Light uniforming device, lighting equipment and optical detection system

Abstract

A light homogenization device, lighting equipment, and optical detection system include a first light homogenization element, a second light homogenization element, and a third light homogenization element, which are sequentially arranged along an optical path. The first light homogenization element is used to homogenize the field of view of a light beam. The second light homogenization element is used to split the output light of the first light homogenization element into multiple sub-beams and converge each sub-beam separately to achieve pupil homogenization. The third light homogenization element is used to homogenize the field of view of the output light of the second light homogenization element. This application can take into account both field of view homogenization and pupil homogenization, and improve the effects of pupil homogenization and field of view homogenization.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor detection technology, and in particular to a light homogenizing device, lighting equipment and an optical detection system. Background Art

[0002] During the semiconductor manufacturing process, optical inspection systems are required to perform quality checks on semiconductors. As semiconductor manufacturing processes evolve toward higher precision and higher integration, optical inspection systems place higher demands on the field of view uniformity and pupil uniformity (i.e., the uniformity of light intensity within the pupil) of lighting equipment. These uniformity directly impacts key performance indicators such as detection sensitivity and linewidth measurement accuracy.

[0003] Currently, light pipes or micro lens arrays (MLAs) are commonly used to achieve light uniformity in semiconductor optical inspection systems. However, light pipes suffer from poor pupil uniformity for light sources that are unevenly distributed at different angles, while micro lens arrays still experience light intensity attenuation at the edges of the field of view, resulting in poor field of view uniformity. Summary of the Invention

[0004] To overcome the above problems, the present application provides a light uniforming device, a lighting device and an optical detection system.

[0005] According to the first aspect, an embodiment provides a light homogenizing device, comprising a first light homogenizing element, a second light homogenizing element, and a third light homogenizing element sequentially arranged along an optical path;

[0006] The first light homogenizing element is used to homogenize the field of view of the light beam;

[0007] The second light homogenizing element is used to split the output light of the first light homogenizing element into multiple sub-beams and converge each sub-beam separately;

[0008] The third light homogenizing element is used to homogenize the field of view of the light emitted by the second light homogenizing element.

[0009] In some embodiments, the light homogenizing device further includes a first collimating element, which is disposed on the optical path between the first light homogenizing element and the second light homogenizing element, and is configured to collimate the outgoing light of the first light homogenizing element and project the collimated light onto the second light homogenizing element.

[0010] In some embodiments, the light homogenizing device further includes a zoom beam expander, which is disposed on the optical path between the first collimating element and the second light homogenizing element.

[0011] In some embodiments, the first light homogenizing element is located on a front focal plane of the first collimating element, and the second light homogenizing element is located on a back focal plane of the first collimating element.

[0012] In some embodiments, the light homogenizing device further includes a field lens device, which is arranged on the optical path between the second light homogenizing element and the third light homogenizing element, and is used to converge the outgoing light of the second light homogenizing element and project it onto the third light homogenizing element.

[0013] In some embodiments, the second light homogenizing element is a microlens array, and the field lens device is a microlens array, and the field lens device is located on the back focal plane of the second light homogenizing element.

[0014] In some embodiments, the distance between the third light homogenizing element and the field lens device is no greater than 1 / 10 of the focal length of the second light homogenizing element.

[0015] In some embodiments, the size of the incident surface of the third light homogenizing element is not smaller than the size of the exit surface of the field lens device.

[0016] In some embodiments, the field lens device includes a second collimating element and a third collimating element, the distance between the second collimating element and the third collimating element is the sum of the focal length of the second collimating element and the focal length of the third collimating element, and the third light homogenizing element is located on the back focal plane of the third collimating element.

[0017] In some embodiments, the first light homogenizing element is a light homogenizing rod, and / or the second light homogenizing element is a microlens array, and / or the third light homogenizing element is a light homogenizing rod.

[0018] According to the second aspect, an embodiment provides a lighting device, which includes a light source and the light homogenizing device described in any embodiment of the first aspect, wherein the light homogenizing device is used to homogenize the light beam emitted by the light source.

[0019] In some embodiments, the lighting device further includes an illumination optical component, the illumination optical component being configured to project the light beam homogenized by the light homogenizing device onto a target object, and the illumination optical component having a circular pupil;

[0020] The first light homogenizing element is a light homogenizing rod, and the cross section of the first light homogenizing element is a polygon with no less than six sides, and / or the third light homogenizing element is a light homogenizing rod, and the cross section of the third light homogenizing element is a polygon with no less than six sides.

[0021] According to a third aspect, an embodiment provides an optical detection system, which includes the lighting device, imaging sensor and processor according to any embodiment of the second aspect;

[0022] The lighting device is used to illuminate the object to be measured;

[0023] The imaging sensor is used to image the object to be measured to obtain an image of the object to be measured;

[0024] The processor is connected to the lighting device and the imaging sensor, and is used to control the lighting device to illuminate the object to be measured, and to obtain an image of the object to be measured for optical detection.

[0025] In some embodiments, the second light homogenizing element is a microlens array, the first light homogenizing element and the third light homogenizing element are light homogenizing rods, the sub-lens aperture of the second light homogenizing element is rectangular, and the cross-section of the first light homogenizing element and the third light homogenizing element is rectangular;

[0026] The aspect ratio of the sub-lens aperture of the second light homogenizing element, the aspect ratio of the cross sections of the first light homogenizing element and the third light homogenizing element are all the same as the aspect ratio of the photosensitive surface of the imaging sensor.

[0027] According to the light homogenization device, lighting equipment, and optical detection system of the above-mentioned embodiment, a three-stage homogenization mechanism is adopted. First, the field of view is homogenized by the first light homogenization element. Then, the outgoing light of the first light homogenization element is divided into multiple sub-beams by the second light homogenization element, and each sub-beam is converged separately. Since the converged sub-beams are the superposition of light within a certain angle range, the difference between the sub-beams after convergence is reduced, which is conducive to achieving pupil homogenization. Finally, the field of view is further homogenized by the third light homogenization element, so that both field of view homogenization and pupil homogenization can be taken into account. Since the field of view is first homogenized by the first light homogenization element before the second light homogenization element, and further homogenized by the third light homogenization element after the second light homogenization element, the effects of pupil homogenization and field of view homogenization are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the structure of a light homogenizing device according to an embodiment;

[0029] Figure 2 Schematic diagram of the structure of a light homogenizing device according to another embodiment;

[0030] Figure 3 Schematic diagram of the structure of a light homogenizing device according to another embodiment;

[0031] Figure 4 Schematic diagram of the structure of a light homogenizing device according to another embodiment;

[0032] Figure 5 Schematic diagram of the structure of a light homogenizing device according to another embodiment;

[0033] Figure 6is a structural schematic diagram of a lighting device according to an embodiment;

[0034] Figure 7 is a structural schematic diagram of a lighting device according to another embodiment;

[0035] Figure 8 Schematic diagram of the structure of an optical detection system according to an embodiment. DETAILED DESCRIPTION

[0036] The present invention will be further described in detail below by means of specific embodiments in conjunction with the accompanying drawings. Similar elements in different embodiments are numbered with associated similar elements. In the following embodiments, many detailed descriptions are provided to enable the present application to be better understood. However, those skilled in the art will readily appreciate that some of the features may be omitted in different circumstances, or may be replaced by other elements, materials, or methods. In some cases, some operations related to the present application are not shown or described in the specification. This is to avoid the core portion of the present application being overwhelmed by excessive descriptions, and for those skilled in the art, it is not necessary to describe these related operations in detail. They will fully understand the related operations based on the description in the specification and the general technical knowledge in the art.

[0037] In addition, the features, operations, or characteristics described in the specification may be combined in any appropriate manner to form various embodiments. Furthermore, the steps or actions in the method description may be reordered or adjusted in a manner readily apparent to those skilled in the art. Therefore, the various sequences in the specification and drawings are provided solely for the purpose of clearly describing a particular embodiment and are not intended to be mandatory, unless otherwise specified.

[0038] Component numbers used herein, such as "first" and "second," are used solely to distinguish the components being described and do not connote any sequential or technical meaning. "Multiple" means two or more. References to "connected" and "coupled" in this application, unless otherwise specified, include both direct and indirect connections (couplings).

[0039] The applicant believes that homogenizer rods and microlens arrays have their limitations. The homogenization effect of the homogenizer rod depends on the angular distribution of the incident light. If the intensity distribution of the incident light at different angles is asymmetric or has local energy concentration, it is difficult for the total internal reflection inside the homogenizer rod to completely eliminate these non-uniformities, resulting in the output light still having intensity attenuation at the edge angle, affecting the uniformity of the pupil. Microlens arrays are prone to light intensity attenuation at the edge of the field of view due to insufficient fill factor, affecting the uniformity of the field of view. The existing technology uses a single homogenizer rod or microlens array to homogenize the light source, so it is impossible to take into account both field of view uniformity and pupil uniformity, and the homogenization effect is poor.

[0040] Based on the above understanding, the present application proposes a light homogenization device that adopts a three-stage homogenization mechanism. First, preliminary light homogenization is performed through the first homogenization element to eliminate the spatial non-uniformity of the light source and achieve pre-homogenization of the field of view; then, the wavefront of the output light of the first homogenization element is secondary modulated to adjust the angular distribution of the light intensity to achieve pupil homogenization, and then the field of view is further homogenized through the third homogenization element. This solves the problem in the existing technology that field of view homogenization and pupil homogenization cannot be taken into account at the same time, and can achieve the pupil homogenization and field of view homogenization effects required for semiconductor detection lighting.

[0041] Please refer to Figure 1 The light homogenizing device 10 provided in the embodiment of the present application includes a first light homogenizing element 11, a second light homogenizing element 12 and a third light homogenizing element 13 arranged in sequence along the light path.

[0042] The first light homogenizing element 11 is used to homogenize the field of view of the light beam, and may specifically be a light homogenizing rod, a DOE (Diffractive Optical Elements), a diffuser, a microlens array, or the like.

[0043] Usually, the field of view distribution of the light source is poor, and the first light homogenizing element 11 pre-homogenizes the light source in the field of view, thereby obtaining a more uniform field of view distribution.

[0044] The second light homogenizing element 12 is used to split the output light of the first light homogenizing element 11 into multiple sub-beams and converge each sub-beam separately. Specifically, the second light homogenizing element 12 may include multiple lens structures. The output light of the first light homogenizing element 11 is irradiated onto the second light homogenizing element 12 and split by each lens. Each lens converges a portion of the light beam. For example, the second light homogenizing element 12 may be a microlens array.

[0045] Because the light source has poor angular uniformity, such as attenuation at edge angles, the light intensity at the edge angles can differ significantly from the light intensity near the center. The second light homogenizing element 12 splits the light at different angles into different sub-beams, effectively dividing the light angles and re-converging them at a specific angle. The converged sub-beams are a superposition of light within a specific angle range, minimizing the differences between the sub-beams after convergence compared to the original differences between the beams at different angles, thus achieving pupil homogenization.

[0046] The third light homogenizing element 13 is used to homogenize the field of view of the light emitted by the second light homogenizing element. Specifically, it can be a light homogenizing rod, a diffractive optical element (DOE), a diffuser, a microlens array, etc. The third light homogenizing element 13 can be located at the back focal plane of the second light homogenizing element 12, which helps to reduce the size of the third light homogenizing element 13.

[0047] It can be seen that the present application can take into account both field of view homogenization and pupil homogenization through the cooperation of the first homogenizing element 11, the second homogenizing element 12, and the third homogenizing element 13. Since the field of view is first homogenized by the first homogenizing element 11 before the second homogenizing element 12, the light beam obtained after the second homogenizing element 12 has a relatively uniform angular distribution and field of view distribution, which can improve the pupil homogenization effect. After the second homogenizing element 12, the field of view is further homogenized by the third homogenizing element 13, which can enhance the field of view homogenization effect and overcome the possible impact of the second homogenizing element 12 on the field of view uniformity.

[0048] Please refer to Figures 2 to 5 In some embodiments, the light homogenizing device 10 further includes a first collimating element 14, which is disposed on the optical path between the first light homogenizing element 11 and the second light homogenizing element 12 and is configured to collimate the light emitted from the first light homogenizing element 11 and project it onto the second light homogenizing element 12. The first collimating element 14 can specifically be a collimating lens, etc.

[0049] The first light homogenizing element 11 may be located on the front focal plane of the first collimating element 14 , and the second light homogenizing element 12 may be located on the back focal plane of the first collimating element 14 .

[0050] The first collimating element 14 can convert the output light of the first light homogenizing element 11 into parallel light and project it onto the second light homogenizing element 12 , thereby ensuring that more light can effectively pass through the second light homogenizing element 12 .

[0051] Please refer to Figures 2 to 5 In some embodiments, the light homogenizing device 10 further includes a field lens device 15, which is arranged on the optical path between the second light homogenizing element 12 and the third light homogenizing element 13, and is used to converge the output light of the second light homogenizing element 12 and project it onto the third light homogenizing element 13.

[0052] The convergence of the field lens device 15 can reduce the light that deviates from the third light homogenizing element 13 and reduce energy loss. The angular distribution uniformity of the light beam after passing through the field lens device 15 is the same as that of the light emitted by the second light homogenizing element 12.

[0053] Please refer to Figure 2 In some embodiments, the second light homogenizing element 12 is a microlens array, and the field lens device 15 is also a microlens array. The field lens device 15 is located on the back focal plane of the second light homogenizing element 12. The specifications of the field lens device 15 can be the same or similar to those of the second light homogenizing element 12. The light emitted from the sub-lenses of the second light homogenizing element 12 is further focused by the corresponding sub-lenses of the field lens device 15, reducing the divergence angle and allowing more light to enter the third light homogenizing element 13.

[0054] To receive more light, the third light homogenizing element 13 can be positioned close to the field lens device 15. In a specific embodiment, the distance between the third light homogenizing element 13 and the field lens device 15 is no greater than 1 / 10 of the focal length of the second light homogenizing element 12. The applicant has discovered that the divergence of light behind the field lens device 15 is primarily determined by the second light homogenizing element 12. Therefore, by setting the distance between the third light homogenizing element 13 and the field lens device 15 to no greater than 1 / 10 of the focal length of the second light homogenizing element 12, sufficient light behind the field lens device 15 can be received.

[0055] Preferably, the size of the incident surface of the third light homogenizing element 13 is not smaller than the size of the exit surface of the field lens device 15. The incident surface here refers to the surface where light enters the optical device, and the exit surface refers to the surface where light exits the optical device.

[0056] Please refer to Figure 3 In some embodiments, the field lens device 15 includes a second collimating element 15a and a third collimating element 15b. The distance between the second collimating element 15a and the third collimating element 15b is the sum of the focal lengths of the second collimating element 15a and the third collimating element 15b. The third light homogenizing element 13 is located on the back focal plane of the third collimating element 15b. The second collimating element 15a and the third collimating element 15b can specifically be collimating lenses, etc.

[0057] The second collimating element 15 a and the third collimating element 15 b form a double telecentric lens, which can make the main ray of the light emitted by the second light homogenizing element 12 parallel to the optical axis without introducing a larger angle, so that more light enters the third light homogenizing element 13 .

[0058] Please refer to Figure 4 In some embodiments, the light homogenizing device 10 further includes a zoom beam expander 16 , which is disposed on the optical path between the first collimating element 14 and the second light homogenizing element 12 .

[0059] By adjusting the beam expansion ratio of the zoom beam expander 16, the size of the light spot incident on the second light homogenizing element 12 can be controlled, thereby changing the size of the light spot before it enters the third light homogenizing element 13. However, the incident angle does not change. In this way, the size of the light spot emitted from the third light homogenizing element 13 also changes accordingly, while the exit angle remains unchanged. This is equivalent to changing the optical invariant of the light emitted by the entire device.

[0060] Usually when performing semiconductor inspection, it is necessary to switch the field of view or NA value of the objective lens of the imaging system, that is, it is necessary to change the optical invariant of the imaging system. By adjusting the beam expansion ratio of the zoom beam expander 16, the above requirements can be adapted and the energy utilization rate of the lighting can be effectively improved.

[0061] The following combination Figure 5 , a specific example is used to illustrate the light uniforming device of this application. Please refer to Figure 5 The light homogenizing device 10 includes a first light homogenizing element 11, a second light homogenizing element 12, a third light homogenizing element 13, a first collimating element 14 and a field lens device 15, wherein the first light homogenizing element 11 and the third light homogenizing element 13 are light homogenizing rods, the second light homogenizing element 12 is a microlens array, and the field lens device 15 is a microlens array.

[0062] like Figure 5 As shown, the light emitted by the light source is incident from the front face of the first light homogenizing element 11, and its field of view uniformity and angular distribution uniformity are both poor. The light undergoes multiple total reflections within the first light homogenizing element 11, completing the pre-homogenization of the light in the field of view. The rear face of the first light homogenizing element 11 presents a uniform field of view distribution, that is, the central field of view point 1 and the edge field of view point 2 at the rear face of the first light homogenizing element 11 have uniform light intensity.

[0063] Typically, the field of view uniformity of a light source is poor, and a uniform field of view distribution can be obtained after passing through the first homogenizing element 11. This also facilitates obtaining a relatively uniform field of view distribution on the rear surface of the field lens device 15. The pupil distribution after the third homogenizing element 13 presents a multi-level array projection imaging of the field of view distribution of the field lens device 15, thus obtaining a more densely packed and uniform pupil after the third homogenizing element 13. However, due to the total internal reflection working mechanism of the homogenizing rod, the light after passing through the first homogenizing element 11 maintains the same poor angular distribution uniformity as the light source.

[0064] Then, the light emitted from the central viewing point 1 at the rear end face of the first light homogenizing element 11 (see Figure 5 The solid line (center line) is collimated by the first collimating element 14 onto the second light homogenizing element 12. Light rays from different angles at the central field of view point 1 are projected onto sub-lenses at different positions on the second light homogenizing element 12. This is equivalent to the sub-lenses splitting the angles of the light rays emitted from the central field of view point 1. The light rays are then re-converged at a specific angle by the second light homogenizing element 12. Due to this splitting effect, the angular distribution uniformity of the light beams formed by the sub-lenses in the second light homogenizing element 12 is significantly improved.

[0065] The light emitted from the edge field point 2 at the edge of the rear end surface of the first light homogenizing element 11 (see Figure 5 The light beams (the middle dotted line) have a certain object height relative to the first collimating element 14, so after passing through the first collimating element 14, they are incident on the second light homogenizing element 12 at an inclined angle and converge after passing through the second light homogenizing element 12, which also improves the angular distribution uniformity.

[0066] The field lens device 15 is located on the rear focal plane of the second light homogenizing element 12. This allows the light emitted from the central field point 1 and the edge field point 2 to pass through the second light homogenizing element 12 and then be further focused by the field lens device 15. The principal rays at each sub-lens of the field lens device 15 are parallel, without introducing a larger angle, thus reducing the deviation of the light from the third light homogenizing element 13. The angular distribution uniformity of the light at the rear surface of the field lens device 15 is the same as that of the light emitted from the second light homogenizing element 12, both having a uniform angular distribution.

[0067] Since the central field of view point 1 and the edge field of view point 2 have a uniform field of view distribution, the light is collimated by the first collimating element 14 and converged by the sub-lenses on the second homogenizing element 12, and projected onto the sub-lenses of the field lens device 15, with a uniform field of view distribution. Due to processing problems, the field lens device 15 will have a certain duty cycle, and the light field distribution on its rear surface will have the sub-aperture profile of the field lens device 15, and cannot be directly provided to the rear-end lighting system for use. The third homogenizing element 13 is closely attached to the rear surface of the field lens device 15. The third homogenizing element 13 homogenizes the field of view of the light transmitted from the field lens device 15, and a uniform field of view distribution can be obtained on the rear end face of the third homogenizing element 13. At the same time, the uniformity of the angular distribution of the light on the rear surface of the third homogenizing element 13 is retained. In this way, a uniform angular distribution and field of view distribution can be obtained at the rear end face of the third homogenizing element 13 at the same time, achieving pupil homogenization and field of view homogenization.

[0068] This application also provides a lighting device, please refer to Figure 6 The lighting device 100 includes a light source 20 and a light homogenizing device 10 according to any embodiment of the present application.

[0069] The light source 20 can be an LED, xenon lamp, laser, or LDLS (Laser Driven Light Source). The light homogenization device 10 is used to homogenize the light beam emitted by the light source 20. The homogenized light beam is used to illuminate the target object A for optical inspection.

[0070] Please refer to Figure 7 In some embodiments, the lighting device 100 further includes an illumination optical component 30, which is used to project the light beam homogenized by the homogenizing device 10 onto the target object A, and the illumination optical component 30 has a circular pupil.

[0071] It can be understood that the illumination optical component 30 may include a lens, an aperture, etc., which can focus and shape the light beam to meet the requirements of optical detection of the target object A.

[0072] The first light homogenizing element 11 in the light homogenizing device 10 is a light homogenizing rod, and the cross section of the first light homogenizing element 11 is a polygon with no less than six sides, and / or the third light homogenizing element 13 is a light homogenizing rod, and the cross section of the third light homogenizing element 13 is a polygon with no less than six sides.

[0073] The cross section of the first light homogenizing element 11 and / or the third light homogenizing element 13 is made into a polygon with no less than six sides, such as a hexagon or an octagon, etc., which has a higher energy utilization rate for a circular pupil.

[0074] This application also provides an optical detection system, please refer to Figure 8 The optical detection system 1000 includes the lighting device 100, the imaging sensor 200 and the processor 300 of the above embodiment.

[0075] The lighting device 100 is used to illuminate the object A to be measured.

[0076] The imaging sensor 200 is used to image the object A to be measured, so as to obtain an image of the object A. The imaging sensor 200 may be a TDI (Time Delay and Integration) camera or the like.

[0077] The processor 300 is connected to the lighting device 100 and the imaging sensor 200, and is used to control the lighting device 100 to illuminate the object A to be measured, and obtain an image of the object A to be measured for optical inspection, such as defect detection.

[0078] The processor 300 may be a central processing unit (CPU), a microcontroller unit (MCU), a field-programmable gate array (FPGA), a digital signal processing (DSP), or other device used to interpret computer instructions and process data in computer software.

[0079] In some embodiments, in the light homogenizing device 10 of the lighting device 100, the second light homogenizing element 12 is a microlens array, and the third light homogenizing element 13 is a light homogenizing rod. The sub-lens aperture of the second light homogenizing element 12 is rectangular (e.g., square or rectangular), and the cross-section of the third light homogenizing element 13 is rectangular (e.g., square or rectangular). The aspect ratio of the sub-lens aperture of the second light homogenizing element 12 and the aspect ratio of the cross-section of the third light homogenizing element 13 are both the same as the aspect ratio of the photosensitive surface of the imaging sensor 200.

[0080] In some embodiments, the light homogenizing device 10 also includes a field lens device 15, and the field lens device 15 is a microlens array. The shape of the sub-lens aperture of the field lens device 15 is rectangular, and the aspect ratio of the sub-lens aperture of the field lens device 15 is also the same as the aspect ratio of the photosensitive surface of the imaging sensor 200.

[0081] In the above embodiment, when the aspect ratio of the sub-lens aperture of the second light homogenizing element 12 (which in some embodiments also includes the field lens device 15) changes, the aspect ratio of the light spot projected onto the end face of the third light homogenizing element 13 also changes. For imaging sensors 200 used in semiconductor inspection, such as TDI cameras, their photosensitive surfaces have a certain aspect ratio, such as 4:1. The third light homogenizing element 13 and the photosensitive surface of the imaging sensor 200 are typically in a conjugate imaging relationship. By setting the aspect ratio of the sub-lens aperture of the second light homogenizing element 12 (which in some embodiments also includes the field lens device 15) and the aspect ratio of the cross-section of the third light homogenizing element 13 to be the same as the aspect ratio of the photosensitive surface of the imaging sensor 200, the energy utilization rate of the illumination light can be significantly improved.

[0082] The above examples are used to illustrate the present invention, which are only used to help understand the present invention and are not intended to limit the present invention. Those skilled in the art can make several simple deductions, modifications or substitutions based on the concept of the present invention.

Claims

1. A light homogenizing device, characterized in that: It includes a first light uniformity element, a second light uniformity element and a third light uniformity element which are sequentially arranged along the optical path; The first light homogenizing element is used to homogenize the field of view of the light beam; The second light homogenizing element is used to split the output light of the first light homogenizing element into multiple sub-beams and converge each sub-beam respectively, and the second light homogenizing element is a microlens array; The third light homogenizing element is used to homogenize the field of view of the output light of the second light homogenizing element; The optical system further includes a first collimating element and a field lens device, wherein the first collimating element is arranged on the optical path between the first light homogenizing element and the second light homogenizing element, the first light homogenizing element is located on the front focal plane of the first collimating element, and the second light homogenizing element is located on the back focal plane of the first collimating element, and the first collimating element is used to collimate the output light of the first light homogenizing element and then project it onto the second light homogenizing element; The field lens device is arranged on the optical path between the second light homogenizing element and the third light homogenizing element, and is used to converge the output light of the second light homogenizing element and project it onto the third light homogenizing element. The distance between the third light homogenizing element and the field lens device is not greater than 1 / 10 of the focal length of the second light homogenizing element, and the size of the incident surface of the third light homogenizing element is not less than the size of the output surface of the field lens device.

2. The light homogenizing device according to claim 1, wherein: It also includes a zoom beam expander, which is arranged on the optical path between the first collimating element and the second light homogenizing element.

3. The light homogenizing device according to claim 1, wherein: The field lens device is a micro lens array, and the field lens device is located on the back focal plane of the second light homogenizing element.

4. The light homogenizing device according to claim 1, wherein: The field lens device includes a second collimating element and a third collimating element, the distance between the second collimating element and the third collimating element is the sum of the focal length of the second collimating element and the focal length of the third collimating element, and the third light homogenizing element is located on the back focal plane of the third collimating element.

5. The light homogenizing device according to claim 1, wherein: The first light homogenizing element is a light homogenizing rod, and / or the third light homogenizing element is a light homogenizing rod.

6. A lighting device, characterized in that: The light homogenizing device comprises a light source and the light homogenizing device according to any one of claims 1 to 5, wherein the light homogenizing device is used to homogenize the light beam emitted by the light source.

7. The lighting device according to claim 6, wherein: It also includes an illumination optical component, the illumination optical component is used to project the light beam homogenized by the light homogenizing device onto the target object, and the illumination optical component has a circular pupil; The first light homogenizing element is a light homogenizing rod, and the cross section of the first light homogenizing element is a polygon with no less than six sides, and / or the third light homogenizing element is a light homogenizing rod, and the cross section of the third light homogenizing element is a polygon with no less than six sides.

8. An optical detection system, characterized in that: comprising the lighting device, imaging sensor and processor according to claim 6 or 7; The lighting device is used to illuminate the object to be measured; The imaging sensor is used to image the object to be measured to obtain an image of the object to be measured; The processor is connected to the lighting device and the imaging sensor, and is used to control the lighting device to illuminate the object to be measured, and to obtain an image of the object to be measured for optical detection.

9. The optical detection system according to claim 8, wherein: The second light homogenizing element is a microlens array, the third light homogenizing element is a light homogenizing rod, the sub-lens aperture of the second light homogenizing element is rectangular, and the cross-section of the third light homogenizing element is rectangular; The aspect ratio of the sub-lens aperture of the second light homogenizing element and the aspect ratio of the cross section of the third light homogenizing element are both the same as the aspect ratio of the photosensitive surface of the imaging sensor.

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