JPH07120401A - Bubble detecting device in transparent object - Google Patents

Abstract

PURPOSE:To inspect three-dimensional distibution of bubbles in a transparent body quickly, accurately, and automatically, by utilizing difference of focal distances due to generation of chromatic aberration at every wavelength. CONSTITUTION:A irradiation light of multi-wavelength emitted from a multi- wavelength light source 1 is dispersed by a chromatic aberration generating means 3, and converged within a body 4 to be inspected 4 with different focal distance at every wavelength. When a bubble (a) exists in the body 4, a part of the irradiation light is reflected on the boundary face. This reflected light is detected by a light detecting means 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting bubbles in a transparent object.

[0002]

2. Description of the Related Art Conventionally, as an apparatus for detecting bubbles in a transparent object, there is an invention described in, for example, Japanese Patent Application Laid-Open No. 4-359106. In the above invention, as shown in FIG. 10, the object to be inspected 91 is moved by the XYZ moving device 94 to a position where an image can be picked up by the TV camera 92, and the surface of the object to be inspected 91 is illuminated by the illuminating device 93 from an oblique upper direction. And the reflected light is captured by the TV camera 92. Then, the obtained image signal is sent to the image processing device 95, various processing is performed on the inspection image to detect bubbles, and the result is displayed on the output monitor 96.

[0003]

However, in the above-mentioned prior art, when detecting air bubbles distributed in the Z direction,
The XYZ moving device 94 must scan the inspected object 91 in the optical axis direction (Z direction) of the TV camera 92, which has a drawback that high-speed detection cannot be performed.

It is an object of claims 1 to 3 to provide a bubble detecting device in a transparent object which can detect a three-dimensional distribution state of bubbles at high speed.

[0005]

According to a first aspect of the present invention, a multi-wavelength light source that emits irradiation light having a plurality of wavelengths and a focal length on the optical axis of the irradiation light and / or off-axis are provided. And chromatic aberration generating means for irradiating the object to be inspected with different chromatic aberrations, and light detection means for detecting the reflected light from the bubbles in the object to be inspected.

According to a second aspect of the present invention, a multi-wavelength light source for emitting irradiation light having a plurality of wavelengths, a wavelength selecting means for selecting a specific wavelength contained in the emitted irradiation light, and an optical axis of the irradiation light are provided. It is composed of chromatic aberration generating means for generating chromatic aberration so that focal lengths on and / or off-axis are different and irradiating the object to be inspected, and light detection means for detecting reflected light from bubbles in the object to be inspected. It is a thing.

According to a third aspect of the invention, the light deflecting means is arranged between the multi-wavelength light source and the object to be inspected.

1 and 2 are conceptual diagrams showing the optical principle of the bubble detecting device according to the present invention. It is assumed that a rectangular parallelepiped transparent body as shown in FIG. 2 is used as the inspection object 4, and the bubbles a are present therein. The multi-wavelength irradiation light emitted from the multi-wavelength light source 1 is dispersed by the chromatic aberration generating means 3 and condensed at different focal lengths 1 ₁ and 1 ₂ for each wavelength (for example, λ ₁ and λ ₂ ). This light collection is set so as to be performed at least inside the inspection object 4 (in the figure, it is set inside and below the back surface).

In this case, if the amount of chromatic aberration of each wavelength by the chromatic aberration generating means 3 is obtained in advance, the wavelength selection means selectively changes the wavelength of the irradiation light from the multi-wavelength light source 1 and the position where bubbles exist. Can be three-dimensionally inspected (in the depth direction indicated by arrow Z in the figure).

If no air bubbles, foreign matter, or the like are mixed inside the object to be inspected 4, the light other than the reflected light on the front surface or the back surface of the object to be inspected 4 is diverged as it is and escapes outside the object to be inspected 4. However, when the bubble a is present inside the inspection object 4, since the inspection object 4 and the gas in the bubble a have different refractive indices, the multi-wavelength irradiation light is partially reflected at the boundary surface. Occurs. The light detecting means 5 detects the reflected light generated by the bubble a. The presence of air bubbles in the inspection object 4 is confirmed by this detection.

FIG. 3 shows a portion 1 of the object 4 to be inspected by the light detecting means 5.
It is a graph which shows the relationship between the specific wavelength by individual bubbles, and the spectral intensity of reflected light. It is confirmed that bubbles are present near the condensing point corresponding to the wavelength at which the peak of the light intensity occurs. In addition, when there are a plurality of bubbles, it is expected that there are bubbles near each peak.

According to the second aspect of the invention, the wavelength selecting means (in FIG. 1, between the multi-wavelength light source 1 and the object to be inspected 4,
Alternatively, by arranging the wavelength on the optical axis between the object to be inspected 4 and the light detecting means 5), the distribution of bubbles is detected as the light intensity distribution for each wavelength as shown in FIG. Therefore, it is possible to determine whether the number of bubbles existing in the Z direction is one or more and the distribution of the depth of the bubbles.

According to the third aspect of the invention, the light deflecting means is arranged between the multi-wavelength light source 1 and the inspection object 4 so that the irradiation light to the inspection object 4 can be scanned. That is, by arranging the light deflection means, the incident position of the irradiation light on the inspection object 4 can be changed, and the inspection object 4 can be changed.
Measurement range (including not only Z direction but also XY direction)
Can be extended.

[0014]

Embodiment 1 FIGS. 4 to 7 show the present embodiment, FIG. 4 is a schematic configuration diagram, FIG. 5 is a perspective view of a rotary filter plate, and FIGS. 6 and 7 are graphs. Reference numeral 10 denotes a white light source including a halogen lamp, a xenon lamp, etc. The irradiation light 31 emitted from the white light source 10 is collimated by the collimator lens 11 and incident on the rotary filter plate 12. The rotary filter plate 12 is formed by a plurality of interference filters λ _{1 to} λ ₅ that selectively transmit only a specific wavelength of the emitted irradiation light 31. If an interference filter formed by vapor-depositing a dielectric multilayer film is used, it is possible to transmit only an arbitrary wavelength with a half width of about 10 nm. The rotary filter plate 12 is rotatably held by a motor 23, and the motor 23 is connected to a motor driver 22 that drives the rotation.

Irradiation light 3 transmitted through the rotary filter plate 12
1 is incident on the color-developing lens 14 that is reflected by the half mirror 13 to generate chromatic aberration, passes through the color-developing lens 14, and is incident on the inspection object 4. The irradiation light 31 is reflected by the bubble a existing inside the inspection object 4, and the reflected light 3
2 passes through the half mirror 13 and is incident on a condenser lens 15 such as a macromart or an apochromat whose chromatic aberration has been corrected for at least two different wavelengths, and is condensed on the light receiving surface of the optical sensor 16. The optical sensor 16 is formed of a photodiode, a phototransistor, or the like, and converts the reflected light 32 reflected by the bubble a into an electric signal.

The optical sensor 16 is connected to an optical sensor controller 17 which controls the operation of the optical sensor 16. The optical sensor controller 17 is connected to the I / F 18, and the I / F 18 controls the arithmetic operation of the entire device by the MPU 21.
It is connected to the. The I / F 18 is a motor driver 2
2 and the control signal is input and output between the optical sensor controller 17 and the MPU 21. In addition, the optical sensor 16
Is A for A / D converting the electric signal from the optical sensor 16.
It is connected to the / D converter 19. The A / D converter 19 is connected to the storage means 20 for storing the measurement data, and the storage means 20 is connected to the MPU 21.

The apparatus having the above-mentioned structure is provided with the white light source 10
The irradiation light 31 emitted from is converted into a parallel light flux by the collimator lens 11. Then, the irradiation light of a certain wavelength λ ₁ selected by the interference filter of the rotary filter plate 12 is reflected by the half mirror 13 and enters the color forming lens 14, and is focused at a certain focal length l ₁ . If the bubble a exists at this focus position, a part of the irradiation light 31 is reflected. The reflected light 32 that has been reflected is transmitted through the color-developing lens 14, condensed by the condenser lens 15 on the light-receiving surface of the optical sensor 16, converted into an electric signal, and detected as a light intensity value.

Here, the rotary filter plate 12 is rotated by the motor driver 22 to switch to another interference filter, and the irradiation light 31 of wavelength λ ₂ is transmitted. This irradiation light 3
1 is incident on the color-developing lens 14 and is focused on another focal position at a focal length l ₂ different from the irradiation light 31 having the wavelength λ ₁ due to chromatic aberration. If a bubble exists at the position of the focal length l ₂ , a part of the irradiation light 31 is reflected as in the above,
The light intensity is detected via the optical sensor 16. Like this
By rotating the rotary filter plate 12 to select the wavelength of the irradiation light 31 and focusing at different focal lengths,
A plurality of peak values as shown in FIG. 3 are obtained, and a plurality of bubbles existing in the Z direction are detected.

In order to perform the above series of processing at high speed, MP
The U21 controls the motor driver 22 and the optical sensor controller 17 via the I / F (interface) 18, and receives the electric signal from the optical sensor 16 from the A / D converter 1
Converted in 9 and taken in as data in the storage means 20,
Bubbles in the Z direction are detected at a predetermined position on the XY plane of the inspection object 4 by calculating the light intensity value for each wavelength by performing the arithmetic processing.

According to this embodiment, the reflection efficiency is improved by collecting the irradiation light on the bubbles existing inside the object to be inspected and detecting the reflected light reflected in the same direction as the incident direction. , The detection sensitivity becomes higher. Further, by rotating the rotary filter plate at a high speed to switch the interference filter, it is possible to scan and detect bubbles existing in the Z direction at a high speed.

The halogen lamp 3 which is the white light source 10
3 and the xenon lamp 34 have spectral radiation characteristics as shown in FIG. On the other hand, the photosensor 16 such as a photodiode or a phototransistor has a spectral sensitivity characteristic as shown in FIG. Therefore, if these spectral characteristic data are stored in the storage means 20, the light intensity value output from the optical sensor 16 is subjected to arithmetic processing, and the influence of the spectral characteristic of the white light source 10 and the optical sensor 16 is corrected, The detection accuracy is improved.

[0022]

Second Embodiment FIG. 8 is a schematic configuration diagram showing this embodiment.
In this embodiment, the same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. In this embodiment, the rotary filter plate 12 in the first embodiment is replaced by a filter 12a. This filter 12a
Is a broadband bandpass filter that transmits only a wavelength λ (λ ₁ <λ <λ ₂ ) in a specific range.

The apparatus having the above-mentioned structure is configured so that the focal length l ₁ of the coloring lens 14 at the wavelength λ ₁ and the coloring lens _{1 at} the wavelength λ ₂
If the focal length of 4 is l ₂ , the light having the wavelength λ (λ ₁ <λ <λ ₂ ) that has passed through the filter 12a is colored by the color-developing lens 14
To focus at a focal length l (l ₁ <l <l ₂ ). Therefore, only the bubbles in the depth range 4a of l ₁ <l <l ₂ in the inspection object 4 can be selectively detected by the light of the wavelength λ (λ ₁ <λ <λ ₂ ). In this case, even if bubbles exist outside the predetermined depth range 4a of the inspection object 4, the measuring device is effective when there is no obstacle in practical use of the inspection object 4.

According to the present embodiment, by providing the filter 12a with a transmission wavelength band, it is possible to selectively detect only bubbles in a specific range within the inspection object 4.

[0025]

Third Embodiment FIG. 9 is a schematic configuration diagram showing this embodiment.
The present embodiment is different in that the acousto-optic element 40, to which the frequency control device 41 is connected, is arranged between the white light source 1 and the inspection object 4 in the first embodiment, and the other configurations are the same. It is composed of constituent parts, the same constituent parts are designated by the same reference numerals, and the description of the structure is omitted.

In the apparatus having the above-mentioned structure, the irradiation light 31 emitted from the white light source 10 is collimated by the collimator lens 11, passes through the rotary filter plate 12, and is incident on the acousto-optic element 40 which is a light deflecting means. . Acousto-optic element 4
The emission direction is deflected when passing through 0, and the half mirror 1
The light passes through 3 and enters the inspection object 4. The irradiation light 31a is reflected by the air bubbles a existing inside the inspection object 4, and the reflected light 32a passes through the half mirror 13 and enters the achromatized condensing lens 15 and is detected by the light detecting means. An image is formed at a point a'on the light receiving surface of a CCD camera 16a.

The acousto-optical element 40 diffracts and deflects the incident light in one direction by the spatial periodic change of the refractive index generated by the sound wave in the transparent medium. By changing the frequency of the sound wave applied to the acousto-optical element 40, the deflection direction of the emitted light can be changed.

The emitted sound beam 31b is deflected in the x direction in FIG. 9 by changing the sound wave applied to the acousto-optic device 40, and is focused by the coloring lens 14 at a point outside the optical axis. If a bubble b in the object to be inspected 4 exists at this condensing point, the reflected light 32b is reflected by the half mirror 13, and the condensing lens 15 causes the point b on the light receiving surface of the CCD camera 16a to be outside its optical axis. To form an image.

Therefore, when the object 4 to be inspected is moved on the XY plane with respect to the optical axis of the color-developing lens 14, or the object 4 to be inspected and the color-developing lens 14 are fixed and the irradiation light 31 is used.
Is used so as to move the optical path in the X and Y directions on the surface of the object 4 to be inspected, or mechanical driving means such as polarizing the optical path by a prism having a horizontally moving triangular cross section is used. Instead, the irradiation light 31 to the inspection object 4 can be scanned.

According to this embodiment, the object to be inspected can be scanned in the Z direction and the x direction without using mechanical driving means, and high-speed bubble detection can be performed. Further, by arranging acousto-optic elements having different deflection directions in series, the light beam can be scanned also in the y direction, and the three-dimensional distribution of bubbles in the inspection object can be detected at higher speed.

[0031]

The effects of the invention according to claims 1 to 3 utilize the difference in focal length due to the occurrence of chromatic aberration for each wavelength, and the three-dimensional distribution of bubbles existing in a transparent object can be accurately measured at high speed. Since the inspection can be performed, the inspection can be automated.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing the present invention.

FIG. 2 is a conceptual diagram showing the present invention.

FIG. 3 is a graph showing the present invention.

FIG. 4 is a schematic configuration diagram showing a first embodiment.

FIG. 5 is a perspective view showing the first embodiment.

FIG. 6 is a graph showing Example 1.

FIG. 7 is a graph showing Example 1.

FIG. 8 is a schematic configuration diagram showing a second embodiment.

FIG. 9 is a schematic configuration diagram showing a third embodiment.

FIG. 10 is a schematic configuration diagram showing a conventional example.

[Explanation of symbols]

 1 multi-wavelength light source 3 chromatic aberration generating means 4 inspected object 5 light detecting means

Claims (3)

[Claims] 1. A multi-wavelength light source that emits irradiation light having a plurality of wavelengths and chromatic aberration is generated so that the irradiation light has different focal lengths on the optical axis and / or off-axis to irradiate an object to be inspected. An apparatus for detecting bubbles in a transparent object, comprising: chromatic aberration generating means and light detecting means for detecting reflected light from bubbles in the object to be inspected. 2. A multi-wavelength light source that emits irradiation light having a plurality of wavelengths, a wavelength selecting unit that selects light of a specific wavelength contained in the emitted irradiation light, and an optical axis of the irradiation light or / And a chromatic aberration generating means for irradiating an object to be inspected by causing chromatic aberration so as to have different off-axis focal lengths, and a light detecting means for detecting reflected light from bubbles in the object to be inspected. A device for detecting bubbles in transparent objects. 3. The bubble detecting device in a transparent object according to claim 1, wherein a light deflecting unit is arranged between the multi-wavelength light source and the inspection object.