Automatic focusing optical system and visual inspection equipment with same

Abstract

The invention discloses an automatic focusing optical system and visual detection equipment with the same, and relates to the technical field of optical detection. The system comprises a focusing module, the focusing module comprises a light source, a collimation unit and a beam expanding unit, the collimation unit is used for collimating a Gaussian beam emitted by the light source into a flat-topped beam, the beam expanding unit comprises a micro-lens array and a convex lens which are sequentially distributed in the emergent direction of the flat-topped beam, and a shielding piece is arranged on the light incident side of the convex lens; the front surface of the micro-lens array is used for dividing the flat-topped light beam into a plurality of sub-light beams, the rear surface of the micro-lens array is used for mutually superposing the focused sub-light beams to form a homogenized light beam, and the convex lens is used for expanding the homogenized light beam into parallel light beams; and the detection module comprises an objective table and an imaging unit, the objective table is used for bearing the to-be-detected sample, and the imaging unit is used for imaging and focusing through the parallel light beams reflected by the to-be-detected sample. By adopting the system provided by the invention, the uniformity of linear light spots can be obviously improved, and burrs and noise are eliminated.

Description

Technical Field

[0001] The present application relates to the field of optical detection technology, and in particular to an autofocus optical system and a visual detection device having the same. Background Art

[0002] Visual inspection equipment can perform imaging inspection on samples on glass slides, and in order to improve work efficiency, it uses an autofocus device to achieve fast focusing. At present, the autofocus device in the related technology mainly uses components such as cylindrical mirrors, diffraction gratings or slits to collimate point light sources into line beams, but the uniformity of the line light spots obtained by these methods is relatively poor, and there are a lot of burrs and noise on the edge of the beam, which will have an adverse effect on the detection results of subsequent detectors. Summary of the invention

[0003] In view of the above-mentioned defects or deficiencies in the related art, it is desired to provide an autofocus optical system and a visual inspection device having the same, which can not only significantly improve the uniformity of the line spot, but also significantly improve the sharp edge of the light beam, eliminate burrs and noise, and improve the detection accuracy.

[0004] In a first aspect, the present application provides an auto-focus optical system, the auto-focus optical system comprising:

[0005] A focusing module, the focusing module comprising a light source, a collimating unit and a beam expanding unit, the collimating unit being used to collimate a Gaussian beam emitted by the light source into a flat-top beam, the beam expanding unit comprising a microlens array and a convex lens sequentially distributed along an exit direction of the flat-top beam, and a shielding sheet being provided on a light incident side of the convex lens, the front surface of the microlens array being used to split the flat-top beam into a plurality of sub-beams and focus the sub-beams, the rear surface of the microlens array being used to superimpose the focused sub-beams to form a homogenized beam, and the convex lens being used to expand the homogenized beam into a parallel beam;

[0006] The detection module comprises an object stage and an imaging unit, wherein the object stage is used to carry the sample to be tested, and the imaging unit is used to perform imaging and focusing through the parallel light beam reflected by the sample to be tested.

[0007] Optionally, in some embodiments of the present application, the microlens array is a cylindrical microlens array, and both sides of each cylindrical microlens in the cylindrical microlens array are convex.

[0008] Optionally, in some embodiments of the present application, the width of the cylindrical microlens is 0.2 mm.

[0009] Optionally, the microlens array in some embodiments of the present application is a refractive microlens array.

[0010] Optionally, in some embodiments of the present application, the light incident surface of the convex lens is a plane, and the light emitting surface of the convex lens is a convex surface.

[0011] Optionally, in some embodiments of the present application, the shielding sheet is located above the optical axis of the convex lens, or the shielding sheet is located below the optical axis of the convex lens.

[0012] Optionally, in some embodiments of the present application, the imaging unit includes a beam splitter arranged along the emitting direction of the parallel light beam, a microscope objective located in the transmission path of the beam splitter, and an imaging lens and a detector located in the reflection path of the beam splitter, the microscope objective being used to focus the parallel light beam reflected by the sample to be tested, and the imaging lens and the detector being used to perform imaging and focusing using the focused parallel light beam reflected by the sample to be tested.

[0013] Optionally, in some embodiments of the present application, the angle between the transmission path and the reflection path is 90 degrees.

[0014] Optionally, in some embodiments of the present application, the imaging unit further includes a reflector disposed between the convex lens and the beam splitter, the parallel light beam expanded by the convex lens is incident on the reflector at 45 degrees, and the reflector is parallel to the beam splitter.

[0015] In a second aspect, the present application provides a visual inspection device, wherein the visual inspection device comprises the autofocus optical system described in any one of the first aspects.

[0016] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

[0017] The embodiment of the present application provides an autofocus optical system and a visual inspection device having the same. After the collimation unit of the focusing module collimates the Gaussian beam emitted by the light source into a flat-top beam, the flat-top beam can be divided into multiple sub-beams through the front surface of the microlens array, and the sub-beams are focused, and the focused sub-beams are superimposed on each other through the rear surface of the microlens array to form a homogenized beam, which significantly improves the uniformity of the line spot. At the same time, the homogenized beam is expanded into a parallel beam through a convex lens, which can significantly improve the sharp edge of the beam and effectively eliminate burrs and noise. A shielding plate is also provided on the light incident side of the convex lens, so that the imaging unit of the detection module can detect the defocus condition of the optical system based on the knife-edge method, and perform automatic imaging and fast focusing through the parallel beam reflected by the sample to be tested, which greatly improves the detection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A structural block diagram of an auto-focus optical system provided in an embodiment of the present application;

[0020] Figure 2 A specific example of an auto-focus optical system provided in an embodiment of the present application;

[0021] Figure 3 A schematic diagram of the structure of a microlens array provided in an embodiment of the present application;

[0022] Figure 4 A schematic diagram of a combined optical path of a cylindrical microlens array and a plano-convex lens provided in an embodiment of the present application;

[0023] Figure 5 A light spot diagram obtained by combining a cylindrical microlens array and a plano-convex lens provided in an embodiment of the present application;

[0024] Figure 6 A schematic diagram of a combined optical path of a negative lens and a positive lens provided for related technology;

[0025] Figure 7 A light spot diagram obtained by combining a negative lens and a positive lens provided in the related art;

[0026] Figure 8 A structural block diagram of a visual inspection device provided in an embodiment of the present application.

[0027] Reference numerals:

[0028] 1-autofocus optical system, 11-focusing module, 111-light source, 112-collimation unit, 113-beam expansion unit, 1131-microlens array, 1132-convex lens, 1133-shielding plate, a1-cylindrical microlens array, a2-plano-convex lens, b1-negative lens, b2-positive lens, 12-detection module, 121-stage, 122-imaging unit, 1221-beam splitter, 1222-microscope objective, 1223-imaging lens, 1224-detector, 1225-reflector, 2-visual detection equipment. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0030] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0031] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. Figures 1 to 8 The auto-focus optical system and the visual inspection device having the same provided by the embodiments of the present application are described in detail.

[0032] Please refer to Figure 1 , which is a structural block diagram of an auto-focus optical system provided in an embodiment of the present application, wherein the auto-focus optical system 1 comprises a focus module 11 and a detection module 12. Figure 2 As shown, the focusing module 11 includes but is not limited to a light source 111, a collimating unit 112 and a beam expanding unit 113, etc. The collimating unit 112 can collimate the Gaussian beam emitted by the light source 111 into a flat-top beam, for example, the collimating unit 112 includes a collimating lens, and the beam expanding unit 113 includes a microlens array 1131 and a convex lens 1132 sequentially distributed along the exit direction of the flat-top beam, and a shielding sheet 1133 is provided on the light incident side of the convex lens 1132, the front surface of the microlens array 1131 can split the flat-top beam into a plurality of sub-beams, and focus the sub-beams, the rear surface of the microlens array 1131 can superimpose the focused sub-beams to form a homogenized beam, and the convex lens 1132 can expand the homogenized beam into a parallel beam. It should be noted that the microlens array 1131 is an array formed by arranging a plurality of microlenses with a clear aperture and a relief depth of micrometers in a specific order.

[0033] In addition, the detection module 12 includes but is not limited to the stage 121 and the imaging unit 122. The stage 121 can carry the sample to be tested. For example, the stage 121 can move along the horizontal plane and the vertical height can be adjusted, and the imaging unit 122 can perform imaging and focusing through the parallel light beam reflected by the sample to be tested. For example, when the shielding plate 1133 is located above the optical axis of the convex lens 1132, that is, it blocks the light in the upper half of the optical axis, and the final imaging effect on the focal plane is that there is light in the lower half. For another example, when the shielding plate 1133 is located below the optical axis of the convex lens 1132, that is, it blocks the light in the lower half of the optical axis, and the final imaging effect on the focal plane is that there is light in the upper half. That is to say, the knife-edge method is used to detect the defocus condition of the optical system, thereby achieving automatic imaging and fast focusing.

[0034] In some embodiments of the present application, Figure 3 As shown, the microlens array 1131 can be a cylindrical microlens array, in which both sides of each cylindrical microlens are convex, and the width of the cylindrical microlens can be 0.2 mm. In other embodiments of the present application, the microlens array 1131 can also be a refractive microlens array. Furthermore, the light incident surface of the convex lens 1132 is a plane, and the light exiting surface of the convex lens 1132 is a convex surface. The test results show that the embodiments of the present application pass Figure 4 The cylindrical microlens array (a1) and the plano-convex lens (a2) are combined to obtain Figure 5 The spot diagram shown in the figure shows that the homogenization effect is better than that of related technologies. Figure 6 The negative lens (b1) and the positive lens (b2) are combined to obtain Figure 7 The light spot diagram shown in the figure shows that the homogenized light beam fills the entire aperture and the edge of the light beam is smooth, which effectively eliminates burrs and noise, reduces the impact of detector background noise, and makes the detection results more accurate.

[0035] In some embodiments of the present application, Figure 2 As shown in the figure, the imaging unit 122 includes a beam splitter 1221 arranged along the emitting direction of the parallel light beam, a microscope objective 1222 located in the transmission path of the beam splitter 1221, an imaging lens 1223 and a detector 1224 located in the reflection path of the beam splitter 1221. For example, the angle between the transmission path and the reflection path is 90 degrees. The microscope objective 1222 can focus the parallel light beam reflected by the sample to be tested, and its performance will affect the resolution and imaging quality of the entire optical system. The imaging lens 1223 and the detector 1224 can use the focused parallel light beam reflected by the sample to be tested for imaging and focusing. For example, the detector 1224 includes but is not limited to a charge coupled device (CCD) and a complementary metal oxide semiconductor (CMOS) device.

[0036] Furthermore, the imaging unit 122 also includes a reflector 1225 arranged between the convex lens 1132 and the beam splitter 1221. The parallel light beam expanded by the convex lens 1132 is incident on the reflector 1225 at 45 degrees, and the reflector 1225 is parallel to the beam splitter 1221. The advantage of this arrangement is that the structure is compact and space resources are saved.

[0037] The autofocus optical system provided in the embodiment of the present application can split the flat-top beam into multiple sub-beams through the front surface of the microlens array and focus the sub-beams after the collimation unit of the focusing module collimates the Gaussian beam emitted by the light source into a flat-top beam, and superimpose the focused sub-beams on each other through the rear surface of the microlens array to form a homogenized beam, which significantly improves the uniformity of the line spot. At the same time, the homogenized beam is expanded into a parallel beam through a convex lens, which can significantly improve the sharp edge of the beam and effectively eliminate burrs and noise. A shielding plate is also provided on the light incident side of the convex lens, so that the imaging unit of the detection module can detect the defocus condition of the optical system based on the knife-edge method, and perform automatic imaging and fast focusing through the parallel beam reflected by the sample to be tested, which greatly improves the detection accuracy.

[0038] Based on the above embodiments, the present application provides a visual inspection device. Figure 8 , which is a structural block diagram of a visual inspection device provided in an embodiment of the present application, the visual inspection device 2 includes Figures 1 to 7 This corresponds to the autofocus optical system 1 of the embodiment.

[0039] It should be noted that, for the description of the same contents in this embodiment as those in other embodiments, reference can be made to the description in other embodiments and will not be repeated here.

[0040] The visual inspection device provided in the embodiment of the present application has an autofocus optical system in which, after the collimation unit of the focusing module collimates the Gaussian beam emitted by the light source into a flat-top beam, the flat-top beam can be split into multiple sub-beams through the front surface of the microlens array, and the sub-beams are focused, and the focused sub-beams are superimposed on each other through the rear surface of the microlens array to form a homogenized beam, which significantly improves the uniformity of the line light spot. At the same time, the homogenized beam is expanded into a parallel beam through a convex lens, which can significantly improve the sharp edge of the beam and effectively eliminate burrs and noise. A shielding plate is also provided on the light incident side of the convex lens, so that the imaging unit of the detection module can detect the defocus condition of the optical system based on the knife-edge method, and automatically image and quickly focus through the parallel beam reflected by the sample to be tested, which greatly improves the detection accuracy.

[0041] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0042] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. An autofocus optical system, characterized in that: The auto-focus optical system (1) comprises: A focusing module (11), the focusing module (11) comprising a light source (111), a collimating unit (112) and a beam expanding unit (113), the collimating unit (112) being used to collimate a Gaussian beam emitted by the light source (111) into a flat-top beam, the beam expanding unit (113) comprising a microlens array (1131) and a convex lens (1132) sequentially distributed along the exit direction of the flat-top beam, and a shielding sheet (1133) being provided on the light entrance side of the convex lens (1132), the front surface of the microlens array (1131) being used to split the flat-top beam into a plurality of sub-beams and to focus the sub-beams, the rear surface of the microlens array (1131) being used to superimpose the focused sub-beams to form a homogenized beam, and the convex lens (1132) being used to expand the homogenized beam into a parallel beam; A detection module (12), the detection module (12) comprising a stage (121) and an imaging unit (122), the stage (121) being used to carry a sample to be tested, and the imaging unit (122) being used to perform imaging and focusing through a parallel light beam reflected by the sample to be tested.

2. The autofocus optical system according to claim 1, characterized in that: The microlens array (1131) is a cylindrical microlens array, and both sides of each cylindrical microlens in the cylindrical microlens array are convex.

3. The autofocus optical system according to claim 2, characterized in that: The width of the cylindrical microlens is 0.2 mm.

4. The autofocus optical system according to claim 1, wherein: The microlens array (1131) is a refractive microlens array.

5. The autofocus optical system according to any one of claims 1 to 4, characterized in that: The light incident surface of the convex lens (1132) is a plane, and the light emitting surface of the convex lens (1132) is a convex surface.

6. The autofocus optical system according to claim 5, characterized in that: The shielding plate (1133) is located above the optical axis of the convex lens (1132), or the shielding plate (1133) is located below the optical axis of the convex lens (1132).

7. The autofocus optical system according to any one of claims 1 to 4, characterized in that: The imaging unit (122) comprises a beam splitter (1221) arranged along the emitting direction of the parallel light beam, a microscope objective lens (1222) located on the transmission path of the beam splitter (1221), and an imaging lens (1223) and a detector (1224) located on the reflection path of the beam splitter (1221); the microscope objective lens (1222) is used to focus the parallel light beam reflected by the sample to be tested, and the imaging lens (1223) and the detector (1224) are used to perform imaging and focusing using the focused parallel light beam reflected by the sample to be tested.

8. The autofocus optical system according to claim 7, characterized in that: The angle between the transmission path and the reflection path is 90 degrees.

9. The autofocus optical system according to claim 7, wherein: The imaging unit (122) further comprises a reflector (1225) arranged between the convex lens (1132) and the beam splitter (1221), wherein the parallel light beam expanded by the convex lens (1132) is incident on the reflector (1225) at a 45-degree angle, and the reflector (1225) is parallel to the beam splitter (1221).

10. A visual inspection device, characterized in that: The visual inspection device (2) comprises the autofocus optical system (1) according to any one of claims 1 to 9.

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