JPH07301608A - Thin film defect inspection method and inspection device therefor - Google Patents

Abstract

PURPOSE:To accurately detect a thin film defect even when an inspection object is vibrated. CONSTITUTION:By using a light source 7 of coherent light for irradiating an inspection object having a light transmissive thin film, an objective lens 10, and a CCD camera 1 for receiving light from the light transmissive thin film, a thin film 9 is irradiated with the coherent light from the light source 7 to form an image of interference light generated by synthesizing thin film obverse boundary surface reflection light and thin film reverse boundary surface reflection light of irradiation light from the light source 7 on the CCD camera 1 through the objective lens 10. Existence of a defect in the thin film 9 is inspected based on existence of information on interference fringes generated in a defective part having film thickness unevenness in an electric main signal of the camera 1. With this constitution, a defect can be inspected even when the inspection object is vibrated, an in-line inspection can be conducted, and even a cylindrical inspection object can be inspected. Also, defect detection with higher accuracy can be attained, and an inspection over the whole area of the inspection object can be conducted. Furthermore, the whole size of an inspection device can be downsized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film defect inspection method and inspection apparatus.

[0002]

2. Description of the Related Art As a method for inspecting the surface state of an object using the phenomenon of optical interference, Japanese Patent Laid-Open No. 63-285452 discloses a method.
A method is known in which coherent light from a laser is applied to the end surface of a linear body such as an optical fiber, and the surface roughness is scrutinized by measuring the surface roughness due to the interference caused by the reflected light.

[0003]

However, since the inspection method described above applies Michelson's interference,
A reference reflection plate with excellent flatness and smoothness is required, and if there is vibration during measurement, the vibration of the reflection plate or the inspected object directly changes the optical path difference, which causes measurement noise. The defects of the thin film could not be detected accurately.

[0004]

DISCLOSURE OF THE INVENTION The inventors of the present invention have made earnest studies in view of the above situation. As a result, the defects are detected not by the application of Michelson's interference but by the application of thin film interference. By doing so, it was found that the defect of the thin film can be detected accurately even if there is vibration during the measurement, and the reflector for reference is not necessary, and the present invention has been completed.

In order to solve the above problems, the present invention provides (1) a light source of a coherent light beam for irradiating an object having an optically transparent thin film, an objective lens, and light from the optically transparent thin film. And a thin film front surface reflected light of the irradiation light from the light source are combined with a thin film front surface reflected light to irradiate the thin film from the light source with a CCD camera Is imaged on a CCD camera through the objective lens, and the presence / absence of a thin film defect is inspected based on the presence / absence of information on an interference fringe generated in a defective portion having a film thickness unevenness in an electric output signal of the camera. Defect inspection method, and (2)
A defect inspection apparatus for a thin film, comprising: a light source of a coherent light beam for irradiating an object having a light-transmissive thin film, an objective lens, and a CCD camera for receiving light from the light-transmissive thin film. ) A mechanism of irradiating a coherent light beam from a light source toward a thin film, (B) Interfering light generated by combining the light reflected from the thin film front surface interface and the light reflected from the thin film back surface interface of the light emitted from the light source, A mechanism for forming an image on a CCD camera through a lens, and (C) a mechanism for inspecting the presence / absence of a thin film defect based on the presence / absence of information of interference fringes generated in a defective portion having uneven film thickness in the electric output signal of the CCD camera. A thin film defect inspection apparatus having the same is provided.

First, a film thickness defect inspection apparatus and a film thickness defect inspection method according to the present invention will be described with reference to FIG.

FIG. 1 is a block diagram of an embodiment of a signal processing unit of the present invention. In the figure, reference numeral 1 denotes a CCD camera for inspecting a thin film, which receives the front surface reflected light and the back surface reflected light from the inspection object and outputs an electric signal.

In the figure, the electrical output signal of the CCD camera 1 is input to, for example, the band pass filter 4, and the output of the band pass filter 4 is input to the image processing unit 6 to determine the presence or absence of a defect.

Next, FIG. 2 shows a block diagram of a signal processing unit in the most preferable apparatus and the most preferable method of the present invention. In this device and method, a system of electric output signals of a CCD camera is passed through an average value extraction circuit to extract the average value of the output signal level, and the output is input to a synchronization section average value replenishment circuit, which will be described later. The other system of the electrical output signal of the camera is also input to the synchronization part average value supplement circuit,
The synchronizing signal included in the output signal of the camera is deleted in the replenishing circuit, and the deleted synchronizing signal is complemented by the average value extracted by the extracting circuit to obtain a corrected output signal. After the output signal is passed through the band pass filter, the output signal is passed through the envelope detection circuit to which the rectifier circuit and the low pass filter circuit are connected in this order, and then the image processing is performed.

As can be seen by comparison with the signal processing units of FIGS. 1 and 2, the signal processing unit of FIG. 2 which is an embodiment of the present invention is different from that of FIG. 1 in that the CCD camera 1 and the band pass filter are used. 4, an average value extraction circuit 2 and a synchronization part average value replenishing circuit 3, and a band pass filter 4 and an image processing part 6
The envelope detection circuit 5 is inserted between the two.

In the apparatus and method of FIG. 2, the CC
After the output of the D camera 1 is divided into two, one system passes through the average value extraction circuit 2 and the average value is extracted and input to the synchronization unit average value supplement circuit 3, and the other system directly supplements the synchronization unit average value. It is input to the circuit 3.

In the synchronizing part average value replenishing circuit 3, the input two-system signals are switched and output at the timing of the synchronizing part in the electric output signal of the CCD camera. That is, the synchronization unit outputs the average value signal, and the units other than the synchronization unit output the electric output signal of the CCD camera.

The output of the synchronizing section average value replenishing circuit 3 is input to, for example, the band pass filter 4, the noise component in the input signal is removed, and the defective signal component is output.

By doing so, the CCD camera is compared with the case where the average value extraction circuit 2 and the synchronization section average value replenishment circuit 3 are not used (when the CCD camera electric output signal is directly passed through the band pass filter 4). There is an advantage that noise generated by the synchronizing signal in the electric output signal can be reduced.

Further, the output of the band pass filter 4 is input to the image processing section 6 to determine the presence / absence of a defect. The output of the band pass filter 4 may be directly input to the image processing unit 6, but after the rectifier circuit and the low pass filter circuit are input to the envelope detection circuit 5 connected in this order and the waveform is shaped. It is also possible to determine whether or not there is a defect by inputting it to the image processing unit 6.

With this configuration, the number of labels detected at the defective portion is reduced as compared with the case where the envelope detection circuit 5 is not used (the output of the bandpass filter 4 is directly input to the image processing unit 6). Also, there is an advantage that the load on the image processing unit can be reduced and that the level of isolated noise can be reduced.

The most preferable inspection apparatus and method of the present invention shown in FIG. 2 can reduce the noise generated by the synchronizing signal in the electric output signal of the CCD camera, and further reduce the number of labels detected at the defective portion to reduce the image. This has the advantage of reducing the load on the processing unit and the effect of reducing the level of isolated noise.

Although FIG. 2 shows the most preferable embodiment of the apparatus of the present invention, in the present invention, one system of the electric output signal of the CCD camera is made to pass through the average value extraction circuit. The average value of the output signal level is extracted, and its output is input to the synchronization section average value replenishment circuit described later, and the other system of the electric output signal of the CCD camera is also input to the synchronization section average value replenishment circuit. Delete the sync signal included in the output signal of the camera, and complement the deleted sync signal with the average value extracted by the extraction circuit to obtain a corrected output signal, and output the output signal of the replenishment circuit to the band. A device that directly processes the output after passing it through a pass filter (Fig. 1).
The described device also includes a device having only the average value extraction circuit 2 and the synchronization part average value replenishment circuit 3.

The output signal of the bandpass filter is
The present invention also provides a device for performing image processing after passing the rectifier circuit and the low-pass filter circuit to the envelope detection circuit connected in this order (the device shown in FIG. 1 has only the envelope detection circuit 5). Of course, it is included in.

Next, a film thickness defect inspection apparatus and a film thickness defect inspection method according to the present invention will be described with reference to FIG. On the light path A from the coherent light source 7, a half mirror 8 tilted at a predetermined angle with respect to the light path A is installed. At the position of the half mirror 8, on one side of the optical path B orthogonal to the optical path A (the direction in which the light beam from the light source 7 is reflected by the half mirror 8), a mechanism for supporting the thin film orthogonal to the optical path B. Alternatively, a substrate (thin film) 9 on which a thin film is mounted is provided so as to be orthogonal to the optical path B. An objective lens 10 is provided at a predetermined interval on the optical path B on the opposite side of the thin film through the half mirror 8. The objective lens 10 forms an image of a light beam passing on the optical path B. A CCD camera 1 is installed in.

Next, a method of using the film thickness defect inspection device having the above construction will be described. First, coherent light is emitted from the light source 7 onto the optical path A. The emitted coherent light is reflected by the half mirror 8 and vertically enters the thin film. The incident light ray is separated into a thin film front surface reflected light and a thin film back surface reflected light, and the thin film back surface reflected light is transmitted through the thin film and is combined with the thin film front surface reflected light, and the interference light due to the optical path difference is half. Mirror 8,
An image is formed on the CCD camera 1 through the objective lens 10.
When the thin film has a film thickness defect, interference fringes are generated due to the interference of the thin film, and an image is formed on the CCD camera 1. At this time, the electric output signal of the CCD camera 1 shows a wave showing the light and dark of the interference fringe. Further, if the thin film has no film thickness defect, no interference fringes are generated and the above-mentioned wave does not appear in the electric output signal of the CCD camera 1. By setting constant upper and lower thresholds for this electric output signal, waves due to interference fringes can be automatically detected, and film thickness defects of the thin film can be detected.

When the thin film of the object to be inspected is flat, the film thickness defect inspection apparatus according to the present invention can have a simple structure as shown in FIG. In FIG. 4, numeral 9 is a thin film or a substrate on which the thin film is mounted, numeral 7 is a coherent light source, which is installed so that a light beam is incident on the thin film at an angle. The objective lens 10 is provided at a predetermined distance from the thin film in the direction in which the reflected light from the thin film is the strongest, and the CCD camera 1 is installed at a position where the reflected light is imaged by the objective lens 10.

The method of using the inspection apparatus having the configuration shown in FIG.
Similar to the inspection apparatus having the above-described configuration, only when the thin film has a film thickness defect, the electric output signal of the CCD camera 1 shows the information of the wave showing the light and dark of the interference fringe. By setting constant upper and lower thresholds for this electric output signal, the film thickness defect of the thin film can be automatically detected.

When the object to be inspected has a cylindrical shape, FIG.
When the apparatus having the above structure is used, a large number of interference fringes are generated in the length direction even if there is no film thickness defect. Therefore, the device having the configuration shown in FIG. 3 is used to detect a film thickness defect in this type of inspection object.

Regardless of whether the apparatus having the structure shown in FIG. 3 or FIG. 4 is used, assuming that the refractive index of the thin film is uniform, the generation of interference fringes is largely controlled by the film thickness, and the object to be inspected Even if there is vibration in the thin film, the relative positional relationship between the front and back interfaces of the thin film does not change, so the optical path difference does not change, and the interference fringes are hardly affected by the vibration.

[0026]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

Example 1 Using the apparatus having the structure shown in FIG. 3, the film thickness defect of the photosensitive drum coating film was inspected. The diameter of the photosensitive drum as the inspection object was 30 mm, the thickness of the coating film was about 20 μm, and the refractive index was 1.59. As the light source 7, a mercury xenon lamp equipped with an interference filter (main wavelength 546 nm, full width at half maximum 12 nm) was used. As the CCD camera 1, a one-dimensional type having a scan rate of 4.7 kHz was used, and an electric output signal from the CCD camera was input to an image processing device so that the device could determine a defect. FIG. 5 and FIG. 6 are examples of detecting a defective portion by this image processing apparatus. There is a defect between the two marks, and in this detection example, a defect having film thickness unevenness on the order of submicrons is detected by setting a threshold value to ± 30% of the average level of the electric output signal.

When the surface condition of the substrate or the thin film becomes rough, the reflected light from the front surface of the thin film or the reflected light from the back surface of the thin film has a strength depending on how rough the surface condition is, and the electric output signal of the CCD camera also responds to it. Noise starts to appear. FIG. 7 and FIG. 8 are examples of defect detection for a photosensitive drum sample in which the surface state of the substrate or the thin film is rough. In this detection example, many defects other than the original noise are detected.

Therefore, the electrical output signal is passed through a band pass filter circuit in advance to remove noise components contained in the signal, and the signal after noise removal is input to the image processing apparatus. FIGS. 9 and 10 show the passband of 300 kHz for the same photosensitive drum sample as in FIGS. 7 and 8.
It is an example of defect detection when a band pass filter circuit of 1.2 MHz is used. It is understood that the bandpass filter circuit removes the noise component, and only the information of the wave showing the defective portion of the uneven film thickness is accurately extracted and detected.

Example 2 For another photosensitive drum sample, as in Example 1,
The inspection was carried out using the most preferred device according to the invention.

FIG. 12 is a schematic diagram showing an inspection method using the signal processing section of FIG. FIG. 1A shows an electric output signal of the CCD camera 1. On this electrical output signal, the information (defect signal) of the wave showing the contrast of interference fringes appears at the defect part,
Only noise appears in the normal part. The electric output signal is also accompanied by a synchronizing section (a section in which the electric output signal becomes substantially zero) representing the scanning start point and the scanning end point of the CCD camera.

After the electric output signal of the CCD camera 1 is divided into two parts, one system passes through the average value extraction circuit 2 and the average value is extracted and input to the synchronizing part average value replenishing circuit 3, and the other system It is directly input to the synchronization unit average value replenishing circuit 3.

For example, when a low-pass filter having an extremely low cutoff frequency is used as the average value extraction circuit 2, the circuit 2 outputs a flat signal representing the average value of the input signal as shown in FIG. 12b. Further, in the synchronization unit average value replenishing circuit 3, the average value signal of another system is inserted in the CCD camera signal which is one system of input in the synchronization section, and a signal as shown in FIG. 12c is obtained as an output. That is, since the synchronization part that formed a large step in the CCD camera output signal is deleted and the average value signal is complemented instead, the step in the synchronization part becomes smaller.

When the output signal of the synchronizing part average value replenishing circuit 3 is passed through the band pass filter 4 whose pass band is set to an appropriate value in advance, as shown in FIG.
The signal component of the defect to be detected passes through, and an output signal in a form in which the noise component included in the cutoff region of the filter is removed is obtained.

The output of the band pass filter 4 is input to the envelope detection circuit 5 in which a rectifying circuit 51 and a low pass filter 52 are connected in this order. The rectifier circuit 51 receives the signal d as an input and outputs a signal rectified to one polarity as shown in FIG. 12e.

Further, when the rectifier circuit output signal e is input to the low pass filter 52, a signal f representing an envelope (a line connecting the peaks of each mountain) is output. After the signal f is input to the image processing section 6, it is binarized based on a constant threshold value Vth as shown in FIG.

Example 3 The same photosensitive drum sample as in Example 2 was inspected by using a general signal processing section of the present invention (of FIG. 1). This will be described with reference to the schematic diagram of FIG. Figure 11a
Is the same electrical output signal of the CCD camera 1 as in FIG. 12a. This CCD camera electric output signal a is input to the band pass filter 4 to remove noise.

At this time, in the band pass filter 4, FIG.
As shown in 1d ′, the signal of the defective portion passes and the noise of the normal portion is removed, but the noise of the pass band frequency is generated due to the influence of the step of the synchronizing portion. In the signal d ′, when the noise caused by this synchronizing portion becomes large and exceeds the threshold value Vth ′, this noise is erroneously detected by the image processing portion 6 as shown in FIG. 11g ′.

When comparing the technical effects of the respective devices used in the second and third embodiments, using the device used in the second embodiment, that is, the signal processing section of FIG. 2, it is shown in FIG. 12d. It can be seen that the noise level caused by the synchronizing section is reduced to less than the threshold value, so that the noise is not erroneously detected.

Further, when the apparatus used in the third embodiment, that is, the signal processing section of FIG. 1 is used, the detection label tends to occur frequently at the defective portion as shown in FIG. The image processing unit 6 is burdened because the defect determination process takes longer than the device, and the image processing device is likely to hang up.

On the other hand, in the case of using the signal processing unit of FIG. 2, as shown in FIGS. 12d to 12g, the wavy signal of the interference fringes generated at the defective portion is shaped and converted into one mountain-shaped signal. Therefore, the number of detection labels in the image processing unit 6 is significantly reduced, which can reduce the load on the image processing unit.

FIGS. 13 and 14 are respectively shown in FIG.
An image of a defective portion obtained by using the signal processing unit described in FIG. 1 and the signal processing unit described in FIG. 1 (using a mechanism for removing a noise component included in an electric output signal of a CCD camera using a bandpass filter). It is a processing example.

In the second and third embodiments, the bandpass filter 4 in both signal processing sections has an attenuation gradient of 48d.
B / oct, a pass band of 300 KHz to 1.2 MHz is used, and the latter envelope detection circuit 5 is a full-wave rectifier circuit, an attenuation gradient of 12 dB / oct, and a cutoff frequency of 10 KHz.
It consisted of a combination of low pass circuits.

13 and 14, a is a three-dimensional display image of the image processing unit input signal, and b is a three-dimensional display image a cut at a threshold value of ± 30% of the average value Vave. FIG. Marks for confirming the position of the defect are attached to the upper and lower ends of the drawing, and the defect exists in the center thereof.

As can be seen from the cross-sectional view of FIG. 14, when the signal processing unit having only the mechanism for removing the noise component contained in the electric output signal of the CCD camera by using the bandpass filter is used, the interference occurs at the defective portion. There are many detection labels that show the shape of stripes. On the other hand, as can be seen from the cross-sectional view of FIG. 13, when the signal processing unit having the configuration of FIG. 2 is used, the number of detected labels is drastically reduced by the function of the envelope detection circuit.

Further, when the signal processing unit of FIG. 2 is used, there is also an effect that the level of the isolated noise can be relatively reduced by the integrating action of the low pass filter in the envelope detection circuit. FIG. 15 shows an example of waveforms of a defective portion and isolated noise before and after the envelope detection circuit. FIG. 6h shows a waveform before the envelope detection circuit, in which a defective portion formed by a large set of waves and an isolated noise of approximately the same size are simultaneously generated. On the other hand, in the waveform j after the envelope detection circuit, it can be seen that the level of the isolated noise is significantly reduced as compared with the size of the defective portion.

[0047]

According to the invention described in claims 1 and 5,
Even if the object to be inspected vibrates, a defect can be detected, and in-line inspection can be performed, which is a particularly remarkable effect.

According to the second and sixth aspects of the present invention, it is possible to inspect even a cylindrical object to be inspected.

Further, according to the invention described in claims 3 and 7, there is an effect that the defect can be detected with higher accuracy.

Furthermore, according to the invention described in claims 4 and 8, there is an effect that the entire region of the object to be inspected can be inspected.

Furthermore, according to the invention described in claim 9, there is an effect that the size of the entire inspection apparatus can be reduced by moving the CCD camera.

According to the tenth and thirteenth inventions, CC
It is possible to reduce the noise generated by the synchronization signal in the D camera electric output signal.

According to the eleventh and fourteenth aspects of the present invention, it is possible to reduce the number of labels to be detected at the defective portion and reduce the load on the image processing portion. In addition, the effect that the level of isolated noise can be reduced is obtained.

According to the twelfth and fifteenth aspects of the present invention, there is an effect that combines the effects of the tenth and thirteenth and the eleventh and the fourteenth aspects.

According to the method and apparatus of the present invention, a defect can be detected even when an object to be inspected vibrates, in-line inspection can be performed, and even a cylindrical object to be inspected can be inspected. Further, the defect can be detected with higher accuracy, and the entire area of the inspection object can be inspected. Furthermore, the size of the entire inspection device can be reduced.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a thin film defect inspection method of the present invention.

FIG. 2 is a block configuration diagram of a most preferable thin film defect inspection method of the present invention.

FIG. 3 is a configuration diagram of a thin film defect inspection apparatus of the present invention.

FIG. 4 is a configuration diagram of a thin film defect inspection apparatus of the present invention.

FIG. 5 is a diagram illustrating a three-dimensional display image obtained by processing an electric output signal in a defect portion obtained by using the thin film defect inspection method and inspection device of the present invention by an image processing device (Example). 1).

FIG. 6 is a sectional view corresponding to FIG. 5 at a threshold value of an electric output signal in a defective portion (Example 1).

FIG. 7 is a diagram showing a three-dimensional display image obtained by processing an electric output signal at a defective portion of a photosensitive drum sample obtained by using the thin film defect inspection method and inspection device of the present invention by an image processing device. (Example 1).

8 is a sectional view corresponding to FIG. 7 at a threshold value of an electric output signal in a defective portion (Example 1).

FIG. 9 is a diagram showing a three-dimensional display image obtained by processing an electric output signal at a defective portion of a photosensitive drum sample obtained by using the thin film defect inspection method and inspection device of the present invention by an image processing device. (Example 1).

FIG. 10 is a cross-sectional view at the threshold of the electric output signal in the defective portion corresponding to FIG. 9 (Example 1).

FIG. 11 is a diagram showing an inspection method using the signal processing unit of FIG. 1 (Example 3).

FIG. 12 is a diagram showing an inspection method using the signal processing unit of FIG. 2 (Example 2).

FIG. 13 is an image processing example of a defective portion obtained by using the signal processing unit of FIG. 2 (a three-dimensional display image of an input signal of the image processing apparatus and a sectional view at a threshold value) (Example 2). .

FIG. 14 is an image processing example of a defective portion obtained by using the signal processing unit in FIG. 1 (three-dimensional display image of an image processing apparatus input signal and a sectional view at a threshold value) (Example 3). .

FIG. 15 is an example of waveforms of a defect portion and isolated noise before and after the envelope detection circuit (Example 2).

[Explanation of symbols]

 1 CCD camera 2 Average value extraction circuit 3 Synchronous part average value replenishing circuit 4 Band pass filter 5 Envelope detection circuit 51 Rectifier circuit 52 Low pass filter 6 Image processing unit 7 Light source 8 Half mirror 9 Thin film (and substrate) 10 Objective lens A optical path B optical path a Electrical output signal of CCD camera 1 Output signal of average value extraction circuit 2 Output signal of synchronous part average value replenishing circuit 3 d Output signal of band pass filter 4 d'Output signal of band pass filter 4 h Output signal of the band-pass filter 4 e Output signal of the rectifier circuit 51 i Output signal of the rectifier circuit f Output signal of the low-pass filter 52 j Output signal of the low-pass filter 52 g Binarization in the image processing unit 6 Signal g'Binarized signal in image processing unit 6 Vave Average value of electric output signal of CCD camera 1 Vth Threshold level Vth Level of threshold

Claims (15)

[Claims] 1. A light source for a coherent light beam that illuminates an object having a light-transmissive thin film, an objective lens, and a CCD camera that receives light from the light-transmissive thin film. A coherent light beam to irradiate the thin film front surface interface reflected light of the light emitted from the light source and the thin film back interface reflected light to form an interference light, which is imaged on the CCD camera through the objective lens. From the presence or absence of the information of the interference fringes generated in the defective portion having the film thickness unevenness in the electric output signal of the camera,
A method for inspecting a defect in a thin film, which comprises inspecting a thin film for defects. 2. The inspection method according to claim 1, wherein the coherent light beam is irradiated so that the irradiation light and the reflected light thereof are coaxial with each other. 3. The inspection method according to claim 1, wherein a noise component contained in an electric output signal of the CCD camera is removed by using a bandpass filter. 4. The CCD camera is fixed and the inspection object is moved, or the inspection object is fixed and the CCD is fixed.
The inspection method according to claim 1, wherein the interference light is focused on the CCD camera by moving the camera. 5. A defect inspection apparatus for a thin film, comprising a coherent light source for irradiating an object having a light-transmissive thin film, an objective lens, and a CCD camera for receiving light from the light-transmissive thin film. Therefore, (A) a mechanism for irradiating the thin film with a coherent light beam toward the thin film, and (B) interference caused by combining the thin film front surface reflected light of the irradiation light from the light source and the thin film back surface reflected light. Mechanism for focusing light on the CCD camera through the objective lens, (C) Presence / absence of thin film defect based on presence / absence of information of interference fringes generated in defective portion having uneven film thickness in electric output signal of the CCD camera A thin film defect inspection device having a mechanism for inspecting 6. The inspection apparatus according to claim 5, further comprising a mechanism for irradiating the coherent light beam so that the irradiation light and the reflected light thereof are coaxial with each other. 7. The inspection apparatus according to claim 5, further comprising a mechanism for removing a noise component included in an electric output signal of the CCD camera by using a bandpass filter. 8. A mechanism is provided which fixes a CCD camera and moves an object to be inspected, or fixes an object to be inspected and moves the CCD camera to form an image of interference light on the CCD camera. The inspection device according to claim 5. 9. A cylindrical object to be inspected is fixed in the axial direction, the CCD camera is moved while rotating the object to be inspected, and the interference light on the front and back interfaces of the object to be inspected by the CCD camera. 9. A mechanism for forming an image is provided.
The inspection device described. 10. A CCD camera which passes a system of electric output signals of a CCD camera to an average value extraction circuit to extract the average value of the output signal level and inputs the output to a synchronization section average value replenishment circuit described later, Another line of electric output signal of
It is input to the synchronization unit average value replenishment circuit, the synchronization signal included in the output signal of the camera is deleted in the replenishment circuit, and the deleted synchronization signal is complemented by the average value extracted by the extraction circuit to be corrected. 4. The method according to claim 3, wherein the output signal is obtained, the output signal of the supplemental circuit is passed through a band pass filter, and then image processing is performed. 11. The method according to claim 3, wherein the output signal of the band pass filter is passed through an envelope detection circuit to which a rectifying circuit and a low pass filter circuit are connected in this order, and then image processing is performed. 12. A CCD camera, wherein a system of electric output signals of a CCD camera is passed through an average value extraction circuit to extract the average value of the output signal level, and the output is input to a synchronization section average value replenishing circuit described later. Another line of electric output signal of
It is input to the synchronization unit average value replenishment circuit, the synchronization signal included in the output signal of the camera is deleted in the replenishment circuit, and the deleted synchronization signal is complemented by the average value extracted by the extraction circuit to be corrected. The output signal of the replenishment circuit and pass it through the band pass filter, and then pass the output signal through the envelope detection circuit where the rectifier circuit and the low pass filter circuit are connected in this order. 4. The method according to claim 3, wherein the image processing is performed from. 13. A CCD camera electric power output signal system is passed through an average value extraction circuit to extract the average value of the output signal level, and the output is input to a synchronization section average value replenishment circuit described later, and a CCD camera Another line of electric output signal of
It is input to the synchronization unit average value replenishment circuit, the synchronization signal included in the output signal of the camera is deleted in the replenishment circuit, and the deleted synchronization signal is complemented by the average value extracted by the extraction circuit to be corrected. 8. The apparatus according to claim 7, wherein the output signal is obtained, the output signal of the supplement circuit is passed through a band pass filter, and then image processing is performed. 14. The apparatus according to claim 7, wherein the output signal of the band pass filter is passed through an envelope detection circuit to which a rectifying circuit and a low pass filter circuit are connected in this order, and then image processing is performed. 15. A CCD camera which passes an electric output signal system of a CCD camera through an average value extraction circuit to extract the average value of the output signal level and inputs the output to a synchronization section average value replenishment circuit to be described later. Another line of electric output signal of
It is input to the synchronization unit average value replenishment circuit, the synchronization signal included in the output signal of the camera is deleted in the replenishment circuit, and the deleted synchronization signal is complemented by the average value extracted by the extraction circuit to be corrected. The output signal of the replenishment circuit and pass it through the band pass filter, and then pass the output signal through the envelope detection circuit where the rectifier circuit and the low pass filter circuit are connected in this order. 8. The apparatus according to claim 7, which performs image processing from.