JP4436162B2 - Laser processing equipment - Google Patents

Description

The present invention relates to a laser pressurized KoSo location to form a direct fine shape on the processed material by irradiation of a laser beam, directed to the laser pressurized KoSo location to form particular processing unit of the plurality of locations simultaneously.

  As a conventional laser processing method, a laser beam is focused and irradiated on the surface of a workpiece, and processing is performed while relatively moving the position of the focusing point and the surface of the workpiece, so that a plurality of locations or planes can be obtained. There is a method of processing.

  In addition, as a method of processing a pattern in a plane at once, there is a processing method in which a mask is used to project and project the pattern onto the surface of the workpiece. Regarding such a technique, for example, Japanese Patent Laid-Open No. 10-319221 is known.

In particular, there is a method of forming a plurality of condensing points by using a diffractive optical element as a method of simultaneously drilling holes at a plurality of locations. Regarding this technique, for example, JP-A-10-34365 and JP-A-2001-138083 are known.
JP 10-319221 A JP 10-34365 A JP 2001-138083 A

  However, the disadvantages of processing by scanning the condensing point are that it takes time because it scans, and it is necessary to align the position, which is particularly expensive when performing highly accurate processing. Is given.

In addition, as a disadvantage of the projection processing method using a mask,
1. 1. It is difficult to produce a highly accurate mask. 3. Light utilization efficiency is poor due to the presence of the light-shielding part 3. Only one pattern can be obtained for one mask.

In addition, as a disadvantage of the method of focusing and processing multiple points by using a diffractive optical element,
1. 1. It is difficult to produce a diffractive optical element, and the cost is high. 2. Speckle noise appears. 3. Only one condensing pattern can be obtained for one diffractive optical element, and the flexibility is poor. For example, the relative irradiation intensity of each of the plurality of condensing points and the irradiation position cannot be changed.

The present invention has been made in view of the above problems, to provide a laser pressurized KoSo location to simultaneously form a number of working portions to the surface of the workpiece and its purpose.

The invention of claim 1 includes a light source for emitting a pulsed laser beam, the wavelength distribution control means for controlling the wavelength distribution of the pulse laser light emitted from the light source, the wavelength distribution is controlled by the wavelength distribution control means and the pulse laser beam, a laser processing apparatus and a light propagation means for propagating a manner spatially different positions depending on the wavelength distribution, the said wavelength distribution control means, the pulsed laser beam A laser provided with at least one set of a set of a wavelength dispersion element that disperses the wavelength and a spatial wavelength selection means that selects the wavelength of the pulsed laser light in which the wavelength is dispersed, provided in the spatial wavelength selection means It has a distribution spatially transmittance to limit the transmission of light, the gray mask, the intensity for each transmission wavelength is controlled, and the propagation of the said light propagation means The pulsed laser beam is irradiated to the processing site of the plurality of locations of the workpiece surface, machined portion of a plurality of locations of said workpiece surface is a laser machining apparatus according to claim Rukoto is laser processing simultaneously.

In the laser processing apparatus according to claim 1, a laser beam that oscillates in a pulsed manner as a light source, a laser beam converted by a wavelength conversion element of the laser beam, a light emitter that emits light using the laser beam, or the like is used. The intensity for each wavelength is adjusted by the intensity adjusting means, or only some wavelengths are selectively extracted. The wavelength distribution can be changed with time or for each pulse, or the selected wavelength can be changed. In addition, the laser light is spatially decomposed for each wavelength by the wavelength dispersion element, and the intensity distribution control is performed on the wavelength-resolved laser light by the spatial wavelength selection means, thereby controlling the wavelength intensity distribution of the laser light. Made. As the wavelength dispersion element, various elements such as a hologram element and a lens that change the spatial propagation position depending on the wavelength can be used. As the spatial wavelength selection means, it is possible to use various elements such as metal plates, slits, pinholes, etc. that limit the transmission of light depending on the spatial position, or ND filters with different transmitted light intensity depending on the spatial position. is there. Further, for example, by utilizing the reflection on the metal film can be formed such as by depositing a Cr on the transparent substrate, that controls the transmission area spatially light.

  The light from the light source whose wavelength distribution is controlled is subsequently propagated by the light propagation means arranged. This light propagation means is composed of, for example, a lens having a different focus depending on the wavelength, a diffraction element having a different propagation direction, a prism, and the like. The light that has passed through the light propagation means is collected at spatially different points on the workpiece surface for each wavelength. At this time, the workpiece can be moved in synchronization with the laser beam.

  Here, by adjusting the intensity of the light source wavelength or selecting the light source wavelength, it is possible to control the place or pattern of light irradiation on the surface of the workpiece. Thereby, the process which controlled the pattern to the several places of a to-be-processed object by one time laser beam irradiation is attained. Here, the processing includes not only a processing method that directly removes a material but also a phenomenon that induces a surface shape change, material alteration, refractive index modulation, and the like due to photoisomerization. Further, in the processing for modifying the material, it is possible to create a shape change by performing a process such as etching thereafter.

According to a second aspect of the present invention, the spatial wavelength selection unit is a photomask that limits light transmittance , further includes a moving unit that moves the photomask , and the selection wavelength is changed with time. The laser processing apparatus according to claim 1, wherein the apparatus is a laser processing apparatus. The photomask can be formed, for example, by vapor-depositing Cr on a transparent substrate, and spatially controls the light transmission region by utilizing reflection on the metal film.

This can be achieved by holding and moving the photomask on the moving stage. At this time, it is desirable that the moving means move in synchronization with the laser irradiation timing, and it is also possible to move in synchronization with the moving means of the workpiece. It is also possible to use various mask patterns by preparing a plurality of mask patterns and controlling the irradiation position by a moving means.

The invention according to claim 3, wherein the spatial wavelength selection means is a laser machining apparatus according to claim 1, characterized in that the spatial intensity modulator.

  As the spatial intensity modulator, a transmissive liquid crystal, a reflective liquid crystal element, a reflective digital micromirror, a MEMS element, or the like can be used. The spatial intensity modulator can change the amount of reflection or transmission over time. The spatial intensity modulator is preferably controlled in synchronism with the laser irradiation timing when controlling every time, and is controlled in synchronism with the moving means when using the workpiece moving means. Is desirable.

A fourth aspect of the present invention is the laser processing apparatus according to the third aspect, wherein the spatial intensity modulator includes a transmissive liquid crystal and a polarization separation element.

  In this configuration, a transmission type liquid crystal is used as the wavelength selection means, and a polarization separation element is provided in a part of the propagating light, thereby controlling the light intensity by the polarized light. As the polarization separation element, a polarization separation prism, a diffraction grating, or the like can be used.

  The transmissive liquid crystal can change the polarization direction of the transmitted light with time, and the liquid crystal pattern can be changed by an external control element. The transmission type liquid crystal is preferably controlled in synchronization with the laser irradiation timing. Further, when using the workpiece moving means, it is desirable to control in synchronization with the moving means.

  As the intensity adjusting means, an ND filter, a polarization separation element, a gray mask, or the like can be used. When forming a spatial wavelength distribution, it is possible to provide means for adjusting the laser intensity at at least some wavelengths. The intensity adjusting means can be controlled in synchronism with laser oscillation or workpiece moving means.

The invention according to claim 5 is the laser processing apparatus according to any one of claims 1 to 4 , wherein the light source is an ultrashort pulse laser.

  As the ultrashort pulse laser, a titanium sapphire laser (Ti: Sapphire laser) having a pulse width in a femtosecond or picosecond region, a fiber laser, or the like can be used. In particular, in an extremely short femtosecond laser, it is necessary in principle to widen the oscillation pulse width for shortening the pulse, and a laser that oscillates in a wide band of several tens of nanometers or more has been developed.

According to the first aspect of the present invention, it is possible to perform processing at a plurality of locations simultaneously by controlling the wavelength of the laser beam irradiated to the workpiece. In addition, an ordinary beam-splitting diffractive optical element can obtain only one processing pattern for one element, but in the present invention, the processing position and processing pattern can be changed by selecting the wavelength of the laser beam to be irradiated. Can be changed. Further, by adjusting the intensity of the laser beam for each wavelength, the intensity of the plurality of irradiation parts can be independently changed. Further, by appropriately changing the transmittance distribution of the gray mask, it is possible to control the intensity with respect to each transmission wavelength.

According to the first aspect of the present invention, various elements can be used for the wavelength distribution by converting the wavelength control into a spatial light position. Thereby, there are advantages such as easy control of the wavelength distribution, high-precision control, a low-cost system, and high-speed control.

According to the first aspect of the present invention, it is easy to manufacture, enables highly accurate spatial position control (wavelength distribution control), and can be used in a wide wavelength range. When using spatial chromatic dispersion, a slit-shaped mask may be used, and by providing a long slit, control is possible only by adjustment in the chromatic dispersion direction. By using a gray level mask, precise wavelength control is possible. There is an advantage that the intensity can be simultaneously controlled by using a gray level mask.

According to the second aspect of the present invention, it is possible to perform processing with different wavelength distributions in time by moving the photomask in accordance with the laser irradiation timing. Thereby, it becomes possible to control the laser beam pattern irradiated to a workpiece for every time. By moving the workpiece in synchronization with this, or scanning with laser light, a large area and complicated machining can be performed.

According to the third aspect of the present invention, it is particularly easy to change the intensity distribution of propagating light into various shapes. It is possible to change the intensity every time and the controllability is high. It is possible to control various transmission shapes with a single element. It is easy to obtain and easy to control.

According to the fourth aspect of the present invention, it is particularly easy to change the intensity distribution of the propagation light into various shapes. Further, the gray level intensity can be adjusted. It is possible to control various transmission shapes with a single element. It is easy to obtain and easy to control.

According to the invention described in claim 5 , by using a short pulse light source, high-accuracy processing that suppresses heat propagation is possible, energy loss due to heat propagation is small, and low-energy processing is possible. There is no plasma re-absorption that the laser beam absorbs the plasma generated by the laser absorption, which is a problem with the second laser, and it is transparent because of the high peak power that enables high-precision processing by suppressing surface damage due to this. It is easy to cause multiphoton absorption of the body, and there is an advantage that the transparent body can be removed and modified with low energy. When a femtosecond laser is used as an ultrashort pulse laser, the laser has a wide band in principle, and can be used as a broadband laser without improvement of the apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing an embodiment of a laser processing apparatus of the present invention for implementing the laser processing method of the present invention.

  As shown in FIG. 1, this laser processing apparatus has a light source 10 that emits pulsed laser light and a wavelength distribution that controls the intensity distribution (hereinafter referred to as wavelength distribution) for each wavelength of the pulsed laser light L1 emitted from the light source 10. The control means 20 and the light propagation means 30 for propagating the pulsed laser light whose wavelength distribution is controlled by the wavelength distribution control means 20 to spatially different positions depending on the wavelength are propagated by the light propagation means 30. Laser processing is performed simultaneously by irradiating a plurality of processing sites 40d and 40e on the surface of the workpiece 40 with pulsed laser light.

  According to this laser processing apparatus, the wavelength distribution of the laser beam L1 as the pulse laser emitted from the light source 10 is controlled, and the laser beam L2 as the pulse laser whose wavelength distribution is controlled is spatially different depending on the wavelength. Implementing a laser processing method of irradiating a plurality of processing parts 40d, 40e on the surface of the workpiece 40 with laser light by simultaneously propagating the propagated pulsed laser light to the position, thereby simultaneously processing the plurality of processing parts 40d, 40e. can do.

  In the present embodiment, the light source 10 has a laser that oscillates in a band having a relatively wide wavelength distribution, such as a titanium sapphire laser (Ti: Sapphire laser), as a pulse laser. The laser light L1 emitted from the light source 10 has a mountain-shaped wavelength distribution in which the intensity of the wavelengths on both sides gradually decreases with a specific wavelength as a peak, as shown by a graph G1 in the figure.

  As a laser that oscillates in a wide band, a white laser, a dye laser having a wide oscillation wavelength range, or the like can be used. Thus, since the oscillation wavelength of the light source 10 is wide, the control range of the processing position by the light propagation means 30 using chromatic dispersion can be widened. Moreover, the selection range of the light propagation means 30 using chromatic dispersion can be expanded. Furthermore, it is possible to use a wavelength dispersion element that can be easily obtained.

  Further, as the light source 10, an ultrashort pulse laser can be used. As the ultrashort pulse laser, a titanium sapphire laser having a pulse width in the femtosecond or picosecond region, a fiber laser, or the like can be used. In particular, in an extremely short femtosecond laser, it is necessary in principle to widen the oscillation pulse width for shortening the pulse, and a laser that oscillates in a wide band of several tens of nanometers or more has been developed. A femtosecond laser has a broad band in principle, and can be used as a wide band laser without improvement of the apparatus.

  By using an extremely short pulse laser as the light source 10, high-accuracy processing with suppressed heat propagation becomes possible. Further, energy loss due to heat propagation is small, and low energy processing is possible. Further, there is no plasma re-absorption that causes the laser light to further absorb the plasma generated by the laser absorption, which is a problem with the nanosecond laser, and surface damage due to this is suppressed, and high-precision processing is possible. In addition, because of the high peak power, it is easy to cause multiphoton absorption of the transparent body, and the transparent body can be removed and modified with low energy.

  Further, as the light source 10, a light source obtained by converting the wavelength of incident laser light by a wavelength conversion unit can be used. As the wavelength conversion means, for example, an ultrashort pulse laser beam is passed through a hollow fiber into which gas has been introduced (gas is enclosed or distributed), and the wavelength of the incident laser beam is changed by using a light source having a wider wavelength or a photonic crystal fiber. It is possible to use one having a wider wavelength.

  Thus, by using a light source obtained by converting the wavelength of incident laser light by the wavelength conversion means as the light source 10, the input laser light can be easily widened with an inexpensive system, and the effect of wavelength dispersion can be enhanced. . In particular, in the photonic crystal fiber, the wavelength distribution of the emitted light can be controlled by designing the fiber structure.

  The wavelength distribution control means 20 spatially generates a wavelength distribution by wavelength-dispersing the laser light L1 from the light source 10 with a wavelength dispersion element such as a diffraction grating, and spatially selects the transmitted light according to the wavelength. The wavelength distribution is controlled as shown in the graph in FIG. That is, the wavelength distribution control means 20 controls the wavelength distribution shown in the graph G1 of the laser light L1 emitted from the light source 10 to a wavelength distribution consisting only of the selected wavelengths a and b as shown in the graph G4.

  The laser light wavelength distribution control means 20 includes at least one set of wavelength dispersion elements and spatial wavelength selection means. The laser light is spatially decomposed for each wavelength by the wavelength dispersion element, and the intensity distribution control is performed on the wavelength-resolved laser light, thereby controlling the wavelength intensity distribution of the laser light.

  As the wavelength dispersion element, various elements such as a hologram element and a lens that change the spatial propagation position depending on the wavelength can be used. As spatial wavelength selection means, various elements such as metal plates, slits, pinholes, etc. that limit the transmission of light according to the spatial position, or ND filters with different transmitted light intensity depending on the spatial position can be used. It is.

  By converting laser light into a spatial light position, various elements can be used for wavelength distribution control. Thereby, there are advantages such as easy control of the wavelength distribution, high-precision control, a low-cost system, and high-speed control.

  In this embodiment, the light propagation means 30 can use a propagation optical system in which a dispersion element such as a prism and a condensing optical element such as a lens are combined.

  The laser beam L2 whose wavelength intensity distribution is controlled is then focused on the surface of the workpiece 40 by the light propagation means 30. The propagation direction of the laser beam L2 is changed for each wavelength by the prism provided in the light propagation means 30, and thereby the condensing point is different for each wavelength, and processing at a plurality of locations is possible.

Since the laser processing is a direct material removal processing by ablation, the following advantages are obtained as compared with lithography.
1. 1. A simple process that does not require resist coating or development, which is necessary in lithography, and has high cost and mass productivity. 2. Processing in the atmosphere, various gases, liquids, etc. is possible without the need for a vacuum. 3. A clean process that does not require reactive gases. 4. Miniaturization is easy by focusing the laser. 5. Spatial control of the processing area is easy by adjusting the optical system. 6. The amount of machining can be easily controlled by controlling the number of laser pulses. By using a short pulse laser, a high-speed reaction can be used. It is easy to generate high energy density and various materials can be processed

  In addition, the exposure sensitivity of a resist by lithography is highly dependent on the exposure sensitivity depending on the wavelength, but the wavelength dependency is lower in ablation. Therefore, when a large number of portions are processed with light of different wavelengths in the processing method of the present invention, ablation processing is advantageous because the wavelength dependence is low and the usable wavelength width is wide.

  Laser light scanning means can be arranged for the propagation of the laser light. As the laser beam scanning means, for example, a galvanometer mirror, a polygon mirror or the like can be used. This laser beam scanning means is desirably controlled in synchronization with the laser oscillation or the laser light shutter, and also uses a moving means for moving the workpiece, and can be controlled in synchronization with this moving means. desirable. At this time, it is also possible to perform processing by changing the wavelength distribution by controlling the wavelength distribution by the laser wavelength control means synchronously. The laser beam scanning means need not be scanned for each irradiation of the laser beam, and can be scanned after many laser irradiations.

  According to the processing method of the present invention, it was possible to simultaneously process a large number without arranging the laser beam scanning means, but by arranging the laser beam scanning means and scanning with the laser beam scanning means, Furthermore, a large number of processed parts can be formed in a shorter time. Further, an arbitrary pattern can be processed on the processing surface by scanning the laser light while adjusting the wavelength intensity distribution.

  One or more wavelength filters can be used as the wavelength distribution control means 20. As the wavelength filter, for example, a color glass filter, an interference filter using a multilayer film, or the like can be used. By using a thin film, it is possible to use lasers in the infrared, deep ultraviolet, and X-ray regions.

  At this time, by using several wavelength filters continuously, various wavelength distributions can be formed, and it is also possible to process continuously while exchanging a plurality of wavelength filters. After passing through the wavelength filter, the laser light is directly transmitted to the light propagation means 30, and is condensed and irradiated to different positions on the surface of the workpiece for each wavelength.

  By using the wavelength filter as the wavelength distribution control means 20 in this way, it becomes possible to simultaneously process a plurality of points with an inexpensive system. Moreover, various processed shapes can be easily obtained by changing the wavelength filter in various ways. Arbitrary pattern processing becomes possible by processing while exchanging the wavelength filter.

  FIG. 2 is a block diagram showing another embodiment of the light propagation means. In this embodiment, a diffractive optical element 301 is used as the light propagation means. As shown in FIG. 2, the laser light L <b> 2 whose wavelength distribution is controlled is collected from the diffractive optical element 301. At this time, the light is condensed on the surface of the workpiece 40, for example, as the propagation light La indicated by a broken line at a certain wavelength a, and as the propagation light Lb indicated by a solid line at a certain wavelength b. Thereby, processing at a plurality of locations is possible. Here, by changing the intensity distribution of the wavelength in time series, for example, it is possible to perform processing while sequentially changing the condensing position in the direction from the broken line propagation light La to the solid line propagation light Lb. Further, the processing does not have to be a point, and it is also possible to perform processing into a line shape from a broken line to a solid line by controlling the wavelength distribution.

  FIG. 3 is a block diagram showing another embodiment of the wavelength distribution control means. As shown in FIG. 3, the laser beam L1 is incident on the diffraction grating 201. At this time, the diffraction grating 201 is configured so that the diffraction efficiency in the primary direction, for example, becomes maximum with respect to the incident wavelength. Light is propagated by the diffraction grating 201 at different reflection angles for each wavelength and is propagated to the diffraction grating 202. The diffraction grating 202 uses the same element as the diffraction grating 201, and reflects it as parallel light by adjusting the angle. At this time, since the incident position differs depending on the wavelength, the laser light reflected by the diffraction grating 202 has a spatial wavelength distribution. For example, the long wavelength side shown in the graph G2 of FIG. 3 can pass through the upper side of the drawing, and the short wavelength side shown in the graph G3 of FIG. 3 can pass through the lower side of the drawing. Here, the spatial distribution of the incident light can be controlled by spatially limiting the transmission of the laser light by the spatial wavelength selection means 203.

  Thereafter, by utilizing the reflection of a similar diffraction grating pair (diffraction grating 204 and diffraction grating 205), it is possible to form laser light L2 having a controlled wavelength distribution, as shown in graph G4. At this time, the spatial wavelength distribution can be controlled by adjusting the pitch of the diffraction grating.

  FIG. 4 is a block diagram showing another embodiment of the wavelength distribution control means. As shown in FIG. 4, the laser light L1 passes through the polarization separation element 206, which is a polarization beam splitter in this embodiment, and is incident on the prism pair (the prism 207 and the prism 208). At this time, the polarization of the incident laser light is set to a direction in which the transmittance of the polarizing beam splitter is maximized. By controlling the apex angles and positions of the prism 207 and the prism 208, the laser light after passing through the prism 207 and the prism 208 becomes parallel light having a spatial distribution depending on the wavelength.

  Here, the spatial distribution of the laser beam can be controlled by spatially limiting the transmission of the laser beam by the spatial wavelength selection unit 203. Thereafter, the light further circularly polarized by the quarter-wave plate 209 is reflected by the reflection mirror 210 and reflected by the same optical path. By passing through the quarter-wave plate 209 again, the polarization direction of the reflection-side laser light changes by 90 degrees, and the light incident on the polarization separation element 206 is reflected again and propagates upward in FIG. At this time, this configuration can be easily realized by using a prism pair having the same apex angle.

  As the spatial wavelength selection means 203, a photomask can be used. The photomask can be formed, for example, by vapor-depositing Cr on a transparent substrate, and spatially controls the light transmission region by utilizing reflection on the metal film. At this time, it is possible to use a gray mask in which the transmittance is continuously changed by controlling the film thickness of the reflective film.

  By using a photomask as the spatial wavelength selection means 203 in this way, manufacturing is easy and highly accurate spatial position control (wavelength distribution control) is possible. In addition, it can be used in a wide wavelength range. In addition, when using spatial wavelength dispersion with a diffraction grating or a prism, a slit-like mask may be used, and by providing a long slit, control is possible only by adjustment in the wavelength dispersion direction. Furthermore, precise wavelength control is possible by using a gray level mask. Further, by using a gray level mask, the intensity can be controlled simultaneously.

  Further, a moving means for the photomask can be provided. This can be achieved by holding and moving the photomask on the moving stage. At this time, it is desirable that the moving means of the photomask move in synchronization with the laser irradiation timing, and it is also possible to move in synchronization with the moving means of the workpiece 40. It is also possible to use various mask patterns by preparing a plurality of mask patterns and controlling the irradiation position by photomask moving means.

  By changing the mask pattern in accordance with the laser irradiation timing, it is possible to perform processing with a wavelength distribution that is temporally different. Thereby, it becomes possible to control the laser beam pattern irradiated to the workpiece 40 for every time. In synchronization with this, the workpiece 40 is moved by the moving means of the workpiece 40, or the laser beam is scanned by the scanning means, so that a large area and complicated machining can be performed.

  FIG. 5 is a block diagram showing another embodiment of the wavelength distribution control means. As shown in FIG. 5, the laser beam L1 passes through the polarization beam splitting element 206 and the quarter wavelength plate 209, and forms a spatial wavelength distribution using a diffraction grating pair (diffraction grating 201 and diffraction grating 202). To do. Part of the laser light is reflected by a DMD (Digital Micro-mirror Device: trade name of Texas Instruments (USA)) element 211 as a spatial wavelength selection means, and returns to the original optical path. The part reflects in different directions and is adjusted so that it is not used. The returned light passes through the quarter-wave plate 209 again, so that the polarization angle rotates by 90 degrees and is reflected by the polarization separation element 206. Thereby, the wavelength distribution of the light after passing through the polarization separation element 206 is controlled. At this time, an arbitrary wavelength distribution can be formed by changing the pattern of the DMD element 211. As a result, the wavelength distribution of the laser light L2 after passing through the wavelength distribution control means 20 is controlled, and a large number of parts can be processed by passing through the subsequent light propagation means 30.

  FIG. 6 is a block diagram showing another embodiment of the wavelength distribution control means. As shown in FIG. 6, the laser light L1 forms a wavelength distribution spatially using a diffraction grating pair (diffraction grating 201 and diffraction grating 202). Thereafter, the polarization of a part of the laser light is rotated by the spatial wavelength selection means 203, in this embodiment, the transmissive liquid crystal. At this time, by inputting an intermediate value, it is possible to arbitrarily control the polarization angle in the direction. The laser light that has passed through the transmissive liquid crystal is reflected by the subsequent polarization separation element 206, in this embodiment, by the polarization beam splitter, depending on the polarization direction, and a certain polarization component is reflected and the rest is transmitted. As a result, the wavelength distribution of the transmitted light is controlled. After that, by controlling the spatial distribution with the diffraction grating pair (diffraction grating 204 and diffraction grating 205), the laser light L2 after passing through the wavelength distribution control means of the present embodiment controls the wavelength distribution and the laser intensity for each wavelength. Then, by passing through the subsequent light propagation means 30, a plurality of places can be processed.

  FIG. 7 is a block diagram showing another embodiment of the wavelength distribution control means. As shown in FIG. 7, this system can also be used in a reflective manner. The laser beam L1 passes through the polarization beam splitter 206 and is spatially wavelength-dispersed by the diffraction grating pair (diffraction grating 201 and diffraction grating 202). Thereafter, the laser light is again polarized by the same optical system by arranging the spatial wavelength selection means 203, in this embodiment, the transmissive liquid crystal and the reflective mirror 210 (or reflective liquid crystal). The separation element 206 is returned to the polarization beam splitter in this embodiment. By using the laser light L2 that is the outgoing light partially reflected by the polarization direction, it is possible to expect an effect that the processing at a plurality of places similar to the above can be performed. This system has an advantage that the optical system is simpler and the number of elements can be reduced than the embodiment of FIG.

  FIG. 8 is a block diagram showing the strength adjusting means. As shown in FIG. 8, for example, the initial wavelength distribution of the incident laser light is assumed to be a distribution shown in a graph G5 in the left diagram in FIG. At this time, for example, in the optical system shown in FIG. 3, a gray mask 212 having a spatially different transmittance is arranged on the front surface of the spatial wavelength selecting unit 203 as a means for spatially limiting the transmission of laser light. In the example of FIG. 8, since the transmittance of the gray mask 212 is made lower as the intensity of the graph G5 is higher, the intensity can be controlled smoothly as in the graph G6. In addition to smoothing, the transmittance distribution of the gray mask 212 is changed so as to decrease the transmittance corresponding to the portion where the intensity is reduced, or the transmittance corresponding to the portion where the intensity is increased is increased. By changing to, the intensity distribution of the graph G5 can be arbitrarily modified. As described above, by appropriately changing the transmittance distribution of the gray mask 212, it is possible to control the intensity with respect to each transmission wavelength.

  FIG. 9 is a configuration diagram illustrating an embodiment of a laser processing apparatus including a control system. As shown in FIG. 9, the light emitted from the light source 10 is converted into a specific wavelength distribution by the wavelength distribution control optical system 20b that controls the wavelength distribution after entering the intensity adjusting mechanism 20a. Thereafter, the light is condensed and irradiated onto the surface of the workpiece 40 through the optical system 30b including the mirror 30a and an element whose propagation direction varies depending on the wavelength. The timing of the pulses emitted from the light source 10, the wavelength distribution control optical system 20b, and the stage 50 on which the workpiece is placed are controlled by the computer 60 in synchronization. As the intensity adjustment mechanism 20a, an ND filter, a polarization separation element, a gray mask, or the like can be used.

  FIG. 10 is a perspective view showing an example of a structure processed by the laser processing method of the present invention. As shown in FIG. 10, periodic processing holes 40c are formed in the transparent body 40b by the laser processing apparatus described above. The element having such a structure acts as a photonic crystal and can be used as an element for controlling light in various ways. It is also possible to produce many replicas by transferring this structure.

  In addition, by using the laser processing apparatus described above, a structure having a plurality of refractive index changing regions, in particular, a refractive index modulation portion, is formed on the surface of the workpiece 40, thereby functioning as a refractive index modulation type diffraction element. In addition, it can function as an optical waveguide, and can function as a hologram element.

  As described above, the present invention is aimed at forming a high-precision part that requires a particularly fine shape, and forming a recording pit of an optical disc, producing an optical disc molding stamper as a master, a surface relief type, diffraction grating Manufacturing of optical elements such as diffraction holograms and photonic crystals and their masters, manufacturing of optical elements such as diffraction gratings, diffraction holograms, photonic crystals and their masters having a refractive index modulation portion on the surface, micromachines, micros It can be applied to shape processing such as sensors and inkjet nozzle hole processing. The present invention is not limited to the above embodiment. That is, various modifications can be made without departing from the scope of the present invention.

It is a block diagram which shows one Embodiment of the laser processing apparatus of this invention which enforces the laser processing method of this invention. It is a block diagram which shows other embodiment of a light propagation means. It is a block diagram which shows other embodiment of a wavelength distribution control means. It is a block diagram which shows other embodiment of a wavelength distribution control means. It is a block diagram which shows other embodiment of a wavelength distribution control means. It is a block diagram which shows other embodiment of a wavelength distribution control means. It is a block diagram which shows other embodiment of a wavelength distribution control means. It is a block diagram which shows an intensity | strength adjustment means. It is a block diagram which shows embodiment of the laser processing apparatus shown including a control system. It is a perspective view which shows an example of the structure processed by the laser processing method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Light source 20 Wavelength distribution control means 20a Intensity adjustment mechanism 20b Wavelength distribution control optical system 30 Light propagation means 30a Mirror 30b Optical system including elements whose propagation differs depending on the wavelength 40 Workpiece 40a Structure 40b Transparent body 40c Multiple processing holes 50 Stage 60 Computer 201 Diffraction grating 202 Diffraction grating 203 Spatial wavelength selection means 204 Diffraction grating 205 Diffraction grating 206 Polarization separation element 207 Prism 208 Prism 209 1/4 wavelength plate 210 Reflection mirror 211 DMD element 301 Diffraction optical element L1 Incident light L2 Wavelength Laser light whose distribution is controlled La Propagating light for a certain wavelength a Lb Propagating light for a certain wavelength b

Claims (5)

A light source that emits pulsed laser light; wavelength distribution control means that controls a wavelength distribution of the pulsed laser light emitted from the light source; and the pulsed laser light whose wavelength distribution is controlled by the wavelength distribution control means. And a light propagation means for propagating to spatially different positions depending on
The wavelength distribution control means includes at least one set of a set of a wavelength dispersion element that disperses the wavelength of the pulsed laser light and a spatial wavelength selection means that selects the wavelength of the pulsed laser light in which the wavelength is dispersed. And
The intensity for each of the transmission wavelengths is controlled by a gray mask provided in the spatial wavelength selection means, having a spatial distribution of transmittance to limit the transmission of laser light, and
The pulse laser beam propagated by the light propagation means is irradiated to a plurality of machining sites on the workpiece surface, and the plurality of machining sites on the workpiece surface are laser processed simultaneously. Laser processing equipment. The said spatial wavelength selection means is a photomask which restrict | transmits the transmittance | permeability of light, It further has a moving means to move the said photomask , The selection wavelength is changed temporally, The selection wavelength is characterized by the above-mentioned. Laser processing equipment.   The laser processing apparatus according to claim 1, wherein the spatial wavelength selection unit is a spatial intensity modulator.   The laser processing apparatus according to claim 3, wherein the spatial intensity modulator includes a transmissive liquid crystal and a polarization separation element. The laser processing apparatus according to any one of claims 1 to 4 wherein the light source is characterized in that it is a ultrashort pulsed laser.

Images