JPH0332078A - Laser oscillator - Google Patents

Abstract

PURPOSE:To improve processing accuracy in fine processing by controlling a voltage applied to a liquid crystal mask in accordance with the variation of laser light energy to stabilize it at a desired value. CONSTITUTION:A beam expander 10, a scattering type liquid crystal mask 11, and a condenser lens 12 are successively provided in a light path of laser light A generated at a laser oscillator B. The laser light A is expanded by the expander 10 to be decreased in energy per unit area, and is incident on the mask 11. Then, it is focused by the lens 12 to be increased again in energy per unit area and irradiate a workpiece 13. A controlling circuit 17 controls a voltage applied to the mask in accordance with the laser light energy detected by a detector 18 provided on the output side of the mask 11 and a predetermined energy variation. Thus, the light transmittance is controlled and the energy of the laser light A is stabilized at a predetermined value, so that the processing accuracy in fine processing of the workpiece 13 can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a laser oscillation device that oscillates a laser beam such as a YAG laser that transmits through glass.

[Conventional technology]

As a laser oscillation device that oscillates a laser beam that passes through glass, a laser oscillator as shown in FIG. 7, for example, is known.

That is, an excitation lamp 4 is disposed opposite a laser rod 3 equipped with a peeling mirror 1 and an exit mirror 2, a power source 6 is connected to an electrode 5 of this excitation lamp 4, and a current is passed through the excitation lamp 4 to generate a laser beam. By exciting the rod 3, the output mirror 2 emits laser light A.

The laser light emitted by such a laser oscillator is used for cutting and drilling workpieces, as well as for forming characters and figures on the surface of parts, and the energy of the laser light greatly affects processing accuracy. However, in the laser oscillator described above, it is necessary to stabilize the energy of the laser beam, that is, the laser power, to a constant value, and to arbitrarily switch the mode of the laser beam to form different characters and figures. Conventionally, an ammeter 8 is provided in the N source circuit 7 between the excitation lamp 4 and the power supply 6, and the ammeter 8 The current value to the excitation lamp 4 is detected and the current is controlled to a constant value to stabilize the energy of the laser beam.

Further, an aperture made of a combination of a lens and a mask is provided in the optical path of the laser beam A to switch the mode of the laser beam.

[Problem to be solved by the invention]

However, the factor that causes the energy of the laser beam to fluctuate is not only the current fluctuation to the excitation lamp 4 but also the fluctuation of the current to the excitation lamp 4.
The energy of the laser beam also fluctuates due to impedance changes, deformation of the laser rod, mirror distortion, dirt on the optical system, efficiency changes in the excitation lamp 4, temperature changes, etc.
The impedance of the excitation lamp 4 not only changes slightly depending on the temperature of the lamp cooling water, but also changes over time, so even if the current to the excitation lamp 4 is controlled as described above, the energy of the laser beam will not change slightly. Therefore, when a laser beam is used for microfabrication, the machining accuracy decreases.

Furthermore, since the mode of the laser beam is switched by the aperture, in order to switch to a different mode, the aperture must be replaced with an aperture suitable for that mode, which is not only troublesome to operate, but also requires the preparation of a large number of apertures.

Therefore, an object of the present invention is to provide a laser oscillation device that can solve the above-mentioned problems.

[Means and actions for solving the problem] 1. Diffuse the laser light and make it enter the scattering type liquid crystal mask, detect the laser light energy with a detector installed on the exit side, and change the detected laser light energy. This is a laser oscillation device that controls the voltage applied to the scattering type liquid crystal mask according to the amount of time, and by changing the light transmittance of the scattering type liquid crystal mask according to the energy change of the laser beam, the laser beam energy can be increased. It can be stabilized.

2. This is a laser oscillation device that diffuses laser light and makes it incident on a screen that divides the transparent electrode of a scattering type liquid crystal mask into arbitrary shapes, and controls the voltage applied to the transparent electrode. By controlling the applied voltage, the light transmittance of the scattering liquid crystal mask can be partially varied to obtain a pattern of arbitrary shape.

〔Example〕

As shown in FIG. 1, a beam expander 10, a scattering type liquid crystal mask 11, and a condensing lens 12 are arranged in the optical path of a laser beam A emitted from a laser oscillator B at intervals.

As a result, the laser beam A oscillated from the laser oscillator B is expanded by the beam expander 10 to lower its energy per unit area, enters the scattering type liquid crystal mask 11, and is focused by the condenser lens 12 to reduce the energy per unit area. The energy is increased again and the workpiece 13 is irradiated with light W, f.

The scattering type liquid crystal mask 11 has a liquid crystal 14 as shown in FIG.
Transparent electrode-attached plastic film 16.16 is arranged on both sides of a polymer matrix 15 having As shown in FIG. 1, it is controlled by the voltage applied to the control circuit 17.

On the exit side of the scattering type liquid crystal mask 11, a detector 18 is provided that can accurately and rapidly measure the energy of light such as a portion of germanium power, and a portion of the laser beam A exiting the scattering type liquid crystal mask 11 is transferred to the detector 18. The other laser beam A is made to have higher energy per unit area again by the condenser lens 12 and is irradiated onto the workpiece 13 .

The energy of the laser beam measured by the detector 18 is input to the control circuit 17, and if the measured value fluctuates from a preset value, the voltage to the scattering liquid crystal mask 11 is adjusted according to the fluctuation. control to keep the energy of the laser beam constant.

One is a variable resistor that precisely controls the laser power of the laser beam.

Next, an example of an operation for correcting and stabilizing fluctuations in the laser power will be described.

When adjusting the laser power, the voltage of the scattering type liquid crystal mask 11 is set to a value that gives a light transmittance of 60% to 80% of the light transmittance at the maximum voltage, and is set in advance to the energy of the laser light measured by the detector 18. The light transmittance is increased from 40% to 20% by controlling the voltage according to the variation with the laser beam energy.
The measured laser beam energy is stabilized by matching it with the preset laser beam energy.

For example, the control circuit 17 calculates the applied voltage control amount corresponding to the variation using P-1-D, learning control, modern control, fuzzy control, etc., and controls the applied voltage of the scattering type liquid crystal mask 11 accordingly. By controlling the light transmittance, the energy of the laser beam exiting the scattering liquid crystal mask 11 is made to match the energy of the laser beam set in advance, and the energy of the laser beam irradiated onto the workpiece 13 is kept constant and stable. become

The control circuit 17 controls the scattering type liquid crystal mask 1 by controlling the above-mentioned variation.
It is equipped with a circuit that determines whether the change in light transmittance caused by the voltage control described in step 1 is within a range that can be corrected. Without the voltage control mentioned above,
A current control signal is output to the power source of the laser oscillator B to control the current of the excitation lamp 4 to control the energy itself of the oscillated laser light, thereby keeping the energy of the laser light exiting the scattering type liquid crystal mask 11 constant. It is stabilized as the value of .

This operation is shown in a flowchart as shown in FIG.

As shown in FIG. 4, a screen 20 is provided between the beam expander lO and the condenser lens 12.

The screen 20 is made by dividing the plastic film 16 with transparent electrodes of the scattering type liquid crystal mask 11 into a plurality of parts in a predetermined pattern, for example, as shown in FIG. The control circuit 17 controls the application of a voltage to each plastic film 16 with transparent electrodes, and the control circuit 17 receives the laser light emitted from the screen 20 by a detector 18. Energy is fed back and a pattern selection signal is manually inputted from the man-machine interface 21.

Therefore, for example, when the first mode selection signal is input, the control circuit 17 lowers the voltage applied to the transparent electrode-attached plastic film 1B in the shaded area in FIG. The voltage applied to the transparent electrode-attached plastic film 16 is increased to make the light transmittance 100%, thereby obtaining mode C shown in FIG. 6(a).

Similarly, when the second mode selection signal is input, the control circuit 17 lowers the voltage applied to the transparent electrode-attached plastic film 16 in the shaded area in FIG. The voltage applied to the film 16 is increased to make the light transmittance 100%, thereby obtaining mode D' shown in FIG. 6(b).

When the third mode selection signal is input, the voltage applied to all the transparent electrode-attached plastic films 16 is increased to make the light transmittance 100%, as shown in FIG. 6(c). Mode E shown in is obtained.

In other words, the light transmittance of the scattering liquid crystal mask 11 changes in the range of 0 to 100% depending on the voltage applied to the transparent electrode, so the transparent electrode is divided into arbitrary shapes and the voltage applied to the arbitrary transparent electrode is increased. However, if the voltage applied to the other transparent electrodes is lowered, the partial light transmittance of the scattering type liquid crystal mask 11 will be different, so that a mode with an arbitrary shape can be obtained.

Furthermore, since the light transmittance can be adjusted by controlling the voltage applied to the transparent electrode, the energy of the laser beam irradiated onto the workpiece 13 can be adjusted.

Further, since the energy of the laser beam exiting the scattering liquid crystal mask 11 is detected by the detector 18 and the value is fed back to the control circuit 17 to control the applied voltage, the energy can be precisely adjusted to a desired value.

〔Effect of the invention〕

1. Control the light transmittance by controlling the voltage applied to the scattering liquid crystal mask 11 according to the variation in the laser beam energy exiting the scattering liquid crystal mask 11, thereby stabilizing the laser beam energy at a desired value. Therefore, the energy of the laser beam can be stabilized even if there are impedance changes of the excitation lamp, deformation of the laser rod, distortion of the mirror, dirt on the optical system, changes in the efficiency of the excitation lamp, temperature changes, etc. Accuracy can be improved.

Beam expand the mater laser beam! -10, the energy per unit area is lowered before entering the scattering type liquid crystal mask 11, and a part of the laser light is also entering the detector 18, so the energy of the laser light entering the scattering type liquid crystal mask 11 and the detector 18 is The density is reduced so that the scattering type liquid crystal mask 11 does not reach a high temperature, and the high polymer material constituting the scattering type liquid crystal mask 11 does not undergo discoloration, deformation, plastic deformation, etc. and has excellent durability.
Since the detector 18 can be made of a highly accurate material such as a semiconductor that is sensitive to thermal energy, the accuracy of detecting the energy of the laser beam can be improved and it can be made more stable.

2. By controlling the voltage applied to the divided transparent electrodes, the partial light transmittance of the scattering type liquid crystal sensor 11 can be varied to create a pattern of any shape, and the operation is simple, just by controlling the applied voltage. The laser beam pattern can be changed arbitrarily.

Since the energy density of the laser beam incident on the scattering type liquid crystal mask 11 is low, the high polymer material constituting the scattering type liquid crystal mask 11 will not be discolored, deformed, or plastically deformed, and its durability can be improved.

[Brief explanation of drawings]

Fig. 1 is an overall diagram showing the first embodiment of the present invention, Fig. 2 is an explanatory diagram of a scattering type liquid crystal mask, Fig. 3 is an operation flowchart, Fig. 4 is an overall diagram of the second embodiment, and Fig. 5 6 is a perspective view of the screen, FIGS. 6A, 6B, and 6C are explanatory diagrams of pattern control, and FIG. 7 is an explanatory diagram of a laser oscillator. 10 is a beam expander, 11 is a scattering type liquid crystal mask,
12 is a condensing lens, 13 is a workpiece, 17 is a control circuit, 1
8 is a detector, 20 is a screen. Figure 3 Figure 5 Figure 5 Figure (0) Figure

Claims (1)

[Claims] 1. A beam expander 10, a scattering liquid crystal mask 11, and a condensing lens 12 are sequentially provided in the laser optical path of the laser oscillator B, and a detector 18 is provided on the exit side of the scattering liquid crystal mask 11. , a laser oscillation device characterized in that a control circuit 17 is provided for controlling the voltage applied to the scattering type liquid crystal mask 11 according to the variation between the laser light energy detected by the detector 18 and a predetermined laser light energy. 2. A control circuit that includes a beam expander 10, a screen 20 obtained by dividing the transparent electrode of the scattering liquid crystal sensor 11 into arbitrary shapes, and a condenser lens 12 in the laser optical path of the laser oscillator B, and controls the voltage applied to the transparent electrode. 17
A laser oscillation device characterized by being provided with.