Light collection module for crystalline silicon cell detection and crystalline silicon cell defect detection device

Abstract

The utility model discloses a light collection module for crystalline silicon cell detection and a crystalline silicon cell defect detection device, the light collection module is used for collecting emitted light after a crystalline silicon cell is excited, and the light collection module sequentially comprises a light beam collimator, a filter and a focusing lens along a light path direction; wherein the light beam collimator is used for collimating the emitted light to output parallel light, the filter is used for filtering the parallel light, and the focusing lens is used for converging the filtered parallel light. According to the utility model, through adding the light collection module and installing the light collection module in front of the CCD camera, the emitted light received by the CCD camera has stronger monochromaticity and optical wavelength signal intensity, the collection area and noise interference are reduced, and the PL imaging precision is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of photovoltaics, and specifically relates to a light collection module for detecting a crystalline silicon cell, and also relates to a crystalline silicon cell defect detection device. Background Art

[0002] At present, the detection of whether there are defects in crystalline silicon cells is generally carried out in a crystalline silicon cell PL (photoluminescence) tester, which uses a high-power laser (specific wavelength of 650nm) to directly irradiate the crystalline silicon cell. After being excited, the crystalline silicon cell emits fluorescence of a certain wavelength; when there are defects in the crystalline silicon cell, the excited emission light is inconsistent with the wavelength of the defect-free crystalline silicon cell, and then the CCD industrial camera is used to image and receive the emission light to analyze whether there are defects. For example, a normal crystalline silicon cell or the entire area of ​​the silicon wafer will be excited to emit light of about 1150nm, but if there is a dirty cell, the dirty part will block the excitation light and emit a wavelength other than 1150nm, so the imaging will be inconsistent and thus detected. The current methods to improve the test accuracy of the PL tester mainly include:

[0003] At the excitation light source end of the PL tester, generally a more powerful laser or a more monochromatic laser is used. A more powerful laser can ensure the intensity of the light beam reaching the crystalline silicon cell, while the more monochromatic excitation light has better stability at the working wavelength. Both can improve the crystalline silicon cell during PL (photoluminescence) testing. It can stimulate better fluorescence, thereby improving the imaging accuracy of the PL tester.

[0004] At the imaging end of the PL tester, generally by using a more accurate CCD camera or improving the image processing algorithm, a more accurate CCD camera can capture the fluorescence information more completely, and the algorithm for optimizing the post-processing image can remove noise, enhance the image, obtain a better PL (photoluminescence) image, and give a more accurate judgment.

[0005] The existing PL tester includes a darkroom, a laser light source, a CCD imaging camera, a stage, and a PC. The laser light source is directly incident on the crystalline silicon cell on the stage in the darkroom. However, in this process, the irradiation area of ​​the laser is actually the bottom surface of the entire darkroom, not the stage alone. When collecting the emitted light, the area of ​​the entire bottom surface of the darkroom is collected, which will reduce the imaging quality. At the same time, the crystalline silicon cell is fragile. During continuous testing, there may be fragments. In addition, the brightness in the darkroom is not strong, and there may be cell fragments in other locations in the darkroom, which will also emit non-working emitted light and be captured by the camera, interfering with the imaging, thereby reducing the cell yield. Taking the R3 type PL tester commonly used in laboratories as an example, the size of the darkroom is about 600mm*650mm*800mm, that is, the bottom area of ​​the darkroom is 600mm*650mm, and the current maximum size of the battery is 210mm*210mm. The emission light collected by the CCD imaging camera is only emitted by the test battery (silicon wafer), but there may be battery fragments in the darkroom, and there will be emission light interference after laser excitation. At the same time, the excitation light source cannot have only a wavelength of 650nm, and stray light of non-working wavelengths will also be generated. It may be reflected into the camera through the devices in the darkroom and become noise. This application aims to collect only emission light of a specific wavelength and filter out stray light through a reasonable collection light path design. Utility Model Content

[0006] Based on this, the utility model provides a light collection module for crystalline silicon cell detection, and also provides a crystalline silicon cell defect detection device.

[0007] In the first aspect, the utility model provides a light collection module for crystalline silicon cell detection, comprising a beam collimator, a filter and a focusing lens arranged in sequence along the light path direction; wherein the beam collimator is used to collimate the emitted light to output parallel light, the filter is used to filter the parallel light, and the focusing lens is used to converge the filtered parallel light to form output light.

[0008] Furthermore, the beam collimator includes a plano-concave lens and a convex lens in sequence along the light path direction.

[0009] Furthermore, the output surface of the plano-concave lens is glued to the input surface of the convex lens.

[0010] Furthermore, the working wavelength of the filter is 1100-1200nm.

[0011] Furthermore, the filter plate includes a circular working area and a non-working area arranged around the working area.

[0012] Furthermore, the focusing lens is a plano-convex lens, the input surface of the plano-convex lens is a flat surface, and the output surface of the plano-convex lens is a convex surface.

[0013] In the second aspect, the utility model provides a crystalline silicon cell defect detection device, comprising a laser light source, an imaging unit, and a light collecting module for crystalline silicon cell detection arranged between the laser light source and the imaging unit; wherein the laser light source is used to excite the crystalline silicon cell to emit emission light, the light collecting module is used to optically process the emission light to output outgoing light, and the imaging unit is used to form a photoluminescence image of the crystalline silicon cell based on the outgoing light.

[0014] Furthermore, the imaging unit is a CCD camera.

[0015] Furthermore, the distance between the beam collimator of the light collection module for crystalline silicon cell detection and the crystalline silicon cell is adjustable.

[0016] Furthermore, the distance between the focusing lens of the light collecting module for crystalline silicon cell detection and the imaging unit is adjustable.

[0017] The beneficial effects of the utility model are:

[0018] 1. The utility model adds a light collection module and installs the light collection module in front of the CCD camera, so that the emitted light received by the CCD camera has stronger monochromaticity and light wavelength signal intensity, while reducing the collection area and noise interference, thereby improving the accuracy of PL (photoluminescence) imaging.

[0019] 2. Compared with other current methods for improving the accuracy of PL testers, the utility model does not need to increase the accuracy of the CCD camera (the higher the accuracy, the more expensive the camera is), but only installs the collection light path in front of the CCD camera, which can be adjusted according to the height of the darkroom, with low investment cost.

[0020] 3. Compared with other current technologies for improving the test accuracy of PL testers, the utility model does not require replacement of equipment, does not make changes to the part for capturing emitted light, has high reliability and low risk. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of a light collection module for crystalline silicon cell detection provided by an embodiment of the utility model;

[0022] Figure 2 This is a schematic diagram of the working principle of the beam collimator in the embodiment of the utility model;

[0023] Figure 3a It is a front view of the filter in the embodiment of the utility model;

[0024] Figure 3b It is a side view of the filter in the embodiment of the utility model;

[0025] Figure 4 This is a schematic diagram of the working principle of the filter in the embodiment of the utility model;

[0026] Figure 5 It is a schematic diagram of the working principle of the focusing lens in the embodiment of the utility model.

[0027] The meanings of the symbols in the accompanying drawings are:

[0028] 1- beam collimator; 11- plano-concave lens; 12- convex lens; 2- filter; 21- working area; 22- non-working area; 3- focusing lens; 4- CCD camera; 5- crystalline silicon cell. DETAILED DESCRIPTION

[0029] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0030] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element at the same time.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0032] The utility model excites a photovoltaic cell (silicon chip) in a PL tester to emit a near-infrared wavelength of about 1150nm, and makes the emitted light pass through a beam collimator, a long-pass filter and a plano-convex lens in sequence to improve the monochromaticity and intensity of the emitted light, and eliminates the interference of stray light, thereby improving the test accuracy of the PL tester.

[0033] like Figure 1As shown, in one embodiment of the utility model, a light collection module for crystalline silicon cell detection is provided, and the light collection module for crystalline silicon cell detection includes a beam collimator 1, a filter 2 and a focusing lens 3. After being excited by the laser, the crystalline silicon cell 5 emits emission light, which passes through the beam collimator 1, the filter 2 and the focusing lens 3 in sequence, and outputs the emission light to the CCD camera 4; wherein, the beam collimator 1 is used to collimate the emission light into parallel light, the filter 2 is used to filter the parallel light output by the beam collimator 1 to filter out the stray light in the parallel light, and the focusing lens 3 is used to converge the filtered parallel light to form the emission light, and the emission light forms a concentrated light spot on the CCD camera 4.

[0034] Figure 2 The figure shows a schematic diagram of the working principle of the beam collimator 1 in some embodiments. The beam collimator 1 includes a plano-concave lens 11 and a convex lens 12 in sequence along the light path direction. The input surface of the plano-concave lens 11 is a plane, the output surface of the plano-concave lens 11 is a concave surface, and the input surface and output surface of the convex lens 12 are convex surfaces respectively. Exemplarily, the beam collimator 1 can be a cemented lens composed of the output surface of the plano-concave lens 11 and the input surface of the convex lens 12. When the divergent light passes through the cemented lens, it undergoes a series of refractions and finally emits in parallel. In this embodiment, the beam collimator 1 collimates the light so that the light beam is parallel when it is finally emitted, so that the light path can be better controlled while reducing the light path loss.

[0035] Figure 3a and Figure 3b Shown are the front view and side view of the filter 2 in some embodiments, respectively, wherein the shaded portion is the working area 21, and the rest is the non-working area 22. Exemplarily, the working area 21 is circular, and the non-working area 22 is arranged around the working area 21. In the background art, the wavelength of the emission light generated by photoluminescence of a general crystalline silicon cell is about 1150nm. In some embodiments, the working wavelength of the filter 2 can be selected to be 1100-1200nm, and the working wavelength light with a wavelength of 1100-1200nm in the parallel light output by the beam collimator 1 can pass through the filter 2, and the non-working wavelength light (stray light) with a wavelength less than 1100nm or a wavelength greater than 1200nm in the parallel light cannot pass through the filter 2. The working principle of the filter 2 is as follows: Figure 4 As shown, in the working area 21, when light is incident on the input surface (front) of the filter 2, only light of the working wavelength can pass through the filter 2 and be emitted from the output surface of the filter 2, and light of other wavelengths cannot pass; in the non-working area 22, neither light of the working wavelength nor stray light can pass.

[0036] In some embodiments, the focusing lens 3 is a plano-convex lens, the input surface of the plano-convex lens is a flat surface, and the output surface of the plano-convex lens is a convex surface. Figure 5 The figure shows a schematic diagram of the working principle of a plano-convex lens, and its working principle is: a parallel light beam is irradiated on the flat surface of the plano-convex lens, and after a series of refractions, the light beam is finally gathered and emitted from the convex surface of the plano-convex lens. The plano-convex lens gathers the parallel light beams and emits them to form a small light spot. In this embodiment, the flat surface of the plano-convex lens receives the parallel light after the impurities are removed, gathers it and emits it from the convex surface of the plano-convex lens.

[0037] In some embodiments, the beam collimator 1 , the filter 2 , and the focusing lens 3 may be integrated together, that is, the beam collimator 1 , the filter 2 , and the focusing lens 3 are packaged in a sealed body.

[0038] In this embodiment, the crystalline silicon cell 5 is excited by the laser of the PL tester to emit light with a wavelength of about 1150nm. The beam collimator 1 collimates the emitted light, converts the divergent light into parallel light, reduces the loss of the emitted light, and controls the emission path of the emitted light; the filter 2 (working wavelength is 1100-1200nm) then filters the parallel light to filter out stray light and increase the monochromaticity of the emitted light; finally, the focusing lens 3 receives the parallel light after the impurities are removed, gathers it into a small light spot, and transmits the light signal of the emitted light to the CCD camera 4. In this way, in order to reduce light loss and eliminate the interference of the light signal emitted by the battery fragments, the collection area can be controlled according to the size of the crystalline silicon cell, and the emitted light of the tested crystalline silicon cell can be reasonably collected; and the 1100-1200nm filter ensures the monochromaticity of the emitted light wavelength signal, which can ensure that the emitted light signal reaching the CCD camera is optimal.

[0039] The purpose of allowing the incident excitation fluorescence to pass through the beam collimator, filter, and focusing lens in sequence is to reduce light loss, increase light intensity, and ensure the monochromaticity of the emission light wavelength signal. If the emission light formed by the photoluminescence of the crystalline silicon cell 5 first passes through the filter, and then passes through the beam collimator and focusing lens, a part of the emission light will be lost, thereby weakening the light intensity of the emission light. If the emission light formed by the photoluminescence of the crystalline silicon cell 5 first passes through the beam collimator and focusing lens, and then passes through the filter, this will cause too much stray light to enter the focusing lens.

[0040] Whether it is reducing light loss, increasing light intensity or improving the monochromaticity of the emitted light signal, the ultimate goal is to allow the CCD camera to capture the optimal emitted light wavelength signal and obtain better and more optimal images, thereby improving the test accuracy of the PL tester.

[0041] The present utility model also provides a crystalline silicon cell defect detection device, which includes a laser light source, a crystalline silicon cell, a light collection module for crystalline silicon cell detection in the above-mentioned embodiment or implementation method, and an imaging unit. Exemplarily, the imaging unit is a CCD camera. The laser light source is used to excite the crystalline silicon cell to emit light; the light collection module is used to perform optical processing on the emitted light to output the emitted light; the CCD camera is used to perform photoelectric conversion on the emitted light to output an electrical signal to obtain a photoluminescence image of the crystalline silicon cell, thereby determining whether the crystalline silicon cell has defects. The CCD camera is preferably of industrial grade, i.e., a CCD industrial camera.

[0042] In some embodiments, the distance between the light collection module for crystalline silicon cell detection and the CCD camera can be adjusted. By adjusting the distance between the CCD camera and the light collection module, the size of the light spot can be changed. Figure 1 As shown, by adjusting the distance between the focusing lens 3 and the CCD camera 4, the spot of the emitted light can be adjusted; the optimal distance between the focusing lens 3 and the CCD camera 4 is that the focus of the spot falls exactly on the CCD camera.

[0043] In some embodiments, the distance between the crystalline silicon cell detection light collection module and the crystalline silicon cell can also be adjusted. Figure 1 As shown, by adjusting the distance between the crystalline silicon cell 5 and the light beam collimator 1 in the light collection module for crystalline silicon cell detection, the intensity of the excitation emission light can be changed.

[0044] 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.

[0045] The above embodiments only express the preferred implementation of the utility model, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the utility model. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the utility model, which all belong to the protection scope of the utility model. Therefore, the protection scope of the utility model shall be based on the attached claims.

Claims

1. A light collection module for crystalline silicon cell detection, characterized in that: It includes a beam collimator, a filter and a focusing lens which are sequentially arranged along the light path direction; wherein the beam collimator is used to collimate the emission light formed after the crystalline silicon cell is excited to output parallel light, the filter is used to filter the parallel light, and the focusing lens is used to converge the filtered parallel light to form output light.

2. The light collection module for crystalline silicon cell detection according to claim 1, characterized in that: The beam collimator comprises a plano-concave lens and a convex lens in sequence along the light path direction.

3. The light collection module for crystalline silicon cell detection according to claim 2, characterized in that: The output surface of the plano-concave lens is glued to the input surface of the convex lens.

4. The light collection module for crystalline silicon cell detection according to claim 1, characterized in that: The working wavelength of the filter is 1100-1200nm.

5. The light collection module for crystalline silicon cell detection according to claim 4, characterized in that: The filter plate includes a circular working area and a non-working area arranged around the working area.

6. The light collection module for crystalline silicon cell detection according to claim 1, characterized in that: The focusing lens is a plano-convex lens, the input surface of the plano-convex lens is a flat surface, and the output surface of the plano-convex lens is a convex surface.

7. A crystalline silicon cell defect detection device, characterized in that: It comprises a laser light source, an imaging unit and a light collecting module for detecting a crystalline silicon cell as described in any one of claims 1 to 6 and is arranged between the laser light source and the imaging unit; wherein the laser light source is used to excite the crystalline silicon cell to emit emission light, the light collecting module is used to optically process the emission light to output outgoing light, and the imaging unit is used to form a photoluminescence image of the crystalline silicon cell based on the outgoing light.

8. The crystalline silicon cell defect detection device according to claim 7, characterized in that: The imaging unit is a CCD camera.

9. The crystalline silicon cell defect detection device according to claim 7, characterized in that: The distance between the beam collimator of the light collecting module for detecting the crystalline silicon cell and the crystalline silicon cell is adjustable.

10. The crystalline silicon cell defect detection device according to claim 7, characterized in that: The distance between the focusing lens of the light collecting module for crystalline silicon cell detection and the imaging unit is adjustable.

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