JPH0354784B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a method for optically inspecting a specimen having a reflective surface.

(Prior Art) As a specimen having a reflective surface, a specimen 1 whose surface 100a is a mirror surface (reflective surface) as shown in FIG.
00, as shown in Figure 5, it is made of a transparent material and has a surface 1
There are specimens 100 in which 00a is a reflective surface, and specimens 100 in which at least the upper layer is transparent and have a multilayer structure as shown in FIG. 6, and whose surface 100a is a reflective surface. In the case of FIG. 4, the specimen 100 may be a transparent body or an opaque body. The specimen 100 in FIG. 4 is, for example, a polished metal. Further, the specimen 100 in FIG. 6 includes a semiconductor substrate coated with multiple layers of transparent material.

In the specimen 100 in FIG. 4, the mirror surface 10
It may be optically inspected to see if there is a defect a such as a scratch, stain, or dust. Sample 10 in Figure 5
0, optical inspection may be performed to determine whether there is a defect b on the front surface 100a, inside, or back surface. The specimen 100 shown in FIG. 6 may be inspected for defects c such as scratches, stains, and dust on the surface 100a and between layers, and defects d such as peeling between layers.

When the specimen 100 is optically inspected, conventionally the inspection has been carried out using a method as shown in FIG. That is, the probe 110 having the light receiving section 111 at its tip and the irradiating section 112 made of a light bulb are arranged at positions separated from each other. And irradiation part 1
12 is reflected by the concave mirror 113 and
00, and further the surface 100a of the specimen 100.
The light is reflected by the light receiving section 111 and supplied to the light receiving section 111. In this way, the specimen 100 is illuminated with high brightness, and the defects a, b, c, d (Figs. 4 to 6) of the specimen 100 are illuminated with high brightness.
Figure) is detected.

However, in the conventional method described above, the irradiating section 112 and the light receiving section 111 are separate bodies, resulting in high cost.

Therefore, as shown in FIG.
The probe 120 has a light receiving section 121 and an irradiating section 122 at the tip of the probe 120.
It is conceivable to provide a test specimen 100 and irradiate illumination light from the front of the specimen 100 to perform the test. However, with this inspection method, 122 images of the high-intensity irradiation area are
It is reflected by the surface 100a of the specimen 100 and the light receiving part 12
1 and causes halation, resulting in a significant deterioration of the S/N ratio during image signal processing, for example.
The required defect image cannot be reliably detected.

Further, the probe 120 is arranged diagonally with respect to the specimen 100, and the illumination light is applied to the surface 100 of the specimen 100.
It is also conceivable to irradiate obliquely to 0a so that the image of the irradiating section 122 does not enter the light receiving section 121. However, in this case, the illumination light is
This background image is reflected on the surface 100a of the specimen 100 and enters the light receiving section 121, which deteriorates the S/N ratio as described above and eliminates the necessary defect. The image cannot be detected reliably.

(Problems to be Solved by the Invention) Due to the above-mentioned circumstances, the development of a probe that is inexpensive, easy to inspect, and can reliably detect defects in specimens has been awaited.

Structure of the Invention (Means for Solving the Problems) The present invention has been made to solve the above problems, and its gist is to provide a method for optically inspecting a specimen having a reflective surface. Illumination light is irradiated obliquely onto the specimen from the irradiating part of the probe, which has a light receiving part at its tip, and the image of the specimen is captured by the light receiving part, and the irradiation range of the irradiating part is determined through the reflective surface of the specimen. and an optical inspection method characterized in that the viewing range of the light receiving section is substantially covered by a shielding body.

(Example) An example of the present invention will be described below with reference to FIG. 1 in FIG. 1 indicates a probe. The probe 1 has a configuration similar to the insertion section of a general rigid endoscope, and is elongated. An image transmission optical system 2 and an optical fiber bundle 3 are built into the probe 1 in parallel with each other. At the tip of the probe 1, a light receiving section 5 of an image transmission optical system 2 and an objective lens are arranged. The image transmission optical system 2 further includes an eyepiece (not shown) disposed at the base end of the probe 1 and a lens group (not shown) leading to this eyepiece. The distal end surface of the optical fiber bundle 3 is exposed at the distal end of the probe 1 and serves as an irradiation section 6. The irradiating section 6 is the light receiving section 5
It is located near the . Image transmission optical system 2
The optical axis A of the optical fiber bundle 3 and the optical axis B of the optical fiber bundle 3 are substantially parallel to each other.

The base end of the optical fiber bundle 3 is connected to a light source device, and the light from this light source device is irradiated from the irradiation section 6 at the tip. Further, at the base end of the image transmission optical system 2, inspection can be performed with the naked eye through an eyepiece, or images can be taken with a camera, television camera, or the like.

9 in the figure is a shielding body, and a surface 9a of this shielding body 9
consists of a patternless white diffuser surface that reflects light diffusely.

In this example, any specimen 1 shown in Figures 4 to 6
00 can also be tested.

First, the probe 1 is placed diagonally with respect to the specimen 100. In addition, the shielding body 9 is tilted with respect to the specimen 100, and the surface 100a of the specimen 100 is
It is arranged so that it has a mirror image positional relationship with the tip of the probe 1 via the probe. That is, the shielding body 9 is arranged so as to substantially block the irradiation range of the irradiation section 6 and the field of view of the light receiving section 5 through reflection on the surface 100a of the specimen 100.

In the above arrangement, illumination light is applied to the specimen 1 from the irradiation unit 6.
Irradiate to 00. The irradiation direction is the surface 1 of the specimen 100.
It is inclined with respect to 00a. The irradiated light is reflected by the surface 100a of the specimen 100, reaches the shield 9, and is diffusely reflected there, illuminating the specimen 100 brightly. The illuminated image of the specimen 100 is transmitted from the light receiving section 5 by the image transmission optical system 2 and captured by a television camera or the like. At this time, sample 10
Because 0 is illuminated brightly and evenly,
Defects not only on the front surface 100a but also on the inside, back surface, etc. can be reliably detected. Note that, as shown in FIG. 6, if the defect is a peeling d, it can be detected as an iris.

In addition, since the irradiation direction is inclined with respect to the surface 100a of the specimen 100, the image of the high-intensity irradiation part 6 is reflected toward the shielding body 9, and is diffusely reflected by the shielding body 9, so that it is incident on the light receiving part 5. do not. Therefore,
For example, the S/N ratio at the image processing stage does not deteriorate,
The defect image of the specimen 100 can be reliably inspected.

In addition, although the illumination light is reflected by the surface 100a of the specimen 100, it is blocked by the shielding body 9, so it does not illuminate the background, and furthermore, since the background image is blocked by the shielding body 9, the illumination light 100a
Since the sample 100 is not reflected by the sample and enters the light receiving section 5, deterioration of the S/N ratio can be prevented from this point as well.
Defect images can be reliably detected.

The present invention is not limited to the above embodiments, and various embodiments are possible. For example, it may be configured as shown in FIG. In this embodiment, members corresponding to those in FIG. 1 are given the same numbers and detailed explanation thereof will be omitted. The same applies to the following examples. In this example, the shield 10 is a concave mirror. The illumination light from the irradiation unit 6 is reflected by the shield 10 and illuminates the specimen 100.
The light is returned to the surface 100a, reflected by this surface 100a, and supplied to the light receiving section 5. The focus of the shielding body 10 is set near the light receiving section 5. In addition, since the image of the irradiation part 6 is reflected by the shielding body 10 which forms a concave mirror, it is not supplied to the light receiving part 5 as an image, and does not become an obstacle to defect detection. In this example, the first
The specimen can be illuminated with even higher brightness than the case shown in the figure, and is particularly suitable for detecting defects inside or on the back surface of the specimen 100.

Alternatively, the surface of the shield may be a black absorption surface, and the light supplied to the shield may be absorbed without being reflected.
This example is used to detect defects such as scratches that would cause irradiated light to be reflected directly in the direction of the probe in a specimen having a mirror surface.

Furthermore, in the above embodiment, the irradiation section was configured by the tip of the optical fiber bundle, but as shown in FIG. Illumination light having an optical axis B substantially parallel to the optical axis A of the transmission optical system 4 may be applied.

Further, in the above embodiment, the light receiving section has a structure similar to the insertion section of a general endoscope, but a photoelectric sensor or a solid-state image sensor may be used.

Furthermore, if a plain wall, paper, a case made of a satin-finished aluminum plate, or the like is placed in the background, this background object itself may be used as a shield.

Effects of the Invention As explained above, according to the present invention, the cost can be reduced by using a probe having an irradiating section and a light receiving section at its tip. Furthermore, since the image of the irradiation section is not supplied to the light receiving section and the background image with a pattern etc. is not supplied to the light receiving section, defects in the specimen can be reliably detected.

[Brief explanation of drawings]

FIGS. 1 to 3 are views showing different embodiments of the present invention, FIGS. 4 to 6 are views showing different aspects of the specimen, and FIG. 7 is a view showing a conventional example.
FIG. 8 is a diagram showing an example considered in the process of devising the present invention. 1... Probe, 5... Light receiving section, 6, 12...
Irradiation section, 9, 10...shielding body, 100... specimen,
100a...Surface (reflecting surface) of the specimen.

Claims (1)

[Claims] 1 In a method of optically inspecting a specimen having a reflective surface, illumination light is irradiated obliquely onto the specimen from the irradiating part of the probe, which has an irradiating part and a light receiving part at the tip, and an image of the specimen is received. 1. An optical inspection method characterized in that the irradiation range of the irradiation part and the viewing range of the light receiving part through the reflective surface of the specimen are substantially covered by a shielding body.