JP-7855469-B2 - Optical inspection apparatus, optical inspection system, optical inspection method, and optical inspection program

Inventors

• 大野 博司
• 加納 宏弥
• 岡野 英明

Assignees

• 株式会社東芝

Dates

Publication Date

20260508

Application Date

20220920

Claims (15)

1. A first illumination beam is shone onto a first point on the surface of an object, A second illumination light, directed in a direction different from the first illumination light, is shone onto a second object point on the surface of the object, which has a normal direction different from the normal direction of the first object point. Lighting section, A wavelength selection unit having at least two wavelength selection regions that selectively allow light of different wavelength spectra to pass through, The system comprises an imaging optical element and an image sensor positioned on the image plane of the imaging optical element, wherein the wavelength selection unit is positioned between the imaging optical element and the surface of the object. When the normal direction at the first object point is opposite to the direction of the first illumination light, the light from the first object point can be passed through the wavelength selection unit and the imaging optical element in order and captured by the image sensor . When the normal direction at the second object point is opposite to the direction of the second illumination light, the light from the second object point can be imaged by the image sensor by passing it sequentially through the wavelength selection unit and the imaging optical element . Imaging unit, Equipped with , Optical inspection equipment.
2. The illumination unit irradiates the surface of the object with the first illumination light and the second illumination light, each as parallel light. The optical inspection apparatus according to claim 1.
3. The imaging optical element of the imaging unit has an optical axis, The wavelength selection section is anisotropic with respect to the optical axis. The optical inspection apparatus according to claim 1 or claim 2.
4. The wavelength selection unit has at least two other wavelength selection regions having the same wavelength spectral characteristics as the at least two wavelength selection regions. The optical inspection apparatus according to claim 1 or claim 2.
5. The first and second illumination lights from the illumination unit are beams of parallel light radiating in multiple directions, and the light spreads out in a fan-like manner toward the surface of the object, irradiating the surface of the object with the light. The optical inspection apparatus according to claim 1.
6. The aforementioned lighting unit is A lens that is uniform in one direction, The optical inspection apparatus according to claim 1 or claim 2, comprising a surface-emitting light source provided at the focal plane of the lens.
7. An optical inspection apparatus according to claim 1 or claim 2, The optical inspection apparatus comprises a processing device connected to the optical inspection apparatus, The aforementioned processing apparatus is The number of colors received by the color channel of each pixel in the imaging unit is acquired. The surface condition of the object is inspected based on the aforementioned number of colors. Optical inspection system.
8. An optical inspection apparatus according to claim 1 or claim 2, An optical inspection system comprising a transport device for transporting the aforementioned object.
9. The lighting unit has an opening near the outlet from which the illumination light is emitted. The transport device transports the object at intervals of illumination field width determined by the width of the aperture, while the imaging unit captures an image of the surface of the object. The optical inspection system according to claim 8 .
10. Illuminating a first point on the surface of an object with a first illumination light, Illuminating a second object point on the surface of the object, having a normal direction different from the normal direction of the first object point, with a second illumination light in a direction different from the first illumination light, When the normal direction at the first object point is opposite to the direction of the first illumination light, the light from the first object point is passed sequentially through a wavelength selection unit having at least two wavelength selection regions that allow light of different wavelength spectra to pass through , and an imaging optical element, and then imaged by an image sensor positioned on the image plane of the imaging optical element . An optical inspection method comprising, when the normal direction at the second object point is opposite to the direction of the second illumination light, imaging the light from the second object point by passing it sequentially through the wavelength selection unit and the imaging optical element with the image sensor at the same time as imaging the light from the first object point.
11. Irradiating the first illumination light and irradiating the second illumination light include irradiating the surface of the object with light that spreads out in a fan shape toward the surface of the object as a plurality of parallel beams of light directed toward a plurality of directions. The optical inspection method according to claim 10.
12. The imaging described above includes imaging while transporting the object in a predetermined transport direction. The optical inspection method according to claim 10 or claim 11 .
13. To illuminate a first point on the surface of an object with a first illumination light, A second object point on the surface of the object, having a normal direction different from the normal direction of the first object point, is illuminated with a second illumination light in a direction different from the first illumination light. When the normal direction at the first object point is opposite to the direction of the first illumination light, the light from the first object point is passed sequentially through a wavelength selection unit having at least two wavelength selection regions that allow light of different wavelength spectra to pass through , and an imaging optical element, and then captured by an image sensor positioned on the image plane of the imaging optical element . An optical inspection program that, when the normal direction at the second object point is opposite to the direction of the second illumination light, causes the processor to simultaneously image the light from the first object point and, at the same time, pass the light from the second object point through the wavelength selection unit and the imaging optical element in sequence to be imaged by the image sensor.
14. The actions of irradiating the object with the first illumination light and the actions of irradiating the object with the second illumination light include irradiating the object's surface with light that spreads out in a fan shape toward the object's surface as a plurality of parallel beams of light moving in a plurality of directions. The optical inspection program according to claim 13.
15. The act of imaging includes imaging while transporting the object in a predetermined transport direction. The optical inspection program according to claim 13 or claim 14 .

Description

Embodiments of the present invention relate to an optical inspection apparatus, an optical inspection system, an optical inspection method, and an optical inspection program. Non-contact surface measurement of objects is becoming increasingly important in various industries. Conventional methods involve illuminating an object by spectrally separating light rays, acquiring images of each spectrally separated ray using an image sensor, and then estimating the direction of each ray to obtain information about the object's surface. U.S. Patent No. 5,675,407 W. L. Hows, “Rainbow schlieren and its application,” Applied Optics, vol. 23, No. 14, 1984.Hiroshi Ohno & Takahiro Kamikawa, “One-shot BRDF imaging system to obtain surface properties,” Optical Review volume 28, pages655-661 (2021). A schematic diagram showing an optical inspection system according to the first embodiment.A schematic block diagram of the processing unit of the optical inspection system shown in Figure 1.A flowchart illustrating the processing flow of the processing unit of the optical inspection system shown in Figure 1.A schematic diagram showing an optical inspection system according to a first modification of the first embodiment.A schematic diagram showing an optical inspection system according to a second modification of the first embodiment.A schematic diagram showing an optical inspection system according to the second embodiment.Figure 6 shows a schematic diagram illustrating the relationship between the cross-sectional view of an object being transported in the transport direction at a certain time, the illumination light, and the BRDF in the optical inspection system.Figure 7 shows a schematic diagram of the image captured by the imaging unit at the time shown.Figure 6 shows a schematic diagram illustrating the relationship between the cross-sectional view of an object being transported in the transport direction at a time later than a certain time shown in Figure 7, and the illumination light and BRDF in the optical inspection system shown in Figure 6.Figure 9 shows a schematic diagram of the image captured by the imaging unit at the time shown.An example of an image including three object points and their vicinity, taken using the optical inspection system shown in Figure 6.An example of a wavelength selector.An example of a wavelength selector.An example of a wavelength selector.An example of a wavelength selector.A schematic diagram showing an optical inspection system according to the third embodiment. The following describes each embodiment with reference to the drawings. The drawings are schematic or conceptual, and the relationships between the thickness and width of each part, the ratios of the sizes of the parts, etc., are not necessarily identical to those of reality. Furthermore, even when representing the same part, the dimensions and ratios may differ between drawings. In this specification and each drawing, elements similar to those described above are denoted by the same reference numerals, and detailed explanations are omitted as appropriate. (First Embodiment) The optical inspection system 10 according to this embodiment will be described below with reference to Figures 1 to 3. In this specification, light is defined as a type of electromagnetic wave, including X-rays, ultraviolet rays, visible light, infrared rays, and microwaves. In this embodiment, the light is defined as visible light, and for example, its wavelength is in the range of 400 nm to 750 nm. The imaging unit 24 is composed of an imaging optical element 42 having an optical axis and a sensor (image sensor) 44. Figure 1 shows a schematic cross-sectional view of the optical inspection device 12 and the processing device 14 of the optical inspection system 10 of this embodiment. This cross-sectional view is assumed to be in the x-z plane. The optical inspection apparatus 12 according to this embodiment includes an illumination unit 22, an imaging unit 24, and a wavelength selection unit 26. The illumination unit 22 emits a first illumination light L1 and a second illumination light L2. Both the first and second illumination lights L1 and L2 are assumed to be white light. The wavelength spectra of both illumination lights L1 and L2 are assumed to have a significant intensity distribution between 400 nm and 750 nm. The first and second illumination lights L1 and L2 are assumed to be substantially parallel light, but their directions are different. Any light source can be used for the illumination light, but here a white LED is used as the light source. In Figure 1, the illumination unit 22 is provided between the surface of object S and the wavelength selection unit 26. However, the light source of the illumination unit 22 does not necessarily have to be located between the surface of object S and the wavelength selection unit 26. In this case, the first illumination light L1 and the second illumination light L2 are irradiated onto the surface of object