JP2002178171A - Laser beam processing method and optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a laser beam processing method which enables processing with high processing surface accuracy. SOLUTION: A solution 3 dispersed with particulates 2 is arranged in contact with the surface of a substrate 1 to be worked and is irradiated with a laser beam 4 from its surface, by which the substrate 1 to be worked is selectively removed and worked of only the segments irradiated with the laser beam 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing method and an optical element, and more particularly to a laser processing method with improved processing accuracy and an optical element produced by the method.

[0002]

2. Description of the Related Art In a conventional direct processing method of a material by laser processing, high-precision processing of about 1 μm or less is difficult due to thermal damage around a processing portion. However, in laser processing, the laser ablation method can narrow the heat affected area by irradiating the surface of the material with a laser beam with a pulse width of about nanoseconds or less. It is said that high-precision processing is possible. This laser ablation processing method
Much research has been conducted mainly on polymers since the early 1980's, and many reports have been made using this method for optical materials such as glass and quartz.

As an invention of a method of processing an optical element using these methods, a method of directly removing a material by laser irradiation (Japanese Patent Application Laid-Open No. 7-27910) and a method of processing by interfering with a laser beam (particularly, (Kaihei 8-220316)
And so on. Further, as a laser processing method using a solvent such as ordinary wet etching, a method using excitation of a solution by laser irradiation (JP-A-3-62831, JP-A-8-277478) has been proposed. In the direct laser processing method described above, the spatial selectivity of the position can be relatively high, but there is a problem that the processing accuracy in the laser irradiation direction and the processing surface accuracy cannot be increased. For these reasons, conventionally, the laser ablation processing method has been conventionally put into practical use limited to processing of a fine-shaped component represented by an ink jet nozzle, removal processing of a thin film, and the like.

By the way, the processing surface roughness usually required for an optical element is often in the order of several nanometers to several hundreds of nanometers. Therefore, the length of laser light penetration into the substrate, the removal process during processing, etc. Processing with such high surface precision is difficult, and adaptation of laser processing to materials having these optical surfaces has conventionally been difficult. Usually, processing of a high-precision surface is performed by mechanical processing such as polishing or lapping, dry etching, or the like. Further, it is known that the surface accuracy of the wet method using a solution is lower than those of these methods. This is the same in the case of the laser-induced etching method using a solution, and it is difficult to process the optical surface with high precision even by the processing method using a laser using a solution.

[0005] The laser processing method has the advantage of high spatial selectivity and can be processed at a high speed in a normal atmospheric environment, and can be said to be a cleaner processing method than other methods. Also, it is difficult to machine an optical element having a fine shape represented by a microlens array, and it is difficult to improve the shape accuracy even in dry etching for transferring a large number of masks and resist shapes. It has been desired that high-precision surface processing be performed by adapting a direct processing method using a laser to these materials.

[0006]

As described above, the conventional laser processing method has an advantage that the spatial selectivity of the position is relatively high, but the processing accuracy in the laser irradiation direction is low.
There was a problem that the machining surface accuracy could not be increased. The present invention solves this problem by a relatively simple method, absorbs the energy of laser light into fine particles, and processes the material by excitation of the fine particles, thereby enabling laser processing with high processing surface accuracy. It is an object to realize a processing method.

[0007]

According to the present invention, there is provided a laser processing method, comprising: disposing a solution in which fine particles are dispersed in contact with a surface of an object to be processed; By irradiating, the surface of the object to be processed is selectively removed only at a laser beam irradiation part.

Further, in the laser processing method, a thin film in which fine particles are dispersed is placed in contact with the surface of the object to be processed, and the surface is irradiated with laser light.
The surface of the object to be processed is selectively removed only at a laser beam irradiation part.

Further, in the laser processing method, the object to be processed is a material transparent to the irradiation laser light, and the fine particle-dispersed material is arranged in contact with the surface to be processed which is the surface opposite to the laser irradiation side, The processing surface of the processing object is selectively removed by laser absorption of the fine particle dispersion material.

Furthermore, in the laser processing method, an object to be processed which is transparent to the irradiation laser light is set on a film in which fine particles are dispersed, and the object is irradiated with laser light from the surface of the object to be processed. A processing surface, which is a contact surface between the processing target object and the fine particle dispersed film, is selectively removed. With these, the energy of the laser beam is absorbed by the fine particles, and the material can be processed by exciting the fine particles, whereby a laser processing method capable of performing laser processing with high processing surface accuracy can be realized.

Further, an optical element is formed by using these processing methods. Thus, an optical element with high surface accuracy can be realized.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, laser energy with a high processing surface accuracy can be realized by absorbing the energy of laser light into fine particles and processing the material by excitation of the fine particles. The processing of the present invention is considered to be due to collision of fine particles excited by laser light with the substrate, electron transition, energy transfer, and it is possible to control the processing accuracy by adjusting the laser light and selecting the shape and material of the fine particles. Will be possible. Further, as the processing of the substrate material progresses, the amount of fine particles in the processed portion changes, and it becomes possible to selectively process the convex portion of the substrate. As a result, improvement in surface accuracy at the laser irradiation position can be expected. At this time, the irradiation position of the laser can be selected by using a mask or adjusting an optical system, and high-precision surface processing can be realized while taking advantage of the laser processing. Also, in normal processing, the processing form changes due to the interaction between the laser beam and the material to be processed, but in this method, the laser light absorption occurs in fine particles, so the selection range of the material to be processed and the processing conditions is limited. It becomes possible to spread.

Hereinafter, a laser processing method according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows the configuration of an embodiment of the laser processing method according to the present invention. In FIG. 1, reference numeral 1 denotes a substrate to be processed,
Reference numeral 2 denotes fine particles, reference numeral 3 denotes a solution, reference numeral 4 denotes a laser beam, and reference numeral 5 denotes a processing hole.

A solution 3 in which fine particles 2 are dispersed is applied on a substrate 1 to be processed, and is disposed on the surface. This solution 3 contains fine particles 2
Is adjusted to such an extent that is kept in a single layer, and is applied thinly. It is desirable that the solvent absorb little laser light, and the solvent is set so that the absorption energy of the fine particles 2 is efficiently transmitted to the substrate. Laser light 4 spatially selected by an optical system or a mask is irradiated from the fine particle side in the figure, and the fine particle 2 absorbs the laser light 4. This laser beam 4
The substrate 1 to be processed is processed by the fine particles 2 excited thereby, and minute removal is performed. The fine particle dispersion solution 3 is supplied to the processing section by surface tension or the like, and the processing is repeated by repeating the processing to form the processing hole 5.

In the case of direct excitation of the substrate to be processed by the ordinary laser ablation method, it is difficult to improve the surface accuracy in the laser irradiation direction because laser absorption penetrates into the substrate. By using energy transfer from fine particles as described above, it becomes possible to process only the very surface of the substrate to be processed. In addition, since the processing is particularly performed on the surface having a high laser irradiation intensity, by repeatedly performing the laser irradiation, the processing is selectively advanced from the convex portion, and a high-precision surface processing according to the irradiation intensity can be realized. In addition, since fine particles are used, the removal action can be controlled by the size, material, density, and the like of the fine particles, and appropriate control of the substrate material can be performed together with laser parameters such as laser irradiation intensity and laser wavelength. Becomes possible. In addition, because the particles absorb laser light, processing on a substrate that is transparent to laser light is also possible, and efficient processing can be performed on materials that are transparent in the ultraviolet to near infrared region, such as quartz substrates. It becomes possible.

FIG. 2 shows the configuration of another embodiment of the laser processing method of the present invention. In FIG. 2, reference numeral 1 denotes a substrate to be processed, reference numeral 2 denotes fine particles, reference numeral 4 denotes a laser beam, reference numeral 5 denotes a processing hole, and reference numeral 6 denotes a fine particle-dispersed thin film.

A transparent film 6 is placed on the surface of a substrate 1 to be processed by contacting a transparent film 6 with a laser beam 4 in which fine particles 2 are dispersed. By irradiating the laser light 4 from the surface of the film 6, the particles are dispersed to excite the fine particles in a space-selective manner, thereby processing the substrate 1 on the lower surface of the film 6. At this time, the substrate 1 is moved while the film 6 is fixed, and the laser irradiation is repeated, whereby large-area processing can be performed. In this way, by using a material in which fine particles are dispersed in a film,
Handling of the material is easy, and thickness control of the fine particle dispersed material is easy. Also, by preparing the fine particles in the form of a film, it is easy to process while moving the material to be processed, which is advantageous when processing a wide area.

FIG. 3 shows the configuration of another embodiment of the laser processing method of the present invention. In FIG. 3, reference numeral 1 denotes a substrate to be processed, reference numeral 2 denotes fine particles, reference numeral 3 denotes a solution, reference numeral 4 denotes a laser beam, reference numeral 5 denotes a processing hole, and reference numeral 7 denotes a solution tank.

A solution 3 in which fine particles 2 are dispersed is prepared in a solution tank 7, and the substrate 1 to be processed is fixed so that the back surface thereof is in contact therewith. Using the laser light 4 that absorbs little on the processing target substrate 1, the fine particle dispersion solution 3 is irradiated from above the processing target substrate 1 with the energy adjusted in a space-selective manner. At this time, the laser beam 4 passes through the processing target substrate 1 which is a transparent substrate,
It is absorbed by the fine particles 2. The fine particles 2 are excited by the absorbed energy and the processing target substrate 1 is removed, whereby the processing proceeds. At this time, the concentration of the fine particles 2 can be adjusted by a laser processing mode. In addition, since processing occurs on the surface of the solvent, it is not necessary to control the amount of the solvent.

FIG. 4 shows the configuration of another embodiment of the laser processing method of the present invention. In FIG. 4, reference numeral 1 denotes a substrate to be processed, reference numeral 2 denotes fine particles, reference numeral 4 denotes laser light, reference numeral 5 denotes a processing hole, reference numeral 8 denotes a fine particle dispersion film, and reference numeral 9 denotes a moving stage.

The substrate 1 to be processed is placed on a film 8 in which fine particles 2 are dispersed. At this time, the thickness of the fine particle dispersed film 8 can be set arbitrarily. By mounting this on the moving stage 9 and moving it, large-area processing becomes possible. Using a laser beam having a small absorption in the substrate 1 to be processed,
The laser light 4 is irradiated from above the substrate 1 onto the fine particle dispersed film 8 by adjusting the energy in a space-selective manner. Laser light 4
Is absorbed by the fine particle dispersion film 8, and the substrate 1 is processed by this energy. In the present embodiment, the fine particles 2
By disposing the film 8 on which the film 8 is dispersed on the back surface of the substrate 1 to be processed, it is not necessary to adjust the film thickness, and the material can be easily obtained.

FIG. 5 shows the configuration of another embodiment of the laser processing method of the present invention. In FIG. 5, reference numeral 1 denotes a substrate to be processed, reference numeral 2 denotes fine particles, reference numeral 3 denotes a solution, reference numeral 4 denotes a laser beam, reference numeral 5 denotes a processing hole, reference numeral 9 denotes a moving stage, and reference numeral
Is a transparent substrate.

A transparent substrate 10 is arranged on the substrate 1 with a space. This space is filled with the fine particle dispersion solution 3. By adjusting the distance between the transparent substrate 10 and the substrate 1 to be processed, the thickness of the fine particle dispersion solution 3 is controlled. Here, by irradiating a laser beam from the surface side of the transparent substrate 10 in the same manner as in the configuration of FIG. 1, the surface of the substrate 1 to be processed can be processed.

In the present embodiment, the thickness of the fine particle dispersion solution 3 can be easily adjusted by sandwiching the fine particle dispersion solution 3 between the transparent substrates 10. Thereby, refraction distortion due to the flow of the solution can be reduced. Further, since the fine particle dispersion solution 3 exists in a narrow space, the solution is permeated by capillary action, and the circulating property of the surface is increased. At this time, by adjusting the laser irradiation intensity and increasing the laser intensity on the surface of the substrate 1 to be processed, the processing of the transparent substrate can be eliminated. By adding a lens and a diffraction function to the transparent substrate, a high NA can be obtained. Processing becomes possible.

FIG. 6 shows the configuration of another embodiment of the laser processing method of the present invention. 6, reference numeral 1 denotes a substrate to be processed, reference numeral 2 denotes fine particles, reference numeral 3 denotes a solution, reference numeral 4 denotes a laser beam, reference numeral 5 denotes a processing hole, reference numeral 9 denotes a moving stage, and reference numeral 11
Is a processed transparent substrate.

A processed transparent substrate 11 having a fine groove or hole shape at least in part is arranged on the surface of the substrate 1 with a space. This space is filled with a fine particle dispersion solution 3 and a laser beam 4 is irradiated from the surface of the transparent substrate 11.
At this time, the amount of the fine particle dispersion solution 3 or the distance from the substrate is changed by the grooves or holes of the processed transparent substrate 11. This makes it possible to spatially change the contribution of the irradiation energy to the surface of the substrate 1 to be processed, for example, the processing amount is large in a portion having a small amount of the fine particles 2 and the processing is not performed in a portion having a large amount of the fine particles 2. Laser processing can be performed.

Thus, the transparent substrate 11 is shaped,
By directing the shape surface toward the substrate 1 to be processed, the amount of fine particles on the surface of the substrate 1 can be spatially selectively controlled. As a result, the laser light is absorbed by particles far from the substrate 1 in a portion where the number of fine particles is large, so that processing on the surface of the substrate 1 to be processed hardly occurs. Therefore, space-selective processing of the workpiece can be performed without adjusting the laser irradiation intensity. At this time, by repeating the laser irradiation while controlling the position of the transparent substrate, the shape transfer processing to a shape close to the substrate processing shape becomes possible.

In the above-mentioned laser processing method of the present invention, a fine particle material such as alumina or selenium oxide used for mechanical polishing or the like can be used for the fine particles. These can be obtained relatively easily by specifying the particle size. In addition, as the abrasive, a material having high workability with respect to a processing target can be selected and used, and efficient processing can be performed.

In the laser processing method of the present invention, laser processing is performed using fine particles of about 0.01 μm to 10 μm as fine particles. The penetration depth of ordinary laser light is about several tens of μm to about 1 μm. By using fine particles of the above size, most of the energy can be absorbed by the whole fine particles, and particularly efficient fine particle processing is possible. become. Also,
These fine particles are relatively easily available as abrasive materials, conductive particles, and the like, and it is easy to select and use a material that is well dispersed in a solution.

FIG. 7 shows the configuration of another embodiment of the laser processing method of the present invention. 7, reference numeral 1 denotes a substrate to be processed, reference numeral 2 denotes fine particles, reference numeral 3 denotes a solution, reference numeral 4 denotes a laser beam, reference numeral 7 denotes a solution tank, reference numeral 12 denotes a pump, and reference numeral 13 denotes a filter.

In addition to the configuration of the irradiation device for the fine particle dispersion solution 3 and the laser beam 4 shown in FIGS. 1, 3 and 5, the fine particles 2 on the surface of the irradiation section are continuously exchanged by using a circulation device for the solution 3. To do it. A pump 12 or the like can be used for circulation, and dust can be filtered by a filter 13 or the like. At this time, the laser light 4 is applied to the surface of the substrate 1 to be processed.
Are continuously processed by repeatedly irradiating. By irradiating a laser beam while controlling the amount of the fine particles 2 or the thickness of the liquid, more efficient processing can be performed. By circulating the solution, the fine particles 2 can always be supplied to the surface of the substrate 1 to be processed, and deep shape processing can be continuously performed at high speed. Further, by processing through the filter 13 or the like, it becomes possible to remove foreign substances and control the particle diameter of fine particles.

FIG. 8 shows the configuration of another embodiment of the laser processing method of the present invention. 8, reference numeral 1 denotes a substrate to be processed, reference numeral 2 denotes fine particles, reference numeral 3 denotes a solution, reference numeral 4 denotes a laser beam, reference numeral 5 denotes a processing hole, reference numeral 14 denotes a spinner, and reference numeral 15 denotes a syringe.

Here, the substrate 1 to be processed is held by a rotating device such as a spinner 14, the concentration and the viscosity of the fine particle dispersion solution 3 are adjusted by supplying the fine particles 2, and the amount of the fine particles on the surface of the substrate 1 to be processed is adjusted. The fine particles 2 are continuously supplied from a syringe 15 or the like, and are processed while adjusting the film thickness by rotating the spinner 14. In the case of processing a circular continuous pattern such as rotary encoder processing, the processing position is set by adjusting laser irradiation and rotational positioning.

By preparing the fine particle dispersion solution 3 while applying it with the spinner 14 or the like, the fine particles 2 can be arranged on the surface in a thin film form, and the fine particles 2 can be supplied continuously. Further, by processing while positioning in the rotation direction, or by irradiating laser light in synchronization with the rotation position, circular continuous pattern processing becomes possible. By using these, it becomes possible to process an aspheric lens, a slit for a rotary encoder, and the like with high accuracy.

In the laser processing method of the present invention, a laser light source and
And the femtosecond (fsec = 10 ^-15sec)
Cosecond (psec = 10^-12sec) ultra-short pulse laser
Is used. These are short pulse and high peak output energy.
Can be used as a source of energy. These are titanium sapphire
Laser or pulse-compressed excimer laser, etc.
Can be. Use of ultra-short pulse laser in this way
Laser processing with high peak output
You. With these ultrashort pulse lasers, multiphoton absorption
It becomes easier to realize a higher excited state, and when laser irradiation
Can reduce the heat affected area of the
Processing becomes possible. In addition, these lasers use
Ablation even when using fine particles with high thermal conductivity
Processing of the workpiece by use becomes possible.

In the optical element of the present invention, a so-called optical material such as glass, quartz, or a transparent polymer is particularly selected as a material to be processed by using the laser processing method according to any one of the first to tenth aspects. Accordingly, an optical element having a highly accurate shape and surface accuracy can be realized. Accordingly, it is possible to realize an optical element having a shape with a particularly high aspect ratio, and it is possible to use the optical element as a microlens array, a diffraction grating, or the like that requires a minute shape.

[0038]

As described above, according to the first aspect of the present invention, by disposing a solution in which fine particles are dispersed in contact with the surface of a workpiece and irradiating the surface with a laser beam, The surface of the object to be processed is selectively removed only at the laser beam irradiation part. Thereby, the laser light is selectively absorbed by the fine particles. These fine particles collide with the surface of the substrate to be processed at a high speed by a laser ablation action. Alternatively, energy transfer occurs from the excited state of the fine particles to the surface of the substrate to be processed. With these energies, the substrate surface is removed, and the position irradiated with the laser is selectively processed. With direct excitation of the substrate to be processed by the ordinary laser ablation method, it is difficult to improve the surface accuracy in the laser irradiation direction because laser absorption penetrates into the substrate, but energy transfer from fine particles is used. This makes it possible to process only the very surface of the substrate to be processed. In addition, since this occurs particularly on a surface having a high laser irradiation intensity, by repeatedly performing the laser irradiation, processing proceeds selectively from the convex portion, and highly accurate surface processing according to the irradiation intensity can be realized. In addition, since fine particles are used, the removal action can be controlled by the size, material, density, etc. of the fine particles, and appropriate control of the substrate material can be performed together with laser parameters such as laser irradiation intensity and laser wavelength. Becomes possible. In addition, since the absorption of laser light is carried out by fine particles, processing on a substrate transparent to laser light becomes possible, and efficient processing of materials that are transparent in the ultraviolet to near-infrared region such as quartz substrates is also possible. Will be possible.

According to a second aspect of the present invention, a thin film in which fine particles are dispersed is placed in contact with the surface of the object to be processed, and a laser beam is irradiated from the surface to thereby provide a surface of the object to be processed. Is selectively removed only in the laser beam irradiation part. By using a material in which fine particles are dispersed in a film as described above, the material can be easily handled and the thickness of the fine particle-dispersed material can be easily controlled. Also, by preparing the fine particles in the form of a film, it is easy to process while moving the material to be processed, which is advantageous when processing a wide area.

According to a third aspect of the present invention, the object to be processed is a material transparent to the irradiation laser beam, and the fine particle-dispersed material is arranged in contact with the surface to be processed which is the surface opposite to the laser irradiation side. Then, the processing surface of the processing object is selectively removed by laser absorption of the fine particle dispersed material. By processing the back surface of the substrate to be processed,
It is not necessary to control the thickness of the solution, and it is possible to reduce the irradiation position shift due to the fluctuation of the refraction of the solution. In addition, even when laser processing is advanced, since fine particles are present in the vicinity of the surface, continuous processing is possible. At this time, since there are many fine particles around the convex portions, the fine particles are selectively processed from the convex portions. Thus, high-precision processing with reduced surface roughness can be realized. Further, since the back surface is processed, the shape can be observed coaxially from the front surface side, and the processing can be performed while performing the shape observation.

According to a fourth aspect of the present invention, an object to be processed which is transparent to an irradiation laser beam is set on a film in which fine particles are dispersed, and a laser beam is irradiated from the surface of the object to be processed. The method is characterized in that a processing surface that is a contact surface between the processing target object and the fine particle dispersed film is selectively removed. By arranging the fine particle-dispersed film on the back surface in this manner, it is not necessary to adjust the thickness of the film, and the material can be easily obtained. At this time, the material need not be dispersed throughout the film, but only needs to be present near the surface. Further, since the back surface is processed, it is possible to observe the surface coaxially from the front surface, as in the case of the third aspect.

According to a fifth aspect of the present invention, a substrate material transparent to an irradiation laser beam is disposed on an object to be processed, and a solution in which fine particles are dispersed is disposed between the object to be processed and the transparent substrate. It is characterized by doing. As described above, by sandwiching the fine particle solution between the transparent substrates, it is easy to adjust the thickness of the fine particle dispersion solution, and it is possible to reduce refraction distortion due to the flow of the solution. In addition, since the solution exists in a narrow space, the solution penetrates by capillary action, and the circulating property of the surface increases. At this time, by adjusting the laser irradiation intensity and increasing the laser intensity on the surface of the workpiece, the processing of the transparent substrate can be eliminated. By adding a lens and a diffraction function to the transparent substrate, a high NA can be achieved. Processing becomes possible.

A sixth aspect of the present invention is characterized in that a surface shape surface of a transparent substrate having a surface shape on at least one surface is arranged on the side of the workpiece. As described above, by shaping the transparent substrate and directing the shape surface toward the substrate to be processed, it is possible to spatially selectively control the amount of fine particles on the surface of the workpiece. As a result, the laser light is absorbed by particles far from the substrate in a portion having a large amount of fine particles, so that processing on the surface of the workpiece is difficult to occur, and conversely, processing occurs efficiently on a surface side with a small amount of fine particles, Space-selective processing of a workpiece can be performed without adjusting the laser irradiation intensity. At this time, by repeating the laser irradiation while controlling the position of the transparent substrate, the shape transfer processing to a shape close to the substrate processing shape becomes possible.

The invention according to claim 7 of the present invention is characterized in that the fine particles are particularly a polishing material. As described above, by using a polishing material as the fine particles, the fine particles can be selected from many materials, and it is possible to prepare inexpensively various particle sizes. In addition, a polishing material having high workability with respect to the substrate can be used, and efficient processing can be realized.

According to the invention of claim 8 of the present invention, the fine particles have a particle diameter of 0.1.
It is characterized in that the thickness is from 01 μm to 10 μm. The penetration depth of ordinary laser light is about several tens of μm to about 1 μm. By using fine particles of the above size, most of the energy can be absorbed by the whole fine particles, and particularly efficient fine particle processing is possible. become. In addition, these fine particles are relatively easily available as abrasive materials, conductive particles, and the like, and it is easy to select and use a material that is well dispersed in a solution.

The ninth aspect of the present invention is characterized in that processing is performed while circulating a solution in which fine particles are dispersed.
In this way, by circulating the solution, it is possible to always supply fine particles to the surface of the material to be processed, and it is possible to continuously perform high-speed deep shape processing. Further, by processing through a filter or the like, it becomes possible to remove foreign substances and to control the particle diameter of fine particles.

A tenth aspect of the present invention is characterized in that the object to be processed is rotated and the processing is performed while replenishing the solution in which the fine particles are dispersed. In this way, by preparing the fine particle dispersion solution while applying it with a spinner or the like, the fine particles can be arranged on the surface in a thin film form, and the fine particles can be supplied continuously. Further, by processing while positioning in the rotation direction, or by irradiating laser light in synchronization with the rotation position, circular continuous pattern processing becomes possible. By using these, it becomes possible to process an aspheric lens, a slit for a rotary encoder, and the like with high accuracy.

According to an eleventh aspect of the present invention, the irradiation laser light is emitted from tens of femtoseconds (fsec) to tens of picoseconds (ps).
ec) is a short pulse laser. As described above, by setting the pulse width of the laser light to be from femtosecond to picosecond, processing by a laser having a high peak output can be realized. When these ultrashort pulse lasers are used, it is easy to realize a highly excited state by multiphoton absorption, and the range of heat influence at the time of laser irradiation can be narrowed, so that more accurate and efficient processing becomes possible. In addition, these lasers make it possible to process a workpiece by ablation even when fine particles having high thermal conductivity such as metal are used.

According to a twelfth aspect of the present invention, by performing the above-mentioned laser processing using an object to be processed as an optical material, it becomes possible to manufacture an optical element by a laser method which has conventionally been difficult to perform optical surface processing. . An optical element formed by the above processing method can have a shape with a high aspect ratio, and can be used as a microlens array, a diffraction grating, or the like that requires a minute shape.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a laser processing method according to the present invention.

FIG. 2 is a block diagram showing a configuration of another embodiment of the laser processing method of the present invention.

FIG. 3 is a block diagram showing a configuration of another embodiment of the laser processing method of the present invention.

FIG. 4 is a block diagram showing a configuration of another embodiment of the laser processing method of the present invention.

FIG. 5 is a block diagram showing a configuration of another embodiment of the laser processing method of the present invention.

FIG. 6 is a block diagram showing a configuration of another embodiment of the laser processing method of the present invention.

FIG. 7 is a block diagram showing a configuration of another embodiment of the laser processing method of the present invention.

FIG. 8 is a block diagram showing a configuration of another embodiment of the laser processing method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate to be processed 2 Fine particle 3 Solution 4 Laser beam 5 Processing hole 6 Fine particle dispersed thin film 7 Solution tank 8 Fine particle dispersed film 9 Moving stage 10 Transparent substrate 11 Processed transparent substrate 12 Pump 13 Filter 14 Spinner 15 Syringe

Claims (12)

[Claims] 1. A solution in which fine particles are dispersed is placed in contact with the surface of an object to be processed, and the surface of the object to be processed is selectively irradiated only with a laser beam irradiation part by irradiating a laser beam from the surface. A laser processing method characterized in that: 2. A thin film, in which fine particles are dispersed, is arranged in contact with the surface of the object to be processed, and the surface of the object to be processed is selected only by a laser beam irradiation part by irradiating the surface with laser light. A laser processing method characterized in that the laser processing method is performed. 3. An object to be processed is a material transparent to an irradiation laser beam, and a fine particle-dispersed material is disposed in contact with a surface to be processed which is a surface opposite to a laser irradiation side, and a laser of the fine particle-dispersed material is used. A laser processing method, wherein a processing surface of the processing object is selectively removed by absorption. 4. An object to be processed which is transparent to an irradiation laser beam is set on a film in which fine particles are dispersed, and a laser beam is irradiated from the surface of the object to be processed, so that the object to be processed is A laser processing method characterized by selectively removing a processing surface that is a contact surface with a fine particle dispersion film. 5. A method of disposing a substrate material transparent to the irradiation laser light on the object to be processed, and disposing a solution in which the fine particles are dispersed between the object to be processed and the transparent substrate. The laser processing method according to claim 1, wherein: 6. The laser processing method according to claim 5, wherein a surface shape surface of a transparent substrate having at least one surface shape is arranged on the processing object side. 7. The laser processing method according to claim 1, wherein the fine particles are a polishing material. 8. The method according to claim 1, wherein the fine particles have a particle size of 0.01 μm to 10 μm.
The laser processing method according to claim 1, wherein: 9. The method according to claim 1, wherein processing is performed while circulating a solution in which the fine particles are dispersed.
Or the laser processing method according to claim 5. 10. The laser processing method according to claim 1, wherein the object to be processed is rotated, and processing is performed while replenishing a solution in which the fine particles are dispersed. 11. The irradiation laser beam according to claim 1, wherein the irradiation laser beam is a short pulse laser of several tens of femtoseconds (fsec) to several tens of picoseconds (psec).
The laser processing method according to any one of the above. 12. An optical element produced by using the laser processing method according to claim 1. Description: