Photodetector, light irradiation device, and photodetector method

Abstract

To provide a technique that can reduce the occurrence of interference fringes due to reflection from a back surface of a cover glass when capturing an image of laser light with a camera.SOLUTION: A photodetection unit 60a is capable of detecting laser light. The photodetection unit 60a includes a diffuser plate 61 and a camera 63. The diffuser plate 61 diffuses a laser beam L1 while maintaining the shape of the intensity distribution of the incident laser beam L1. The camera 63 includes an image sensor 631 and a cover glass 633. The image sensor 631 images diffused laser light diffused by the diffuser plate 61. The cover glass 633 is located between the diffuser plate 61 and the image sensor 631.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The subject matter disclosed in this specification relates to a light detection device, a light irradiation device, and a light detection method.

Background Art

[0002] Conventionally, a light irradiation device has been proposed that images laser light with a camera, measures the beam diameter and parallelism from the image of the laser light, and adjusts the laser light (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when imaging laser light with a camera, the laser light reflected from the back surface by the cover glass for sealing the image sensor such as a CMOS or a CCD may interfere with the original laser light, and interference fringes may occur. When such interference fringes occur, it becomes difficult to accurately detect the center of the laser light.

[0005] An object of the present invention is to provide a technique capable of reducing the occurrence of interference fringes due to back surface reflection in a cover glass when imaging laser light with a camera.

Means for Solving the Problems

[0006] To solve the above problems, a first aspect is a light detection device for detecting laser light, including a diffusion unit that diffuses the laser light while maintaining the shape of the intensity distribution of the incident laser light, an image sensor that images the laser light diffused in the diffusion unit, and a camera having a cover glass located between the diffusion unit and the image sensor The system further comprises a center position calculation unit, the image sensor being a two-dimensional image sensor, and the center position of the laser beam being calculated based on the image acquired by the image sensor. .

[0009] The 2 The first aspect is Mr. / Ms. A light detection device wherein the camera further comprises a housing provided with an aperture through which the laser light passes, the image sensor is located inside the housing, and the cover glass closes the aperture.

[0010] The 3 The aspect is, 2 A light detection device of the form wherein the diffusion unit is attached to the housing.

[0011] The 4 The embodiments are, from the first embodiment to the second embodiment. 3 A light detection device according to any one embodiment, wherein the diffusing portion includes frosted glass.

[0012] The 5 The embodiments are, from the first embodiment to the second embodiment. 3 A photodetector according to any one embodiment, wherein the diffusion section includes a microlens array.

[0013] The 6 The embodiment is a light irradiation device comprising a holding part for holding a substrate, a laser light source that outputs laser light, and the laser light output from the laser light source Holding part The system comprises an optical system that guides the laser light to the substrate held therein, and at least one photodetector that detects the laser light, wherein the at least one photodetector includes a diffusion unit that diffuses the laser light while maintaining the shape of the intensity distribution of the incident laser light, an image sensor that captures the laser light diffused in the diffusion unit, and a camera having a cover glass located between the diffusion unit and the image sensor. The system further comprises a center position calculation unit, which calculates the center position of the laser beam based on an image acquired by the image sensor, and the image sensor is a two-dimensional image sensor. .

[0014] The 7 The aspect is, 6A light irradiation device according to an aspect, wherein the optical system includes a first beam splitter that splits the laser light output from the laser light source, and a second beam splitter that splits the laser light split by the first beam splitter, and the at least one light detection unit includes a first light detection unit that detects the laser light split by the first beam splitter, and a second light detection unit that detects the laser light split by the second beam splitter.

[0015] First 8 An aspect is a light detection method for detecting laser light, including: a) a step of diffusing the laser light while maintaining the shape of the intensity distribution of the laser light; and b) a step of imaging, with an image sensor, the laser light that has passed through a cover glass after being diffused in the step a). (i) The image sensor is a two-dimensional image sensor, and the process further includes (a) calculating the center position of the laser beam based on the image acquired by the image sensor. .

Advantages of the Invention

[0016] According to the light detection device of the first aspect to the 5 aspect, by diffusing the laser light, even if back surface reflection occurs on the cover glass, the generation of interference fringes can be reduced. Also, since the shape of the intensity distribution before diffusion is maintained, the position of the laser light can be accurately specified from the intensity distribution.

[0017] First 1 According to the light detection device of the aspect, the intensity distribution of the laser light can be detected two-dimensionally.

[0018] First 1 According to the light detection device of the aspect, the position of the optical axis of the laser light can be detected.

[0019] First 4 According to the light detection device of the aspect, light can be easily diffused uniformly by the ground glass.

[0020] First 5 According to the light detection device of the aspect, the divergence angle and shape of the laser light can be controlled by the microlens array.

[0021] First 6According to the light irradiation device of this type, by diffusing the laser light, the generation of interference fringes can be reduced even if back reflection occurs on the cover glass. Furthermore, since the shape of the intensity distribution before diffusion is maintained, the position of the laser light can be accurately determined from the intensity distribution.

[0022] The 7 According to the light irradiation device of this embodiment, the parallelism of the laser beam can be measured based on the position of the laser beam detected by the first light detection unit and the second light detection unit.

[0023] The 8 According to the optical detection method of this embodiment, by diffusing the laser light, the generation of interference fringes can be reduced even if back reflection occurs on the cover glass. Furthermore, since the shape of the intensity distribution before diffusion is preserved, the position of the laser light can be accurately determined from the intensity distribution. [Brief explanation of the drawing]

[0024] [Figure 1] This is a schematic perspective view showing the configuration of the light irradiation device according to the embodiment. [Figure 2] Figure 1 is a cross-sectional view showing the internal and peripheral configurations of the vacuum chamber of the light irradiation device. [Figure 3] Figures 1 and 2 show a schematic perspective view of the configuration of the light irradiation unit. [Figure 4] This is a schematic cross-sectional view showing the configuration of the light detection unit. [Figure 5] This figure shows an image of the laser beam acquired by the photodetector and the brightness distribution at the position indicated by the dashed line in the image. [Figure 6] This is a diagram showing a photodetector related to a comparative example. [Figure 7] This figure shows an image of laser light acquired by the photodetector in the comparative example, and the brightness distribution at the position indicated by the dashed line in the image. [Modes for carrying out the invention]

[0025] Embodiments of the present invention will be described below with reference to the attached drawings. Note that the components described in these embodiments are merely illustrative and are not intended to limit the scope of the present invention to them alone. In the drawings, for ease of understanding, the dimensions and number of parts may be exaggerated or simplified as needed.

[0026] Figure 1 and subsequent figures may show arrows indicating the intersecting X, Y, and Z axes. The X, Y, and Z axes are preferably orthogonal. The direction in which the tip of each arrow points is considered the + (plus) side, and the opposite side is considered the - (minus) side.

[0027] In the following explanation, the direction along the Z-axis is defined as the vertical direction, and the directions along the X-axis and Y-axis are defined as horizontal directions parallel to the horizontal plane. Furthermore, the +Z side is referred to as the "upper side," and the -Z side as the "lower side." However, these directions do not necessarily limit the positional relationships of the device configuration.

[0028] <1. Embodiment> Figure 1 is a schematic perspective view showing the configuration of the light irradiation device 1 according to an embodiment. In Figure 1, the chamber frame supporting the vacuum chamber 12, or the wiring that is actually connected, are omitted from the illustration for convenience.

[0029] As shown in Figure 1, the light irradiation device 1 comprises a vacuum chamber 12, an external fixing part 14, a bellows 16A, a light irradiation unit 18, a vacuum pump 21, and a control unit 22.

[0030] The vacuum chamber 12 has a space inside which a substrate W is housed. The substrate W is, for example, a semiconductor wafer, a glass substrate for a liquid crystal display device, a substrate for an FPD (Flat Panel Display) such as an organic EL (Electroluminescence) display device, a substrate for an optical disk, a substrate for a magnetic disk, a substrate for a magneto-optical disk, a glass substrate for a photomask, a ceramic substrate, a substrate for a field emission display (FED), or a substrate for a solar cell. The substrate W is, for example, a substrate with a thin film formed on its upper surface.

[0031] Furthermore, the side of the vacuum chamber 12 has an opening 12A through which the substrate W passes when it is loaded and unloaded. The opening 12A is closed as appropriate when the inside of the vacuum chamber 12 is in a vacuum state.

[0032] The external fixing part 14 is, for example, a granite surface plate. The bellows 16A connects the vacuum chamber 12 and the external fixing part 14. The bellows 16A is an expandable member made of, for example, stainless steel. The bellows 16A as an expandable member may be made of a metal other than stainless steel or a resin. Also, the expandable member does not necessarily have to be in a bellows shape.

[0033] The light irradiation unit 18 irradiates laser light into the vacuum chamber 12. The light irradiation unit 18 irradiates laser light toward the upper surface of the substrate W housed in the vacuum chamber 12. The light irradiation unit 18 performs ablation processing of the substrate W by irradiating it with laser light, for example.

[0034] The light irradiation unit 18 irradiates light onto the upper surface of the substrate W housed inside the vacuum chamber 12 from outside the vacuum chamber 12 through an irradiation window (for example, a transparent plate made of quartz or the like) not shown. The light also scans the upper surface of the substrate W by the relative movement of the substrate W inside the vacuum chamber 12 with respect to the light irradiation unit 18, or by the control of the optical system in the light irradiation unit 18. The light irradiation unit 18 is located on the upper surface of the stand 24 attached to the external fixing unit 14.

[0035] The vacuum pump 21 creates a vacuum inside the vacuum chamber 12. In this disclosure, "vacuum" is preferably a high vacuum (for example, 0.00001 Pa) to prevent deterioration of the properties of the substrate W, but it also includes a degree of vacuum that does not reach such a high vacuum. For example, the degree of vacuum inside the vacuum chamber 12 may be lower than the atmospheric pressure outside the vacuum chamber 12.

[0036] The control unit 22 includes a storage device, a processing circuit, an input device, and an output device. The storage device consists of memory (storage medium) including, for example, a hard disk drive (HDD), random access memory (RAM), read-only memory (ROM), flash memory, volatile or non-volatile semiconductor memory, magnetic disk, flexible disk, optical disk, compact disk, minidisc, or DVD. The processing circuit consists of, for example, a central processing unit (CPU) that executes programs stored in the storage device. The input device consists of, for example, a device capable of inputting information, such as a mouse, keyboard, touch panel, or various switches. The output device consists of, for example, a device capable of outputting information, such as a display, liquid crystal display device, or lamp.

[0037] The control unit 22 controls each drive unit of the light irradiation device 1. For example, the control unit 22 controls the drive of the light irradiation unit 18, the vacuum pump 21, and the linear motor mechanism 50, which will be described later. In addition, as will be described later, the control unit 22 performs a process to calculate the center position of the laser beam based on the images acquired by the light detection units 60a and 60b.

[0038] Figure 2 is a cross-sectional view showing the internal and peripheral configuration of the vacuum chamber 12 of the light irradiation device 1 shown in Figure 1. As shown in Figure 2, a stage 42, a slider 44, a base 46, a linear guide 48, a linear motor mechanism 50, and a lift pin mechanism 52 are arranged inside the vacuum chamber 12.

[0039] The stage 42 has an upper surface on which the substrate W is placed. The slider 44 is movable in the Y-axis direction and supports the stage 42 from below. The base 46 is attached to the external fixing part 14 independently of the vacuum chamber 12. The linear guide 48 is attached to the base 46 and extends in the Y-axis direction. The linear motor mechanism 50 moves the slider 44 along the linear guide 48 in the Y-axis direction. The lift pin mechanism 52 has lift pins 52A that pass through through holes (not shown) formed in the stage 42 and support the substrate W. The lift pin mechanism 52 is attached to the base 46, for example.

[0040] The stage 42 holds the substrate W in a nearly horizontal position with the processing surface of the substrate W facing upward. As the slider 44 moves in the Y-axis direction by the linear motor mechanism 50, and the light from the light irradiation unit 18 moves in the X-axis direction, the entire processing area of ​​the substrate W is scanned with light in a plan view.

[0041] The linear motor mechanism 50 is attached to external fixing parts 14 located on the +X and -X sides of the vacuum chamber 12 via an opening 12B formed on the -X side of the vacuum chamber 12. Specifically, the linear motor mechanism 50 is attached to the end of a hollow columnar member 14A that passes through a bellows 16A welded to the opening 12B. Wiring and other connections to the linear motor mechanism 50 are appropriately routed outside the vacuum chamber 12 through the inside of the columnar member 14A. The columnar member 14A is located away from the bellows 16A.

[0042] The base 46 is fixed to an external fixing part 14 located on the -Z side of the vacuum chamber 12 through an opening 12C formed in the bottom surface of the vacuum chamber 12. Specifically, the base 46 is attached to the end of a columnar member 14C that passes through a bellows 16B welded to the opening 12C. The columnar member 14C is attached to an external member 14B included in the external fixing part 14. The columnar member 14C is located away from the bellows 16B connected to the bottom surface of the vacuum chamber 12.

[0043] In the example shown in Figure 2, the external fixing part 14 is located across the +X, -X, and -Z sides of the vacuum chamber 12. However, it is not necessary for the external fixing part 14 to be continuous at these locations; it may be distributed across these locations. Furthermore, the external fixing part 14 may be located at only a portion of the +X, -X, and -Z sides of the vacuum chamber 12. In addition, the vacuum chamber 12 is supported and fixed from below vertically by a chamber frame (not shown), separate from the bellows 16B. However, this chamber frame may be located independently of the external fixing part 14.

[0044] Figure 3 is a schematic perspective view showing the configuration of the light irradiation unit 18 shown in Figures 1 and 2. The light irradiation unit 18 includes a laser light source 31, an optical system 35, and two light detection units 60a and 60b (light detection devices).

[0045] The laser light source 31 outputs laser light. The laser light output by the laser light source 31 may be continuous light or pulsed light. The optical system 35 guides the light output from the laser light source to the substrate W held on the stage 42. The optical system 35 includes two beam splitters 350a and 350b, a wedge plate 351, an acousto-optic element 353, a beam expander 355, a galvanometer scanner 357, and an fθ lens 359.

[0046] The beam splitter 350a (first beam splitter) splits the laser light output from the laser light source 31 into two. Of the two laser beams split by the beam splitter 350a, one is incident on the photodetector 60a (first photodetector) and the other is incident on the beam splitter 350b. That is, the photodetector 60a detects the laser light split by the beam splitter 350a. The laser light incident on the beam splitter 350b is further split into two, one is incident on the photodetector 60b (second photodetector) and the other is incident on the wedge plate 351. That is, the photodetector 60b detects the laser light split by the beam splitter 350b.

[0047] The wedge plate 351 is positioned in front of the acousto-optic element 353 (on the side of the laser light source 31). The wedge plate 351 deflects the laser light so that the optical path of the primary light in the acousto-optic element 353 is parallel to the light incident on the acousto-optic element 353.

[0048] The laser light input to the optical system 35 passes through the wedge plate 351 and is then input to the acousto-optic element 353. The acousto-optic element 353 is an example of a diffraction-type deflection element. The acousto-optic element 353 is an optical element that uses a diffraction grating to create periodic fluctuations in the refractive index (compression waves) within a crystal that can be transmitted by laser light, by vibrating the crystal with a piezoelectric element.

[0049] The lattice width of the diffraction grating in the acousto-optic element 353 is adjusted by the vibration frequency applied to the crystal. By adjusting this lattice width, the diffraction angle (diffraction direction) of the laser light can be changed to any angle according to Bragg's law. When the angle of the diffraction grating formed on the crystal with respect to the lattice plane (i.e., the Bragg angle) is θ, the diffraction angle is 2θ. The vibration frequency applied to the crystal of the acousto-optic element 353 is changed based on the control signal of the control unit 22. That is, the diffraction angle of the acousto-optic element 353 is changed based on the command of the control unit 22.

[0050] The beam expander 355 expands the beam diameter of the laser light output from the acousto-optic element 353 to the required diameter. The beam expander 355 is composed of multiple lenses.

[0051] The galvanoscanner 357 is a mechanism that swings the laser beam output from the beam expander 355 in the X-axis and Y-axis directions. The galvanoscanner 357 has a first galvano mirror 357a and a second galvano mirror 357b. The first galvano mirror 357a has a reflective surface parallel to the Y-axis and is rotated within a predetermined angle range around an axis extending in the Y-axis direction. The second galvano mirror 357b has a reflective surface parallel to the Z-axis and is rotated within a predetermined angle range around an axis extending in the Z-axis direction. The laser beam output from the beam expander 355 is first reflected by the second galvano mirror 357b and then reflected by the first galvano mirror 357a. The driving of the first galvano mirror 357a and the second galvano mirror 357b is controlled by the control unit 22.

[0052] The control unit 22 drives the first galvanometer mirror 357a to scan the substrate W in the X-axis direction with the laser beam. The control unit 22 can also drive the second galvanometer mirror 357b to move the position of the laser beam on the substrate W in the Y-axis direction. The galvanometer scanner 357 is an example of a scanning unit. The scanning unit may also include a polygon mirror instead of the galvanometer scanner 357. Alternatively, scanning in the X-axis direction may be performed by moving the substrate W in the X-axis direction relative to the laser beam.

[0053] The fθ lens 359 is positioned between the galvanoscanner 357 and the substrate W in the optical path of the laser beam. The fθ lens 359 focuses the beam diameter of the laser beam output from the galvanoscanner 357 to a desired beam diameter. The fθ lens 359 also converts the constant angular velocity motion of the galvanoscanner 357 into constant velocity scanning of the laser beam on the plane of the substrate W.

[0054] Figure 4 is a schematic cross-sectional view showing the configuration of the photodetectors 60a and 60b. Each of the photodetectors 60a and 60b includes a diffuser plate 61 (diffusing unit) and a camera 63 that captures the laser light L1 diffused by the diffuser plate 61.

[0055] The diffuser plate 61 diffuses the laser beam L1 while maintaining the shape of the intensity distribution of the laser beam L1. The diffuser plate 61 is made of frosted glass, for example, with uniform irregularities formed on its surface by sandblasting. By making the diffuser plate 61 of frosted glass, it is easy to diffuse the laser beam L1 uniformly. The diffuser plate 61 may also be a translucent plate containing a diffusing agent. Furthermore, the diffuser plate 61 may have a microlens array to control the divergence angle and shape of the laser beam L1.

[0056] The camera 63 includes an image sensor 631 and a cover glass 633. The image sensor 631 captures the laser light L1 diffused by the diffuser plate 61. The image sensor 631 is preferably a two-dimensional image sensor composed of a CMOS sensor or a CCD sensor. However, the image sensor 631 may be a one-dimensional image sensor. The cover glass 633 is located in front of the image sensor 631. That is, the cover glass 633 is located between the diffuser plate 61 and the image sensor 631.

[0057] The camera 63 has a housing 635. The housing 635 has an opening 636 through which the laser beam L1 passes. The image sensor 631 is located inside the housing 635. The cover glass 633 covers the opening 636 of the housing 635. By covering the opening 636, the cover glass 633 seals the image sensor 631 inside the housing 635.

[0058] The housing 635 has a cylindrical portion 637. The cylindrical portion 637 is cylindrical through which the laser beam L1 passes. The diffuser plate 61 is installed inside the cylindrical portion 637. That is, the diffuser plate 61 is attached to the housing 635 of the camera 63. This allows the diffuser plate 61 and the camera 63 to be handled as a single unit.

[0059] As shown in Figure 4, the laser light L1 incident on the diffuser plate 61 is diffused by the diffuser plate 61, then passes through the cylindrical portion 637, through the cover glass 633, and is incident on the image sensor 631. In other words, the image sensor 631 captures the laser light L1 that has passed through the cover glass 633.

[0060] Figure 5 shows an image IM1 of the laser beam acquired by the photodetector 60a, and the brightness distribution at the position indicated by the dashed line in the image IM1. As shown in Figure 5, the laser beam L1 is diffused by the diffuser plate 61, and therefore has a spread compared to before diffusion. The control unit 22 calculates the center position of the laser beam L1 from the brightness distribution in this image IM1. Specifically, the center position of the laser beam L1 may be calculated as the position of the brightness peak, the centroid of the position brightness, or the center position of the spread of the laser beam L1 in the image IM1.

[0061] In this embodiment, as shown in Figure 3, the laser light output from the laser light source 31 is detected by two photodetectors 60a and 60b. In this way, the parallelism of the laser light can be measured based on the positions of the laser light detected by the two photodetectors 60a and 60b.

[0062] Figure 6 shows the photodetector 60c according to the comparative example. Figure 7 shows the image IM2 of the laser beam acquired by the photodetector 60c according to the comparative example, and the brightness distribution at the position indicated by the dashed line in the image IM2. The photodetector 60c is equipped with a camera 63, similar to the photodetectors 60a and 60b, but the diffuser plate 61 is omitted. When the photodetector 60c detects the laser beam L1, the reflected laser beam L2 generated by back surface reflection on the cover glass 633 interferes with the original laser beam L1, which may generate interference fringes as shown in the image IM2. When interference fringes occur, multiple peaks appear in the brightness distribution of the image IM2, corresponding to the brightness of the interference fringes. The shape of these interference fringes can vary depending on the incident position and incident angle of the laser beam L1. Therefore, it is difficult to accurately determine the center position of the laser beam L1.

[0063] In the photodetectors 60a and 60b of this embodiment, the laser light L1 is uniformly diffused by the diffuser plate 61. As a result, the intensity of the reflected laser light L2, which can cause interference fringes, is reduced compared to the case without the diffuser plate 61. Therefore, as shown in Figure 5, the generation of interference fringes is suppressed. Also, as is clear from the comparison of Figure 5 and Figure 7, although the Gaussian peak is reduced by the diffuser plate 61, the distribution maintains the shape of the Gaussian. Therefore, since the peak is easy to detect, the center position of the laser light can be determined with high accuracy.

[0064] Furthermore, as the laser beam L1 spreads through the diffuser plate 61, the power density of the laser beam L1 irradiated onto the image sensor 631 also decreases. This prevents the laser from exceeding the threshold Th1, which could damage the image sensor 631, thus enabling the adjustment of a higher-intensity laser.

[0065] Another method for attenuating the intensity of the laser beam is to use an ND filter. However, using an ND filter may cause interference fringes or optical axis shift. Therefore, by using the diffuser plate 61, the position of the laser beam can be determined with greater accuracy than when using an ND filter.

[0066] <2. Variant Example> Although embodiments have been described above, the present invention is not limited to those described above, and various modifications are possible.

[0067] In the above embodiment, the photodetectors 60a and 60b detect laser light within the optical system 35. However, the photodetectors may also detect laser light output from the optical system 35. For example, the photodetectors may be located on or near the stage 42.

[0068] The control unit 22 may calculate the beam diameter of the laser light L1 before diffusion from the image IM1. For example, if the spreading rate due to the diffuser plate 61 is known, the beam diameter before diffusion may be determined based on that spreading rate and the beam diameter obtained from the image IM1.

[0069] The light irradiation device 1 may include an adjustment unit for adjusting the optical axis position, optical axis direction, or beam diameter of the laser light output from the laser light source 31. The adjustment unit may consist of, for example, multiple lenses or mirrors. The control unit 22 may control the adjustment unit based on the detection results from the light detection units 60a and 60b so that the laser light is automatically adjusted.

[0070] Although this invention has been described in detail, the above description is illustrative in all respects, and the invention is not limited thereto. It is understood that countless variations not illustrated can be conceived without falling outside the scope of this invention. The components described in each of the above embodiments and variations can be combined or omitted as appropriate, as long as they do not contradict each other. [Explanation of Symbols]

[0071] 1 Light irradiation device 18 Light-irradiating section 22 Control Unit (Center Position Calculation Unit) 31 Laser light source 35 Optical system 42 Stages (Holding parts) 60a Photodetector (First photodetector) 60b Photodetector (Second photodetector) 61 Diffuser plate (diffusion section) 63 Cameras 350a Beam Splitter (First Beam Splitter) 350b Beam Splitter (Second Beam Splitter) 631 Image Sensor 633 Cover glass 635 cabinets 636 Aperture

Claims

1. A photodetector that detects laser light, A diffusion unit that diffuses the laser light while maintaining the shape of the intensity distribution of the incident laser light, An image sensor for capturing the laser light diffused in the diffusion section, and a camera having a cover glass located between the diffusion section and the image sensor, Equipped with, The aforementioned image sensor is a two-dimensional image sensor. A center position calculation unit calculates the center position of the laser beam based on the image acquired by the image sensor. A light detection device that further incorporates the following features.

2. A light detection device according to claim 1, The camera further comprises a housing through which the laser light passes, The image sensor is located inside the housing. The cover glass is a light detection device that closes the opening.

3. The photodetector according to claim 2, A light detection device in which the diffusion section is attached to the housing.

4. A light detection device according to any one of claims 1 to 3, The aforementioned diffusion section is a light detection device including frosted glass.

5. A light detection device according to any one of claims 1 to 3, The diffusion section is a light detection device including a microlens array.

6. A light irradiation device, A holding part for holding the substrate, A laser light source that emits laser light, An optical system that guides the laser light output from the laser light source to the substrate held in the holding part, The laser light is detected by at least one light detection unit, Equipped with, The at least one light detection unit is A diffusion unit that diffuses the laser light while maintaining the shape of the intensity distribution of the incident laser light, An image sensor for capturing the laser light diffused in the diffusion section, and a camera having a cover glass located between the diffusion section and the image sensor, It has, The aforementioned image sensor is a two-dimensional image sensor. Based on the image acquired by the image sensor, the center position of the laser beam is calculated. The unit that calculates the center position, A light irradiation device that further includes the following features.

7. A light irradiation device according to claim 6, The optical system described above is A first beam splitter that splits the laser light output from the laser light source, A second beam splitter that splits the laser light that has been split by the first beam splitter, Includes, The at least one light detection unit is A first photodetector for detecting the laser light split by the first beam splitter, A second photodetector detects the laser light that has been split by the second beam splitter, A light irradiation device, including a light irradiation device.

8. A photodetection method for detecting laser light, a) A step of diffusing the laser light while maintaining the shape of the intensity distribution of the laser light, b) A step of imaging the laser light that has been diffused in step a) and then passed through the cover glass with an image sensor, Includes, The aforementioned image sensor is a two-dimensional image sensor. c) A step of calculating the center position of the laser beam based on the image acquired by the image sensor. A light detection method further including the following.

Images