WO2004005902A1

WO2004005902A1 - Optical measuring method and device therefor

Info

Publication number: WO2004005902A1
Application number: PCT/JP2003/008675
Authority: WO
Inventors: Junichi Matsumura; Mutsumi Hayashi
Original assignee: Toray Engineering Co., Ltd.
Priority date: 2002-07-08
Filing date: 2003-07-08
Publication date: 2004-01-15
Also published as: CN100570342C; JP2004037400A; KR100876257B1; KR20050035243A; CN1666100A; JP4104924B2; TW200409912A; TWI320099B

Abstract

An optical measuring device comprising a front surface measurement data holding section (7) for creating and holding two-dimensional optical measurement data corresponding to the front surface of a transparent measurement object (1) by applying a line beam to the surface of the object (1) at a predetermined angle, receiving the front surface light and back surface light generated at the front and back surfaces of the object (1) by means of a front surface light sensor (5) and a back surface light sensor (6), respectively, and receiving the output signal from the front surface light sensor (5) and operation information on a support mechanism, a back surface measurement data holding section (8) for creating and holding two-dimensional optical measurement data corresponding to the back surface of the object (1) by receiving the output signal from the back surface light sensor (6) and operation information on the support mechanism, and a front/back data creating/holding section (9) for creating and holding front surface data and back surface data on the object (1) by receiving both the front surface two-dimensional optical measurement data and the back surface two-dimensional optical measurement data and conducting front/back judgment. Without increasing the time required for scanning, the accuracy of detection of a foreign matter on the surface to be detected is enhanced, and the state of the back surface as well as that of the front surface can be detected.

Description

Description Optical measuring method and its device

The present invention relates to an optical measurement method and an apparatus for measuring the state of the front and back surfaces of a transparent measurement object using laser light. Background art

2. Description of the Related Art Conventionally, there has been proposed an optical measurement device for inspecting foreign substances attached to a thin substrate surface such as a glass substrate for a liquid crystal display device and a substrate with a transparent film for a flat panel display device. For example, the foreign substance inspection device disclosed by the inventors described in the separate volume of the Monthly Display in February 2001 issued a clever use of the device configuration that combines the imaging detection method and the sensor. As a result, it is possible to accurately detect foreign matter attached to the front surface without detecting foreign matter attached to the back surface.

Scattered light from foreign matter adhering to the back surface of the glass substrate is imaged far ahead of the line sensor via the imaging optics, and slightly off the position where the line sensor waits. It is composed of For this reason, foreign matter adhering to the back surface is hardly detected. In this method, a mechanism utilizing the basic properties of the optical system is employed, so that the inspection can be performed with high reliability and stability.

Alternatively, the optical measuring device described in Japanese Patent No. 26711241 irradiates a glass plate with a laser beam at a first incident angle. A first laser light source for making the laser light incident on the glass plate at a second incidence and angle, and a condensing optical system for condensing light originating from each laser light. The light receiving element receives the condensed light, and performs a predetermined process based on a signal from the light receiving element to detect a foreign substance on the inspection surface of the glass plate.

Therefore, for example, it is considered that foreign matter adhering to the front surface can be detected with high accuracy by eliminating the influence of foreign matter adhering to the back surface of the glass plate.

In the foreign object inspection device described in the separate volume of the Monthly Display for February 2001, the scattered light is slightly applied when the size of the foreign matter attached to the back surface exceeds the size due to the characteristics of the optical system. Entering into the sensor .. Foreign matter adhering to the back side is detected and mixed together.

For example, one for LCD. Attempting to detect foreign matter with a size of Ιμιη or more on the front surface of a 1mm glass substrate will simultaneously detect foreign matter with a size of 20μπι or more on the back surface. Since practically no dust of about 20 μm is present in the ordinary LCD process, the practical problem is not so large. However, it is desirable not to completely detect foreign matter adhering to the back surface.

Naturally, this method could not detect foreign substances adhering to the back surface, only to remove foreign substances adhering to the back surface.

In the optical measuring device described in Japanese Patent No. 26711241, the irradiation of laser light by the first laser light source and the irradiation of laser light by the second laser light source are independent of each other. The scanning time is doubled. In addition, since the light condensed by the condensing optical system is guided to the light receiving element, the influence of the saturation of the light receiving element makes it impossible to distinguish between the foreign matter on the front and the foreign matter on the back. Limits inevitably exist, and even with this method, foreign substances adhering to the back surface of a certain size or more are mixedly detected.

Furthermore, since only foreign substances adhering to the lower surface of the glass plate are detected, foreign substances adhering to the rear surface of the glass plate cannot be detected. Specifically, the state of the front surface of the glass plate could be detected as much as possible, and the state of the back surface could not be detected.

The present invention has been made in view of the above-described problems, and is transparent without increasing the scanning time, and can improve the measurement accuracy of the measurement target surface of the body. It is an object of the present invention to provide an optical measuring method and an apparatus capable of measuring the state of the backside as well. Summary of the Invention

The optical measurement method according to the present invention includes irradiating the surface of the transparent measurement object supported by the support member with a linear laser beam at a predetermined angle from obliquely above, so that the light from the surface of the transparent measurement object and The light from the back side is imaged on the light-receiving part of the detector, which has a corresponding linear light-receiving part by the imaging optics, and performs predetermined processing based on the signals output from both detectors. This method selectively assigns one of the signal corresponding to the front surface and the symbol corresponding to the back surface, and displays the allocation signal corresponding to the front surface and the assignment signal corresponding to the back surface.

Therefore, when the optical measurement method of the present invention is adopted, scanning using laser light only needs to be performed once. Without increasing the time required for scanning, the light from the front and back surfaces of the transparent object to be measured is imaged by the imaging optical system onto the light-receiving part of the corresponding detector, and the measurement object surface is measured. The measurement accuracy can be increased, and the condition of not only the front surface but also the back surface can be measured.

'' The optical measuring device of the present invention irradiates a linear member at a predetermined angle from obliquely above the surface of the transparent measuring object supported by the supporting member and the transparent measuring object supported by the supporting member. Laser light irradiation means, imaging optical system for imaging light from the front surface and light from the back surface of the transparent measurement object, and arranged corresponding to the imaging position of each light by the imaging optical system , A pair of light receiving means having a linear light receiving portion, and performing predetermined processing based on signals output from both light receiving means to selectively generate one of a signal corresponding to the front surface and a signal corresponding to the back surface. It includes a processing means for allocating, and a display means for displaying an allocation signal corresponding to the front side and an allocation signal corresponding to the back side. Therefore, when the optical measuring device of the present invention is adopted, the transparent measurement can be performed without increasing the scanning time due to the fact that scanning with laser light only needs to be performed once. Pairing the light from the front and back surfaces of the object with the imaging optical system to form an image on the light-receiving part of the corresponding detector can improve the measurement accuracy of the surface to be measured. It is possible to measure not only the front surface but also the rear surface condition r. '' Brief description of the drawings

FIG. 1 is a schematic diagram showing an embodiment of the optical measuring device of the present invention. FIG. 2 is a view showing a result of inspecting a scattered surface of a glass plate on which sphere particles are intentionally scattered, and outputting the scattered particles as surface-attached foreign matter. 'FIG. 3 is a diagram showing the result of inspecting the glass substrate of FIG. 2 on which the true spherical particles are intentionally scattered by turning the glass substrate upside down and turning over the glass substrate, and outputting the result as foreign matter adhering to the back surface. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of an optical measurement method and an optical measurement apparatus according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic view showing a foreign matter and an inspection device as one embodiment of the optical measurement device of the present invention.

This optical measuring device is composed of a transparent measuring object supported by a support mechanism (not shown) (for example, a thin substrate such as a glass substrate for a liquid crystal display device or a substrate with a transparent film for a flat panel display device). 'A laser light source 2 that irradiates a line beam at a predetermined angle of incidence on the surface of 1, and surface scattered light and back surface scatter generated from the front and back surfaces of the transparent measurement object 1 due to the irradiated line beam An imaging optical system 3 for imaging light, a half mirror 4 provided at a predetermined position upstream of the imaging position, and a light receiving surface located at an imaging position of surface light transmitted through the half mirror 4. Surface light sensor 5, a back light sensor 6 arranged so that the light receiving surface is located at an image forming position of the back light reflected by the half mirror 4, and a surface light sensor Exit from 5 Signal ^Contact:. Yobi支transparent measured as input operation information of the lifting mechanism, the surface measurement data holding unit 7 for holding and generates a two-dimensional optical measurement data corresponding to the surface of the object 1, back -The output signal from the surface light sensor 6 and the operation information of the support The backside measurement data holding unit 8 that holds and stores two-dimensional optical measurement and constant data corresponding to the backside of the object 1, and the optical measurement data held in the frontside measurement data holding unit 7. The front and back judgment processing is performed by inputting the optical measurement data held in the backside measurement data holding section 8 and the front side data corresponding to only the front side of the transparent measurement target 1 and the back side corresponding to only the back side It has a front and back data generation and holding unit 9 that generates and holds data, and a display unit 10 that displays only based on the front surface data and a display unit that displays based only on the back surface data. An encoder that outputs a signal indicating the position of the transparent measurement target 1, and 12 is a control signal and a control signal from a stage operation control unit (included in the measurement data holding unit 7 for the surface in this embodiment). The signal from the Zen coder 1 1 is input. A stage con preparative roller for outputting an operation command with respect to the support mechanism.

The laser light source 2 irradiates the surface of the transparent measurement object 1 with a line beam at an incident angle of 45 ° or more and less than 90 °, preferably an incident angle of 0 °. The laser light emitted from the laser light source 2 is preferably S-polarized light and has a wavelength of 400 to 120011 m, and preferably 800 nm. Further, the width of the line beam is preferably set to be equal to the width of the visual field of the front light sensor 5 and the back light sensor 6.

* The imaging optical system 3 only needs to have a depth of focus smaller than the thickness of the transparent measurement target 1, and preferably has a depth of focus of 12 or less of the thickness of the transparent measurement target 1. In addition, it is preferable that the swell of the transparent measuring object 1 is set to a depth of focus or less.

The positions of the front-surface light sensor 5 and the back-surface light sensor 6 depend on the refractive index, thickness, incident angle of laser light, wavelength, etc. of the transparent measuring object 1. In consideration of the position offset value (deviation amount) determined by this method, the position is set to the same position as the position where the front and back surfaces of the transparent and bright measurement object 1 are imaged.

The front-side measurement data holding unit 7 and the back-side measurement data holding unit 8 receive signals from the front-side light sensor 5 and the back-side light sensor 6 and the movement data of the transparent measurement target 1 as inputs and correspond to the signals. In this case, two-dimensional optical measurement data corresponding to the front surface and the back surface of the transparent measurement target 1 are generated and held in consideration of the offset value.

The front / back data generation / holding unit 9 is an optical measurement corresponding to the same position among the two-dimensional optical measurement data held in the front side measurement 'data holding unit 7 and the back side measurement data holding unit 8. It is determined which optical measurement data to use based on the relationship between the data, and based on this determination result, only the front surface data corresponding to the front surface of the transparent measurement target 1 and the back surface only are supported. It generates and holds backside data. Specifically, in the case of a foreign matter inspection device, the optical measurement data held in the front-side measurement data holding unit 7 corresponding to the same position is A, and the optical measurement data held in the back-side measurement data holding unit 8 If the experimental measurement data is B, the output signals of A and B to be handled are both unknown at this time, but become the scattered light intensity signal from the foreign matter attached to either the front surface or the back surface. Since the intensity of the scattered light increases as the size increases, since the imaging optical system and the linear light receiving unit, that is, the line sensor, are used, if this output signal is used as the total luminance signal of the image of the foreign matter, However, the increase in the output signal with the increase in the size of the foreign substance is quite steep at first (not only due to the change in the image size but also to the change in the luminance). With the increase Degree is saturated, change of brightness After the influence of the image has almost disappeared, the output signal gradually increases under the influence of the large image. Therefore, an output signal suitable for the size of the foreign object can be obtained without causing saturation of the output signal.

Furthermore, since the signals of A and B are compared and the shape of the light receiving unit, that is, the line sensor, is used, if A> kB, the surface data corresponding to only the surface of the transparent measurement target 1 if A> kB That is, the data is the data of the foreign matter attached to the front surface, and conversely, if A≤kB, the data is the back surface data corresponding to only the back surface of the transparent measurement target 1, that is, the data of the foreign material attached to the back surface. Here, k is a value determined from the intensity ratio between the light from the front surface and the light from the back surface of the transparent measurement object 1, the optical imaging characteristics of the imaging optical system, the depth of focus, and the like. For example, when S-polarized light is used as the laser beam and the incident angle is set to 80 °, the light intensity from the back surface is about 1/1 of the light intensity from the front surface. When this is taken into account with the optical characteristics, k becomes larger than about 2.

Furthermore, by using this determination formula properly before and after the increase in the output signal becomes more gradual, a more accurate determination can be performed. That is, at this time, the decision formula becomes a more complicated nonlinear decision formula.

The operation of the optical measuring device having the above configuration is as follows.

When a line beam is irradiated from the laser light source 2 to the surface of the transparent measuring object 1 at a predetermined incident angle, the line beam refracts based on Snell's law and penetrates into the transparent measuring object 1. It is emitted from the back side. Therefore, the irradiation position of the line beam on the front side of the transparent measurement target 1 and the emission position from the back side are different from each other with reference to the optical axis of the imaging optical system 3, and ideally, the transparent measurement target. Object 1 The sensor placed at the image formation position of light (scattered light, etc.) from the irradiation position on the front surface is insensitive to light (scattered light, etc.) from the emission position on the back surface of the transparent measurement target 1 (this The light is received by a sensor arranged at the position where the light is focused on the rear surface of the transparent measurement target 1 from the irradiation position). In addition, since the line beam is not irradiated on the back surface directly opposite to the irradiation position on the surface of the transparent measurement object Γ, this portion does not affect the sensor.

However, in practice, due to the nature of the laser light, even a small amount of light is radiated to the front surface of the transparent measurement object 1 and the back surface opposite to the irradiation position, which may affect the sensor. However, this may cause an optical measurement error.

In this embodiment, such a situation is taken into account, and by performing the following processing, optical measurement errors can be significantly suppressed. .

This will be explained further.

When the transparent measurement object 1 is scanned by the line beam from the laser light source 2, light from the line beam incident position of the transparent measurement object 1 is transmitted to the surface by the imaging optical system 3 and through the half mirror 4. An image is formed on the light receiving surface of the optical sensor 5. In addition, although the amount of light is greatly reduced, light from the back surface facing the line beam incident position is received by the imaging optical system 3 and through the half mirror 4, but the depth of focus is transparent. Since it is smaller than the thickness of 1, it becomes out of focus.

Further, the line beam is guided to the back surface of the transparent measurement object 1 according to Snell's law and is emitted as it is. Therefore, the back side position directly opposite the line beam incident position and the line beam The position of the back surface to be cut differs from each other. As a result, light from the rear surface position where the light beam is guided is reflected by the imaging optical system 3 and by the half mirror 14 to form an image on the light receiving surface of the rear light sensor 6. .

Now, when the content of the measurement is a foreign substance inspection, in these cases, if there is no foreign substance at the place affected by the line beam, the intensity of scattered light is extremely low. The optical sensor 6 outputs a signal indicating that no foreign matter is present.

Conversely, if there is a foreign substance in the place affected by the line beam, the intensity of scattered light etc. will increase, so the presence of the foreign substance from the front light sensor 5 and the backside light sensor 6 Signals indicating and are output.

Here, the output signals of the front-surface light sensor 5 and the back-surface light sensor 6 increase as the size of the foreign matter increases. And the increase in the output signal 'is quite steep at first (the effect of the change in brightness is greater than the effect of the change in image size). In addition, after the influence of the change in luminance is almost eliminated, the output signal gradually increases under the influence of the change in the image size. Therefore, an output signal suitable for the size of the foreign object can be obtained without causing saturation of the output signal. As a result, the presence of foreign matter and its size determination can be made favorable.

The signals from the front light sensor 5 and the back light sensor 6 and the movement data of the transparent measuring object 1 are input and, if applicable, the position offset value is taken into account. The measurement data holding unit 7 for the front surface and the measurement data holding unit for the back surface ^{: The} unit 8 generates two-dimensional optical measurement data respectively corresponding to the front surface and the back surface of the transparent measurement target 1. Hold. Therefore, the front surface measurement data holding unit 7 and the back surface / surface measurement data holding unit 8 hold the front surface measurement data and the back surface measurement data corresponding to the same position.

After that, the front and back data generation and holding unit 9 compares the measurement data for the front surface and the measurement data for the back surface corresponding to the same position stored in the measurement data holding unit for front surface 7 and the measurement data holding unit 8 for back surface. Then, which optical measurement data is to be adopted is determined, and based on this determination result, front surface data corresponding only to the front surface of the transparent measurement target 1 and back surface data corresponding only to the back surface are generated. Hold.

Then, the display unit 10 can perform a display based on only the front surface data and a display based on only the back surface data.

In the case of a foreign matter inspection device, the presence / absence, position, and size of foreign matter adhering to the surface are obtained from the surface data

Thus, the presence / absence, position, and size of the foreign matter adhering to the back surface can be obtained from the back surface data.

Therefore, based on these displays, it is possible to easily and accurately grasp not only the surface of the transparent measurement target 1 but also the presence or absence of foreign matter attached to the back surface, the density of the foreign matter, and the like. Further, for example, by performing the above-described series of processing before and after cleaning the transparent measurement target 1, the effect of the cleaning can be confirmed.

In addition, only one scan by the laser light source 2 can be used to obtain front surface data corresponding to only the front surface of the transparent measurement target 1 and back surface data corresponding only to the back surface, thereby reducing the required time. You can.

Next, another embodiment of the optical measurement method of the present invention will be described. In addition, this method was applied to the inspection of foreign substances on the transparent glass substrate, Inspection results obtained by the front, back and back inspection cameras with the focus on the front and back of the substrate, respectively, and the front and back inspection cameras Are represented by C and D, respectively.

First, the necessity of the front / back separation processing is set. Specifically, for example, when the inspection target is a transparent glass substrate, the front and back separation processing is necessary, and when the inspection target is an opaque substrate, the front and back separation processing is unnecessary. In the latter case, only the inspection result by the table inspection camera is significant, so that the same processing as in the past can be performed (detailed description is omitted).

If it is determined that front and back separation processing is necessary, save the inspection and inspection results C and .D and make them aware that they are related. Specifically, for example, a flag indicating that there is relevance is set.

Then, the offset amount of inspection results C and D is corrected. As a correction amount for performing this correction, it is possible to prepare in advance so that a predetermined value can be set, and the offset deviation is corrected using the predetermined value. Since this correction process is conventionally known, a detailed description will be omitted.

Next, an example of a calculation process based on both inspection results C and D will be described. First, a foreign substance existing at the same coordinates is recognized based on the position coordinates of the detection results C and D in which the offset deviation has been corrected. Here, tolerance parameters (0.01 to 5: 00 mm) are set for the same coordinate determination, and foreign objects within this distance are identified. If there are a plurality of foreign substances within this distance, only the closer one is identified.

In the two detection results C and D thus identified, the foreign substance information group of C is represented by C & D, and the foreign substance information group of D is represented by D & C. Also, C-D from which C & D is removed is denoted by C-D, and D-C from which .D is removed is denoted by D-C.

In this case, foreign substances can be detected as shown in Table 1.

table 1

For C & D and D & C, which are unknown in Table 1, the magnitudes of the detected values are compared for each identified foreign substance. However, instead of searching for the detected value of C as it is, a value multiplied by a predetermined coefficient k is adopted. Here, the coefficient k is a value in the range of 0.:! To 10.0, and is preferably set based on, for example, an actual measurement result. Further, for simplicity of operation, the default value of the coefficient k (e.g., 2.0) preferred to have set arbitrary ₀

In this case, foreign substances can be detected as shown in Table 2.

Table 2

C & D k C> D 〇

C & D k C≤ D-x (c surface = waste)

D & C D≤ k C 〇

D &CD> k CX (D surface-waste) Therefore, the judgment of front and back is as follows.

Table = (C-D). + {(C & D) & (k C> D)}

Ura ni (D-C) + {(D & C) & (D k C)}

In addition, the data on the back surface found by the front inspection camera is (C & D) & (k C ≤ D),

The surface data found by the back inspection camera is (D & C) & (D> k C)

These are not adopted as the foreign substance detection results and are discarded. The results of the above processing and foreign substance detection are shown in FIGS. 2 and 3. .

FIG. 2 is a diagram showing a result of inspecting a scattered surface of a glass substrate on which sphere particles are intentionally scattered, and outputting the scattered particles as surface-attached foreign matter. In FIG. 2, the left side is the foreign matter map, the periphery is the entire surface of the glass substrate, the white square area is the inspection area, and the gray partial force S is the non-inspection area. And the small dots indicate the presence of foreign matter.

Also, the histogram (frequency distribution) is shown on the upper right side in FIG. 2, where the horizontal axis represents the size of the foreign substance and the vertical axis represents the number of foreign substances of that size. _{C From} this histogram, It can be seen that the surface of the glass substrate has many foreign substances with a size almost in the middle of the horizontal axis. These foreign particles are dispersed particles.

In addition, the lower right in FIG. 2 shows the number of foreign substances and the total number of foreign substances for each of the S, M, and L size classifications. As can be seen from these, about 10,000 foreign substances were detected.

Fig. 3 shows the glass substrate of Fig. 2 that is intentionally scattered as spherical particles. It is a figure showing the result of having done.

In FIG. 3, the left side is the foreign matter map, the periphery represents the entire surface of the glass substrate, the white square region represents the inspection region, and the gray peripheral portion represents the non-inspection region. And the small dots indicate the presence of foreign matter. This map is similar to the map in Fig. 2 turned upside down.

The histogram (frequency distribution) is shown on the upper right side in FIG. 3, where the horizontal axis represents the size of foreign substances and the vertical axis represents the number of foreign substances of that size. From this histogram, it can be seen that many foreign substances having a size almost in the middle of the horizontal axis are present on the surface of the glass substrate. .. These foreign particles are dispersed particles.

In addition, the lower right in FIG. 3 shows the number of foreign particles and the total number of foreign particles for each of the S, M, and L size classifications. As can be seen from these, about 10,000 foreign substances were detected.

As can be seen from FIG. 2 and FIG. 3, the surface-attached foreign matter and the rear-surface attached foreign matter were accurately detected.

Although a specific example of detecting foreign matter on the front and back of a transparent substrate has been described above, the present invention can be applied to the detection of a defect such as a scratch or a chip on the front and back of a transparent substrate. The present invention can also be applied to the case of detecting the roughness of the front and back surfaces of a substrate.

Furthermore, the present invention can be applied to the case of measuring a micropatterned pattern on the front and back of a transparent substrate, and to inspect the pattern. However, in these cases, any pattern that allows light transmission (for example, a pattern made of a remarkably thin metal thin film formed on a transparent substrate) may be used. It can be ensured that light is irradiated to the back surface of the substrate.

Claims

The scope of the claims

1. Irradiate a linear laser beam at a predetermined angle from obliquely above the surface of the transparent measurement object supported by the support member, and illuminate the light from the front surface of the transparent measurement object from the back. Each of the light beams corresponds to a corresponding one of the imaging optical systems, has a linear light receiving portion, and forms an image on the light receiving portion of the detector.Performs predetermined processing based on signals output from the two detectors. Optical measurement characterized by selectively assigning one of the signal corresponding to the front surface and the signal corresponding to the back surface, and displaying the assignment signal corresponding to the front surface and the assignment signal corresponding to the back surface, respectively. Method.

2. The optical measurement method according to claim 1, wherein a predetermined operation is performed based on an assignment signal corresponding to the front side and an assignment signal corresponding to the back side to generate a signal representing a front and back defect of the transparent measurement object.

'3. The optical measurement according to claim 1, which performs a predetermined operation based on the assignment signal corresponding to the front side and the assignment signal corresponding to the back side to generate a signal representing the foreign matter on the front and back of the object. Method.

4. a support member for supporting the transparent measurement object (1);

A laser beam irradiation means (2) for irradiating a linear laser beam at a predetermined angle from obliquely above the surface of the transparent measurement object (1) supported by the support member;

An imaging optical system (3) for imaging light from the front surface and light from the back surface of the transparent measurement object (1);

A pair of light receiving means (5) "(6) having a linear light receiving portion arranged corresponding to an image forming position of each light by the image forming optical system (3);

Processing means (7) (8) that performs predetermined processing based on the signals output from both light receiving means (5) and (6) and selectively assigns one of a signal corresponding to the front side and a signal corresponding to the back side. ) (9) and Display means (10) 'for displaying the assignment signal corresponding to the front side and the assignment signal corresponding to the back side

An optical measurement device comprising:

5. The optical measuring device according to claim 4, wherein the imaging optical system (3) includes a half mirror (4).

6. A signal generating means for performing a predetermined operation based on the assignment signal corresponding to the front surface and the assignment signal corresponding to the back surface to generate a signal representing a defect on the front and back of the transparent measurement object. 4. An optical measuring device according to claim 5 or claim 5.

7. A signal generating means for performing a predetermined operation based on the assignment signal corresponding to the front surface and the assignment signal corresponding to the back surface to generate a signal representing foreign matter on the front and back of the transparent measurement object is further provided. Optical measuring device as described in 4 or claim 5.