JPH0449094B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laser processing device, and more particularly to a laser processing device that can easily change the processing shape.

Laser processing equipment includes a laser oscillator that emits a high-energy-density laser beam, a processing optical system that irradiates the laser beam onto the workpiece in a desired shape, and a laser beam that irradiates the desired position on the workpiece. It consists of a stage that moves to move the object.

Conventionally, in this type of laser compounding apparatus, the emitted beam of the laser is used as it is, or it is passed through a mask made of an opening such as a symbol or character pattern punched out of a metal plate, or a slit, and used as a desired irradiation shape. For example, in a laser processing device such as a normal laser reveyor or scrye, a mask generator is used that mechanically changes the opening width of a slit or changes the opening of a metal plate provided with a rectangular or circular opening. The aperture of this mask generator is placed in a laser beam, and an image of the aperture is focused and focused onto the workpiece surface by an objective lens.

A laser processing machine called a marker is commercially available as a device that uses this imaging method to engrave numbers, letters, and symbols with at least one laser beam irradiation. The mask generator of this marker uses a metal plate on which various numbers and letters are punched and engraved, and by combining these metal plates, various inscriptions are engraved. However, in order to engrave various inscriptions, it is necessary to prepare a large number of metal plate masks. In addition, changing the name requires resetting each time, making handling complicated, and replacing the masking device by hand is dangerous because it uses a high-power laser. Furthermore, the mass production line must be stopped during replacement, resulting in a decrease in work efficiency.

An object of the present invention is to provide a laser processing device that uses a liquid crystal light valve in a mask generator for the laser processing device and can form beams of various desired processing shapes under microcomputer control. .

According to the present invention, a laser processing device with excellent mass productivity without complicated handling or danger during mask replacement can be obtained.

According to the present invention, there is provided a laser processing apparatus that engraves a desired pattern on a workpiece with a laser beam, which includes a laser light source that generates a laser beam, and a first laser beam that enlarges the diameter of the laser beam from the laser light source.
an optical system, and a liquid crystal that generates polarized light or a transmission pattern in a shape corresponding to the processed shape of the workpiece by optical or electrical signals, and polarizes the incident beam to a predetermined polarization plane according to the polarization or transmission pattern. The expanded laser beam emitted from the liquid crystal light valve optical system and the first optical system is introduced into the liquid crystal light valve optical system, and the laser beam introduced into the liquid phase light valve optical system is polarized or polarized. a polarization separation means for detecting a laser beam having a predetermined plane of polarization after passing through a portion in which a light transmission pattern is formed; and a third optical system for focusing the laser beam from the polarization separation means on a workpiece. A laser processing apparatus is characterized in that a pattern in the shape of the polarization or light transmission pattern of a liquid crystal light valve optical system is etched into a workpiece by a laser beam focused by a third optical system. can get.

The present invention uses an optical writing type liquid crystal light valve that operates by optical writing or an electrode driven liquid crystal light valve that operates by matrix electrode driving as a liquid crystal light valve used in a liquid crystal ride valve optical system.

Since normal laser processing equipment such as repair machines, trimmers, and markers use a laser power of several millijoules/pulse at most, this is a laser power that the liquid crystal of the liquid crystal light valve can withstand. However, since the batch marking method uses a high optical output laser of about 1 joule/pulse, in the present invention, it is necessary to sufficiently spread the luminous flux of the laser beam and appropriately select the laser power density with which the liquid crystal is irradiated.

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a first embodiment of a laser processing apparatus according to the present invention. In the figure, 1 is a Na:YAG laser light source, and 2 is a processing optical system, which includes an optically written liquid crystal light valve 21, a polarizing beam splitter 22, a reflecting mirror 23, a processing lens 24, and a CRT 26. Reference numeral 3 denotes a laser beam introducing optical system for expanding the luminous flux of the laser beam emitted from the laser light source 1 and guiding it to the polarizing beam splitter 22 of the processing optical system 2. Further, 4 is a sample, and 5 is a stage for moving the sample 4 to a desired processing position. The processing lens 24 has an aperture pattern formed by the optical writing type liquid crystal light valve 21 on the sample 4 of about 1/100, 1/50,
It is used to form an image reduced to 1/25 times or the like. The width of the opening on the optically writable liquid crystal light valve 21 is typically 10 microns to several millimeters.

In this embodiment, this optical writing type liquid crystal light valve is used as a mask generator. The aperture is formed by reducing the display formed on the CRT fluorescent surface to about one-tenth the size and forming an image using the imaging lens 25, and writing this fluorescent pattern to the liquid crystal light valve 21 as an optical writing address. It is done by.

On the other hand, the laser light source 1 emits linearly polarized laser light. This laser beam is expanded by the laser beam introducing optical system 3, and then reflected by the polarizing beam splitter 22, and is reflected by the optical writing type liquid crystal light valve 21.
will be introduced to This optical writing type liquid crystal light bulb 2
As shown in FIG. 3, the configuration of No. 1 includes two transparent conductive electrode glass substrates 30 and 31, and a transparent conductive electrode 30a on the substrate 30 facing the imaging lens 25.
Laminated thereon is a cadmium sulfide photoconductor film 32 formed by a reactive sputtering method using argon-based hydrogen sulfide, a sputtered tellurium sulfide light shielding film 33, and a multilayer dielectric film. A mirror layer 34, horizontally aligned liquid crystal alignment layers 35a and 35b made of obliquely deposited silicon oxide, a spacer 36, a liquid crystal 37 narrowed by these liquid phase alignment layers and spacers, and a transparent conductive electrode 31a. The liquid crystal 37 is a twisted nematic mode liquid crystal material commonly known as E7.

Here, the light shielding film 33 assumes that processing laser light of a wavelength to which the photoconductor film 32 is particularly sensitive is incident on the substrate 31 from the polarizing beam splitter 22, and the photoconductor film 32 does not respond to this laser light. It was set up like this. Since the liquid crystal material E7 is a twisted nematic mode liquid crystal material of the compound field effect type, when an alternating current electric field is applied between the transparent conductive electrodes 30a and 31a, the writing light on the photoconductor film 32 by the image of the CRT 26 is Depending on the presence or absence of this, the polarization plane of the linearly polarized incident laser beam for processing may or may not be rotated by 90 degrees. In this way, the polarization plane of the incident laser beam is rotated by 90°, and the reflected laser beam from the front surface of the liquid crystal passes through the polarizing beam splitter 22 and is focused by the objective lens 24, and is irradiated onto the sample 4 for processing.

In this embodiment, many aperture patterns can be imaged at once by writing images of the required number and size on the CRT 26, and processing can be performed simultaneously using the machining beam shape of this aperture pattern, which improves processing efficiency. You can improve your performance.

FIG. 2 is a block diagram showing a second embodiment of the laser processing apparatus according to the present invention, in which 1 is a Nd:YAG laser light source, 7 is a processing optical system, and 3 is a laser beam introducing optical system. Of these, the processing optical system 7 includes a beam scanning mirror 71, a collimator lens 72, a polarizing prism 73, a quarter-wave plate 74, a thermally written crystal light valve 75 driven by a matrix electrode, and a processing lens 76.

The laser beam introducing optical system 3 shapes the linearly polarized laser beam emitted from the laser light source 1 into a rectangular beam and irradiates it onto the beam scanning mirror 71 . The beam scanning mirror 71 determines the scanning direction of the incident rectangular laser beam. The linearly polarized laser beam is collimated by a collimator lens 72, passes through a polarizing prism 73, and becomes circularly polarized by a quarter-wave plate 74.

In this embodiment, the liquid crystal light valve 75 has a fourth
The one shown in the figure is used. This structure has a glass substrate 40 in place of one substrate 30 and transparent electrode 30a of the liquid crystal light valve shown in FIG.
200 to 300 chromium-gold electrodes 42 arranged with a pitch of about 15 μm, and chromium-gold electrodes 4 of about 100 similarly arranged in the vertical direction in place of the light shielding film 33.
3 matrix electrodes and OCBP are used as the liquid crystal material. By heating the intersections of the matrix electrodes with electricity, the device is operated in a thermal-light scattering mode. The opposing transparent conductive electrodes 31a are used to create a non-light scattering state by applying an electric field.
Scanning of the electrodes is performed by energizing one electrode (for example, a horizontal electrode) of the non-light scattering state matrix electrode while energizing the other electrode (for example, a vertical electrode).
After forming a full aperture pattern by sequentially performing thermal writing by line sequential scanning in which aperture pattern information is input into the liquid crystal 37, the liquid crystal 37 is irradiated with a laser beam for processing. At this time, the circularly polarized laser beam from the 1/4 wavelength plate 74 that is incident on the liquid crystal on the electrode that is heated by electricity is scattered. On the other hand, the laser beam incident on the liquid crystal on the electrode that is not heated by electricity is reflected by the multilayer dielectric mirror layer 34, passes through the 1/4 wavelength plate 74, and is linearly polarized. The polarizing prism 73 reflects this linearly polarized laser beam and introduces it into the processing lens 76 . Therefore, the shape of the laser beam focused by the processing lens 76 becomes a desired beam shape. However, since this laser beam also contains scattered light from the liquid crystal light valve 75, the aperture 77 blocks the extra scattered light and increases the contrast of the laser processing beam on the sample 4. The power required for thermal writing in the liquid crystal light valve 75 is approximately 0.6 joules per 1 cm ² of the intersection area of the matrix electrodes, and the writing time per line of electrodes is approximately 1 millisecond or less. Therefore, for example, 200 lines can be written in less than 200 milliseconds, and processing can be performed in real time enough for laser processing.

In a liquid crystal light valve using a matrix electrode, the electrode width of the matrix electrode can be 50 to several 100 μm, and the gap between the electrodes can be 10 μm to several 10 μm, and when the liquid crystal surface is irradiated with a rectangular laser beam with one width of 20 to 50 mm, Within this width, several hundred decomposition points can be obtained. If you reduce this to a width of 3 to 10 mm and engrave it, you can engrave it with a sufficiently high resolution. At this time, the laser power density on the liquid crystal can be reduced to 100 mJ/cm ² or less by setting the width of the other rectangular beam incident on the liquid crystal to 15 to 30 mm, which is a low power that does not damage the liquid crystal light valve. At the focal position, it is approximately 0.6 J/cm ² or more, allowing for good batch marking.

In the first and second embodiments described above, any pattern can be simultaneously engraved by laser beam irradiation without causing optical damage to the liquid crystal light valve.

In the present invention, various liquid crystal light valves other than those used in the first and second embodiments can be used as a mask generator for laser processing. For example, the matrix electrodes 42 and 43 of the liquid crystal light valve mask generator used in the second embodiment shown in FIG. 4 are transparent conductive electrodes, and the liquid crystal is narrowed by a vertically aligned liquid crystal alignment layer. Using a P-type cholesteric liquid crystal nematic or cholesteric phase transition type liquid crystal material, which is driven only by the electric field applied to the liquid crystal from the matrix electrode, light scattering is caused by applying an electric field by line sequential scanning of the matrix electrode, resulting in an accumulation effect. You may also use a liquid crystal light bulb that can display images.
In this case, a reflecting means such as a multilayer dielectric mirror may not be used in the liquid crystal light valve, and a reflecting mirror may be provided behind the liquid crystal light valve, allowing the liquid crystal light valve to be used as a reflective light valve. Alternatively, a transmission type light valve may be used in which a reflecting means such as a reflecting mirror is removed and the light bulb is inserted into the beam of the laser beam for processing.

In addition, we use a twisted nematic mode liquid crystal that utilizes field-effect birefringence, which is widely used in calculators and watches. A liquid crystal light valve that causes birefringence in the liquid crystal by time-divisionally driving may be used as a mask generator. In this case, the liquid crystal is irradiated with linearly polarized laser light. Furthermore, since the liquid crystal light valve is not provided with a reflecting means, it can be used as a transmission type light valve.

As described in detail above, when used in the present invention, it becomes easy to set an opening to obtain an arbitrary processed shape, there is no complicated handling, there is no danger when changing the processed shape, and it is excellent in mass production. Further, since the opening can be set externally and a microcomputer can be used to control the setting, the range of application of the laser processing device can be expanded and the processing speed can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a first embodiment of a laser processing device according to the present invention, FIG. 2 is a block diagram showing a second embodiment of a laser processing device according to the present invention, and FIG. 4 shows a liquid crystal light valve used in the laser processing apparatus shown in FIG. 2. FIG. 4 shows a liquid crystal light valve used in the laser processing apparatus shown in FIG. 1... Laser light source, 2, 7... Processing optical system, 4
...Sample, 5...Mountain stage, 21,75...Liquid crystal light valve.

Claims (1)

[Scope of Claims] 1. A laser processing device that engraves a desired pattern on a workpiece with a laser beam, comprising: a laser light source that generates the laser beam; a first optical system that expands the diameter of the laser beam; or a liquid crystal light valve optical system that includes a liquid crystal that generates polarized light or a transmission pattern in a shape corresponding to the processing shape of a workpiece according to an electric signal, and that polarizes an incident beam to a predetermined polarization plane according to the polarization or transmission pattern. a system for introducing an expanded laser beam emitted from the first optical system into the liquid crystal light valve optical system; and a third optical system that focuses the laser beam from the polarization separation means on the workpiece. . A laser processing apparatus, wherein a pattern in the shape of the polarized light or light transmission pattern is etched into the workpiece by a laser beam focused by the third optical system. 2. The laser processing apparatus according to claim 1, wherein the liquid crystal light valve optical system includes an optical writing type liquid crystal light valve operated by optical writing. 3. The laser processing apparatus according to claim 1, wherein the liquid crystal light valve optical system includes an electrode-driven liquid crystal light valve operated by a matrix electrode.