JP2020030053A - Optical inspection system - Google Patents

Abstract

To provide an optical inspection system in which interference fringes of received interference light are clear and have high contrast.SOLUTION: An optical inspection system has a light source that irradiates an inspection object with light and a light receiving system that receives interference light generated in the inspection object. There is no mechanism for limiting the spectrum of light between the light source and the inspection object. The light receiving system includes a narrow band filter by which only light in the interference light having a narrower spectral width than light emitted from the light source within a wavelength band of light emitted from the light source is transmitted. It is preferable that the light source have one or more light emitting elements that are disposed on the substrate and emit light, and include a diffusion plate that converts light emitted from the light emitting element to diffused light and irradiates the inspection object with the diffused light. The light emitting element is preferably an LED element or an organic EL element. The narrow band filter is a band-pass filter, a long-pass filter, a short-pass filter, or the like, and preferably has a spectral width of transmitted light of 10 nm or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical inspection system.

A low-pressure sodium lamp as a light source is used, for example, for tunnel lighting.
Further, since the low-pressure sodium lamp itself has a narrow band monochromaticity, it is also used as a light source for an interference fringe measuring device or the like. In an interference fringe measuring device or the like, based on interference light from an inspection object, for example, measurement of a film thickness of an inspection object, inspection of bubbles generated when the film is attached to a substrate, inspection of a substrate surface as an inspection object It is used for applications such as dust inspection, dust inspection, and fingerprint inspection when dust or the like adheres.
Further, for example, in a factory that produces liquid crystal color filters, a uniformity inspection of each color layer is performed using an interference fringe measuring device or the like.
The wavelength of the light source used for the interference fringe measuring device or the like is not limited to the wavelength of a low-pressure sodium lamp of 589 nm or 589.6 nm, but narrow-band monochromatic light of another wavelength extracted from another light source using a narrow-band filter. Can also be used.

  For example, Patent Literature 1 and Patent Literature 2 describe a color filter using a low-pressure sodium lamp, and an inspection device for film thickness and the like. Patent Document 3 discloses an inspection apparatus that detects unevenness in film thickness by an interference phenomenon caused by infrared light.

JP-A-4-118544 JP 2005-221401 A JP 2007-205743 A

However, the production of low-pressure sodium lamps has fallen due to the fall in demand, and stable supply in the future is at stake. There is a demand for an alternative to a low-pressure sodium lamp as a light source, an inspection device without using a low-pressure sodium lamp, and the like.
For example, it is assumed that a yellow LED (wavelength peak: about 590 nm) is prepared as an alternative light source for the low-pressure sodium lamp to match the color that the inspector is familiar with. However, even though a normal LED looks monochromatic to the human eye, the spectral width is too wide for observing interference fringes (about 20 nm at full width at half maximum), which is insufficient for inspection.
On the other hand, by attaching a narrow band filter to an alternative light source such as an LED, it is possible to realize a band narrow enough for observing interference fringes. Some low-pressure sodium lamps have a light emission length much longer than 1 m, and although it is technically possible to arrange a narrow-band filter over the entire surface, an alternative system for the low-pressure sodium lamp is used. It lacks economic rationality.

The optical inspection system of the present invention has at least the following configuration.
A light source for irradiating the test object with light,
A light receiving system for receiving interference light generated in the inspection object,
In an optical inspection system in which a mechanism for limiting a spectrum of light is not provided between the inspection object and the light source,
The light receiving system, from the interference light, within a wavelength band of light emitted from the light source, a narrow band filter that transmits only light having a spectral width narrower than the light emitted from the light source. Features.

  ADVANTAGE OF THE INVENTION According to this invention, the interference fringe etc. of the received interference light are clear, and the optical inspection system with a high contrast can be provided with an inexpensive structure.

It is a figure showing an example of an optical inspection system concerning one embodiment of the present invention. It is a figure showing an example of an optical inspection system concerning a comparative example. It is a conceptual diagram for explaining an example of the interference light by a test object. 5A is a conceptual diagram showing an example of the spectrum of light emitted from a light source, the characteristics of a narrow band filter, and the spectrum of light transmitted through a narrow band filter. FIG. 7A shows the spectrum of light emitted from an LED light source and the characteristics of a bandpass filter. FIG. 1B is a diagram for explaining an example of a spectrum of light transmitted through a bandpass filter. FIG. 2B illustrates an example of a spectrum of light emitted from an LED light source, characteristics of a longpass filter, and a spectrum of light transmitted through a longpass filter. FIG. 3C is a diagram for explaining an example of a spectrum of light emitted from the LED light source, characteristics of a short-pass filter, and a spectrum of light transmitted through the short-pass filter. 1 is a conceptual diagram showing an example of an optical inspection system including a light receiving system having glasses provided with a narrow band filter according to the present invention. FIG. 4 is a diagram for explaining an example of an incident angle dependence characteristic of a bandpass filter. It is a figure which shows an example of the interference fringe which shows the result of an experiment, (a) is a figure which shows an example of the interference fringe imaged via the band pass filter of the light receiving system of the optical inspection system which concerns on this invention, (b) FIG. 7 is a diagram illustrating an example of interference fringes of a single LED of a comparative example. FIG. 3 is a diagram illustrating a relationship between incident angles of s-polarized light and p-polarized light and the reflectance of glass when a glass plate as an inspection object is irradiated with light. It is a conceptual perspective view which shows an example of the glasses (goggles) of the light receiving system of an optical inspection system. It is a figure showing an example of other embodiments concerning the present invention, and is a conceptual diagram showing an example of an optical inspection system including a light sensing system which has an imaging part provided with a narrow band filter.

  An optical inspection system according to an embodiment of the present invention includes a light source that irradiates light to an object to be inspected, and a light receiving system that receives interference light generated in the object to be inspected. In the optical inspection system of the present embodiment, a mechanism for limiting the spectrum of light from the light source is not provided between the inspection object and the light source, and the light receiving system emits light from the light source from the interference light. A narrow-band filter that transmits only light having a spectral width narrower than the light emitted from the light source within the range of the wavelength band of the light to be emitted. For example, an optical inspection system that can irradiate light from a light source to an object to be inspected and clearly inspect interference light, interference fringes, and the like generated in the object with high contrast can be provided with an inexpensive configuration.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Embodiments of the invention include, but are not limited to, those shown. In the following description of each drawing, portions common to those already described are denoted by the same reference numerals, and a redundant description is partially omitted.

  FIG. 1 is a diagram illustrating an example of an optical inspection system 1 according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of an optical inspection system according to a comparative example. FIG. 3 is a conceptual diagram for explaining an example of the interference light by the inspection object 3.

As shown in FIG. 1, an optical inspection system 1 according to an embodiment of the present invention includes a light source 110 that irradiates light to the inspection object 3, a light receiving system 150 that receives interference light generated in the inspection object 3, Having. The light receiving system 150 includes a narrow band filter 151. The narrow band filter 151 transmits only light having a narrower spectral width than the light emitted from the light source within the wavelength band of the light emitted from the light source from the interference light. The narrow band filter 151 is only provided in the light receiving system 150, and no mechanism (for example, a narrow band filter or the like) for limiting the spectrum is provided between the light source 110 and the inspection object 3. For example, light emitted from the light source 110 is directly applied to the inspection object 3. Note that the light emitted from the light source 110 may be applied to the inspection object 3 via an optical element such as a mirror or a lens.
Then, light from the test object 3 enters the narrow-band filter 151, and light transmitted through the narrow-band filter 151 is received by, for example, the eye 155 of the inspector. A light-shielding partition 156 may be provided around the narrow-band filter 151.

  The light source 110 has, for example, one or a plurality of light emitting elements 111 that are arranged on a substrate 112 and emit light. The light emitting element 111 is, for example, an LED (Light emitting diode) light emitting element, an organic EL (Organic electro-luminescence) light emitting element, or the like. In the present embodiment, the light emitting element emits visible light. In this embodiment, an LED light emitting element (also referred to as an LED element) is employed as the light emitting element 111. A diffusion plate 113 is provided on the light emitting side of the light emitting element 111.

The diffusion plate 113 converts light from the light emitting element 111 into diffused light, and irradiates the diffused light to the inspection object 3. A general monochromatic LED element has a spectral width (full width at half maximum) of about 20 nm in a wavelength band of emitted light.
When a surface-emitting type organic EL element is employed as the light emitting element 111, the diffusion plate 113 may not be provided. The spectral width (full width at half maximum) of the wavelength band of the light emitted from the organic EL element is about 70 nm to 100 nm for each color. In the present embodiment, the light emitting element of the light source 110 may be a white light source having a center wavelength in a visible light region (wavelength of about 420 nm to 760 nm).

  For example, as shown in FIG. 3, when light is irradiated on the inspection object 3 (inspection target) such as a thin film, light reflected on the surface of the inspection object 3 having a thin film and light reflected on the back surface of the thin film are generated. The interference light is received by the inspector's eyes 155 via the narrow band filter 151.

  As shown in FIG. 3, when the wavelength of light is λ, the refractive index of the thin film is n, the refractive index of air is 1, the thickness of the thin film is t, and the refractive angle is θ, and the interference light is dark, for example, as the inspection object 3. The condition is defined by Expression (1). The condition under which the interference light becomes brighter is defined by Expression (2). Here, m = 0, 1, 2, 3,....

2 nt × cos θ = m × λ (1)
2nt × cos θ = (m + (1/2)) × λ (2)

According to Expressions (1) and (2), when the film thickness is not uniform, unevenness of the interference fringes is visible, and when the viewing angle changes, the interval and the shading of the interference fringes also change.
However, when the wavelength λ of the light is distributed plurally or continuously with a width, the intervals of the shading of the interference fringes are shifted, and the shading of the interference fringes becomes unclear by overlapping each other, and the interference fringes are substantially reduced. It becomes difficult to see and cannot withstand inspection.
Conventional solutions attempt to create interference fringes by irradiating a narrow band of monochromatic light, but as a result of extensive studies by the inventors of the present invention, light of a wavelength having a plurality or a continuous width has been obtained. It was found that even when irradiated, the interference light did not exist, but was merely difficult to be recognized by the observer. Conversely, if only the necessary wavelength region is extracted on the light receiving system side as an observer, interference fringes with sufficiently clear shading can be seen.

As shown in FIG. 2, the monochromatic light source 110z of the comparative example includes, for example, a low-pressure sodium lamp, and irradiates the inspection object 3 (inspection target) such as a thin film with monochromatic light. In the case of a low-pressure sodium lamp, the light source itself emits narrow-band monochromatic light, but in the case of other light sources, the light source is adjusted to narrow-band monochromatic light as necessary. In the comparative example of FIG. 2, the interference light generated in the inspection object 3 is directly received by the inspector's eye 155 without passing through the narrow band filter.
The low-pressure sodium lamp emits light having a wavelength of 589 nm or 589.6 nm, and the spectral width of the wavelength band of the light is about 5 nm, and the contrast of interference fringes is high and clear.

  By the way, as described above, when a general monochromatic LED element is employed as the light source 110, the spectral width of the wavelength band of the light emitted from the LED element is about 20 nm, and the light is emitted directly without passing through a narrow band filter. When the light is received by the eyes 155, the contrast of the interference fringes may be low and not clear. It is considered that this is not because the interference fringes do not exist as described above, but because the interference fringes due to a plurality of wavelengths having different widths overlap each other and become difficult to see.

In the embodiment of the present invention shown in FIG. 1, even when a general monochromatic LED element is used as the light source 110, the light receiving system 150 includes the narrow band filter 151. Due to 151, only light having a spectrum width narrower than the light emitted from the light source 110 is transmitted from the interference light generated in the inspection object 3 within the wavelength band of the light emitted from the light source 110, for example, The light is received by the examiner's eyes 155.
The spectral width of the light transmitted through the narrow band filter 151 is preferably, for example, 10 nm or less. When the spectral width of the light becomes smaller and becomes closer to a single color, when the light is received by the eye 155 or the like, the interference fringes become clear and the contrast becomes higher.

  FIG. 4 is a conceptual diagram showing an example of the spectrum of the light emitted from the light source 110, the filter characteristics of the narrow band filter 151, and the spectrum of the received light.

4A illustrates an example of a spectrum of light emitted from an LED light source as the light source 110, a characteristic of a band-pass filter as the narrow-band filter 151, and an example of a spectrum of light transmitted through the band-pass filter. FIG. In FIG. 4, the horizontal axis represents the wavelength [nm], the vertical axis represents the spectral irradiance (arbitrary unit) of the light from the light source, the transmittance (%) of the filter, and the spectral irradiance (optional) of the light transmitted through the filter. Unit).
In the example shown in FIG. 4A, the center wavelength of the light emitted from the LED light source is 590 nm, and the spectral width of the wavelength band is relatively large. The center wavelength of the band-pass filter is 590 nm (same or substantially the same as the center wavelength of the light emitted from the light source), and the full width at half maximum is specified to be about 10 nm or less. The light transmitted through the bandpass filter has a wavelength band of about 10 nm, which is close to monochromatic light.

  Further, as shown in FIG. 4B, a long-pass filter may be employed as the narrow-band filter 151. In the example shown in FIG. 4B, the cutoff wavelength of the long-pass filter is defined such that the light transmitted through the long-pass filter has a wavelength band of about 10 nm. The cutoff wavelength is a wavelength within the wavelength band of light emitted from the LED light source as the light source 110.

  Further, as shown in FIG. 4C, a short-pass filter may be employed as the narrow-band filter 151. In the example shown in FIG. 4C, the cut-off wavelength of the short-pass filter is defined so that the light transmitted through the short-pass filter has a wavelength band of about 10 nm. The cutoff wavelength is a wavelength within the wavelength band of light emitted from the LED light source as the light source 110.

  That is, the cutoff wavelength of the long-pass filter or the short-pass filter as the narrow-band filter 151, the center wavelength of the band-pass filter, the half-value It is preferable that the full width, the upper cutoff wavelength, the lower cutoff wavelength, and the like are optimally defined.

  FIG. 5 is a conceptual diagram showing an example of the light receiving system 150 of the optical inspection system 1 according to the present invention. 5 is a conceptual diagram illustrating an example of a light receiving system 150 having glasses provided with a narrow band filter 151. FIG. 6 is a diagram for explaining an example of the incident angle dependence characteristic of the bandpass filter. In FIG. 6, the horizontal axis indicates the wavelength [nm], the vertical axis indicates the transmittance (%) of the filter, and the solid line indicates the angle of light (incident angle) incident on the surface of the plate-shaped narrow band filter. Is 0 °, and the broken line indicates the case where the incident angle is 15 °.

  In the example shown in FIG. 5, in the light receiving system 150, a narrow band filter 151 is arranged in front of the examiner's eye 155 or the like. The distance d between the narrow-band filter 151 and the eye 155, the size of the narrow-band filter 151 (the size φ such as the vertical width and the horizontal width), and the viewing angle θs have a relationship represented by Expression (3). For example, the optical axis 150ax passes through the center of the narrow-band filter 151 and the eye 155. The viewing angle θs is an angle formed by two straight lines connecting the upper and lower or left and right ends of the narrow band filter 151 and the eyes. In the present embodiment, the distance d is, for example, about 3 mm to 100 mm, preferably about 30 mm to 50 mm. The narrow band filter is a disk having a size φ of, for example, about 15 mm to 50 mm in diameter, preferably about 20 mm to 35 mm. Note that the narrow band filter is not limited to a circular shape, and may have an arbitrary shape such as a rectangular shape.

  φ = 2d × tan (θs / 2) (3)

As shown in FIG. 6, the narrow-band filter 151 such as a band-pass filter shifts the wavelength as the incident angle increases, but when the incident angle is 20 ° or more, the influence of the wavelength shift increases, and the wavelength shift is ignored. become unable.
In the embodiment of the present invention, the size of the narrow-band filter 151 (length such as width and height) is set so that the viewing angle θs shown in FIG. 5 is 60 ° or less, preferably 50 ° or less, more preferably 40 ° or less. Is relatively small, the field of view is limited. When the field of view is limited, humans try to confirm by shaking their heads instead of moving their eyes when looking at an object. As a result, the eye, the narrow-band filter, and the object (in this case, the object to be inspected) are arranged so as to face each other substantially. As a result, the influence of the wavelength shift can be reduced and the optical inspection can be performed with high accuracy. In the example shown in FIG. 5, the viewing angle θs corresponds to twice the incident angle.
As a comparative example, for example, when a narrow-band filter is provided on the light source side, it is necessary to arrange a large-sized narrow-band filter, which increases the manufacturing cost.

Next, the inventor of the present application actually produced an optical inspection system according to the present invention and an optical inspection apparatus of a comparative example, and performed experiments to confirm the effects of the present invention.
Specifically, as the light source 110 of the optical inspection system according to the present invention, an LED light emitting element having a center wavelength of 590 nm was used (a light source similar to a Na lamp having a center wavelength of 589 nm). Further, 81 LED light emitting elements were arranged in a grid pattern on the substrate (9 vertical × 9 horizontal), and the diffusion plate 113 was arranged at a position of about 10 cm on the light emitting side of the LED light emitting elements.
As the light receiving system 150 of the optical inspection system according to the present invention, a bandpass filter (narrowband filter 151) having a spectral width of 10 nm was provided in glasses (goggles). A camera (imaging unit) was placed at the position of the examiner's eye and an image was taken.

  In addition, a wedge-shaped air layer, which is often used in an interference fringe experiment, was manufactured as the inspection object 3 (test sample). In detail, a pair of glass plates was prepared, and a wedge-shaped air layer was formed between the pair of glass plates by sandwiching thin paper or the like at one end of the glass plates.

  When light is emitted from the light source, the light is incident on one glass plate, the reflected light is reflected at the boundary between the back surface of the one glass plate and the wedge-shaped air layer, and the wedge-shaped air layer is reflected without reflection. The transmitted light is reflected on the surface of the other glass plate, interferes with the reflected light transmitted through and emitted from the one glass plate, and the interference light is received by the light receiving system.

In the experiment, as a comparative example, a low-pressure Na (sodium) lamp irradiator was prepared as a light source, and light was received without passing through a narrow band filter.
In addition, as another comparative example, a yellow LED light-emitting unit was prepared and received without passing through a narrow band filter.

  FIG. 7A is a diagram illustrating an example of an interference fringe imaged through a band-pass filter (BPF) of a light receiving system of the optical inspection system according to the present invention. FIG. 7B is a diagram illustrating an example of interference fringes of the LED light emitting element alone (without a bandpass filter) of the comparative example.

  The experiment was actually performed, and the results shown in FIGS. 7A and 7B and Table 1 were obtained. Double circle marks indicate that the interference fringes were clearly visible, circle marks indicate that the interference fringes were slightly clear, triangular marks indicate that the interference fringes were difficult to see, and x marks indicate that the interference fringes were difficult to see. Indicates that it was not visible.

  In detail, as a comparative example (prior art), when monochromatic light is emitted from a low-pressure sodium lamp alone as a light source and received by a light receiving system without a bandpass filter, a wedge-shaped air of an object to be inspected (test sample) is used. When the gap thickness of the layers was 3 μm, 5 μm, and 10 μm, interference fringes could be clearly seen.

  Further, as another comparative example, when light is emitted from a single LED light emitting element as a light source and received by a light receiving system without a bandpass filter, the gap thickness of the wedge-shaped air layer of the inspection object (test sample) is reduced. At 3 μm, 5 μm, and 10 μm, the interference fringes were hard to see. Specifically, the interference fringes were hard to see as the gap thickness increased (see FIG. 7B).

  On the other hand, in the optical inspection system according to the present invention, when light is received through a narrow-band filter (band-pass filter), the interference fringe pattern is changed when the gap thickness of the wedge-shaped air layer is 3 μm, 5 μm, and 10 μm, respectively. Of the low-pressure Na lamp.

  Further, although the bandpass filter is expensive, in the optical inspection system according to the present invention, a relatively small size bandpass filter is provided in the light receiving system, so that the light receiving system can be realized at low cost, and When a bandpass filter is manufactured by a method of evaporating a predetermined evaporation material on a base material such as a glass plate, the dependency on the incident angle does not need to be considered.

FIG. 8 is a diagram showing the relationship between the incident angle of s-polarized light and p-polarized light when a glass plate (refractive index n = about 1.5) as an inspection object is irradiated with light, and the reflectance of the glass.
When light is irradiated on a glass plate (refractive index n = about 1.5) as an object to be inspected, the polarization state of the reflection on the glass surface changes as shown in FIG.
For example, interference fringes are generated by interference between reflected light on the surface of a glass plate as an object to be inspected and reflected light on the lower surface. Therefore, when the reflection angle is about 45 to 80 °, the contrast may increase due to polarization restriction. is there.
In the optical inspection system according to one embodiment of the present invention, the light receiving system 150 may include a linear polarization filter 152 between the narrow band filter 151 and the inspection object 3. Further, it is preferable that the linear polarization filter 152 is provided so that the polarization angle can be adjusted.
For example, the reflected light on the surface of the inspection object such as a glass plate changes its polarization state. In one embodiment of the present invention, by adjusting the polarization angle of the linear polarization filter 152, for example, the reflected light is transmitted through the polarization filter. By optimizing the mixing ratio of the s-polarized light and the p-polarized light, the contrast is increased and the optical inspection can be performed with high accuracy. For example, the inspector adjusts the polarization angle of the linear polarization filter 152 so that the contrast of the received interference fringes increases. The light receiving system includes an adjusting unit that adjusts the polarization angle of the linear polarization filter 152 so that the computer (159) increases the contrast of the interference fringes based on the image (the image of the interference fringes) obtained by the imaging unit. May be provided.

FIG. 9 is a conceptual perspective view showing an example of glasses (goggles) of the light receiving system 150 according to one embodiment of the present invention.
The light receiving system 150 may be, for example, glasses (goggles) provided with a narrow band filter 151 as shown in FIG. The glasses (such as goggles) having the narrow band filter 151 are worn by an inspector, for example.
The examiner wears the glasses (goggles or the like) and sees interference light and interference fringes from the inspection object through the narrow band filter 151, so that the contrast of the interference light and interference fringes increases, and Optical inspection can be performed with high accuracy.

The glasses (goggles) as the light receiving system 150 shown in FIG. 9 have a fixed main body 154 provided with two through-holes (not shown), and on the front side of the through-hole of the fixed main body, A cylindrical movable section 153 is provided.
A disk-shaped narrow band filter 151 is provided on the front side of the movable main body 153a of the movable section 153, and a linear polarization filter 152 (polarizing plate) is provided on the front side of the narrow band filter 151. The narrow band filter 151 and the linear polarization filter 152 are held by a cylindrical filter holding section 153b. The linear polarization filter 152 is held by a cylindrical filter holding section 153b so that the polarization angle can be adjusted. In addition, on the front side of the movable section 153, a light-shielding section 153c is provided other than the section where the narrow band filter 151 and the linear polarization filter 152 are arranged.
In addition, the linear polarization filter 152 may be provided detachably as needed.

  The movable body 153a of the movable section 153 is provided on the fixed body 154 of the glasses so as to be rotatable upward by 90 ° to 180 ° by a hinge 154h. In other words, the glasses (goggles) shown in FIG. 9 can receive light via the narrow band filter 151 at the time of inspection, and move the movable portion 153 upward to be in the open state at the time of non-inspection. The inspection object or the like can be easily viewed directly without intervention.

It is preferable that the glasses (goggles) illustrated in FIG. For example, when the inspector wears the glasses (such as goggles) according to the present invention and inspects the object to be inspected, the glasses (e.g., glasses) are used to prevent light from entering the inspector's eyes other than from the narrow band filter 151. By providing the light-shielding partition 156 in goggles or the like, unnecessary light can be prevented from entering the eyes of the inspector, and an optical inspection can be performed with high accuracy.
Further, it is preferable that a belt 157 (an elastic member such as rubber) is provided for fixing the glasses (goggles) when the examiner wears the glasses (goggles). In the example shown in FIG. 9, both ends of the belt 157 are connected to the light shielding partition 156. By providing the belt 157, the glasses (goggles) do not slip off during the inspection. Further, the inspector can use both hands freely during the inspection.

  FIG. 10 is a conceptual diagram illustrating an example in which the observation medium of the light receiving system 150 according to another embodiment of the present invention is replaced with an imaging unit 158 from the eye 155. In the example illustrated in FIG. 10, the light receiving system 150 includes the imaging unit 158, and the narrow band filter 151 is disposed in front of the imaging unit 158. In the example illustrated in FIG. 10, the light receiving system 150 includes a narrow band filter 151, an imaging unit 158 configured to receive light transmitted through the narrow band filter 151, and an inspection target based on an image obtained by the imaging unit 158. 3 has an inspection processing unit 159 that performs an inspection process. The inspection processing unit 159 includes a computer, a control unit (control device), and the like. In addition, the inspection processing unit 159 (computer or the like) controls the intensity of light output from the light source 110, the timing of light emission, the position of light emission, the irradiation angle on the object to be inspected, and the like. The optical inspection may be performed with high accuracy based on the image obtained by the imaging unit 158.

As described above, the optical inspection system 1 according to the embodiment of the present invention includes the light source 110 that irradiates the inspection object 3 with light, and the light receiving system 150 that receives the interference light generated in the inspection object 3. Having. No mechanism (such as a narrow band filter) for limiting the spectrum of light emitted from the light source 110 is provided between the inspection object 3 and the light source 110. For example, the light emitted from the light source 110 is directly applied to the inspection object 3. The light emitted from the light source 110 may be applied to the inspection object 3 via an optical element such as a mirror or a lens.
The light receiving system 150 is configured to transmit only light having a narrower spectral width than the light emitted from the light source 110 within the wavelength band of the light emitted from the light source 110 from the interference light generated in the inspection object 3. A band filter 151 is provided. For example, the light receiving system 150 receives interference light, interference fringes, and the like generated by the inspection object 3. The interference light from the inspection object may be reflected light or transmitted light.
That is, since the light receiving system 150 has the narrow band filter 151, interference fringes of the interference light received by the light receiving system 150 are clear and have high contrast. That is, it is possible to provide an optical inspection system that can easily perform optical inspection with high accuracy with a simple configuration.
Specifically, in the optical inspection system according to the present invention, instead of narrowing the spectrum on the light source side, or instead of emitting the light having a narrow spectral width, the light source 110 emits light having a wide spectral width. By emitting the light to the object to be inspected and receiving the light from the object to be inspected 3 through the narrow-band filter 151, for example, the interference fringe of a predetermined wavelength band that has been buried in the absence of the narrow-band filter 151 can be eliminated. By providing the narrow band filter 151 for extraction, a high contrast and clear interference fringes can be received. That is, an inexpensive optical inspection system can be realized with a simple configuration.

Further, the light source 110 of the optical inspection system 1 according to one embodiment of the present invention includes one or a plurality of light emitting elements 111 that are arranged on a substrate and emits light, and the light from the light emitting element 111 is diffused light. And a diffusion plate 113 for irradiating the inspection object 3 with the diffused light.
That is, for example, when a plurality of LED light emitting elements (LED elements) and the like are arranged at predetermined positions such as a lattice, a straight line, and a concentric circle on the substrate 112, light emitted from the light emitting element 111 is emitted. By providing the diffusing plate 113 on the emission side of the light emitting element, the light source 110 becomes a surface light source, and the light receiving system 150 can receive clear and high-contrast interference fringes.

Further, as the light emitting element 111 of the optical inspection system 1 according to one embodiment of the present invention, for example, an LED element, an organic EL element, or the like can be adopted.
In the present invention, since the light receiving system 150 includes the narrow band filter 151, for example, a monochromatic low-pressure sodium lamp or the like (monochromatic light source) having a small spectral width is not used. An LED element or an organic EL element can be employed as a light source.
When an organic EL element that emits surface light of a predetermined size is used as the light source, the light source does not need to include the diffusion plate 113.

Further, the narrow band filter 151 of the optical inspection system 1 according to one embodiment of the present invention is any one of a band pass filter, a long pass filter, a short pass filter, or a combination of two or more thereof. The narrower the spectral width of the light transmitted through the narrow-band filter 151, the clearer the interference fringes becomes, which is advantageous. However, if the spectral width is too narrow, the light becomes darker and more difficult to see. , A certain spectral width is required. Specifically, for example, the spectral width of the light transmitted through the narrow band filter 151 is defined to be 15 nm or less, preferably 10 nm or less, 4 nm or more, more preferably 8 nm or less, 5 nm or more, and still more preferably 6 nm or less, 5 nm or more. Is preferred.
That is, for example, as shown in FIG. 4, a band-pass filter, a long-pass filter, and a short-pass filter (narrow-band filter 151) having the filter characteristics shown in FIG. When the light receiving system 150 employs such a method, light having a narrow band spectrum can be received, and the interference pattern is clear, the contrast is high, and the optical inspection can be performed with high accuracy.
In other words, the narrow band filter 151 may be a bandpass filter with both sides limited (having a width) or a dichroic filter with one side limited (long pass filter, short pass filter, etc.). However, in this case, it is necessary to have monochromaticity, and the spectral width of the light transmitted through the narrow band filter is set to 10 nm or less.
In addition, since filters on one side (long-pass filters, short-pass filters, etc.) are less expensive than band-pass filters, an inexpensive light receiving system and an inexpensive optical inspection system can be provided.

  When the narrowband filter 151 has a bandpass filter having a filter characteristic in which the full width at half maximum of the spectrum of the transmitted light is 10 nm or less, the center wavelength of the bandpass filter is set to the center of the spectrum of the light emitted from the light source 110. Preferably, the wavelength is the same or substantially the same. Further, it is preferable that the difference between the center wavelengths is about 5 nm or less.

In addition, it is preferable that the narrow-band filter of the light receiving system 150 of the optical inspection system 1 according to the embodiment of the present invention is defined to have a size (length such as width and height) in which the viewing angle is 60 ° or less. . For example, when the examiner wears glasses (goggles or the like), the size (length such as width and height) of the narrow band filter 151 is defined so that the viewing angle of the narrow band filter 151 is 60 ° or less. Is preferred.
That is, the narrow-band filter 151 such as a band-pass filter has a size (length such as width and height) of the narrow-band filter 151 such that the viewing angle is 60 ° or less, preferably 50 ° or less, and more preferably 40 ° or less. Is relatively small, the influence of the wavelength shift can be reduced, and the optical inspection can be performed with high accuracy. Further, by providing the narrow band filter 151 having a relatively small size in the light receiving system 150, the light receiving system 150 can be realized at low cost.
As a comparative example, for example, when a narrow-band filter is provided on the light source side, it is necessary to arrange a large-sized narrow-band filter, which increases the manufacturing cost.

In addition, the light receiving system 150 of the optical inspection system 1 according to the embodiment of the present invention includes an imaging unit 158 that receives light transmitted through the narrowband filter 151, and an inspection target based on an image obtained by the imaging unit 158. And an inspection processing unit 159 (computer, control unit, and the like) that performs a process of inspecting No. 3.
In other words, the interference light and interference fringes from the inspection object are clearly received by the imaging unit 158 with high contrast, so that the inspection processing unit 159 can perform the optical inspection with high accuracy based on the obtained image.

  When the narrow-band filter 151 and the imaging unit 158 are adopted as the light receiving system 150, a light-shielding partition may be provided from other than the narrow-band filter 151 so that light does not enter the imaging unit 158. Thus, unnecessary light can be prevented from entering the imaging unit 158, and the inspection processing unit 159 can perform an optical inspection with high accuracy.

As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to these embodiments, and there may be a design change or the like without departing from the gist of the present invention. This is also included in the present invention.
In addition, the embodiments shown in the above-described drawings can be combined with each other as long as there is no particular inconsistency or problem in the purpose, configuration, or the like.
Further, the contents described in each drawing can be independent embodiments, and the embodiments of the present invention are not limited to one embodiment combining the drawings.

  In the above-described embodiment, the optical inspection system performs the interference fringe inspection. However, the present invention is not limited to this mode. For example, the optical inspection system irradiates the inspection object with light from a light source to detect the interference from the inspection object. Based on light, for example, measurement of film thickness as an object to be inspected, inspection of air bubbles generated when the film is attached to a substrate, inspection of dust when dust or the like adheres to the substrate surface as an object to be inspected, inspection of foreign matter , A fingerprint test or the like may be performed.

1. Optical inspection system 3. Inspection object (inspection object)
110: Light source 111: Light emitting element (LED element, organic EL element, etc.)
113 ... Diffusion plate (diffusion part)
150: light receiving system 151: narrow band filter (band pass filter, long pass filter, short pass filter, etc.)
152 ... Linear polarizing filter (polarizing plate)
153: movable part 153a: movable body part 153b: filter holding part 154 ... fixed body part 154h ... hinge 156 ... light shielding partition 158 ... imaging part 159 ... inspection processing part (control part, computer, etc.)

Claims (9)

A light source for irradiating the test object with light,
A light receiving system for receiving interference light generated in the inspection object,
In an optical inspection system in which a mechanism for limiting a spectrum of light is not provided between the inspection object and the light source,
The light receiving system includes a narrow band filter that transmits only light having a narrower spectral width than light emitted from the light source within a wavelength band of light emitted from the light source from the interference light. Optical inspection system featuring. The light source is disposed on a substrate, and has one or more light-emitting elements that emit light,
The optical inspection system according to claim 1, further comprising: a diffusion plate that converts light from the light emitting element into diffused light and irradiates the diffused light to the inspection object.   The optical inspection system according to claim 2, wherein the light emitting element is an LED element or an organic EL element. The narrow band filter is a bandpass filter, a longpass filter, or a shortpass filter, or a combination of two or more of the same,
The optical inspection system according to any one of claims 1 to 3, wherein the narrow band filter has a spectral width of transmitted light of 10 nm or less. The light receiving system has a linear polarization filter disposed between the narrow band filter and the test object,
The optical inspection system according to claim 1, wherein the linear polarization filter is provided such that a polarization angle is adjustable.   The optical inspection system according to any one of claims 1 to 5, wherein the light receiving system includes glasses provided with the narrow band filter.   The optical inspection system according to claim 6, wherein the narrow-band filter has a size such that a viewing angle is 60 ° or less.   The optical inspection system according to claim 1, wherein the light receiving system includes a light shielding partition. The light receiving system, an imaging unit that receives light transmitted through the narrow band filter,
The optical inspection device according to claim 1, further comprising: an inspection processing unit configured to perform a process of inspecting the inspection object based on an image obtained by the imaging unit. system.

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