocus direction and distance, leading to focusing failure.

[0004] Therefore, there is an urgent need for a microscopic autofocus device to reduce or even eliminate stray light generated by reflections from the internal lenses of the objective lens group, so as to improve the accuracy of autofocus results. Utility Model Content

[0005] This invention proposes a microscopic autofocus device and electronic device based on a laser spot, which is used to reduce or even eliminate stray light generated by reflections from the internal lenses of the objective lens group, thereby improving the accuracy of autofocus results.

[0006] To achieve the above objectives, the present invention proposes the following technical solution:

[0007] In a first aspect, this invention provides a microscopic autofocus device based on a laser spot, comprising:

[0008] One or more rotators are set inside the objective lens group or between the objective lens group and the object being measured, and are used to rotate the polarization direction of all linearly polarized detection light received by the autofocus sensor once or multiple times, so as to distinguish it from the polarization direction of all or part of the light reflected from the surface of the objective lens group.

[0009] A first polarizer, positioned in front of the autofocus sensor, is used solely to eliminate all or part of the reflected light other than the linearly polarized detection light.

[0010] Optional, also includes:

[0011] A linearly polarized laser is used to provide linearly polarized light with consistent polarization direction. The linearly polarized light reflected from the surface of all or part of the objective lens group to the autofocus sensor is used as reflected light. The linearly polarized light that passes through the objective lens group and is reflected from the surface of the object being measured to the autofocus sensor is used as linearly polarized detection light to form a laser spot.

[0012] Optional, also includes:

[0013] Parallel lasers provide laser beams with parallel directions;

[0014] The second polarizer is disposed in front of the parallel laser and is used to adjust the laser beam irradiated by the objective lens group into linearly polarized light with the same polarization direction. The linearly polarized light reflected by all or part of the objective lens group surface to the autofocus sensor is used as reflected light. The linearly polarized light that passes through the objective lens group and is reflected by the surface of the object under test to the autofocus sensor is used as linearly polarized detection light to form a laser spot.

[0015] Optionally, the polarization direction of the linearly polarized detection light after being rotated by the one or more optical rotators is consistent with the polarization direction of the first polarizer.

[0016] Optionally, one or more of the optical rotators may be of the type of Faraday rotator or waveplate.

[0017] Optionally, there may be only one optical rotator, which is located between the objective lens group and the object being measured.

[0018] Optionally, the rotator completely covers the bottom surface of the objective lens group.

[0019] Optionally, the angle between the polarization direction of the first polarizer and the polarization direction of the reflected light is 90°.

[0020] Optionally, the rotation angle of the optical rotator relative to the polarization direction is 45°.

[0021] In a second aspect, an electronic device is provided, comprising:

[0022] As described in any of the first aspects, a microscopic autofocus device.

[0023] The beneficial effects of this utility model are as follows:

[0024] This utility model provides a microscopic autofocus device based on a laser spot, comprising:

[0025] One or more rotators are set inside the objective lens group or between the objective lens group and the object being measured, and are used to rotate the polarization direction of all linearly polarized detection light received by the autofocus sensor once or multiple times, so as to distinguish it from the polarization direction of all or part of the light reflected from the surface of the objective lens group.

[0026] A first polarizer, positioned in front of the autofocus sensor, is used solely to eliminate all or part of the reflected light other than the linearly polarized detection light.

[0027] As is generally accepted in the field of autofocus, in laser-spot-based autofocus schemes, a laser spot is formed by reflecting light from the surface of the object to the autofocus sensor. The defocus amount is then calculated using this laser spot, thereby controlling the distance between the objective lens and the object's surface to achieve microscopic autofocus. Simultaneously, reflected light directly from the objective lens assembly surface to the focus sensor serves as stray light affecting the defocus calculation. Here, the objective lens assembly surface refers to the surface of all or part of the lenses within the objective lens assembly; that is, the reflected light is formed by reflection from the surfaces of all or part of the lenses within the objective lens assembly. In this invention, the linearly polarized detection light refers to the linearly polarized light reflected from the object's surface to the autofocus sensor, serving as the normal light for calculating the defocus amount.

[0028] Based on the above-mentioned utility model solution, the laser used to form the laser spot in the existing autofocus solution is adjusted to linearly polarized light. Combined with the setting of a rotator and a first polarizer, the rotator changes the polarization direction of the linearly polarized detection light reflected from the surface of the object to the focus sensor, making this polarization direction different from the polarization direction of stray light directly reflected from the objective lens surface to the focus sensor. Based on Malus's law, by utilizing the inconsistency between the polarization direction of the linearly polarized detection light and the polarization direction of the stray light reflected from the objective lens surface, and by using the first polarizer to eliminate all or part of the reflected light, the aim of reducing stray light generated by reflections from the internal lenses of the objective lens group is achieved. Because the stray light intensity is completely blocked or reduced, the stability of the microscopic autofocus device and the accuracy of the autofocus results are enhanced. Attached Figure Description

[0029] The accompanying drawings, which are included to provide a further understanding of the present invention and constitute a part of this invention, illustrate exemplary embodiments of the present invention and, together with the description thereof, serve to explain the present invention and do not constitute an undue limitation thereof. In the drawings:

[0030] Figure 1 This is a schematic diagram of the optical path structure of a microscopic autofocus device in the prior art;

[0031] Figure 2 This is a schematic diagram of the optical path structure of another microscopic autofocus device in the prior art;

[0032] Figure 3 This is a schematic diagram of the optical path structure of a microscopic autofocus device provided by this utility model;

[0033] Figure 4 This is a schematic diagram of the optical path structure of another microscopic autofocus device provided by this utility model;

[0034] Figure 5 This is a schematic diagram of the optical path structure of another microscopic autofocus device provided by this utility model.

[0035] In the diagram: 1-Parallel laser, 2-Cylindrical lens, 3-Baffle, 4-Reflector, 5-First beam splitter, 6-Second beam splitter, 7-Objective lens group, 8-Motor, 9-Object under test, 10-Focusing lens, 11-Autofocus sensor, 12-Third beam splitter, 13-Illumination LED, 14-Tube lens, 15-Imaging sensor, 16-Optical rotator, 17-First polarizer, 18-Second polarizer, 19-Linearly polarized laser. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0037] Optical microscopes magnify images of the surface of an object through lens imaging. To obtain meaningful images, the microscope objectives (i.e., the objective lens group or objective lens in this invention) must be precisely focused on the sample surface. However, the depth of field of high-magnification microscope objectives is generally only a few micrometers. Operators often need to spend a lot of time manually adjusting the distance between the objective lens and the object to achieve focus. Microscopic autofocus technology calculates the current defocusing amount of the objective lens through feedback signals and converts it into a motion signal for the motor. The motor then drives the objective lens to move, automating the focusing process.

[0038] Based on the type of feedback signal, microscopic autofocus technology can be divided into two types: image autofocus and laser autofocus. Image autofocus technology calculates the sharpness of the current image using digital image processing by designing an image sharpness evaluation function, and determines the current defocus amount based on the quantified sharpness value. Laser autofocus technology projects a laser directly onto the surface of the object being measured, and determines the defocus amount of the objective lens by observing the state of the laser spot reflected back from the object's surface. Image autofocus technology relies entirely on the acquired image state, is easily affected by the lighting environment, requires scanning back and forth around the focal point to determine the optimal focusing position, and has a slower focusing speed and a smaller focusing range. In contrast, laser autofocus technology, based on a conventional microscope, adds a laser signal, resulting in a larger focusing range and faster focusing speed, and is widely used in industrial inspection fields.

[0039] Laser spot-based microscopic autofocus is a type of active focusing technology. It calculates the defocus amount of the object under test by analyzing the laser spot morphology (including centroid, radius, and curvature), and then controls the objective lens's movement direction and distance based on this defocus amount. This ensures that the distance between the objective lens and the object's surface remains within the objective lens's depth of field, thus achieving automatic focusing. For example, in the line laser microscopic autofocus schemes provided in Chinese patents CN114994896A or CN118584643A, the defocus amount is obtained by calculating the offset between the real-time centroid of the laser spot and a reference centroid, thereby achieving automatic focusing of the microscope objective lens.

[0040] like Figure 1 As shown, this utility model provides a schematic diagram of the optical path structure of a prior art microscopic autofocus scheme based on a laser spot. The overall optical path of this microscopic autofocus scheme includes a parallel laser 1, a cylindrical lens 2, a baffle 3, a reflecting mirror 4, a first beam splitter 5, a second beam splitter 6, an objective lens group 7 (usually an infinity conjugate microscope objective lens in actual work), a motor 8, the object under test 9, a focusing lens 10, an autofocus sensor 11, a third beam splitter 12, an illumination LED 13, a tube lens 14, and an imaging sensor 15.

[0041] The existing microscopic autofocus process is briefly described as follows: A parallel laser beam is emitted from a parallel laser source 1. This laser beam enters a cylindrical lens 2 and, after being modulated by the cylindrical lens 2, becomes an asymmetric beam that diverges in the curvature direction of the cylindrical lens 2 and is collimated in the direction without curvature. After passing through a baffle 3, the asymmetric beam loses half its energy and propagates only on one side of the optical axis. After being reflected by the surface of a reflecting mirror 4, it passes through a first beam splitter 5 and is reflected by the surface of a second beam splitter 6 before entering an infinity conjugate microscope objective. After passing through the infinity conjugate microscope objective (i.e., objective lens group 7 in this invention), the laser beam converges on the surface of the object under test 9. Due to the reflection from the surface of the object under test 9, the laser beam passes through the infinity conjugate microscope objective again, and then is continuously reflected by the second beam splitter 6 and the first beam splitter 5. Finally, the focusing lens 10 converges the laser beam onto the surface of the autofocus sensor 11 to form a laser spot. Then, the defocus amount is calculated based on the shape of the laser spot image, and the defocus amount is converted into a control signal for motor 8, which drives the infinity conjugate microscope objective to move, thereby achieving automatic focusing. The illumination LED 13 forms a coaxial illumination optical path through the third beam splitter 12 and the infinity conjugate microscope objective, and the tube lens 14, the imaging sensor 15, and the infinity conjugate microscope objective group 7 form the imaging optical path, thereby acquiring the surface image of the object 9 after focusing.

[0042] To facilitate understanding of this scheme, the relevant components of the coaxial illumination and imaging optical paths, including the third beam splitter 12, illumination LED 13, tube mirror 14, and imaging sensor 15, are omitted in the subsequent structural diagram of the microscopic autofocus device. Furthermore, in existing microscopic autofocus devices, the reflecting mirror 4 can also be removed, and the corresponding optical path structure is as follows: Figure 2 As shown.

[0043] In existing microscopic autofocus technology, after the autofocus sensor 11 is installed, a portion of the laser beam will not pass through the surface of the object 9 due to the reflection effect of the objective lens group 7, but will return directly to the surface of the autofocus sensor 11, forming stray light, which will have an adverse effect on the autofocus effect.

[0044] To reduce or even eliminate stray light reflected by the internal lenses of objective lens group 7, this invention provides a microscopic autofocus device based on a laser spot, such as... Figure 3 As shown, a first polarizer 17 and a rotator 16 are added inside the existing microscopic autofocus device to suppress stray light generated inside the device and improve its stability. Specifically, the microscopic autofocus device includes:

[0045] One or more rotators 16 are disposed within the objective lens group 7 or between the objective lens group 7 and the object 9 to be measured, for rotating the polarization direction of all linearly polarized detection light received by the autofocus sensor 11 once or multiple times, so as to distinguish it from the polarization direction of all or part of the light reflected from the surface of the objective lens group 7.

[0046] The first polarizer 17 is disposed in front of the autofocus sensor 11 and is used only to eliminate all or part of the reflected light other than the linearly polarized detection light.

[0047] Based on the above-mentioned utility model solution, the laser used to form the laser spot in the existing autofocus solution is adjusted to linearly polarized light. Combined with the setting of the optical rotator 16 and the first polarizer 17, the optical rotator 16 changes the polarization direction of the fully polarized detection light reflected from the surface of the object 9 to the autofocus sensor 11, making this polarization direction different from the polarization direction of the stray light directly reflected from the surface of the objective lens group 7 to the autofocus sensor 11. Based on Malus's law, by utilizing the characteristic that the polarization direction of the linearly polarized detection light is inconsistent with the polarization direction of the stray light reflected from the surface of the objective lens group 7, and since the polarization direction of the linearly polarized detection light after being rotated by the one or more optical rotators 16 is consistent with the polarization direction of the first polarizer 17, the first polarizer 17 eliminates all or part of the reflected light, achieving the purpose of reducing the stray light generated by reflection from the internal lenses of the objective lens group 7. Because the stray light intensity is completely blocked or reduced, the stability of the microscopic autofocus device and the accuracy of the autofocus result are also enhanced.

[0048] In the microscopic autofocus solution provided by this utility model, the number of optical rotators 16 can be one or more, and their setting area can be inside the objective lens group 7, including the interval between multiple lenses in the objective lens group 7 or the bottom of the objective lens group 7; or, they can be set between the objective lens group 7 and the object 9 being measured.

[0049] Considering that the objective lens group 7 contains multiple lenses, and due to factors such as lens transmittance and surface reflectivity, most of the stray light within the objective lens group 7 (i.e., the reflected light of this invention) is usually generated by reflection from the front few lenses. Therefore, in some cases, when the optical rotator 16 is positioned between the rear lenses within the objective lens group 7, it can avoid rotating the polarization direction of most of the stray light to be consistent with the polarization direction of the linearly polarized detection light, thereby reducing or even completely extinguishing the light intensity of most of the stray light, which can meet the requirement of a low stray light ratio in microscopic autofocus schemes. For example, assuming that the objective lens group 7 contains 10 lenses, each with a transmittance of 95% and a reflectance of 2.5% on each surface, the stray light generated by the first six lenses accounts for more than 70% of all stray light. In this case, setting a rotator 16 after the sixth lens can ensure that the polarization direction of more than 70% of the stray light is not rotated by the rotator 16, that is, it is not consistent with the polarization direction after the linear polarization detection light is rotated, so that the first polarizer 17 has the ability to reduce the light intensity or extinct most of the stray light.

[0050] In some embodiments, the type of optical rotator 16 in this invention includes a Faraday rotator or a waveplate. For example, when the rotation angle of the polarization direction is 45°, the optical rotator 16 can be a quarter-wave plate. Multiple optical rotators 16 can be a combination of a Faraday rotator and a waveplate, or a combination of multiple waveplates. Typically, the area of ​​a single optical rotator 16 is sufficient to cover the incident and reflected light beams within the objective lens group 7; that is, the optical rotator 16 covers all linearly polarized light incident on the surface of the object 9 and reflected from the surface of the object 9 back to the objective lens group 7 via the objective lens group 7.

[0051] In some scenarios, multiple rotators 16 positioned at different locations can be combined to cover the incident and reflected light beams within the objective lens group 7, with each reflected or incident light beam passing through the rotator 16 only once. For example, four waveplates, each with a quarter-circle area, can be placed under different lenses. The combined coverage of these waveplates can completely cover the incident and reflected light beams within the objective lens group 7 without any overlapping areas. Alternatively, two waveplates with a half-circle area can be placed at the bottom and surface of the objective lens group 7, respectively. The combined coverage of these two waveplates can completely cover the incident and reflected light beams within the objective lens group 7 without any overlapping areas.

[0052] The light reflected from the surface of all or part of the objective lens group 7 can be understood as the reflected light formed by the reflection of an externally incident laser beam (such as linearly polarized light in this invention) from the surface of all or part of the lenses within the objective lens group 7. Typically, there is only one optical rotator 16, which is positioned between the bottom surface of the objective lens group 7 and the object 9 being measured, such as... Figure 3 , 4As shown. Furthermore, when there are multiple optical rotators 16, the rotation angle of the polarization direction of the linearly polarized detection light is the sum of the rotation angles of the multiple optical rotators 16.

[0053] like Figure 3 As shown, the first polarizer 17 is positioned in front of the autofocus sensor 11, acting as an analyzer. Its polarization direction is the same as the polarization direction of the linearly polarized detection light after rotation. Since the polarization direction of the light reflected from the surface of the objective lens group 7 differs from the aforementioned polarization direction, according to Malus's law, the intensity of the linearly polarized detection light passing through the first polarizer 17 remains unchanged, while the intensity of the reflected light passing through the first polarizer 17 will decrease or even be completely eliminated. Therefore, this invention can eliminate all or part of the reflected light other than the linearly polarized detection light through the first polarizer 17, thereby reducing stray light generated by reflection from the internal lenses of the objective lens group 7. It should be noted that the difference between the polarization directions of the reflected light and the linearly polarized detection light after rotation does not include the case of reversal, that is, the angular difference between the polarization directions does not include 180°.

[0054] In some embodiments, such as Figure 5 As shown, the microscopic autofocus device also includes:

[0055] A linearly polarized laser 19 is used to provide linearly polarized light with consistent polarization direction. The linearly polarized light reflected from all or part of the objective lens group 7 to the autofocus sensor 11 serves as reflected light. The linearly polarized light that passes through the objective lens group 7 and is reflected from the surface of the object 9 to the autofocus sensor 11 serves as linearly polarized detection light, used to form the laser spot.

[0056] Specifically, the linearly polarized light in the microscopic autofocus device is directly generated by the linearly polarized laser 19. After entering the objective lens group 7, it is reflected by the various mirror surfaces within the objective lens group 7 to form reflected light, which serves as stray light affecting the calculation of the defocus amount. The linearly polarized light that passes through the objective lens group 7, enters the surface of the object 9, is reflected, passes through the objective lens group 7, and then passes through the second beam splitter 6, the first beam splitter 5, and the focusing lens 10 before entering the autofocus sensor 11. This linearly polarized light serves as the linearly polarized detection light, used to form the laser spot, and represents the normal light used to calculate the defocus amount. Furthermore, the linearly polarized laser 19 refers to a laser that directly outputs linearly polarized light with a fixed or controllable polarization direction, and can be a dichroic polarizer or a laser with an integrated laser polarizing prism, etc.

[0057] In some embodiments, such as Figure 3 , 4 As shown, the microscopic autofocus device provided by this utility model also includes:

[0058] Parallel laser 1 provides a laser beam with a parallel direction.

[0059] The second polarizer 18 is disposed in front of the parallel laser 1 and is used to adjust the laser beam irradiating the objective lens group 7 into linearly polarized light with the same polarization direction. That is, the combination of the parallel laser 1 and the second polarizer 18 is used to replace the linearly polarized laser 19 to provide linearly polarized light.

[0060] In one implementation, the second polarizer 18 is typically a polarizer used to adjust the laser beam provided by the parallel laser 1 into linearly polarized light and control the polarization direction of the linearly polarized light. For example... Figure 3 As shown, the polarization direction of the second polarizer 18 is consistent with the polarization direction of the linearly polarized light incident on the surface of the objective lens group 7 and the linearly polarized light reflected from the surface of the objective lens group 7 (i.e., the linearly polarized light that has not been rotated by the optical rotator 16).

[0061] Typically, the second polarizer 18 is positioned below the parallel laser 1, and this polarizer does not intersect with the first optical path. The first optical path refers to the path of linearly polarized light reflected from the surface of the objective lens group 7 to the autofocus sensor 11. That is, the polarization direction of the second polarizer 18 does not affect the polarization direction of the linearly polarized light reflected from the surface of the object 9 to the autofocus sensor 11. Figure 3 As shown, the second polarizer 18 can be disposed inside the parallel laser 1, or in the interval between any two of the parallel laser 1, the cylindrical lens 2, the baffle 3, the reflector 4 and the first beam splitter 5.

[0062] Accordingly, the first polarizer 17, acting as an analyzer, is positioned in front of the autofocus sensor 11 and does not intersect with the second optical path. The second optical path refers to the path of the laser beam as it travels from the parallel laser 1 or the linearly polarized laser 19 onto the surface of the objective lens group 7. This design prevents the first polarizer 17 from affecting the polarization direction of the linearly polarized light incident on the surface of the objective lens group 7. For example... Figure 3 As shown, the first polarizer 17 can be disposed between the autofocus sensor 11 and the focusing lens 10, and between the focusing lens 10 and the first beam splitter 5.

[0063] In some embodiments, the rotator 16 completely covers the bottom surface of the objective lens group 7. This avoids the unfavorable situation where, due to factors such as the roughness or tilt of the surface of the object under test 9, the linearly polarized detection light reflected from the surface of the object under test 9 directly enters the bottom surface of the objective lens group 7 from the uncovered area of ​​the rotator 16, resulting in some linearly polarized detection light not rotating in polarization direction. This ensures that all linearly polarized detection light passes through the rotator 16. It can be understood that the rotator 16 covers all linearly polarized light that enters the surface of the object under test 9 through the objective lens group 7 and is reflected back to the objective lens group 7 from the surface of the object under test 9, rotating the polarization direction of the linearly polarized light that enters the surface of the object under test 9 from the bottom surface of the objective lens group 7 and is reflected back to the bottom surface of the objective lens group 7.

[0064] In the above scenario, the linearly polarized detection light incident on the autofocus sensor 11 passes through the rotator 16 twice, resulting in two rotations of the polarization direction. Therefore, when the angle between the polarization direction of the first polarizer 17 and the polarization direction of the linearly polarized detection light before rotation is α, the rotation angle of the rotator 16 relative to the polarization direction is α / 2, ensuring that the polarization direction of the linearly polarized detection light after rotation is the same as the polarization direction of the first polarizer 17.

[0065] In some embodiments, such as Figure 3 As shown, the optical rotator 16 is disposed between the objective lens group 7 and the surface of the object 9, and is used to rotate the polarization direction of the linearly polarized light that enters from the bottom surface of the objective lens group 7 onto the surface of the object 9 and is reflected from the surface of the object 9 back to the bottom surface of the objective lens group 7. The linearly polarized light is used to form a laser spot on the surface of the autofocus sensor 11.

[0066] The first polarizer 17, acting as an analyzer, is positioned below the autofocus sensor 11. Its polarization direction is the same as the polarization direction of the linearly polarized light reflected from the surface of the object 9 to the bottom surface of the objective lens group 7 after rotation, but different from the polarization direction of the linearly polarized light incident on the surface of the objective lens group 7. It is only used to pass through the linearly polarized light reflected from the surface of the objective lens group 7 to the autofocus sensor 11 and to eliminate part of the linearly polarized light reflected from the surface of the objective lens group 7 to the autofocus sensor 11.

[0067] Based on the above-mentioned utility model solution, the laser used to form the laser spot in the existing autofocus solution is adjusted to linearly polarized light. Combined with the optical rotator 16, the analyzer (i.e., the first polarizer 17) and their polarization direction settings, the optical rotator 16 changes the polarization direction of the linearly polarized light reflected from the surface of the object 9 to the autofocus sensor 11, so that the polarization direction is different from the polarization direction of the stray light directly reflected from the surface of the objective lens group 7 to the autofocus sensor 11. Furthermore, by combining the polarization direction in the analyzer with the polarization direction of the linearly polarized light reflected from the surface of the object under test 9 to the bottom surface of the objective lens group 7 after rotation, and with the polarization direction of the linearly polarized light incident on the surface of the objective lens group 7, the intensity of the laser reflected from the surface of the object under test 9 to the surface of the autofocus sensor 11 remains unchanged, while the intensity of stray light directly reflected from the surface of the objective lens group 7 to the surface of the autofocus sensor 11 is suppressed due to the different polarization direction. This reduces stray light generated by reflection from the internal lenses of the objective lens group 7, and improves the stability of the microscopic autofocus device and the accuracy of the autofocus results.

[0068] In some embodiments, the optical path structure of the microscopic autofocus device provided by this utility model is as follows: Figure 3As shown, the laser beam emitted by the parallel laser 1 passes through the second polarizer 18 to form linearly polarized light. This linearly polarized light is reflected by the surface of the objective lens group 7 to form stray light. The linearly polarized detection light, which passes through the objective lens group 7 and the optical rotator 16, is reflected by the surface of the object under test 9 to the autofocus sensor 11 and serves as the normal light for calculating the defocus amount. The polarization direction of the stray light reflected by the surface of the objective lens group 7 to the surface of the autofocus sensor 11 is the same as the polarization direction of the linearly polarized light incident on the surface of the objective lens group 7. Simultaneously, the polarization directions of the linearly polarized light incident from the bottom surface of the objective lens group 7 to the surface of the object under test 9 and reflected from the surface of the object under test 9 to the bottom surface of the objective lens group 7 are both rotated by the same angle by the optical rotator 16. Therefore, the normal light reflected from the surface of the object under test to the autofocus sensor 11 has a polarization direction rotated by a certain angle by the optical rotator 16 compared to the stray light directly reflected from the surface of the objective lens group 7 to the autofocus sensor 11. Furthermore, considering the two rotations during the incident and reflection processes, this certain angle is twice the rotation angle of the optical rotator 16 itself. In order to avoid the polarization direction of the aforementioned normal light being the same as or completely opposite to the polarization direction of the stray light (i.e., differing by 180°), the rotation angle of the optical rotator 16 with respect to the polarization direction does not include integer multiples of 90°, such as 0°, 90°, and 180°.

[0069] As mentioned earlier, to ensure that the polarization direction of the first polarizer 17 is the same as the polarization direction of the linearly polarized detection light after rotation, when the angle between the polarization direction of the first polarizer 17 and the polarization direction of the second polarizer 18 is α, the rotation angle of the optical rotator 16 with respect to the polarization direction is α / 2. Here, the polarization direction of the first polarizer 17, acting as an analyzer, can be understood as the polarization direction, that is, the polarization direction of all linearly polarized light allowed to pass through the analyzer, or the transmission axis direction.

[0070] According to Malus's law, when the polarization direction of linearly polarized light is the same as or completely opposite to the polarization direction of the first polarizer 17, the intensity of the linearly polarized light passing through the first polarizer 17 remains unchanged. However, when the angle between the polarization direction of the linearly polarized light and the polarization direction of the first polarizer 17 is not 0 or π, the intensity of the linearly polarized light after passing through the first polarizer 17 weakens. In particular, when the polarization direction of the linearly polarized light is orthogonal to the polarization direction of the first polarizer 17, the intensity of the linearly polarized light after passing through the first polarizer 17 is 0, meaning that the first polarizer 17 completely eliminates the linearly polarized light.

[0071] The angle between the polarization direction of the first polarizer 17 and the polarization direction of the linearly polarized detection light represents the angle through which the polarization direction of the linearly polarized detection light rotates to the polarization direction of the first polarizer 17, and this rotation direction is the same as the rotation direction of the optical rotator 16 relative to the polarization direction. Furthermore, when the aforementioned rotation directions are opposite, the rotation angle of the optical rotator 16 relative to the polarization direction is... .

[0072] In one implementation, the polarization direction of the first polarizer 17 is orthogonal to the polarization direction of the linearly polarized detection light before rotation (i.e., the polarization direction of the linearly polarized light incident on the objective lens surface), meaning the angle between it and the polarization direction of the reflected light is 90°, and the rotation angle of the rotator 16 relative to the polarization direction is 45°. According to Malus's law, stray light reflected from the surface of the objective lens group 7 cannot pass through the first polarizer 17, which acts as an analyzer, and therefore cannot reach the surface of the autofocus sensor 11. This eliminates stray light. The rotator 16's 45° rotation angle ensures that the polarization direction of the normal light used for defocus calculation is consistent with the polarization direction of the first polarizer 17, maintaining the same intensity and guaranteeing the accuracy of the defocus calculation result.

[0073] In practical work, such as Figure 3 As shown, the microscopic autofocus device provided by this utility model, compared with the prior art (such as...), Figure 1 As shown, a second polarizer 18 is added between the reflecting mirror 4 and the first beam splitter 5 as a polarizer. The laser emitted by the parallel laser 1 is modulated by the second polarizer 18 to form linearly polarized light. The first polarizer 17 acts as an analyzer, and its polarization direction is orthogonal to the second polarizer 18. The optical rotator 16 is set between the objective lens group 7 and the surface of the object 9, and can rotate the polarization direction of the linearly polarized light by 45°. Therefore, the stray light formed by the linearly polarized light reaching the objective lens group 7 for the first time and being reflected by its internal lenses is orthogonal to the direction of the first polarizer 17 and cannot reach the autofocus sensor 11 through the analyzer. However, the linearly polarized light that passes through the objective lens group 7 to reach the surface of the object 9 and is reflected back to the surface of the autofocus sensor 11 passes through the optical rotator twice, and its polarization direction is rotated by 90°, which is the same as the polarization direction of the first polarizer 17. Therefore, it can pass through the first polarizer 17 to reach the surface of the autofocus sensor 11 and form an effective defocus detection signal.

[0074] Therefore, the microscopic autofocus device provided by this utility model, compared with the existing microscopic autofocus system, by introducing a first polarizer 17 and a rotator 16, adjusts the ordinary laser beam into linearly polarized light and changes the polarization direction of the normal light reflected from the surface of the object 9 to the autofocus sensor 11, so that its polarization direction is different from that of the stray light directly reflected from the surface of the objective lens group 7 to the autofocus sensor 11. In addition, by setting the rotation angle of the polarization direction through the rotator 16, the technical effect of keeping the light intensity of the normal light unchanged after passing through the first polarizer 17 while reducing or even eliminating the light intensity of the stray light after passing through the first polarizer 17 is achieved. This suppresses the stray light formed inside the microscopic autofocus device and improves the stability and reliability of the microscopic autofocus system.

[0075] On the other hand, this utility model also provides an electronic device, including the above-mentioned microscopic autofocus device.

[0076] In the description of this specification, references to terms such as "an embodiment," "example," and "specific example" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0077] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model.

Claims

1. A microscopic autofocus device based on a laser spot, characterized in that, include: One or more rotators are set inside the objective lens group or between the objective lens group and the object being measured, and are used to rotate the polarization direction of all linearly polarized detection light received by the autofocus sensor once or multiple times, so as to distinguish it from the polarization direction of all or part of the light reflected from the surface of the objective lens group. A first polarizer, positioned in front of the autofocus sensor, is used solely to eliminate all or part of the reflected light other than the linearly polarized detection light.

2. The microscopic autofocus device according to claim 1, characterized in that, Also includes: A linearly polarized laser is used to provide linearly polarized light with a consistent polarization direction; wherein, the linearly polarized light reflected by all or part of the objective lens group surface to the autofocus sensor is used as reflected light. Linearly polarized light, after passing through the objective lens group and being reflected by the surface of the object being measured to the autofocus sensor, is used as linearly polarized detection light to form a laser spot.

3. The microscopic autofocus device according to claim 2, characterized in that, Also includes: Parallel lasers provide laser beams with parallel directions; The second polarizer is disposed in front of the parallel laser and is used to adjust the laser beam irradiated by the objective lens group into linearly polarized light with the same polarization direction. The linearly polarized light reflected by all or part of the objective lens group surface to the autofocus sensor is used as reflected light. The linearly polarized light that passes through the objective lens group and is reflected by the surface of the object under test to the autofocus sensor is used as linearly polarized detection light to form a laser spot.

4. The microscopic autofocus device according to claim 1, characterized in that, The polarization direction of the linearly polarized detection light after being rotated by the one or more optical rotators is consistent with the polarization direction of the first polarizer.

5. The microscopic autofocus device according to claim 1, characterized in that, One or more of the optical rotators include Faraday mirrors or waveplates.

6. The microscopic autofocus apparatus according to any one of claims 1 to 5, characterized in that, There is only one optical rotator, which is located between the objective lens group and the object being measured.

7. The microscopic autofocus device according to claim 6, characterized in that, The optical rotator completely covers the bottom surface of the objective lens group.

8. The microscopic autofocus device according to claim 7, characterized in that, The angle between the polarization direction of the first polarizer and the polarization direction of the reflected light is 90°.

9. The microscopic autofocus device according to claim 8, characterized in that, The rotation angle of the optical rotator relative to the polarization direction is 45°.

10. An electronic device, characterized in that, Includes the microscopic autofocus device as described in any one of claims 1-9.

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