JP2002122555A - Light source for transparent body, transparent body inspection device, and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To highly accurately inspect the state of beveling work and convex work and to inspect the state of flat plate work by the same light source. SOLUTION: A composite light source comprised of a light source 10 for dark-field observation and a light source 20 for polarized-light observation is used. Light from the light source 20 for polarized-light observation is diffused by a diffusing plate 2, polarized by a polarizer 3, and shone to a crystal blank B on which beveling work or convex work is performed. Simultaneously with this, the crystal blank B is also irradiated with light from the light source 10 for dark-field observation. Light transmitted through the crystal blank B or scattered and diffracted at the crystal blank B is extracted by a polarizer 4 as light in a polarized state at a predetermined angle. By picking up the image of the light in the polarized state by an image pickup means 30, it is possible to observe contour lines due to the light source 10 for dark-field observation in addition to interference fringes due to the light source 20 for polarized- light observation. The image signals are transmitted to an image processing device 40, and the shapes of beveling work and convex work are inspected from the location of the interference fringes to the contour lines.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a light source for inspecting a transparent object,
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent body inspection apparatus and an inspection method thereof, and more particularly to an apparatus suitable for shape inspection of beveling / convex processing performed on a quartz substrate for a quartz oscillator or a quartz filter.

[0002]

2. Description of the Related Art In general, when manufacturing a cut crystal resonator, as shown in FIG. 6, an artificial crystal is cut to cut out a crystal blank (step 61), and the surface of the cut crystal blank is ground with an abrasive material. A lapping process is performed using the grains (step 62). As a result, a work-affected layer and a secondary crack layer (hereinafter referred to as a work layer) are generated on the surface, and the surface is in a roughened state.
In addition, in order to remove this processed layer, lapping may be performed using grinding grains having a smaller particle size.
After lapping, in order to reduce acoustic loss on the surface of the quartz blank, a polished finish (including chemical etching), which is a final finishing process, is applied to mirror-finish (step 63). Then, electrodes are vapor-deposited (step 64) and packaged to form a quartz oscillator (step 65).

[0003] By the way, since a quartz blank for a quartz oscillator is small, thin, lightweight and transparent, it is difficult to visualize it and it is difficult to inspect a minute scratch on the quartz blank. Therefore, a flaw generated in the quartz blank is raised by using a dark-field observation method of observing only the light scattered or diffracted by the flaw on the quartz blank without putting the illumination light directly into the visual field of the CCD camera. A technique has been developed in which the surface of the crystal blank is imaged by a CCD camera and the image signal is processed to perform an image inspection of the appearance of the crystal blank (for example, Japanese Patent No. 282460).
By applying this dark-field observation method, a flaw that could not be visually inspected, for example, a flaw such as a chip, can be detected, and the flaw inspection technology for a quartz substrate has been dramatically improved.

[0004] However, although the dark-field observation method can inspect the surface condition of the quartz crystal blank, the shape inspection of the beveling process or the convex process relating to the cross-sectional shape or thickness cannot be effectively performed. This will be described below. The beveling process refers to chamfering a peripheral portion as shown in FIG. 7A, and the convex process refers to a convex lens process (either one-side convex type or double-side convex type) as shown in FIG. 7B. Is included).

[0005] As described above, the surface of the quartz blank is subjected to lapping and further polished (or chemically etched). In the lapping stage, a relatively coarse abrasive of # 4000 or less is used as a grain anchor to be used, so that the surface of the quartz blank is in a rough state (0.1 μm or more). When beveling is performed using this level of abrasive, the processed portion of the quartz blank surface is roughened. Therefore, scattering at the surface roughness,
The dark-field observation method for observing diffraction can distinguish between a roughened processed portion and a non-roughened non-processed portion, so that a shape inspection of beveling processing can be performed.

FIG. 8 shows a specific example of an image obtained by dark-field observation of a quartz blank having a beveled peripheral portion.
A region surrounded by a black oval at the center is a non-processed portion, and a white region on the outer periphery is a processed portion. The point is that the beveling process is to form a rough surface around the surface of the quartz crystal blank, so the beveling process is viewed as a scratch. The beveling shape can be inspected from this image. In the dark-field observation method, the outline of the quartz blank also shines white as shown in the figure, so that the external dimensions can be measured, and the relative processing accuracy of beveling with respect to the outline can also be inspected.

However, if the beveled quartz blank is further subjected to fine polishing or fine chemical etching of grains whose abrasive grain number anchor exceeds # 4000, the roughened surface is mirror-finished. In addition, scattering and diffraction on the surface of the quartz blank hardly occur, making it impossible to perform a beveling shape inspection by a dark-field observation method that was possible in the lapping stage.

Further, in the convex processing for processing the entire surface of the crystal blank, the entire surface is originally roughened uniformly, so that the shape inspection of the convex processing by the dark-field observation method cannot be performed regardless of the abrasive grain anchor. .

Therefore, instead of using scattered light or diffracted light that depends on the roughness of the quartz substrate surface for inspection, a polarization observation method that uses a transmitted light that does not depend on the quartz substrate surface roughness has been introduced. The present inventor has previously proposed an appearance inspection method that enables a shape inspection of beveling processing and convex processing (for example, JP-A-2000-81312).
This is because a light from a light source is polarized by a polarizer and applied to a crystal blank made of a birefringent medium, and among the light that has passed through the crystal blank, only light in a polarization state forming a predetermined angle with respect to the polarized light is analyzed. And visualize the phase difference due to the difference in thickness of the quartz blank as interference fringes due to polarization interference,
The cross-sectional shape of the quartz blank is inspected based on the shape of the interference fringes.

FIG. 9 shows an image example of a rectangular quartz crystal blank by the polarization observation method. This rectangular quartz blank is subjected to convex processing, and two substantially elliptical interference fringes are formed concentrically on the image. The upper half of the figure is a plan view, and the lower half shows a luminance distribution corresponding to the plan view. As can be seen, since the interference fringes are shining white, the shape of the interference fringes can be easily measured. The processing finish is inspected by the shape of the interference fringes themselves. Note that the contour image obtained by the polarization observation method has slightly bright left and right short sides, but the contour has not been accurately extracted. Also, for the upper and lower long sides,
It is the same color as the background and dark, and the outline is unclear. Therefore, it is not possible to inspect the relative position of the interference fringes based on the outline of the crystal blank. In the beveling process, the relative position of the interference fringes is, for example, a process distribution such as a bevel width and a center deviation, a flat range and eccentricity of beveling,
In convex processing, it refers to the distribution of processing such as the center deviation and inclination of the convex. In the polarization observation method, although the absolute shape of the interference fringes separated from the crystal blank image can be measured, the relative shape measurement, such as where the interference fringes are formed on the crystal blank image and the symmetry is formed, is performed. You can't.

It is important for a transparent body, particularly a quartz blank for a quartz oscillator, to know not only the absolute shape of the interference fringes but also the relative position of the interference fringes with respect to the outline of the quartz blank, that is, on the quartz blank. To know the shape of the beveling / convex processing.

This is extremely important because the surface of the finally finished quartz blank has physical factors such as roughness (flatness) and parallelism, and both are the basis for determining the performance as a vibrator. Here, the parallelism of a thickness difference in the blank surface, the one-side convex convex shape in Figure 10, the perpendicular dropped from the peak P of the center thickness of the blank to the diameter d _e of the vibrating region by the length h is there. Note that the vibration region is a region where the thickness shear vibration energy of the convex vibrator is concentrated at the central portion. The roughness (flatness) can be maintained at 0.06 μm or less by polishing or etching, so that there is no particular problem. Therefore, the remaining factor, the parallelism h, is an important factor related to whether or not the function as a vibrator can be exhibited. The peak of the center thickness defining the parallelism h corresponds to the center of beveling / convex processing on the quartz blank, and the vibration region corresponds to the relative position of beveling / convex working on the quartz blank. Therefore, it is more important for the vibrator to inspect the relative position of the interference fringes with respect to the contour of the quartz blank than the cross-sectional shape or thickness of the quartz blank.

[0013]

Conventionally, after inspecting dimensions and flaws by a dark-field observation method, a bevel / convex shape inspection by a polarization observation method is performed to perform an appearance inspection. Independent bevel / convex shape inspection has the following problems.

(1) In the convex processing, unlike the beveling processing for processing a part of the crystal blank, the entire surface is processed. For this reason, in order to inspect the convex shape, a polarization observation method is used instead of a dark field observation method. According to this polarization observation method, an interference fringe having a shape corresponding to the thickness of the quartz blank is formed. Therefore, the convex processing shape can be inspected by measuring the shape and size of the interference fringe. This inspection method can also be applied to the above-described deep etching and beveling processing in which the number of abrasive grains is 4000 or more.

However, even though the shape (absolute shape) of the interference fringes themselves can be inspected, the shape of the interference fringes (relative shape) relative to the contours is unclear because the polarization observation method makes the outline unclear unlike the dark-field observation method. Cannot be inspected. It is sufficient that the position of the crystal blank placed on the mounting table is always constant, but each time the crystal blank is transported, the position of the crystal blank on the mounting table is not constant, and it tilts or shifts left, right, up and down, This is because the relative shape cannot be inspected unless the outline of the crystal blank is clear. Since the contour data obtained by the dark-field observation method performed prior to the polarization observation method is not obtained by the same measurement as the interference fringe data obtained by the polarization observation method, correlation cannot be obtained, and bevel / convex data cannot be obtained. It is useless for relative shape inspection of processing.

(2) In order to shift from the dark-field observation method to the polarization observation method, it is necessary to cut off the dark-field observation light source and switch to the polarization observation light source. Since the polarizer and the analyzer need to be inserted into the optical path, the switching structure of the light source system becomes complicated.

(3) By the way, the crystal blank for the crystal unit includes a flat plate blank and a deformed blank. The flat plate blank corresponds to a normal type (plate processing type) having the same cross section and the same thickness. The deformed blank corresponds to a deformed type (deformed processing type) having the same cross section and a different thickness by processing, for example, the above-described beveling processing or convex processing. In a normal type inspection, a light source for dark field observation is required to perform a flaw inspection and an external dimension inspection. In the inspection of the deformed type, in addition to the light source for dark-field observation, a light source for polarization observation is required in order to further inspect processing conditions such as thickness. The processing condition cannot be inspected with a dark-field observation light source. Conversely, the light source for polarized light observation cannot perform a flaw inspection or an external dimension inspection. Therefore, conventionally,
When inspecting a flat plate type using the same quartz substrate inspection apparatus and when inspecting a deformed type, the inspection light source must be replaced, and the operability is poor.

An object of the present invention is to solve the above-mentioned problems of the prior art and to inspect the shape of beveling / convex processing with high accuracy, and furthermore, to provide a light source for inspection and a transparent body having a simple structure. An object of the present invention is to provide an inspection apparatus and an inspection method thereof. It is another object of the present invention to provide a method of inspecting a transparent body that does not require replacement of an inspection light source even when inspecting a transparent body having different specifications.

[0019]

A feature of the present invention resides in a compound observation method, in which two observation methods of the dark field observation method and the polarization observation method are combined, and the same transparent body is observed simultaneously by the two observation methods. Polarization observation method If one observation method is used, it is possible to clearly confirm the interference fringes corresponding to the processed finish in the field of view, but it is necessary to go one step further and determine the position of the interference fringes on the transparent body. Whether the interference fringes are not eccentric or not inclined cannot be confirmed because the outline of the transparent body is dark.
The outline of the transparent body cannot be clearly seen in the polarized light observation method because it becomes the same color as the background color. Therefore, if the dark-field observation method in which the contour is visible is observed in combination with the polarization observation method, the position and relative shape of the interference fringes can be observed, and it can be seen whether the interference fringes are inclined. In addition, in the conventional microscope, this complex observation was mechanically complicated and difficult, but was easily performed because the optical system was designed at infinity.

According to a first aspect of the present invention, there is provided a transparent body inspection apparatus for irradiating a transparent body made of a birefringent medium having the same cross section with different thicknesses by processing with light to inspect the appearance of the transparent body. In the light source, a dark-field observation light source that irradiates light from substantially the entire circumferential direction of the side surface of the transparent body to enable acquisition of a contour image of the transparent body, and an interference fringe image according to the finish of the processing. A polarization observation light source that irradiates light diffused from below the transparent body to enable acquisition, and is provided between the dark field observation light source and the polarization observation light source,
A polarizer that irradiates the transparent body with only the diffused light emitted from the polarization observation light source as polarized light, and is scattered or diffracted by the light transparent body when irradiated with light from the dark field observation light source. Light, and for the birefringent light that has passed through the polarizer from the light source for polarization observation and passed through the transparent body, comprising a polarizer and a pair of analyzers that take out light in a polarization state at a predetermined angle, A transparent object inspection light source configured to be capable of simultaneously irradiating light from the dark field observation light source and the polarization observation light source to perform composite observation of a contour image of the transparent object and interference fringes.

According to the inspection light source of the present invention, on the other hand, the analyzer polarizes only the diffused light from the polarization observation light source,
Since the light from the dark-field observation light source is not polarized, scattering,
Even if the analyzer is present in the optical path of the diffracted light, it does not mean that the light is not shielded, and the light in the polarization state that forms a predetermined angle with respect to the scattered and diffracted light is extracted. Dark-field observation with emphasis becomes possible. On the other hand, the diffused light from the light source for polarization observation is polarized by the polarizer and given to the transparent body, and the light having passed through the transparent body is passed through the analyzer to pass light in a polarization state forming a predetermined angle with respect to the polarized light. In addition, the phase difference due to the difference in the thickness of the transparent body is visualized due to the polarization interference, and polarization observation in which interference fringes corresponding to the cross-sectional shape of the transparent body are formed on the transparent body surface becomes possible. In the present invention, since the dark-field illumination and the polarized illumination are performed at the same time, it is possible to perform a composite observation combining both of the above.

According to a second aspect of the present invention, there is provided an inspection light source in which the inspection light source according to the first aspect is unitized.

When the power supply for inspection is unitized as in the present invention, it is not necessary to assemble each time and can be attached and detached with one touch, so that maintenance is easy.

According to a third aspect of the present invention, there is provided the inspection light source according to the first or second aspect, a transparent mounting table on which the transparent body is mounted, and light emitted from the dark field observation light source. The light scattered or diffracted by the light transparent body placed on the mounting table and the birefringent light passing through the transparent body through the polarizer from the polarization observation light source form a predetermined angle. An analyzer that extracts light in a polarized state, and an imaging unit that captures an image of the transparent body of the light extracted from the analyzer and obtains a contour image of the transparent body and an interference fringe image according to the finish of the processing. An image processing apparatus configured to image-process the contour image and the interference fringe image of the transparent body obtained by the imaging unit and to inspect a relative position of the interference fringe image with respect to the contour image of the transparent body. It is a physical examination device.

According to the present invention, since the dark field light source and the polarization light source are simultaneously illuminated and observed by the imaging means, the interference fringes formed on the transparent body surface image with reference to the contour of the transparent body. Shape and symmetry can be inspected with high accuracy. In addition, the polarizer used in the polarization observation method polarizes only the diffused light emitted from the polarization observation light source, and does not polarize the light emitted from the dark field observation light source used in the dark field observation method. When the visual field observation method is performed alone, there is no hindrance to dark field observation even when the polarizer and the analyzer remain inserted in the optical path. Also, when shifting from the dark-field observation method to the polarization observation method, the light source for dark-field observation is kept turned on without being cut off, so that only the light source for polarization observation needs to be further inserted, and light source switching is unnecessary. . In addition, since the polarizer and analyzer are already attached to the optical path when observing with the dark field observation method, there is no need to insert a new polarizer and analyzer into the optical path during polarization observation. The structure of the device is simplified.

According to a fourth aspect of the present invention, there is provided the transparent body inspection apparatus according to the third aspect, wherein the mounting table is made of hard synthetic quartz glass.

The mounting table may be made of a transparent material, for example, sapphire harder than quartz. However, sapphire has birefringence depending on the angle of the cut crystal. It is necessary to control the angle. In this regard, it is preferable that the mounting table is made of hard synthetic quartz glass as in the present invention, since air bubbles hardly enter at the time of manufacture, and have no birefringence and are as hard as quartz, regardless of the cut-out angle of the crystal.

According to a fifth aspect of the present invention, there is provided a transparent body inspection method for inspecting the appearance of a transparent body made of a birefringent medium having the same cross section and different thickness by processing, wherein the transparent body has a dark field observation light source. And simultaneously irradiating the light from the light source for polarization observation, the contour image of the transparent body obtained by the light of the light source for dark field observation, and interference according to the finish of the processing obtained by the light of the light source for polarization observation Obtaining an image of the transparent body on which the fringe image is superimposed, from the contour image and the interference fringe image of the created transparent body image, to inspect the relative position of the interference fringe fringe with respect to the contour image. This is a transparent body inspection method.

According to the present invention, the illumination for dark-field observation and the illumination for polarization observation are performed simultaneously, so that the outline of the transparent body becomes clearer than in the case of only the illumination for polarization observation. Inspection of the shape of the contour of the interference fringe formed in the above, that is, the shape inspection of processing can be performed with high accuracy. In addition, since the appearance inspection by the dark field observation method can be performed while the polarizer and the analyzer are inserted in the optical path, the operation is easier than when the polarizer and the analyzer are extracted from the optical path.

According to a sixth aspect of the present invention, there is provided a transparent body inspection method for inspecting transparent bodies having different specifications by using the inspection light source according to claim 1 or 2 in common, wherein the transparent bodies having different specifications are provided. Is characterized by including a transparent flat plate made of a birefringent medium having the same cross section and the same thickness, and a deformed transparent body made of a birefringent medium having the same cross section and having a different thickness. Is the way. According to the present invention, since the flat transparent body and the deformed transparent body can be inspected using the same inspection light source, there is no need to replace the inspection light source even when inspecting transparent bodies having different specifications.

[0031]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a transparent body inspection apparatus that inspects a finished finish of a transparent body.

The transparent body inspection apparatus performs an appearance inspection of the transparent body based on an image signal of the crystal blank B obtained by irradiating a crystal blank B for a crystal unit, which is a birefringent medium, with light, for example. Here, the crystal blank B has a rectangular shape. The size is as small as about 1 mm square and several tens to 200 μm thick, and is beveled or convex processed. This inspection apparatus includes a mounting table 1 made of a transparent member on which a crystal blank B is mounted horizontally.
And two observation light sources 10 and 20 for irradiating the crystal blank B on the mounting table 1 with light, and imaging means 30 for imaging the surface of the crystal blank B from a direction perpendicular to the surface of the crystal blank B. Prepare. The imaging means 30 is a quartz blank B
And a CCD camera 32 that converts an observation image into an electric signal.

Crystal blank B imaged by imaging means 30
The surface image signal is applied to the image processing device 40. The image processing apparatus 40 converts the crystal blank B
The characteristic of a flaw such as a dent existing in the cradle is extracted, and the flaw or the like is inspected based on the extracted signal. Further, a characteristic of an interference fringe formed by transmitting the crystal blank B and birefringent from the captured image signal is extracted, and a beveling / convex processing shape is inspected based on the extracted signal.
The mounting table 1 described above is made of, for example, hard synthetic quartz glass which is harder than quartz and is hardly damaged. The two observation light sources 10 and 20 described above are composed of a dark-field observation light source 10 and a polarization observation light source 20.
0 is unitized and incorporated into one visual inspection device.

One dark-field observation light source 10 includes a plurality of L light sources.
EDs (not shown) are arranged in a ring shape, and are arranged coaxially with the center of the mounting table 1 so as to surround substantially the entire circumference of the mounting table 1, more precisely, the entire circumference of the crystal blank B. It is arranged in. As the LED, the wavelength 60 with the highest brightness
A red LED of the 0 nm class is preferred. In addition, blue LE
D may be used. The dark-field observation light source 10 has a two-stage configuration arranged vertically above and below the mounting table 1, and is arranged so that the mounting table 1 is located exactly in the middle between the upper and lower two stages. The upper portion 11 extends the surface of the crystal blank B on the mounting table 1 from a horizontal direction or from a shallow diagonally upper position by 0 to +
Irradiation is performed at an angle of 15 ° (arrow). The lower stage portion 12 penetrates the mounting table 1 from the horizontal direction or from a shallow diagonally lower position, and moves the back surface of the crystal blank B from 0 to −
Irradiation is performed at an angle of 15 ° (arrow). The light intensity of the dark-field observation light source 10 can be adjusted by controlling the power supply. As a result, of the light scattered or diffracted by the nick scar etc., only the light entering the microscope is observed to inspect the scratch.

The other light source 20 for polarization observation is constituted by a monochromatic light source having no polarization, is disposed below the light source 10 for dark field observation, and the illumination axis is aligned with the microscope axis 5. Light source 2 for polarized light observation
Numeral 0 denotes a configuration in which a plurality of LEDs (not shown) are arranged in a dot, plane or hemisphere, and a red LED or a blue LED
To make the light source wavelength the same as that of the dark-field observation light source 10 (600 nm) or shorter (455 to 492).
nm) and dimming is possible.

The polarization observation light source 20 is provided with the diffusion plate 2,
The light source system is configured by adding the polarizer 3. When an analyzer 4 that is paired with the polarizer 3 is added to this light source system, a polarization observation optical system including the light source is completed. The diffusion plate 2 is a light source 2 for polarization observation.
The crystal blank B is uniformly irradiated from the back surface by diffusing light from 0. The polarizer 3 polarizes only light that has passed through the diffusion plate 2. The polarizer 3 is provided with a light source for dark-field observation and a light source for polarization observation so that the polarizer 3 polarizes only the light that has passed through the diffusion plate 2 and does not polarize the light emitted from the dark-field observation light source 10. It is provided between the light source 20 and the optical path of the light source 20 for polarization observation.

The analyzer 4 irradiates the light from the dark-field observation light source 10 and scatters or diffracts the light with a transparent body, and the polarization observation light source 20 passes through the diffusion plate 2 and the polarizer 3 to form a quartz blank B. With respect to the birefringent light that has passed through, light having a predetermined angle is passed. The birefringent light that has passed through the analyzer 4 causes polarization interference, and the phase difference due to the difference in thickness can be visualized with bright and dark contrast due to the polarization interference.

The imaging means 30 captures a contrast image of the scattered, diffracted light, and polarized light of the crystal blank L that has passed through the analyzer 4, and transfers the contrast image to the image processing device 40.
This is contrast-enhanced, and the relative position of the interference fringe with respect to the outline of the crystal blank B is inspected to inspect the state of beveling and convex processing.

When inspecting the finish of processing,
The light amounts of the light sources 10 and 20 and the rotation angles of the polarizer 3, the analyzer 4, and the mounting table 1 are adjusted with each other in advance so that these light amounts and angles are adjusted so that interference fringes appearing on the image are optimal for the processing finish inspection. Perform calibration to adjust. In order to inspect the finishing of the entire blank surface, a threshold value is determined and a binarized image is obtained. The processed state can be quantitatively grasped from the image. Here, the finished processing state is the inner major axis, inner minor axis dimensions of the ring-shaped dark part,
It can be grasped by measuring the center deviation and the like.
The contents to be grasped include deviation of the polishing amount in the peripheral part of the crystal blank (difference in the band width of the ring-shaped dark part), curvature of the convex or cross-sectional shape (number of interference fringes), excessive shaving or insufficient shaving (interference fringe width) ), Eccentricity of polishing (center shift), and the like.

The above-described light source for polarization observation 20, the light source for dark field observation 10, the diffusion plate 2, and the polarizer 3 are collectively 1
The light source unit U is configured so that maintenance of the device can be performed in units of the light source unit U. This light source unit U
In the above, not only the diffusion plate 2 but also the polarizer 3
It is placed outside the illumination axis of the dark-field observation light source 10 (corresponding to a substantially arrow). This is to prevent dark field illumination light from being polarized. If the dark field illumination light is not polarized by polarizer 3,
Passing through the analyzer 4 only dims the light and does not affect the flaw inspection. The amount of dimming may be compensated by dimming the dark-field observation light source 10 to increase the power.

Further, if necessary, a condenser lens for condensing light on the crystal blank B may be provided between the diffusion plate 2 and the polarizer 3, or a compensator for clearly raising the crystal blank image from the background may be detected. Photon 4 and mounting table 1
May be inserted between them.

Next, the operation of the above configuration will be described. The inspection target is, for example, a size of 1 mm square and a thickness of 1
It is a rectangular quartz blank that is beveled or convexed on the order of 0 to 200 μm. The surface finish is at any stage of lapping, polishing, or chemical etching.

In the actual inspection, first, the dark-field observation light source 1
When 0 is turned on, the size measurement and the flaw inspection are inspected by the dark field observation method. At this time, the polarizer 3 and the analyzer 4 are connected to the microscope axis 5.
It may be left inserted above. The dimension measurement of the rectangular crystal blank includes vertical and horizontal dimensions, oblique diagonal distance, Taure dimension, and parallelism of long and short sides. Scratches include scratches, chips, cracks, cracks, chippings,
There are spots, twins, seeds, and foreign substances.

Next, beveling processing by a polarization observation method,
In addition, shape inspection of convex processing is performed. At this time,
The polarization observation light source 20 is simultaneously turned on without turning off the dark field observation light source 10. Polarization observation contents,
The absolute shape of the interference fringe obtained by the polarization observation method alone and the relative shape of the interference fringe image obtained by the composite observation.

When the light from the polarization observation light source 20 is irradiated, the light from the polarization observation light source 20 is transmitted light, and the effect of the flaw inspection by the dark field observation light source 10 utilizing scattering or diffraction is reduced. . However, in this inspection, since the outline of the crystal blank B, which cannot be obtained by the polarization observation light source 20 alone, is to be imaged by irradiation of the dark field observation light source 10, even the outline is clearly shown in the image. If so, other reductions are fine. That is, since the flaw inspection is performed only by the preceding dark field observation, the flaw of the crystal blank B does not have to be visible in this combined observation.

The composite observation will be described with reference to the captured image of the crystal blank surface shown in FIG. (A) and (b) are reference diagrams, and (c) is a composite observation image. (A) is a surface image of the quartz crystal blank B when only the light from the dark-field observation light source 10 is irradiated. The contour and the surface condition at the lapping stage can be effectively observed. (B) is a light source 2 for polarization observation.
It is a surface image when only the light from 0 is irradiated. A black belt-like substantially elliptical interference fringe indicating the beveling / convex processing state appears in the periphery. The four corners glow, but the other outlines are hidden by the background and unclear. (C)
Is a composite observation image when the dark field illumination light and the polarized illumination light are simultaneously irradiated. Both the outline and the interference fringe are clearly projected.

In the image shown in FIG. 2C, since a bright border is formed on the quartz crystal blank B, the outline data of the border and the interference fringe data obtained by the polarization observation are simultaneously obtained by the composite observation. These data are transferred to the image processing device 4
By processing at 0, it is possible to observe the relative position, eccentricity, inclination, etc. of the interference fringes based on the contour dimensions. That is,
As shown in FIG. 3, in the beveling process (a) and the convex process (b), the displacement (eccentricity) or symmetry of the interference fringes with respect to the center (intersection of diagonal lines) of the rectangular quartz crystal blank, and the interference fringes Can be inspected for inclination or eccentricity. These are inspection items that are possible only when the outline is known.

As described above, according to the embodiment, at the time of observation of polarized light, dark field illumination, which has not been conventionally performed, is added to perform composite observation of the polarization observation method and the dark field observation method. The accuracy of the contour inspection, which was not accurate during the polarization observation, is improved, and the relative position of the interference fringe with respect to the contour can be observed with high precision. As a result, the relative shape of beveling or convex processing can be inspected with high accuracy. This cannot be done only by the polarization observation method alone, nor by the dark field observation method alone. This is only possible with compound observation that combines both observation methods. Then, by combining the two observation results organically, an excellent effect is obtained that the relative position of the interference fringe, which cannot be predicted from the known polarization observation method and the known dark field observation method, can be inspected.

In particular, the quartz blank is a “salt of the IC industry”
With the dramatic progress of information communication such as mobile phones, PCs, DVDs, game consoles, digital TVs, GPSs, and electronic transportation systems, more and more miniaturization and high precision are required, and stable frequency (vibration) characteristics Is required. In order to meet this demand, it is ideal that the shape of the interference fringes corresponding to the state of beveling and convex processing is symmetric and symmetric, and it is necessary to inspect this. The present invention can perform an inspection that can sufficiently meet this demand.

In the embodiment, the mounting table 1 on which the crystal blank B is mounted is made of hard synthetic quartz glass. This is because the mounting table 1 is preferably made of hard glass without birefringence, and more preferably hard synthetic quartz glass. Pyrex (trademark), Tempax (trademark)
Is likely to contain air bubbles at the time of production and cannot be supplied stably. Sapphire is hard, but is accompanied by birefringence. With birefringence, the phase shifts, and an error occurs. Glass is preferred in this regard. Hard synthetic quartz glass does not have such difficulties and can be produced with good reproducibility.

Further, the combined observation of the polarization observation method and the dark field observation method has made it possible to accurately inspect the shape of the beveling or convex processing. However, if the dark field observation method is used together, the polarization observation can be performed. If the accuracy of the single test by the method decreases, as shown in FIG.
The single observation by the polarization observation method P2 may be added after the single observation by the dark field observation method P1 and the composite observation by the dark field observation method P1 and the polarization observation method P2.

Further, in the inspection of a flat plate blank, a light source for dark field observation is required to perform a flaw inspection and an outer dimension inspection. In the beveling and convex type inspection, in addition to the light source for dark field observation, Further, as described above, a light source for polarization observation is required to perform a processing condition inspection using interference fringes or the like. In this regard, the light source according to the present embodiment is configured so as to enable a composite observation of dark field observation and polarization observation. Therefore, it is not necessary to replace the inspection light source when inspecting the flat plate type or the irregular type inspection using the same quartz substrate inspection apparatus, so that the convenience of the apparatus is dramatically improved. improves.

Although the embodiment has been described with reference to a rectangular crystal blank, the present invention can be applied to other shapes, for example, a circular crystal blank as shown in FIG. For quartz blank applications, besides quartz oscillators, SAW
(Surface acoustic wave) There is a crystal filter called a device.

[0054]

According to the present invention, since the dark-field illumination light and the polarized illumination light are simultaneously radiated to the transparent body, the outline of the transparent body which could not be clarified by the polarized illumination light alone can be clarified. As a result, the shapes of the beveling process and the convex process based on the contour can be inspected with high accuracy.

Further, according to the present invention, the flat transparent body and the deformed transparent body can be inspected by using the same inspection light source. Therefore, even when inspecting a transparent body having a different specification, the inspection light source can be replaced. There is no need to do so, and convenience is improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a transparent object inspection apparatus according to an embodiment.

FIGS. 2A and 2B show observation images of the quartz crystal blank surface according to the embodiment, wherein FIG. 2A shows a case of single irradiation from a dark-field observation light source, and FIG.
(C) shows the case where the light source for dark-field observation and the light source for polarization observation are simultaneously irradiated.

FIG. 3 is an explanatory diagram showing a processing state for a contour according to the embodiment;

FIG. 4 is an explanatory diagram of light source irradiation timing according to the embodiment.

FIG. 5 is a diagram illustrating an application to a circular quartz crystal blank according to an embodiment.

FIG. 6 is a general manufacturing process diagram of a quartz oscillator.

FIGS. 7A and 7B are explanatory views showing a processing state of a quartz crystal blank, wherein FIG. 7A shows beveling processing and FIG. 7B shows convex processing, respectively.

FIG. 8 is an explanatory diagram showing an observation image of the surface of a quartz crystal blank that is independently irradiated by a dark-field observation light source according to a conventional example.

FIG. 9 is an explanatory view showing an observation image of the surface of a quartz crystal blank that is solely irradiated by a polarization observation light source according to a conventional example.

FIG. 10 is an explanatory diagram of a parallelism h, which is a thickness dimensional difference in the plane of a quartz crystal blank.

[Explanation of symbols]

 2 Diffusion plate 3 Polarizer 4 Analyzer 5 Microscope axis 10 Light source for dark field observation 20 Light source for polarization observation B Crystal blank (transparent body) U Light source unit

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yoshio Kawabe 1-10-15 Takadanobaba, Shinjuku-ku, Tokyo F-term in Maxis Japan (reference) 2F065 AA49 AA52 BB22 CC00 FF04 FF51 GG07 GG13 GG15 GG21 GG22 HH02 HH08 HH12 HH16 JJ03 JJ26 LL33 LL34 LL49 NN02 PP11 PP24 QQ31 2G051 AA73 AB02 BA01 BA04 BA11 BB07 CA04 CB02 CB05 EA12 EA16 FA01

Claims (6)

[Claims] 1. A transparent body inspection light source for irradiating a transparent body made of a birefringent medium having a different thickness with the same cross section by processing to inspect the appearance of the transparent body, wherein: A dark-field observation light source that irradiates light from substantially the entire circumferential direction of the side surface of the transparent body to enable acquisition of a contour image of the transparent body, and an interference fringe image corresponding to a finish of the processing is enabled. A light source for polarization observation that irradiates light diffused from below the transparent body, provided between the light source for dark field observation and the light source for polarization observation, and only diffused light emitted from the light source for polarization observation. A polarizer that irradiates the transparent body with polarized light, wherein the light is irradiated from the dark field observation light source and scattered or diffracted by the light transparent body, and the polarizer from the polarization observation light source. To the birefringent light that has passed through the transparent body The light source for dark field observation and the light source for polarization observation are simultaneously irradiated with light from the light source for dark field observation and the light source for polarization observation. A transparent object inspection light source configured to enable complex observation of a contour image and interference fringes. 2. The transparent object inspection light source according to claim 1, which is unitized. 3. The inspection light source according to claim 1 or 2, a transparent mounting table on which the transparent body is mounted, and a light that is irradiated from the dark field observation light source and is mounted on the mounting table. Light scattered or diffracted by the light transparent body,
And for the birefringent light that has passed through the transparent body through the polarizer from the polarization observation light source, an analyzer that extracts light in a polarization state that forms a predetermined angle, and the light that is extracted from the analyzer. An imaging unit that captures an image of a transparent body and obtains a contour image of the transparent body and an interference fringe image according to a finish of the processing; and image processing the contour image and the interference fringe image of the transparent body obtained by the imaging unit. And an image processing device configured to inspect the relative position of the interference fringe image with respect to the contour image of the transparent body. 4. The transparent body inspection apparatus according to claim 3, wherein the mounting table is made of hard synthetic quartz glass. 5. A transparent body inspection method for inspecting the appearance of a transparent body made of a birefringent medium having the same cross section and different thickness by processing, wherein the transparent body is provided with a light from a dark field observation light source and a polarized light observation light source. Simultaneously, the contour image of the transparent body obtained by the light of the dark field observation light source, and the interference fringe image according to the finish of the processing obtained by the light of the polarization observation light source overlapped. A transparent body inspection method, wherein an image of a transparent body is obtained, and a relative position of the interference fringe image with respect to the outline image is inspected from the outline image and the interference fringe image of the created transparent body image. 6. A transparent body inspection method for inspecting transparent bodies having different specifications by using the inspection light source according to claim 1 or 2 in common, wherein the transparent bodies having different specifications have the same cross section in the same section. A method for inspecting a transparent body, comprising: a flat transparent body made of a birefringent medium having a thickness; and a deformed transparent body made of a birefringent medium having the same cross section and different thicknesses.