JPH04177743A - Plate surface inspecting device - Google Patents

Abstract

PURPOSE:To detect very small variation of a plate surface by detecting reflected light of the first scanning beam from the surface to be inspected and, turning off the second beam when the light quantity of the reflected light exceeds a fixed level. CONSTITUTION:The optical axes of two beams 21 and 22 are precisely set so that the two beams can adjoin each other on a surface 37 to be inspected. The two beams are made incident to a lens 7 after they are reflected by the surface 37 to be inspected and the beam 21 is passed through a wavelength selecting filter 10. The beam 22 is reflected by the filter 10 and made incident to a photodetector 11. The beam 22 scans 25usec prior to the beam 21 which actually makes surface inspections and, when the quantity of the reflected light made incident to the photodetector 11 is so large that a photomultiplier tube 9 is saturated, a light controller 12 turns off the beam 21 after 25usec. Therefore, even such weak randomly reflected light as that from a scratch on the silicon surface of a solar battery panel can be detected.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a flat plate surface inspection device, and particularly to a flat plate surface inspection device that has a portion where the reflectance of light changes greatly on the surface, such as the silicon surface and electrode portion of a solar panel. The present invention relates to a flat plate surface inspection device that can be applied to inspecting flat plates for scratches, etc.

[Conventional technology]

As a conventional description, for example, Japanese Patent Application Laid-Open No. 59-68653
There is a flat plate surface inspection device for the surface of an object as shown in the above publication. FIG. 5 is a sectional view showing a conventional flat plate surface inspection device. The flat plate surface inspection apparatus shown in FIG. 5 includes a laser oscillator 31, a modulator 32, a collimator 33, a light shield 34, a photoreceptor 35, and appropriate processing according to the amount of light received by the photoreceptor 35. A processing device 36 is provided.

The laser beam emitted from the laser oscillator 3 is transmitted to the modulator 3.
2 and enters the collimator 33, where the laser light is converted into parallel light and irradiated onto the surface of the object 37.

The irradiated light is reflected by the surface 37 of the object to be inspected. The reflection angle of reflected light varies depending on the condition of the surface of the object. In a normal state where there are no scratches on the surface and no dust (4), the reflection pattern of the reflected light falls within a certain area, but in an abnormal state where the surface is scratched or has dust attached, the reflected light may be scattered. It becomes larger and is scattered outside the normal reflection pattern area.

Therefore, a light shield 34 having an area at least larger than the area of the pattern is provided on the reflected light pattern during normal operation to block the reflected light during normal operation.
is provided, and when the object 37 is abnormal, the amount of abnormal reflected light scattered to the outside of the light shielding body 34 is received by the light receiving body 35.

The received light is appropriately processed by a processing device 36.

[Problem to be solved by the invention]

In the conventional flat plate surface inspection device described above, a single photoreceptor receives diffusely reflected light, and when the cane of the photoreceptor amplifier is set to detect weak light, for example, an electrode attached to a solar panel If the light is diffusely reflected from a part such as a part, the test will become saturated and the inspection will be interrupted. Conversely, if the gain is set according to the amount of diffusely reflected light from parts such as electrodes, there is a drawback that, for example, weak diffusely reflected light from parts such as scratches on the silicon surface of a solar panel cannot be detected. Ta.

[Means to solve the problem]

The flat plate surface inspection apparatus of the present invention includes: a first light source that emits a first light beam; a second light source that emits a second light beam having a different wavelength from the first light beam; an optical deflector that deflects and scans a beam of light on a surface to be inspected; and an optical deflector that directs the first and second light beams in the same direction so that the scanning direction of the optical deflector is higher than that of the first light beam or the second light beam. an optical system that irradiates the surface to be inspected so as to be slightly backward; a lens system that enters and collects the reflected light of the first and second light beams from the surface to be inspected; a light separator that separates the emitted light into the first light beam portion and the second light beam portion; and blocking a specular reflection portion of the first light beam of the light collected by the lens system. a first photodetector that receives the diffusely reflected portion of the first light beam out of the light collected by the lens system; the light detector, and a light controller that modulates the first light source in accordance with an output signal from the second light detector.

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of the present invention.

In FIG. 1, a flat plate surface inspection apparatus includes a semiconductor laser oscillator 1 having an oscillation wavelength different from that of a He-Ne laser, and a HeNe laser oscillator 2 disposed at right angles to the semiconductor laser oscillator 1.
Beams 21. each emitted from these two laser oscillators. A filter 3 for aligning the optical axis with the beam 22 in the same direction, a lens 4 for focusing the beams 21 and 22 on the surface to be inspected, and a lens 4 for scanning the beams 21 and 22 on the surface to be inspected. polygon mirror 5
, a cylindrical lens 6 that makes the beams 21 and 22 modified by the polygon mirror 5 enter the surface to be inspected 37 at right angles to the scanning direction, and beams 21 and 22 reflected on the surface to be inspected 37. A mask 8 is installed at the focal point of the lens 7 to block the specularly reflected light of the beam 21, and a photomultiplier tube that enters the diffusely reflected light of the beam 21 is provided between the lens 7 and the mask 8. A wavelength selection filter 10 is installed to transmit the beam 21 and reflect the beam 22, and a photoelectron 6 multiplier tube 9 is installed at a position conjugate to each other with respect to the filter 10, which receives the beam 22 reflected by the wavelength selection filter 10. The photodetector 11 and the signal from the photodetector 11 are input, and after a certain period of time, the semiconductor laser oscillation 2)) is changed! The optical controller 12 that outputs the rl signal is arranged in a different direction.

Next, with reference to FIGS. 1 and 2, the operation of the flat plate surface inspection apparatus of the wooden embodiment will be explained step by step.

The beam 21 emitted from the semiconductor laser 1 and HeN
The beam 22 emitted from the e-laser 2 is transmitted by the filter 3, and the beam 22 is reflected at right angles to form optical axes in the same direction.At this time, as shown in FIG. The optical axis of the beams 21 and 22 is the surface to be inspected 3.
7, the two beams are set to be slightly different so that they are adjacent to each other. The two beams 21 and 22 are focused by the lens 4 on the surface to be inspected 37 so that the heel diameter thereof becomes 1100 u, and are deflected by the polycon mirror 5.

The deflected beam passes through the cylindrical force lens 6 and enters the surface to be inspected 37 at right angles to the scanning direction. 2 at this time
The distance between the two beams is set to 1100u. The two beams are reflected by the surface to be inspected 37 and enter the lens 7. The beam 21 passes through the wavelength selection filter 10, the specularly reflected light is blocked by the mask 9, and the diffusely reflected light enters the photomultiplier tube 9.
You can check the above condition.

On the other hand, the beam 22 is reflected by the wavelength selection filter 10 and enters the photodetector 1]. When the amount of light incident on the photodetector 11 is above a certain value, the light controller 12 turns off the emission of the semiconductor laser oscillator 1 after a certain period of time. beam 22
is scanning 1100u beyond the beam 21. When the scanning speed is 4m/sec, 1100u is 25 uses
It is c. Beam 22 is beam 2 that actually performs surface inspection.
When scanning 25 usec ahead of 1 and the amount of reflected light entering the photodetector 1 is large enough to saturate the photomultiplier tube 9, 2
Turn off the beam 21 after S usec.

While the gain range of the photomultiplier tube 9 is 102 to 103, for example, the reflected light thrust on the surface of the solar cell panel is about 104 at the silicon surface and electrode portions. When the photomultiplier tube 9 is set to a gain that detects the reflected light from the silicon surface, if the reflected light from the electrode section is incident, the photomultiplier tube 9
7.1 Accurate output cannot be obtained due to saturation. To prevent this, the electrode section is detected by a photodetector set to a gain that detects the reflected light from the electrode section, and the beam 21 is turned off while the beam 2] passes through the electrode section.

FIG. 3 shows a schematic diagram of a solar cell 23 with a kiss. Fourth
Figure (a) shows an example of the reflected light M pattern when scanning a place where there is a kiss on the silicon part 24 (scanning ■ in Figure 3), and Figure 4 (one) shows the silicon part 24 and Electrode part 25
The reflected light amount pattern when scanning the boundary (scanning ■ in FIG. 3) is shown, and FIG. 4(c) shows the reflected light amount pattern when scanning on the electrode section 25 (scanning ■ in FIG. 3). show. Scan ■
In this case, the amount of reflected light increases at edges a and b of the solar cell, and the amount of reflected light also increases at the scratch 26 portion. The kiss 26 can be distinguished from other silicon parts by dividing the amount of reflected light according to the amount of light indicated by the dotted line and converting it into two values. As shown in scan (2), there is a moment when the amount of reflected light at the boundary between the silicon portion 24 and the electrode portion 25 becomes equal to the amount of reflected light at the kiss 26 in scan (2).

Therefore, the boundary between the silicon portion 24 and the electrode portion 25 is always determined to be a flaw. In order to prevent this, the kiss determination is canceled immediately before and after the pattern is output, not shown in scanning (3). While scanning the solar cell, the amount of light is at the saturation level of the photomultiplier tube 9, and at this time the amount of light is detected by the photodetector 1.
] and turns off the drive of the semiconductor laser oscillator 1. After that, the photodetector 1] detects that the amount of light has taken up the scanning pattern on the silicon part as shown in scanning (■),
At this time, driving of the semiconductor laser oscillator 1 is restarted.

〔Effect of the invention〕

The flat plate surface inspection apparatus of the present invention is provided with two beams and two photodetectors, and scans the surface to be inspected with the two beams adjacent to each other in the scanning direction. When the reflected light from the surface is detected and the amount of light exceeds a certain value of -10, the other beam (hereinafter referred to as the inspection light) is turned off so that the photodetector detecting the inspection light becomes saturated. There is an effect that by removing a portion, it is possible to detect a minute change in the surface condition of another portion (for example, a minute kiss on the surface of the silicon 1 by removing an electrode portion of a solar cell panel).

[Brief explanation of drawings]

FIG. 1 is a perspective view showing one embodiment of the present invention, and FIG. 2 is a perspective view showing one embodiment of the present invention.
A plan view showing the positions of the two beams on the surface to be inspected in the example shown in the figure, Fig. 3 is a schematic plan view of a solar cell with a kiss, and Fig. 4 shows when the solar cell is scanned with the beam. FIG. 5 is a side view of the flat plate surface inspection apparatus. DESCRIPTION OF SYMBOLS 1...Semiconductor laser oscillator, 2...HeNe laser oscillator, 5...Polygon mirror, 7. Lens, 8.
- Mask, 9... Photomultiplier tube, ]0... Filter, 11... Photodetector, 12... Light controller.

Claims (1)

[Claims] a first light source that emits a first light ray; a second light source that emits a second light ray having a different wavelength from the first light ray; and a deflector that deflects the first and second light rays on a surface to be inspected. A scanning optical deflector and the first and second light beams are directed in the same direction so that the first light beam is slightly behind the second light beam in the scanning direction by the optical deflector. an optical system that irradiates the surface to be inspected; a lens system that receives and collects the reflected light of the first and second light beams from the surface to be inspected; a light separator that separates the light beam into a light beam portion and the second light beam portion; a mask that blocks a specularly reflected portion of the first light beam out of the light focused by the lens system; a first photodetector into which a diffusely reflected portion of the first beam of light is incident; a photodetector which receives a portion of the second beam of light collected by the lens system; , and a light controller that modulates the first light source according to an output signal from the second photodetector.