JPH04116453A - Flaw inspecting apparatus - Google Patents

Abstract

PURPOSE:To inspect a defect with high accuracy at a high speed by providing optical systems which scan projecting lights from two light sources in a main scanning direction and a sub scanning direction vertical to each other, and making the two lights adjacent to each other in the sub scanning direction with different beam diameters, an optical switching shutter, etc. CONSTITUTION:Beams 6 from a laser oscillator 1 are turned to parallel beams of the diameter approximately 1mm by a collimator 3 to scan the surface to be inspected. If the surface is defective, a scattering light is generated and enters a photoreceptor 10. An output corresponding to the quantity of the scattering light is input to a measuring/display device 11, where the output is compared with a set value. Accordingly, the presence/absence of a defect is inspected. Meanwhile, beams 7 from a laser oscillator 2 are turned into parallel beams of an enlarged diameter by a collimator 4 and deflected at right angles. The focus of the beams is met on the surface to be inspected, so that the presence/ absence of a defect can be inspected through scanning. The beams 6 enable inspection of a large area, while the beams 7 inspects a small area. A minute defect, the position, shape and the like of the defect, etc., can be inspected in detail. Accordingly, a high speed and highly accurate inspection is achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a flaw inspection device, and more particularly to a flaw inspection device that can be applied to high-speed inspection of large-area planes.

[Conventional technology]

As a conventional technique, for example, Japanese Patent Application Laid-Open No. 59-68653
There is a method for inspecting flaws on the surface of an object as shown in the above publication.

Conventional flaw inspection equipment uses a laser oscillator, a collimator,
It is configured to include a light shielding body and a light receiving body. FIG. 3 is a sectional view showing an example of a conventional flaw inspection device. The flaw inspection device shown in FIG. 3 includes a laser oscillator 3], a modulator 32,
It includes a collimator 33, a light shield 34, a light receiver 35, and an indicator 36 that outputs a signal proportional to the amount of light when the light receiver 35 receives light. racer oscillator 3
The laser beam oscillated from the laser beam 1 is modulated by a modulator 32 and input into a collimator 33, where the laser beam is converted into parallel light and irradiated onto the surface of the object. The irradiated light is reflected by the surface of the object. At this time, the reflection angle of the reflected light varies depending on the condition of the surface of the object. In other words, in a normal state with no scratches on the surface and no dust attached, the reflection pattern of the reflected light falls within a certain area, but in an abnormal state with scratches on the surface and dust attached, the reflected light The scattering of the light becomes large, and the light is scattered outside the normal reflection pattern area.

Therefore, in the present invention, 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, and a light receptor 35 is provided outside of the light shield 34. Thus, when an object is abnormal, only the abnormal reflected light scattered outside the light shielding body 34 is received by the light receiving body 35.

[Problem to be solved by the invention]

In the conventional flaw inspection apparatus described above, the beam diameter is made small to improve resolution in order to improve inspection accuracy.

Since all scanning is performed with high precision, that is, with a small beam, there is a drawback that the larger the inspection surface, the longer the inspection time.

[Means to solve the problem]

The present invention includes first and second light sources, a main scanning means for scanning a surface to be scanned using a rotating polygon mirror with light emitted from the two light sources, and a main scanning means for scanning a surface to be scanned with a rotating polygon mirror, and a sub-scanning means for driving the surface to be scanned; an optical system for directing the two lights to be adjacent to each other in the sub-scanning direction with different beam diameters on the surface to be scanned; a shutter for switching the two lights; and a shutter for switching the two lights; It is composed of a light receiving means that receives scattered light from the scanning surface.

〔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.

The flaw inspection apparatus shown in FIG. 1 includes two laser oscillators] and a laser oscillator 2; The parallel light is focused on the surface to be inspected (beam diameter: approx. 0.1 mm).
mm) and a laser oscillator 1.
a beam combiner 8 that combines the optical axes of the beam 6 emitted from the laser oscillator 2 and the beam 7 emitted from the laser oscillator 2; and a galvanometer mirror that scans the entire combined beam with the axis of the surface to be inspected. -9, a photoreceptor 10 for receiving the scattered light from the surface to be inspected, and the output of the photoreceptor ]O, and the measurement display 11 that shows the size, and the beams 6 and 7 are turned on and off. A stage]4 for moving the object to be inspected in a direction perpendicular to the scanning direction.

Next, the function and operation of the flaw inspection apparatus shown in FIG. 1 will be explained in order.

The beam 6 emitted from the laser oscillator 1 is turned into parallel light with a beam diameter of about 1 mm by the collimator 3. Then, the beam passes through the beam combiner 8, is deflected by the galvanometer mirror 9, and scans the surface to be inspected. The photoreceptor 10 is installed on both sides parallel to the scanning direction so that the light reflected from the surface to be inspected does not directly enter the photoreceptor 10 . During scanning, if there is a flaw on the surface to be inspected, scattered light is generated and enters the photoreceptor 10, and an output corresponding to the amount of light is obtained from the measurement display 11. By comparing this output with a preset value, the presence or absence of scratches can be inspected. At this time, by moving the surface to be inspected by the stage 14 in a direction perpendicular to the scanning direction by the beam diameter, inspection within the two-dimensional plane can be performed.

On the other hand, the beam 7 emitted from the laser oscillator 2 is expanded in beam diameter by a collimator and becomes parallel light. and,
The beam passes through an optical lens 5 and enters a beam combiner 8, is deflected at right angles, becomes a beam 6, and the optical axis is shifted parallel to the beam by the radius of this beam, and enters a galvanometer mirror 9. It is deflected by this galvano mirror 9 and scans the surface to be inspected.

In addition, the beam 7 passes through the optical lens 5 and is focused there (beam diameter: approximately 0.1 mm). At this time,
If there is a flaw on the surface to be inspected, scattered light is generated, and by receiving the light with the photoreceptor 10, it is possible to inspect the presence or absence of a flaw on the surface to be inspected.

Since the beam 6 has a large beam diameter on the surface to be inspected, a large area can be inspected for flaws in one scan.

On the other hand, since the beam 7 is focused on the surface to be inspected, it is possible to inspect only a small area of flaws in one scan, but compared to the beam 6, it is possible to inspect minute flaws.

Furthermore, compared to the beam 6, it is possible to inspect not only the presence or absence of scratches but also information such as the position and shape of the scratches.

Next, an inspection method using the flaw inspection apparatus of the present invention will be explained. First, the beam 7 is blocked by a shutter, and a flaw inspection is performed using the beam 6. At this time, the beam diameter is larger than the beam 7, and therefore inspection can be performed at high speed. At this time, if there is a scratch on the surface to be inspected, some output change will occur on the measurement display 11. Since the beam diameter is large, output changes due to scratches are relatively small, making it impossible to accurately detect information such as the position and size of scratches. However, in response to this slight change in output, the shutter 12 is immediately opened, the shutter 13 is closed, and the beam is switched to beam 7 to perform scanning. beam 7
The beam diameter is smaller than that of beam 6, and information such as the position and size of a flaw can be detected with higher accuracy than when inspecting with beam 6.

FIG. 2 shows the positional relationship between beam 6 and beam 7. Beam 7 is adjacent to beam 6 on the opposite side to the direction of movement of the surface to be inspected.

〔Effect of the invention〕

The flaw inspection device of the present invention has two adjacent large and small beams, and by switching the beams depending on the presence or absence of flaws, it has the advantage of being able to inspect flaws in a two-dimensional plane at high speed and with high precision.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the present invention, FIG. 2 is a perspective view showing the positional relationship between two large and small beams, and FIG. 3 is a sectional view showing a conventional example. 1.2... Laser oscillator, 3, 4... Collimator, 5... Optical lens, 6.7... Beam, 8...
Beam combiner, 9... Galvanometer mirror 10... Photoreceptor, 11... Measurement display, 12.13... Shutter, 14... Stage.

Claims (1)

[Claims] a first and a second light source; a main scanning means for scanning a surface to be scanned using a rotating polygon mirror with light emitted from the two light sources; a sub-investigation means to be driven; an optical system that causes the two lights to be adjacent to each other in the sub-scanning direction with different beam diameters on the surface to be scanned; a shutter to switch the two lights; and scattered light from the surface to be scanned. A flaw inspection device comprising: a light receiving means for receiving light.