Ultra-high-speed camera

Abstract

An ultra-high-speed imaging device is provided, which can perform imaging with a higher resolution. The imaging unit of the ultra-high-speed imaging device includes: an objective lens, which is opposite to a workpiece supported by a chuck table; a beam splitter, which is arranged on a first optical path extending from the objective lens; an image processing unit, which is arranged on a second optical path extending from the beam splitter; and an illumination unit, which is arranged on a third optical path extending from the beam splitter. The illumination unit includes: a broadband pulse light source; and a beam splitter, which splits a single pulse of light emitted from the broadband pulse light source into a plurality of wavelengths and generates a time difference. The image processing unit includes: a diffraction grating, which splits the return light irradiated to the workpiece supported by the chuck table with a time difference by changing the angle for each wavelength; and an image sensor, which photographs the return light split by the diffraction grating in an area at each angle corresponding to the wavelength, like a decomposed photograph.

Description

Technical Field

[0001] The present invention relates to an ultra-high speed imaging device which continuously images a workpiece supported by a supporting unit at a high speed. Background Art

[0002] The workpiece having multiple devices such as IC and LSI formed on the front side divided by a plurality of intersecting predetermined dividing lines is divided into individual device chips by a cutting device with a cutting tool, a laser processing device with a laser condenser, etc. The divided device chips are used in electronic devices such as mobile phones and personal computers.

[0003] In addition, in the cutting device, a method of continuously photographing the cutting tool and the workpiece using a so-called high-speed camera to verify the mechanism during the cutting process has been tried. Here, when the rotation speed of the cutting tool is, for example, about 30,000 rpm and the number of shooting frames of the high-speed camera is, for example, 45,000 / second, the situation during one rotation of the cutting tool can be put into about 90 frames of images, so the cutting process of the cutting tool can be fully verified.

[0004] On the other hand, for example, when verifying the mechanism of forming processing marks by irradiating laser light (for example, refer to Patent Document 1), or verifying the mechanism of how the crack propagates when a crack is generated by performing a destructive test, etc., the resolution of the above-mentioned previously known high-speed cameras is at most tens of thousands of frames per second, so it is impossible to fully verify the mechanism, and an ultra-high-speed imaging device that can capture images with a higher resolution is required.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2014-221483 Summary of the invention

[0006] Therefore, an object of the present invention is to provide an ultra-high-speed imaging device capable of imaging at a higher resolution.

[0007] According to the present invention, an ultra-high-speed imaging device is provided, wherein the ultra-high-speed imaging device comprises: a chuck table that supports a workpiece; and a imaging unit that photographs the workpiece supported by the chuck table, the imaging unit comprising: an objective lens that is opposite to the workpiece supported by the chuck table; a beam splitter that is arranged on a first optical path extending from the objective lens; an image processing unit that is arranged on a second optical path extending from the beam splitter; and an illumination unit that is arranged on a third optical path extending from the beam splitter, the illumination unit comprising: a broadband pulse light source; and a spectrometer that splits a single pulse of light emitted from the broadband pulse light source into a plurality of wavelengths and generates a time difference, the image processing unit comprising: a diffraction grating that splits the return light irradiated to the workpiece supported by the chuck table according to the time difference by changing the angle for each wavelength; and an image sensor that photographs the return light split by the diffraction grating in an area at each angle corresponding to the wavelength like a decomposed photograph.

[0008] Preferably, the ultra-high-speed imaging device further includes: a storage unit that stores the image captured by the image sensor; and a display unit that displays the image stored in the storage unit.

[0009] The diffraction grating preferably includes a first diffraction grating and a second diffraction grating, wherein the first diffraction grating splits the return light by changing the angle for each wavelength, and the second diffraction grating converts the return light split by the first diffraction grating into parallel light and introduces it to the image sensor. The diffraction grating preferably splits the return light reflected at a predetermined angle by a reflector by changing the angle for each wavelength and introduces it to the image sensor through a collimating lens.

[0010] Preferably, the spectrometer includes: a diffraction grating that splits one pulse of light from the wide-band pulse light source by changing the angle for each of a plurality of wavelengths; a delay line that makes the optical path length different for each wavelength split by the diffraction grating, thereby generating a time difference; and a combiner that combines the light delayed for each wavelength through the delay line.

[0011] According to the present invention, the return light irradiated to the workpiece with a time difference of 10 ns, for example, can be split by changing the angle for each wavelength, and the split return light can be photographed like a decomposed photograph in the area at each angle corresponding to the wavelength, so that an ultra-high-speed image with a resolution of 10 ns / 1 second, i.e., 1 / 100 million, can be easily obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a perspective view of an ultra-high speed imaging device according to an embodiment of the present invention.

[0013] Figure 2It is equipped with Figure 1 The block diagram of the imaging unit in the ultra-high-speed imaging device shown in FIG.

[0014] Figure 3 This is a top view of the workpiece supported by the chuck table of the ultra-high-speed imaging device.

[0015] Figure 4 It is shown that the Figure 2 FIG. 2 is a diagram of another embodiment of an image processing unit in a photographing unit.

[0016] Figure 5 It is shown that the Figure 2 Figures showing other embodiments of the lighting unit in the photographing unit.

[0017] Description of symbols

[0018] 1: ultra-high-speed imaging device; 2: base; 4: frame; 10: workpiece; 12: plate; 20: support unit; 24: chuck table; 30: moving mechanism; 31: X-axis direction moving mechanism; 32: Y-axis direction moving mechanism; 40: imaging unit; 41: imaging device; 411: objective lens; 42: beam splitter; 43A, 43B: image processing unit; 431: first diffraction grating; 432: second diffraction grating; 44A, 44B: illumination unit; 441: broadband pulse light source; 442A, 442B: beam splitter; 45: reflector; 46: third diffraction grating; 47: fourth diffraction grating; 49: delay line; 50: alignment unit; 60: laser light irradiation unit; 62: condenser; 80: combiner; R1: first optical path; R2: second optical path; R3: third optical path. DETAILED DESCRIPTION

[0019] Hereinafter, an ultra-high speed imaging device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0020] exist Figure 1 , a perspective view of the ultra-high speed imaging device 1 of the present embodiment is shown. The ultra-high speed imaging device 1 comprises: a support unit 20 for supporting the workpiece 10; a moving mechanism 30 for moving the support unit 20; an imaging unit 40 for imaging the workpiece 10; and an alignment unit 50. In addition, in the present embodiment, in order to verify the mechanism when the laser beam LB is irradiated to the workpiece 10, a laser beam irradiation unit 60 for irradiating the laser beam LB to the workpiece 10 supported by the support unit 20 is also provided.

[0021] The supporting unit 20 includes: a rectangular X-axis movable plate 21, which is mounted on the base 2 so as to be movably disposed in the X-axis direction indicated by the arrow X in the figure; a rectangular Y-axis movable plate 22, which is mounted on the X-axis movable plate 21 so as to be movably disposed in the Y-axis direction indicated by the arrow Y in the figure; a cylindrical support 23, which is fixed to the upper surface of the Y-axis movable plate 22; and a rectangular cover plate 26, which is fixed to the upper end of the support 23. A circular chuck table 24 extending upward through a long hole 26a formed on the cover plate 26 is provided on the cover plate 26. The chuck table 24 supports the workpiece 10 and is configured to be rotatable by a rotation drive unit not shown in the figure. A circular adsorption chuck (not shown) is arranged on the upper surface of the chuck table 24. The adsorption chuck is formed of a porous material and extends substantially horizontally. In addition, Figure 1 In the embodiment, a circular plate 12 having a workpiece 10 bonded at the center is arranged on the upper surface of the chuck table 24 , and the workpiece 10 is supported on the chuck table 24 via the plate 12 .

[0022] The moving mechanism 30 is disposed on the base 2, and includes an X-axis moving mechanism 31 that moves the support unit 20 in the X-axis direction, and a Y-axis moving mechanism 32 that moves the support unit 20 in the Y-axis direction. The X-axis moving mechanism 31 converts the rotational motion of the pulse motor 33 into a linear motion via a ball screw 34 and transmits the linear motion to the X-axis movable plate 21, so that the X-axis movable plate 21 moves forward and backward in the X-axis direction along the guide rails 2a, 2a on the base 2. The Y-axis moving mechanism 32 converts the rotational motion of the pulse motor 35 into a linear motion via a ball screw 36 and transmits the linear motion to the Y-axis movable plate 22, so that the Y-axis movable plate 22 moves forward and backward in the Y-axis direction along the guide rails 21a, 21a on the X-axis movable plate 21. In addition, although not shown in the figure, the X-axis moving mechanism 31, the Y-axis moving mechanism 32, and the chuck table 24 are equipped with position detection units, which can accurately detect the X-axis position, the Y-axis position, and the circumferential rotation position of the chuck table 24. The position of the chuck table 24 is transmitted to the control unit 100 described later, and the X-axis moving mechanism 31, the Y-axis moving mechanism 32, and the rotation drive unit of the chuck table 24 (not shown) are driven according to the instruction signal indicated by the control unit 100, so that the chuck table 24 can be positioned at an arbitrary coordinate position and rotation angle.

[0023] A frame 4 is erected on the side of the moving mechanism 30. The frame 4 has a vertical wall 4a disposed on the base 2 and a horizontal wall 4b extending in the horizontal direction from the upper end of the vertical wall 4a. The optical system of the imaging unit 40 is built into the horizontal wall 4b of the frame 4. Figure 1 as well as Figure 2 The schematic structure of the imaging unit 40 is described with reference to the block diagram of the imaging unit 40 shown in FIG.

[0024] The imaging unit 40 includes: an objective lens 411, which is built into the imaging device 41 opposite to the workpiece 10 supported by the supporting unit 20; a beam splitter 42, which is arranged on a first optical path R1 extending from the objective lens 411; an image processing unit 43A, which is arranged on a second optical path R2 extending from the beam splitter 42 to one side; and an illumination unit 44A, which is arranged on a third optical path R3 extending from the beam splitter 42 to the other side.

[0025] The illumination unit 44A includes a broadband pulse light source 441 and a spectrometer 442A that splits a single pulse of light output from the broadband pulse light source 441 into a plurality of wavelengths and generates a time difference. The broadband pulse light source 441 is a light source that can oscillate broadband pulsed light, and can be composed of, for example, a pulsed laser oscillator, a super continuous light source, a flash lamp, or the like.

[0026] The broadband pulse light source 441 can irradiate light under the following conditions, for example.

[0027]

[0028] As an example, the optical splitter 442A is Figure 2 The FBG (Fiber Bragg Grating) shown in FIG. FBG is achieved by engraving a plurality of diffraction gratings at a predetermined interval at a predetermined position in the optical fiber to form a reflection portion 442a, and only light of a specific wavelength component of the incident light can be reflected in the reflection portion 442a. A plurality of such reflection portions 442a that reflect light of a predetermined wavelength are arranged at a predetermined distance in the optical fiber, so that the light L1 oscillated from the broadband pulse light source 441 is split into lights of a plurality of wavelengths, and each light split according to the wavelength is outputted with a time difference corresponding to the predetermined distance. More specifically, the broadband light (white light) including the wavelength of 400nm to 900nm oscillated from the broadband pulse light source 441, namely the pulse light L1, is introduced into the spectrometer 442A composed of FBG via the optical fiber 443, and the spectrometer 442A splits the light L1 into light L2 according to the wavelength (400nm, 450nm...850nm, 900nm) at intervals of 50nm. The light L2 is composed of the spectrometers P1 to P11 with a time difference of 10ns according to each wavelength. The light L2 split by the spectrometer 442A is introduced into the optical fiber 444 connected to the spectrometer 442A, and is output to the outside from the end 444a.

[0029] The light L2 output from the end 444a of the optical fiber 444 is converted into parallel light L3 via the collimating lens 445, converged by the focusing lens 446, and introduced into the beam splitter 42. As described above, the parallel light L3 is composed of split lights P1 to P11 that have a time difference of 10ns according to the wavelength. In the figure, for the sake of convenience, only P1, P2, P9, P10 and P11 are shown, but in fact, P3 to P8 are also included. The parallel light L3 introduced into the beam splitter 42 is reflected by the inclined surface 42a of the beam splitter 42 at a specified ratio and introduced into the first optical path R1 side including the beam splitter 42 and the objective lens 411, and irradiated to the workpiece 10 as the illumination light L4 via the objective lens 411.

[0030] The return light L5 reflected on the workpiece 10 irradiated with the illumination light L4 is converted into parallel light by the objective lens 411, returns to the beam splitter 42, passes through the inclined surface 42a of the beam splitter 42, becomes the return light L6 which is condensed by the condenser lens 447, and is introduced into the image processing unit 43A. In addition, the optical path extending from the beam splitter 42 and provided with the image processing unit 43A is referred to as the second optical path R2.

[0031] The image processing unit 43A is a unit for photographing the workpiece 10 by the return light L6 reflected and transmitted from the workpiece 10. More specifically, the image processing unit 43A has a first diffraction grating 431 and a second diffraction grating 432 for splitting the return light L6. The first diffraction grating 431 makes the return light L6 into return light L7 split by changing the angle for each wavelength, and the second diffraction grating 432 makes the return light L7 into return light L8 adjusted to be parallel by adjusting the angle for each wavelength. The return light L8 is introduced into the image sensor 435 as the return light L9 whose expansion range is adjusted through the condenser lens 433 and the collimator lens 434. The image sensor 435 is connected to the control unit 100.

[0032] The control unit 100 is composed of a computer, and the control unit 100 has: a central processing unit (CPU) that performs calculations according to a control program; a read-only memory (ROM) that stores the control program, etc.; a readable and writable random access memory (RAM) that temporarily stores the captured image information, etc.; and an input interface and an output interface (the details are omitted in the figure). The image information captured by the image sensor 435 is stored in the storage unit 110 composed of a memory (RAM) of the control unit 100, and can be output to the display unit 70 connected via the output interface of the control unit 100. By configuring the image processing unit 43A in this way, the image sensor 435 can capture the workpiece 10 at a time interval of 10ns, such as a decomposed photograph, based on the return light L9 reflected and transmitted on the workpiece 10. In addition, various sensors and various operating units provided in the ultra-high-speed imaging device 1, such as the X-axis direction moving mechanism 31, the Y-axis direction moving mechanism 32, the laser light irradiation unit 60, etc., are also connected to the control unit 100, and are controlled by the control unit 100.

[0033] return Figure 1 Continuing the description, an optical system (not shown) of a laser beam irradiation unit 60 is also built inside the horizontal wall portion 4b of the frame 4. A condenser 62 constituting a part of the laser beam irradiation unit 60 is provided on the lower surface of the front end portion of the horizontal wall portion 4b, and a condenser lens (not shown) and the like are built inside the condenser 62. The laser beam irradiation unit 60 is provided with a laser oscillator (not shown), and the laser beam LB emitted from the laser oscillator is condensed by the condenser 62 and irradiated to a predetermined irradiation position of the workpiece 10 held by the support unit 20.

[0034] The alignment unit 50 is disposed on the lower surface of the front end of the horizontal wall portion 4b at a position adjacent to the camera 41 of the camera unit 40 in the X-axis direction. The alignment unit 50 includes an illumination unit for irradiating visible light and an image pickup element (CCD) for taking an image using visible light. The alignment unit 50 takes an image of the workpiece 10, thereby accurately aligning the position photographed by the camera 41 with the position of the workpiece 10 supported by the chuck table 24 to be photographed.

[0035] The ultra-high speed imaging device 1 of the present embodiment has a structure roughly as described above. The following describes the steps of photographing a process of forming a processing mark by using the ultra-high speed imaging device 1 to irradiate the workpiece 10 supported by the support unit 20 with a laser beam LB as a decomposed photograph.

[0036] First, according to Figure 1As described, a workpiece group is prepared in which a workpiece 10 formed of, for example, silicon (Si) and formed into a rectangular plate is bonded at the center of a circular plate 12, and is placed on a chuck table 24 and supported by suction by operating a suction unit (not shown).

[0037] If the workpiece 10 is supported on the chuck table 24 of the support unit 20 as described above, the X-axis direction moving mechanism 31 and the Y-axis direction moving mechanism 32 are operated to move the chuck table 24, and the workpiece 10 is positioned directly below the alignment unit 50, and the position of the irradiation position of the irradiation laser beam LB is detected. In addition, it is preferable to add a desired mark at the irradiation position.

[0038] When the irradiation position is detected by the alignment unit 50, the moving mechanism 30 is operated to position the irradiation position of the workpiece 10 directly below the imaging device 41 having the objective lens 411. Figure 3 4 shows the workpiece 10 viewed from the objective lens 411 side, and the irradiation position Q of the laser beam LB irradiated by the laser beam irradiation unit 60 and the area A focused and imaged by the objective lens 411 are shown by dotted lines.

[0039] If the workpiece 10 is positioned directly below the camera 41, Figure 2 The lighting unit 44A of the imaging unit 40 shown in the figure is in operation. By operating the lighting unit 44A, a broadband light L1 with a pulse width of 100 ns is introduced from the broadband pulse light source 441 to the spectrometer 442A via the optical fiber 443. The spectrometer 442A splits the light L1 introduced to the spectrometer 442A into light with a wavelength of 50 nm intervals (400 nm, 450 nm ... 800 nm, 850 nm, 900 nm), and converts the light L1 into light L2 with a time difference of 10 ns corresponding to the split light, and outputs it via the optical fiber 444. The light L2 irradiated from the end 444a of the optical fiber 444 is converted into parallel light by the collimating lens 445, and is converted into split light P1 to split light P11 (parallel light L3) with a time difference of 10 ns and a wavelength of 400 nm, 450 nm ... 800 nm, 850 nm, 900 nm, and is output. In addition, broadband pulsed white light L1 corresponding to a predetermined frequency is repeatedly irradiated from the broadband pulse light source 441 , and each light L1 is split as described above by the spectrometer 442 in response to each pulsed light L1 .

[0040] The parallel light L3 is introduced into the beam splitter 42 via the condenser lens 446, and is reflected at a predetermined ratio by the inclined surface 42a, and changes the optical path to the chuck table 24 side to become the light L4. The light L4 whose optical path is changed by the beam splitter 42 is introduced into the workpiece 10 via the objective lens 411. Accordingly, the laser beam LB for processing is irradiated from the laser beam irradiation unit 60 to the irradiation position Q of the workpiece 10.

[0041] Regarding the area A (see Figure 3 ) and the return light L5 reflected in the range including the peripheral area of ​​area A are made parallel by the objective lens 411, introduced into the beam splitter 42 and passed through the beam splitter 42. The return light L5 that has passed through the beam splitter 42 becomes the return light L6 that is condensed by the condensing lens 447 and introduced into the image processing unit 43A.

[0042] The return light L6 introduced into the image processing unit 43A is first introduced into the first diffraction grating 431. The first diffraction grating 431 is formed with: a central portion 431a, which functions as a diffraction grating; and a mask portion 431b, which is masked so as not to function as a diffraction grating and has a function as a one-dimensional mask that limits the area A irradiated by the laser light LB to only the vicinity of a narrower irradiation position Q. The return light L6 introduced into the first diffraction grating 431 is as follows: Figure 2 The light is split as shown, and becomes return light L7 which has expansibility and changes its angle according to each wavelength.

[0043] The return light L7 dispersed by the first diffraction grating 431 is introduced into the second diffraction grating 432 to become the return light L8 of the dispersed light P1 to P11 of each wavelength in parallel. The return light L8 reflected by the second diffraction grating 432 is introduced into the image sensor 435 after the expansion range is adjusted in accordance with the shooting area of ​​the image sensor 435 through the focusing lens 433 and the collimating lens 434.

[0044] Regarding the process of irradiating the workpiece 10 with the laser beam LB through the spectroscopic beams P1 to P11 irradiating the workpiece 10 at time intervals of 10 ns, the state in which the angle is changed by the first diffraction grating 431 and the second diffraction grating 432 is transmitted to the image sensor 435 as image information.

[0045] The image information captured by the image sensor 435 is stored in the storage unit 110 provided in the control unit 100, and is output to the display unit 70 connected to the control unit 100, such as Figure 2As shown, the spectra P1 to P11 are displayed continuously corresponding to each other. The spectra P1 to P11 capture the area A including the irradiation position Q of the workpiece 10 every 10 ns, and shoot the changes in the time period of 100 ns in total at 10 ns intervals like a decomposed photo and output as image information. That is, the resolution of the decomposed image captured by the image processing unit 43A is 10 ns / second, so it is an ultra-high-speed image with a resolution of 1 / 100 million, which can accurately verify the mechanism of the workpiece 10 being processed by the laser light LB at high speed. In addition, by appropriately adjusting the repetition frequency of the broadband pulse light source 441 and the time interval of the spectra P1 to P11 generated by the spectrometer 442A, the mechanism of the workpiece 10 being processed can be further continuously verified.

[0046] According to the present invention, various modifications are provided without being limited to the above-mentioned embodiment. Figure 2 In the image processing unit 43A of the imaging unit 40 shown in FIG. 1 , the return light irradiated to the workpiece 10 and reflected is split by changing the angle for each wavelength by the first diffraction grating 431 and the second diffraction grating 432, but the present invention is not limited thereto and may also be adopted. Figure 4 The other image processing unit 43B shown in FIG. Figure 4 The image processing unit 43B shown in FIG. 40 is a photographing unit, except that Figure 4 The other image processing units other than the image processing unit 43B are Figure 2 The structure of the photographing unit 40 shown in FIG. 1 is the same as that of the photographing unit 40, so the description thereof is omitted. Figure 4 In the image processing unit 43B shown in FIG. Figure 2 The first diffraction grating 431 and the second diffraction grating 432 shown in the figure are provided with a reflector 45 and a third diffraction grating 46. The reflector 45 reflects the return light L6 including the spectroscopic light P1 to P11 spectroscopically divided at wavelengths of 50 nm intervals (400 nm, 450 nm ... 850 nm, 900 nm) introduced into the image processing unit 43B, and adjusts the direction of its optical path to become the return light L7'. In addition, the reflector 45 also has a central portion 45a that functions as a reflector and a mask portion 45b that is masked in a manner that does not function as a reflector, and has a function as a one-dimensional mask that limits the shooting area to a narrower area with respect to the area A irradiated with the laser light LB.

[0047] The return light L7' is introduced into the third diffraction grating 46. The return light L7' introduced into the third diffraction grating 46 is as follows: Figure 4The light is split as shown, and the return light L8' is expanded by changing the angle according to each wavelength. The return light L8' passes through the collimating lens 434 to become parallel light, which is introduced into the image sensor 435 and captured as image information. The image information introduced into the image sensor 435 is transmitted to the control unit 100 in the same manner as in the above embodiment, and is stored in the storage unit 110 provided in the control unit 100, and is output to the display unit 70 connected to the control unit 100, and becomes corresponding to the split light P1 to P11. Figure 2 The image information shown is taken at 10ns intervals like a decomposed photograph.

[0048] In addition, the present invention may replace the lighting unit 44A of the above embodiment with Figure 5 The other lighting unit 44B shown. Figure 5 The other lighting unit 44B will be described.

[0049] exist Figure 5 The lighting unit 44B shown is also provided with a broadband pulse light source 441 similar to the lighting unit 44A. The broadband light L1 irradiated from the broadband pulse light source 441 is introduced into the spectrometer 442B via the optical fiber 443. The light L1 introduced into the spectrometer 442B becomes parallel light by the collimating lens 448 provided in the spectrometer 442B, and is introduced into the fourth diffraction grating 47. The light L1 introduced into the fourth diffraction grating 47 becomes light L10 including spectroscopic light P1 to P11 with wavelengths (400nm, 450nm…850nm, 900nm) whose angles are changed according to the wavelength and are split at intervals of 50nm by the fourth diffraction grating 47, and the light L10 is introduced into the reflector 48. In addition, at Figure 5 In FIG. 1 , only the optical axis of each wavelength is shown, but in reality, the light is irradiated while continuously changing the angle according to the wavelength.

[0050] The light L10 reflected by the reflector 48 passes through the collimating lens 449 to become parallel light L11, and is introduced into the introduction part 49A of the delay line 49 having different optical path lengths and time differences according to each wavelength split by the fourth diffraction grating 47. The delay line 49 is composed of 11 optical fibers 49a to 49k of different lengths, and the split lights P1 to P11 of wavelengths (400nm, 450nm...850nm, 900nm) whose angles are changed by the fourth diffraction grating 47 for each wavelength at 50nm intervals are introduced into the optical fibers 49a to 49k respectively. The split lights P1 to P11 introduced into the delay line 49 are introduced into the combiner 80 through the optical fibers 49a to 49k constituting the delay line 49.

[0051] The optical fibers 49a to 49k constituting the delay line 49 are set such that the optical fiber 49a is the shortest, and the optical fibers 49b, 49c, ... are longer in order, and the optical fiber 49k is the longest. At this time, the difference in length of adjacent optical fibers is set such that the light simultaneously introduced into the introduction portion 49A arrives at the combiner 80 at a time interval of 10ns. The split light P1 to P11 introduced into the combiner 80 is combined in the combiner 80, output from the end 444a of the optical fiber 444 as light L2, and introduced into the collimating lens 445 of the shooting unit 40. In addition, the above-mentioned combiner 80 can be composed of a well-known optical fiber coupler, an integration rod, etc. According to the lighting unit 44B, it can also play the same role as that according to Figure 2 The lighting unit 44A described above has exactly the same functions.

[0052] In the above-mentioned embodiment, in order to photograph the process of forming a processing mark by irradiating the laser beam LB emitted from the laser beam irradiation unit 60 to the workpiece 10, the laser beam irradiation unit 60 is provided in the ultra-high-speed imaging unit 1. However, in the present invention, the laser beam irradiation unit 60 is not necessarily provided in the ultra-high-speed imaging unit 1, and the laser beam irradiation unit 60 may be prepared separately from the ultra-high-speed imaging unit 1. In addition, as a unit for processing the workpiece 10 supported by the ultra-high-speed imaging device 1, it is not necessarily necessary to have the laser beam irradiation unit 60. In order to photograph the process of generating cracks, a device that applies an impact to the workpiece 10 may be used. The unit provided for photographing the processing process is not limited to a specific unit.

Claims

1. An ultra-high-speed photographing device, wherein: The ultra-high-speed imaging device has: A chuck table that supports a workpiece; and A photographing unit is used to photograph the workpiece supported by the chuck table. The shooting unit includes: An objective lens, which is opposite to the workpiece supported by the chuck table; A beam splitter is arranged on a first optical path extending from the objective lens; an image processing unit disposed on a second optical path extending from the beam splitter; as well as an illumination unit disposed on a third optical path extending from the beam splitter, The lighting unit comprises: A broadband pulse light source capable of oscillating broadband pulsed light; and a spectrometer that splits a single pulse of light emitted from the broadband pulse light source into a plurality of wavelengths of light included in the broadband pulse light and generates a time difference, The image processing unit includes: a diffraction grating for splitting the return light irradiated to the workpiece supported by the chuck table according to the time difference by changing the angle for each wavelength; and An image sensor captures the return light dispersed by the diffraction grating in the region for each angle corresponding to the wavelength, like a resolved photograph.

2. The ultra-high-speed imaging device according to claim 1, wherein: The ultra-high-speed filming device also has: a storage unit for storing images captured by the image sensor; and The display unit displays the image stored in the storage unit.

3. The ultra-high-speed imaging device according to claim 1, wherein: The diffraction grating includes a first diffraction grating that separates the return light by changing the angle for each wavelength and a second diffraction grating that parallelizes the return light separated by the first diffraction grating and guides the parallelized light to the image sensor.

4. The ultra-high-speed imaging device according to claim 1, wherein: The diffraction grating splits the return light reflected at a predetermined angle by the reflection mirror at different angles for each wavelength, and guides the light to the image sensor through a collimator lens.

5. The ultra-high-speed imaging device according to claim 1, wherein: The beam splitter contains: a diffraction grating for splitting light of one pulse from the broadband pulse light source by changing an angle for each of a plurality of wavelengths; a delay line that makes the optical path length different for each wavelength separated by the diffraction grating, thereby generating a time difference; and A combiner combines the light delayed by each wavelength through the delay line.

Images