阅读说明：本技术 超高速拍摄装置 (Ultra-high speed shooting device ) 是由 能丸圭司 伊藤优作 于 2020-03-19 设计创作，主要内容包括：提供超高速拍摄装置,其能够以更高的分辨率进行拍摄。超高速拍摄装置的拍摄单元包含：物镜,其与卡盘工作台所支承的被加工物对置；分束器,其配设于从物镜延伸的第一光路上；图像处理单元,其配设于从分束器延伸的第二光路上；以及照明单元,其配设于从分束器延伸的第三光路上。照明单元包含：宽频带脉冲光源；以及分光器,其将从宽频带脉冲光源射出的1脉冲的光分光成多个波长并且产生时间差。图像处理单元包含：衍射光栅,其将以时间差照射至卡盘工作台所支承的被加工物的返回光按照每个波长改变角度而进行分光；以及图像传感器,其在与波长对应的每个角度的区域如分解照片那样拍摄通过衍射光栅而分光的返回光。(Provided is an ultra-high-speed imaging device capable of imaging with a higher resolution. The shooting unit of the ultra-high speed shooting device comprises: an objective lens which is opposite to the processed object supported by the chuck worktable; a beam splitter disposed 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; and an illumination unit disposed on a third light path extending from the beam splitter. The illumination unit includes: a broadband pulsed light source; and a beam splitter that splits 1-pulse 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 for splitting the return light irradiated to the workpiece supported by the chuck table at a time difference by changing an angle for each wavelength; and an image sensor that captures return light split by the diffraction grating as a resolved photograph in a region of each angle corresponding to a wavelength.)

1. An ultra-high speed photographing apparatus, wherein,

the ultra-high speed shooting device comprises:

a chuck table for supporting a workpiece; and

an imaging unit for imaging the workpiece supported by the chuck table,

the shooting unit includes:

an objective lens facing the workpiece supported by the chuck table;

a beam splitter disposed 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; and

an illumination unit disposed on a third light path extending from the beam splitter,

the lighting unit includes:

a broadband pulsed light source; and

a beam splitter for splitting the 1-pulse light emitted from the broadband pulse light source into a plurality of wavelengths and generating 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 at time intervals by changing the angle for each wavelength; and

and an image sensor that captures return light split by the diffraction grating in a region of each angle corresponding to a wavelength as a resolved photograph.

2. The ultra-high speed photographing apparatus according to claim 1, wherein,

the ultra-high speed photographing apparatus further includes:

a storage unit that stores an image captured by the image sensor; and

and a display unit that displays the image stored in the storage unit.

3. The ultra-high speed photographing apparatus according to claim 1, wherein,

the diffraction grating includes a first diffraction grating that splits the return light by changing the angle for each wavelength, and a second diffraction grating that introduces the return light split by the first diffraction grating into parallel light to the image sensor.

4. The ultra-high speed photographing apparatus according to claim 1, wherein,

the diffraction grating splits return light reflected at a predetermined angle by a mirror by changing the angle for each wavelength, and introduces the split return light to the image sensor through a collimator lens.

5. The ultra-high speed photographing apparatus according to claim 1, wherein,

the optical splitter includes:

a diffraction grating for splitting the 1-pulse light from the broadband pulse light source by changing an angle for each of a plurality of wavelengths;

a delay line that generates a time difference by making an optical path length different for each wavelength of light split by the diffraction grating; and

and a multiplexer for multiplexing the light delayed for each wavelength by the delay line.

Technical Field

The present invention relates to an ultra-high speed imaging device that continuously images a workpiece supported by a support unit at a high speed.

Background

A workpiece having a plurality of devices such as an IC and an LSI formed on a front surface thereof and partitioned by a plurality of intersecting planned dividing lines is divided into device chips by a dicing apparatus having a cutting blade, a laser processing apparatus having a laser condenser, or the like, and the divided device chips are used for electronic devices such as a mobile phone and a personal computer.

In addition, in the cutting apparatus, a method of continuously photographing a cutting tool and a workpiece with a so-called high-speed camera and verifying a mechanism in a process of performing cutting processing is attempted. Here, when the rotation speed of the cutting tool is, for example, about 30,000rpm and the number of imaging frames of the high-speed camera is, for example, 45,000/sec, the time period during which the cutting tool rotates once can be put in an image of about 90 frames, and therefore the condition of the cutting process of the cutting tool can be sufficiently verified.

On the other hand, for example, in the case of verifying the mechanism when a machining mark is formed by performing machining by irradiating a laser beam (for example, see patent document 1), or in the case of verifying the mechanism how a crack propagates when a crack is generated by performing a fracture test or the like, the resolution of the above-described conventionally known high-speed camera is about several tens of thousands of frames/second at best, and therefore, the mechanism cannot be verified sufficiently, and an ultra-high-speed imaging device capable of imaging with a higher resolution is required.

Patent document 1: japanese patent laid-open publication No. 2014-221483

Disclosure of Invention

Accordingly, an object of the present invention is to provide an ultra-high speed imaging device capable of imaging with a higher resolution.

According to the present invention, there is provided an ultra-high speed photographing apparatus, comprising: a chuck table for supporting a workpiece; and an imaging unit that images the workpiece supported by the chuck table, the imaging unit including: an objective lens facing the workpiece supported by the chuck table; a beam splitter disposed 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; and an illumination unit disposed on a third light path extending from the beam splitter, the illumination unit including: a broadband pulsed light source; and a beam splitter that splits 1-pulse light emitted from the broadband pulse light source into a plurality of wavelengths and generates a time difference, the image processing unit including: a diffraction grating for splitting the return light irradiated to the workpiece supported by the chuck table at time intervals by changing the angle for each wavelength; and an image sensor that captures return light split by the diffraction grating in a region of each angle corresponding to a wavelength as a resolved photograph.

Preferably, the ultra-high speed photographing apparatus further includes: a storage unit that stores an image captured by the image sensor; and a display unit that displays the image stored in the storage unit.

Preferably, the diffraction grating includes a first diffraction grating that splits the return light by changing an angle for each wavelength, and a second diffraction grating that introduces the return light split by the first diffraction grating into parallel light to the image sensor. Preferably, the diffraction grating splits the return light reflected at a predetermined angle by the mirror by changing the angle for each wavelength, and introduces the split return light to the image sensor through the collimator lens.

Preferably, the optical splitter comprises: a diffraction grating for splitting the 1-pulse light from the broadband pulse light source by changing an angle for each of a plurality of wavelengths; a delay line that generates a time difference by making an optical path length different for each wavelength of light split by the diffraction grating; and a combiner that combines the light delayed for each wavelength by the delay line.

According to the present invention, for example, since the return light applied to the workpiece with a time difference of 10ns can be split by changing the angle for each wavelength and the split return light can be captured as an exploded photograph in the region of each angle corresponding to the wavelength, it is possible to easily acquire a super high speed image with a resolution of 10ns/1 second, that is, 1/1 billion.

Drawings

Fig. 1 is a perspective view of an ultra-high speed photographing apparatus according to an embodiment of the present invention.

Fig. 2 is a block diagram of an imaging unit provided in the ultra-high speed imaging apparatus shown in fig. 1.

Fig. 3 is a plan view of a workpiece supported by a chuck table of the ultra-high speed imaging device.

Fig. 4 is a diagram showing another embodiment of an image processing unit provided in the photographing unit shown in fig. 2.

Fig. 5 is a diagram showing another embodiment of the illumination unit provided in the photographing unit shown in fig. 2.

Description of the reference symbols

1: an ultra-high speed photographing device; 2: a base station; 4: a frame body; 10: a workpiece; 12: a plate; 20: a support unit; 24: a chuck table; 30: a moving mechanism; 31: an X-axis direction moving mechanism; 32: a Y-axis direction moving mechanism; 40: a shooting unit; 41: a camera; 411: an objective lens; 42: a beam splitter; 43A, 43B: an image processing unit; 431: a first diffraction grating; 432: a second diffraction grating; 44A, 44B: a lighting unit; 441: a broadband pulsed light source; 442A, 442B: a light splitter; 45: a mirror; 46: a third diffraction grating; 47: a fourth diffraction grating; 49: a delay line; 50: an alignment unit; 60: a laser beam irradiation unit; 62: a condenser; 80: a combiner; r1: a first optical path; r2: a second optical path; r3: and a third light path.

Detailed Description

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

Fig. 1 is a perspective view of an ultra-high speed imaging apparatus 1 according to the present embodiment. The ultra-high speed imaging device 1 includes: 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 the present embodiment, in order to verify the mechanism when the workpiece 10 is irradiated with the laser beam LB, a laser beam irradiation unit 60 is further provided for irradiating the workpiece 10 supported by the support unit 20 with the laser beam LB.

The support unit 20 includes: a rectangular X-axis movable plate 21 which is movably mounted on the base 2 in an X-axis direction indicated by an arrow X in the figure; a rectangular Y-axis movable plate 22 movably mounted on the X-axis movable plate 21 in the Y-axis direction indicated by an arrow Y in the figure; a cylindrical support column 23 fixed to the upper surface of the Y-axis movable plate 22; and a rectangular cover plate 26 fixed to the upper end of the support column 23. The cover plate 26 is provided with a circular chuck table 24 extending upward through a long hole 26a formed in the cover plate 26. The chuck table 24 supports the workpiece 10 and is configured to be rotatable by a rotation driving unit, not shown. A circular suction chuck (not shown) formed of a porous material and extending substantially horizontally is disposed on the upper surface of the chuck table 24. In fig. 1, a circular plate 12 having a workpiece 10 adhered to the center thereof is disposed on the upper surface of a chuck table 24, and the workpiece 10 is supported by the chuck table 24 via the plate 12.

The moving mechanism 30 is disposed on the base 2, and the moving mechanism 30 includes: an X-axis direction moving mechanism 31 that moves the support unit 20 in the X-axis direction; and a Y-axis direction 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 linear motion via the ball screw 34, and transmits the linear motion to the X-axis movable plate 21, thereby moving the X-axis movable plate 21 forward and backward in the X-axis direction along the guide rails 2a, 2a on the base 2. The Y-axis direction moving mechanism 32 converts the rotational motion of the pulse motor 35 into linear motion via the ball screw 36 and transmits the linear motion to the Y-axis direction movable plate 22, and moves the Y-axis direction movable plate 22 forward and backward in the Y-axis direction along the guide rails 21a, 21a on the X-axis direction movable plate 21. Although not shown, position detection means are disposed in the X-axis direction moving mechanism 31, the Y-axis direction moving mechanism 32, and the chuck table 24, and the position in the X-axis direction, the position in the Y-axis direction, and the circumferential rotation position of the chuck table 24 can be accurately detected. The position of the chuck table 24 is transmitted to a control unit 100, which will be described later, and the X-axis direction moving mechanism 31, the Y-axis direction moving mechanism 32, and a rotation driving unit of the chuck table 24, which is not shown, are driven in accordance with an instruction signal instructed from the control unit 100, so that the chuck table 24 can be positioned at an arbitrary coordinate position and rotation angle.

The frame 4 is erected on a side of the moving mechanism 30. The frame 4 includes a vertical wall 4a disposed on the base 2 and a horizontal wall 4b extending horizontally from an upper end of the vertical wall 4 a. The horizontal wall portion 4b of the housing 4 contains an optical system of the imaging unit 40. A schematic configuration of the imaging unit 40 will be described with reference to block diagrams of the imaging unit 40 shown in fig. 1 and 2.

The photographing unit 40 includes: an objective lens 411 which is placed in the imaging device 41 facing the workpiece 10 supported by the support unit 20; a beam splitter 42 disposed on a first optical path R1 extending from the objective lens 411; an image processing unit 43A disposed on a second optical path R2 extending in one direction from the beam splitter 42; and an illumination unit 44A disposed on a third optical path R3 extending from the beam splitter 42 to the other side.

The illumination unit 44A has: a broadband pulsed light source 441; and a beam splitter 442A that splits the 1-pulse 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 pulse light, and may be configured by, for example, a pulse laser oscillator, a Super continuous light (Super continuous) light source, a flash lamp, or the like.

The broadband pulse light source 441 can emit light under the following conditions, for example.

The beam splitter 442A is implemented by an FBG (Fiber Bragg Grating) shown in fig. 2, for example. The FBG has a reflection section 442a formed by etching a plurality of diffraction gratings at predetermined positions at predetermined intervals in an optical fiber, and is capable of reflecting only light of a specific wavelength component of incident light in the reflection section 442 a. A plurality of such reflecting portions 442a that reflect light of a predetermined wavelength are arranged at predetermined distances in the optical fiber, so that the light L1 emitted from the broadband pulse light source 441 is split into light of a plurality of wavelengths, and each split light is output with a time difference corresponding to the predetermined distance. More specifically, pulsed light L1, which is broad-band light (white light) including wavelengths of 400nm to 900nm oscillated from the broad-band pulsed light source 441, is introduced into the spectroscope 442A formed of an FBG through the optical fiber 443, and the light L1 is dispersed by the spectroscope 442A at wavelengths of 50nm intervals (400nm, 450nm … 850nm, 900nm) to become light L2, and the light L2 is formed of light components P1 to P11 having time differences of 10ns depending on the wavelengths. The light L2 split by the beam splitter 442A is guided to the optical fiber 444 connected to the beam splitter 442A, and is output to the outside from the end 444 a.

The light L2 output from the end 444a of the optical fiber 444 is collimated by the collimator lens 445 into the parallel light L3, and is condensed by the condenser lens 446 and introduced into the beam splitter 42. As described above, the parallel light L3 is composed of the spectral light P1 to P11 in which the time difference of 10ns is generated depending on the wavelength. In the drawings, for convenience of explanation, only P1, P2, P9, P10 and P11 are shown, but actually, P3 to P8 are also included. The parallel light L3 guided to the beam splitter 42 is reflected at a predetermined ratio by the inclined surface 42a of the beam splitter 42, guided to the first optical path R1 side including the beam splitter 42 and the objective lens 411, and irradiated as illumination light L4 to the workpiece 10 via the objective lens 411.

The return light L5 reflected on the workpiece 10 irradiated with the illumination light L4 is collimated 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 condensed by the condenser lens 447, and is introduced into the image processing unit 43A. The optical path extending from the beam splitter 42 and provided with the image processing unit 43A is defined as a second optical path R2.

The image processing unit 43A is a unit that images the workpiece 10 by the return light L6 reflected and transmitted from the workpiece 10, and more specifically, the image processing unit 43A includes a first diffraction grating 431 and a second diffraction grating 432 that split the return light L6. The first diffraction grating 431 makes the return light L6 become the return light L7 which is split while changing the angle for each wavelength, and the second diffraction grating 432 makes the return light L7 become the return light L8 which is adjusted to be parallel while adjusting the angle for each wavelength. The return light L8 is guided to the image sensor 435 as return light L9 whose extension range is adjusted by the condenser lens 433 and the collimator lens 434. The image sensor 435 is connected to the control unit 100.

The control unit 100 is constituted by a computer, and the control unit 100 includes: a Central Processing Unit (CPU) that performs arithmetic processing in accordance with a control program; a Read Only Memory (ROM) that stores a control program and the like; a read-write capable Random Access Memory (RAM) for temporarily storing captured image information and the like; and an input interface and an output interface (details are omitted from the figure). Image information captured by the image sensor 435 is stored in the storage unit 110 of the control unit 100, which is configured by a memory (RAM), and can be output to the display unit 70 connected via an 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 as an exploded photograph at time intervals of 10ns from the return light L9 reflected and transmitted on the workpiece 10. Various sensors and various operating units disposed in the ultra-high speed imaging apparatus 1, for example, the X-axis direction moving mechanism 31, the Y-axis direction moving mechanism 32, the laser beam irradiation unit 60, and the like are connected to the control unit 100, and are controlled by the control unit 100.

Returning to fig. 1, the horizontal wall portion 4b of the housing 4 further includes an optical system (not shown) of the laser beam irradiation unit 60. A condenser 62 constituting a part of the laser beam irradiation unit 60 is disposed on the lower surface of the distal end portion of the horizontal wall portion 4b, and a condenser lens, not shown, is built in 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 converged by a condenser 62 and irradiated to a predetermined irradiation position of the workpiece 10 held by the support unit 20.

The alignment unit 50 is disposed at a position adjacent to the imager 41 of the imaging unit 40 in the X-axis direction on the lower surface of the front end portion of the horizontal wall portion 4 b. The alignment unit 50 has an illumination unit that irradiates visible rays and a photographing element (CCD) that performs photographing by the visible rays. The alignment unit 50 images the workpiece 10, and thereby precisely aligns the position imaged by the imaging device 41 with the position to be imaged of the workpiece 10 supported by the chuck table 24.

The super speed imaging apparatus 1 of the present embodiment has a configuration substantially as described above, and a procedure of taking an image of the object 10 supported by the support unit 20 by the super speed imaging apparatus 1 as an exploded photograph using the super speed imaging apparatus 1 to form a processing mark by irradiating the object with the laser beam LB will be described below.

First, as described with reference to fig. 1, a workpiece group in which a rectangular plate-shaped workpiece 10 made of, for example, silicon (Si) is bonded to the center of a circular plate 12 is prepared, placed on a chuck table 24, and suction-supported by operating a suction means (not shown).

When 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, the workpiece 10 is positioned directly below the alignment unit 50, and the position of the irradiation laser beam LB is detected. In addition, it is preferable to apply a desired mark at the irradiation position.

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. Fig. 3 shows the workpiece 10 viewed from the objective lens 411, and the irradiation position Q of the laser beam LB irradiated by the laser beam irradiation unit 60 and the region a imaged by focusing the objective lens 411 are shown by broken lines.

When the workpiece 10 is positioned directly below the imaging device 41, the illumination unit 44A of the imaging unit 40 shown in fig. 2 is operated. By operating the illumination unit 44A, the broad-band light L1 having a pulse width of 100ns is introduced from the broad-band pulse light source 441 to the beam splitter 442A via the optical fiber 443. The spectrometer 442A splits the light L1 introduced into the spectrometer 442A into light having wavelengths at intervals of 50nm (400nm, 450nm … 800nm, 850nm, 900nm), converts the light L1 into light L2 having a time difference of 10ns according to the split light, and outputs the light L2 via the optical fiber 444. The light L2 irradiated from the end 444a of the optical fiber 444 is collimated by the collimator lens 445, and is output as a beam P1 to a beam P11 (collimated light L3) having a time lag of 10ns and wavelengths of 400nm, 450nm … 800nm, 850nm, and 900 nm. Further, the wide-band pulse light source 441 repeatedly emits wide-band pulse-like white light L1 corresponding to a predetermined frequency, and the spectroscope 442 disperses the light L1 corresponding to the pulse-like light L1 as described above.

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

The return light L5 reflected in the region a (see fig. 3) including the irradiation position Q irradiated with the laser beam LB and in the region including the peripheral region of the region a is collimated by the objective lens 411, introduced into the beam splitter 42, and transmitted through the beam splitter 42. The return light L5 transmitted through the beam splitter 42 becomes return light L6 condensed by the condenser lens 447, and is introduced into the image processing unit 43A.

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 has formed therein: a center portion 431a functioning as a diffraction grating; and a mask portion 431b that is subjected to a masking process so as not to function as a diffraction grating and that has a function as a one-dimensional mask for limiting the region a irradiated with the laser beam LB to only the vicinity of the narrower irradiation position Q. The return light L6 introduced into the first diffraction grating 431 is split into return light L7 having the spreading property by changing the angle for each wavelength, as shown in fig. 2.

The return light L7 split by the first diffraction grating 431 is guided to the second diffraction grating 432 and becomes return light L8 in which the split lights P1 to P11 of the respective wavelengths are parallel. The return light L8 reflected by the second diffraction grating 432 and made parallel is guided to the image sensor 435 by adjusting the expansion range so as to match the imaging area of the image sensor 435 by the condenser lens 433 and the collimator lens 434.

The process of irradiating the workpiece 10 with the laser beam LB by the spectral beams P1 to P11 irradiated onto the workpiece 10 at time intervals of 10ns is transmitted to the image sensor 435 as image information in a state where the angles are changed by the first diffraction grating 431 and the second diffraction grating 432.

The image information captured by the image sensor 435 is stored in the storage unit 110 provided in the control unit 100, is output to the display unit 70 connected to the control unit 100, and is displayed in succession in accordance with the split lights P1 to P11, as shown in fig. 2. The spectral beams P1 to P11 capture the region a including the irradiation position Q of the workpiece 10 every 10ns, and capture changes over a total time period of 100ns at intervals of 10ns as decomposed photographs, and output the changes as image information. That is, since the resolution of the decomposed image captured by the image processing unit 43A is 10 ns/sec, it is an ultra-high-speed image with a resolution of 1/1 billion, and it is possible to accurately verify the mechanism of the workpiece 10 at the time of high-speed processing by the laser beam LB. Further, by appropriately adjusting the repetition frequency of the broadband pulse light source 441 and the time interval between the beam splitters P1 to P11 by the beam splitter 442A, the mechanism of the workpiece 10 during processing can be verified more continuously.

The present invention is not limited to the above embodiments and various modifications are provided. In the image processing unit 43A disposed in the imaging unit 40 shown in fig. 2, 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 to this, and another image processing unit 43B shown in fig. 4 may be employed. The imaging unit 40 using the image processing unit 43B shown in fig. 4 has the same configuration as the imaging unit 40 shown in fig. 2 except for the other image processing unit 43B shown in fig. 4, and therefore, the description thereof is omitted. In the image processing unit 43B shown in fig. 4, a mirror 45 and a third diffraction grating 46 are arranged instead of the first diffraction grating 431 and the second diffraction grating 432 shown in fig. 2. The mirror 45 reflects the return light L6, which is introduced into the image processing unit 43B and includes the spectral light P1 to P11 that is split at wavelengths (400nm, 450nm … 850nm, 900nm) of 50nm intervals, and adjusts the optical path direction thereof to be the return light L7'. The mirror 45 also has a central portion 45a that functions as a mirror and a mask portion 45b that is masked so as not to function as a mirror, and functions as a one-dimensional mask that limits the imaging area to a narrower area with respect to the area a to which the laser beam LB is applied.

The return light L7 ' is guided to the third diffraction grating 46, and the return light L7 ' guided to the third diffraction grating 46 is split into the return light L8 ' having spread by changing the angle for each wavelength, as shown in fig. 4. The return light L8' is collimated by the collimator lens 434, guided to 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-described embodiment, is stored in the storage unit 110 provided in the control unit 100, is output to the display unit 70 connected to the control unit 100, and is converted into image information captured as an exploded photograph at intervals of 10ns as shown in fig. 2 in accordance with the split beams P1 to P11.

In the present invention, another illumination unit 44B shown in fig. 5 may be used instead of the illumination unit 44A of the above embodiment. The other illumination unit 44B is explained with reference to fig. 5.

A broadband pulse light source 441 similar to the illumination unit 44A is also disposed in the illumination unit 44B shown in fig. 5. The broadband light L1 emitted from the broadband pulse light source 441 is introduced into the beam splitter 442B through the optical fiber 443. The light L1 guided to the beam splitter 442B is collimated by the collimator lens 448 provided in the beam splitter 442B and guided to the fourth diffraction grating 47. The light L1 introduced into the fourth diffraction grating 47 passes through the fourth diffraction grating 47 to become light L10 including the spectra P1 to P11 which are angularly changed according to the wavelength and are dispersed at the wavelength intervals of 50nm (400nm, 450nm … 850nm, 900nm), and the light L10 is introduced into the reflecting mirror 48. In fig. 5, only the optical axis for each wavelength is shown, but actually, light whose angle is continuously changed according to the wavelength is irradiated.

The light L10 reflected by the mirror 48 is collimated by the collimator lens 449 into light L11, and is introduced into the introduction portion 49A of the delay line 49, which has different optical path lengths and generates a time difference, for each wavelength of light split by the fourth diffraction grating 47. The delay line 49 is composed of 11 optical fibers 49a to 49k having different lengths, and the spectral beams P1 to P11 having wavelengths (400nm, 450nm … 850nm, 900nm) whose angles are changed for each wavelength at intervals of 50nm by the fourth diffraction grating 47 are introduced into the optical fibers 49a to 49k, respectively. The split beams P1 to P11 guided to the delay line 49 are guided to the multiplexer 80 through the optical fibers 49a to 49k constituting the delay line 49.

The optical fibers 49a to 49k constituting the delay line 49 are set so that the optical fiber 49a is shortest, the optical fiber 49b and the optical fiber 49c … are lengthened, and the optical fiber 49k is longest. At this time, the difference in length between the adjacent optical fibers is set so that the light introduced into the introduction portion 49A reaches the multiplexer 80 at time intervals of 10 ns. The split beams P1 to P11 guided to the combiner 80 are combined by the combiner 80, output as light L2 from the end 444a of the optical fiber 444, and guided to the collimator lens 445 of the imaging unit 40. The combiner 80 may be formed of a known fiber coupler, an integrated rod (integrated rod), or the like. The illumination unit 44B can also perform exactly the same function as the illumination unit 44A described with reference to fig. 2.

In the above embodiment, the laser beam irradiation unit 60 is provided in the ultrafast imaging unit 1 in order to image the workpiece 10 with the laser beam LB irradiated from the laser beam irradiation unit 60 to form the processing mark, but in the present invention, the laser beam irradiation unit 60 is not necessarily provided in the ultrafast imaging unit 1, and the laser beam irradiation unit 60 may be provided separately from the ultrafast imaging unit 1. The means for processing the workpiece 10 supported by the ultra-high speed imaging device 1 does not necessarily need to include the laser beam irradiation means 60, and may be a means for applying an impact to the workpiece 10 in order to image the crack generation process, and the means disposed for imaging the processing process is not limited to a specific means.