JPH03154854A - Detecting device for extremely small defect of thin wire - Google Patents

Abstract

PURPOSE:To detect the defect of the thin wire over a wide range with high accuracy and high reliability by providing a cylindrical lens group, a light shield plate, and a device which reduces and detects the disorder of a Fourier pattern due to scattered light. CONSTITUTION:A light source 2 emits single-wavelength laser light and when the light is transmitted through the cylindrical lens group 3, the light spreads into a plane in the lengthwise direction of a body 1 to be measured to become laser light which is thicker than the body 1 to be measured. The laser light is scattered by the body 1 to be measured and is reduced and imaged on the image pickup surface of a TV camera 5 through a lens 4 as a Fourier- transformed image pattern. At this time, laser light which travels straight at the periphery of the body to be measured is cut off by the light shield plate 6. The Fourier pattern of the image is sent as a video signal to an image processor 8 and sent to a monitor TV. The Fourier pattern is disordered by an extremely small defect of the body to be measured and the disorder is recognized by an image recognizing device 8 to detect the defect. When the body is irradiated with laser light beams in two directions, the detection dead angle is reducible and the thin wire defect can be detected with higher accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a device for detecting minute defects in thin wires in a visual inspection device or the like using optical means.

2. Description of the Related Art Hereinafter, a conventional fine wire defect detection device will be described with reference to the drawings.

FIG. 3 is a schematic diagram of a conventional fine wire defect detection device. In the figure, 1 is a thin line as an object to be measured. The light source section includes a light source 13 such as a halogen lamp and a half mirror 14.
Consists of. The detection part consists of a TV camera 5 and a magnifying lens 1.
Consists of 2. The processing section is composed of a monitor television 7 and an image recognition device 8.

The operation of the thin wire fine defect detection apparatus configured as described above will be described below.

First, light emitted from the light source 13 is reflected by the half mirror 14, passes through the magnifying lens 12, and is irradiated onto the object to be measured 1. The light irradiated onto the object to be measured 1 is reflected by the object beam.
, the magnifying lens 12 and the half mirror 14
, and is imaged on the imaging surface of the television camera 5 as an enlarged solid image. The formed enlarged solid image is transmitted as a video signal to the image recognition device 8, and further transmitted to the monitor television 7. Defects within the measurable field of view of the inspection department are detected visually using a monitor television 7 or by an image recognition device 8.
Detected by automatic detection.

Problems to be Solved by the Invention However, in the above-mentioned conventional configuration, the field of view is reduced due to the high magnification of the optical system to obtain high resolution. Therefore, in order to measure the entire image, it is necessary to scan either the object to be measured or the measuring device.
There have been problems in that measurement takes a long time and accurate measurement is difficult.

In addition, when a thin wire as an object to be measured is enlarged, it has a three-dimensional shape, and reflected light is scattered near the wire on both sides, making the image dark and making it difficult to detect defects. had.

The present invention solves the above-mentioned conventional problems, and provides a highly accurate and highly reliable method for detecting minute defects in thin wires, which can simultaneously detect defects in a wide range of thin wires on an object to be measured. With the goal.

Means for Solving the Problems In order to achieve this object, the first invention of the present invention provides a method for measuring a workpiece, which extends in a plane in the longitudinal direction of the workpiece and has a thickness greater than the thickness of the workpiece. A group of cylindrical lenses for irradiating laser light with a luminous flux, a light shielding plate for blocking laser light other than the scattered light that has passed through the object to be measured, and a Fourier-transformed pattern of the image created by the scattered light (hereinafter referred to as the Fourier pattern). It has an optical system and an image recognition device configured to reduce and detect disturbances (which may occur).

Moreover, the second invention of the present invention is the above detection method,
It has means for irradiating the object to be measured with uniform plane wave laser light from two directions, and means for detecting a Fourier pattern of an image formed by each scattered light.

Function: The first aspect of the present invention is capable of detecting only scattered light based on the number of light shielding plates, so that defects in thin wires can be detected with high accuracy. Furthermore, the cylindrical lens group enables irradiation of laser light with a luminous flux that spreads out in a plane in the longitudinal direction of the object to be measured and whose thickness is greater than the thickness of the object to be measured, and the optical system reduces the Fourier pattern of the image caused by scattered light. Since it can be detected, it is possible to detect defects in a wide range of thin lines all at once.

In addition, the second aspect of the present invention is that the laser beam is irradiated from two directions, and the Fourier pattern of the image due to the respective scattered lights can be detected. Can detect defects.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram of a fine wire fine defect detection apparatus according to a first embodiment of the present invention. In the figure, 1 is a thin line as an object to be measured. The light source section is composed of a laser light source 2 and a cylindrical lens group 3. The detection section is composed of a condensing lens 4, a television camera 5, and a light shielding plate 6. This light shielding plate 6 blocks direct light. The processing section is composed of a monitor television 7 and an image recognition device 8.

The operation of the thin wire micro defect detection apparatus configured as described above will be described below.

First, a single-wavelength laser beam is emitted from a laser light source 2, and when it passes through the cylindrical lens group 3, it spreads in a planar manner in the longitudinal direction of the object to be measured 1, and the luminous flux has a thickness larger than the thickness of the object to be measured 1. The laser beam is converted into a laser beam with The laser beam is measured - treasure '1
The light is scattered by the condenser lens 4 and focused on the imaging surface of the television camera 5 as a reduced Fourier pattern. At this time, the laser beam that has passed straight through the periphery of the object to be measured 1 is blocked by the light blocking plate 6.

The Fourier pattern of the image created by the scattered light is transmitted as a video signal to the image processing device 8 and then to the monitor television 7. The Fourier pattern of the image created by the scattered light is disturbed by minute defects in the object to be measured 1, and this disturbance is recognized by the image recognition device 8.
recognition and detect defects.

As described above, according to this embodiment, since only scattered light can be detected by eliminating the influence of direct light using the light shielding plate 6, it is possible to detect thin wire defects with high precision. In addition, the cylindrical lens group 3 can irradiate the object 1 with a laser beam having a luminous flux that spreads in a plane in the longitudinal direction of the object and has a thickness larger than the thickness of the object. 5
Since the Fourier pattern of the image caused by scattered light can be detected in a reduced size, a wide range of thin line defects can be detected at once.

FIG. 2 is a schematic diagram of a fine line defect detection device according to a second embodiment of the present invention. In the figure, 1 is an object to be measured. The light source section is composed of a laser light source 2 and cylindrical lens groups 3-a and 3-b. The detection section is composed of condenser lenses 4-a, 4-b, television cameras 5-a, 5-b, and light shielding plates 6-a, 6-b. The processing section is a monitor television 7-a.

7-b and an image recognition device 8.

The above configuration is similar to the configuration shown in FIG. The difference from the configuration shown in Fig. 1 is that a half mirror 9 and a total reflection mirror 10.1 are used to irradiate the object to be measured with laser light from two directions.
1 point.

The operation of the thin wire fine defect detection apparatus configured as described above will be described below.

First, a single wavelength laser beam emitted from the laser light source 2 is divided into two by a half mirror 9, one is sent to a cylindrical lens group 3-a, and the other is controlled by a total reflection mirror 10.11, and then the optical axis is controlled by a cylindrical lens. Group 3-b is irradiated. Furthermore, the irradiated laser beam is applied to the cylindrical lens group 3-a.

3-b, it is converted into a laser beam having a luminous flux that spreads flat in the longitudinal direction of the object to be measured 1 and has a thickness larger than the thickness of the object to be measured 1, and is transmitted to the object to be measured 1 from two directions. It is irradiated and scattered by the object to be measured 1, and the condensing lens 4-a
, 4-b, the images are formed as Fourier patterns on the imaging surfaces of television cameras 5-a and 5-b, respectively. At this time, the laser beam that has passed through the object to be measured 1 is directed to the light shielding plate 6-a.

The light is blocked by 6-b.

The Fourier pattern of the image created by the scattered light is transmitted as a video signal to the image processing device 8, and is then sent to the monitor televisions 7-a, 7-a.
-b is sent. The Fourier pattern of the image created by the scattered light is disturbed by minute defects in the object to be measured 1, and each of these disturbances is recognized by the image recognition device 8, and defects in thin lines observed from two directions are simultaneously detected.

As described above, according to this embodiment, in addition to the effects obtained in the first embodiment, the blind spot for defect detection can be reduced, and more reliable thin line defect detection can be performed.

In the first embodiment, the detection system is a television camera and an image recognition device, but the detection system may be a photomultiplier tube to detect changes in the amount of light.

Further, in the second embodiment, the detection system is a television camera and an image recognition device, but it goes without saying that the detection system may be a photomultiplier tube to detect changes in the amount of light.

Effects of the Invention As described above, according to the first invention, the object to be measured is irradiated with a laser beam having a luminous flux that spreads in a plane in the longitudinal direction of the object and has a thickness larger than the thickness of the object to be measured. It is equipped with a cylindrical lens group, a light-shielding plate that blocks laser light other than the scattered light that has passed through the object to be measured, and an optical system and image recognition device that reduce and detect disturbances in the Fourier pattern of the image caused by the scattered light. Therefore, a wide range of fine defects can be detected at once, and the inspection of the entire object to be measured can be speeded up.

Further, according to the second invention, since the object to be measured is configured to irradiate the laser beam from two directions and detect the Fourier pattern of the image formed by each scattered light, the effect obtained in the first invention is not improved. In addition, the blind spot for defect detection can be reduced,
This makes it possible to realize a more reliable and superior fine wire defect detection device.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a fine wire defect detection device according to a first embodiment of the present invention, FIG. 2 is a schematic diagram of a thin wire fine defect detection device according to a second embodiment of the present invention, and FIG. FIG. 1 is a schematic diagram of a conventional thin wire micro defect detection device. 1...Object to be measured, 2...Laser light source, 3...Cylindrical lens group, 4...
...Condensing lens, 5...TV camera, 6...
... Light shielding plate, 7 ... Monitor TV, 8.
...Image recognition device.

Claims (2)

[Claims] (1) In a device that uses a television camera to observe a Fourier-transformed pattern of an image formed by irradiating a single-wavelength laser beam onto an object to be measured, the object to be measured is a thin line. a cylindrical lens group that forms a light beam that spreads in a planar manner in the longitudinal direction of the object to be measured and has a thickness greater than the thickness of the object to be measured; and a light shielding plate that blocks laser light other than the scattered light that has passed through the object to be measured. 1. An apparatus for detecting minute defects in thin wires, characterized by comprising an optical system and an image recognition device for reducing and detecting disturbances in a Fourier-transformed pattern of an image caused by scattered light. (2) In the thin wire micro defect detection device according to claim 1, means for irradiating the object to be measured with a laser beam whose thickness is measured by spreading in a plane in the longitudinal direction of the object from two directions;
1. An apparatus for detecting minute defects in thin wires, comprising means for detecting a pattern obtained by Gourier transformation of an image caused by each random light beam.