JPS5893294A - Laser oscillator - Google Patents

Abstract

PURPOSE:To automatize the alignment work and to always obtain the desired laser output by disposing a thermal detector, obtaining the displacement of a laser light beam as the variation in the distribution of the temperature and correcting the position of a mirror as the optimum position. CONSTITUTION:The measured temperature data from thermal detectors 25 are, for example, amplified and obtained for four detectors as four temperature values, and the average value and the n difference of the maximum and minimum temperatures is calculated by an arithmetic unit 29. A mirror drive signal is obtained by a comparison arithmetic unit 30 which compares the calculated result with the reference data from a reference data memory 31 having the temperature distribution, a mirror drive pattern and the reference data, thereby obtaining a mirror drive signal and setting via a reversible rotation drive unit 24 and a mirror driving mechanism 27 via a laser light 4b so that the four temperature data of the thermal detectors 25 become equal to each other. In this manner, the optimum alignment can be automatized, thereby always obtaining the desired laser output.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laser oscillation device, and particularly to an automatic control device suitable for adjusting the alignment of a laser beam resonator.

Conventionally, carbon dioxide laser devices have a drawback that the optical axis alignment, that is, the alignment adjustment between the total reflection mirror and the output mirror of the laser beam resonator varies slightly.

That is, the alignment dynamically changes due to the laser beam reflection loss heat at room temperature and during laser beam oscillation, reducing the laser output value. In order to eliminate this drawback, structural measures were taken for the pedestal, bellows, and vernier dial for adjusting the mirror position, and the alignment was manually adjusted each time so that the laser output was adjusted to a constant value. Therefore, when using the device continuously for several hours, it is necessary to check the alignment midway.

An object of the present invention is to provide a laser oscillation device that automates such delicate alignment work and can always obtain a desired laser output.

In other words, the mirror layer is equipped with a thermal detection element that detects the deviation of the optical axis of the laser beam, determines the beam deviation as a temperature distribution change, and after calculating the temperature distribution, the mirror position can be adjusted to the optimal position. By providing a moving mechanism, automatic alignment adjustment is possible, and a predetermined laser output can always be brought into the optimum optical resonator state.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As an example of the present invention, an application example of a high-speed axial flow type carbon dioxide laser device will be described below with reference to the drawings.

FIG. 1 is an explanatory diagram of the operation of the carbon dioxide laser device. An optical system mount 3 is arranged on the mount 1 via a bearing 2,
An output mirror 5 and a reflecting mirror 6 are fixed to both ends thereof. Output mirror 5
Between the optical axes of the reflecting mirror 6 and the optical axis of the filled gas 13, a hollow discharge tube 8 having the electrodes 9 at both ends, and an electrode 9 for discharging and exciting a mixed gas such as carbon dioxide, nitrogen, helium, etc. are arranged. There is a T-shape 〒714 for distributing the gas flow.

On the other hand, a gantry 1 (1111 includes a promotor 11 for forcedly circulating the sealed gas 13 and a heat exchanger for cooling the sealed gas 13 by discharge excitation and improving laser heating efficiency) 2, and an electrode 9 Insulating cylinder 10 for ground voltage insulation of
There is.

When the power supply 7 is applied to the electrode 9 at a high speed, the sealed gas 13 that is being forcedly circulated within the discharge tube 8 is actively excited, increasing the energy level of the sealed gas and maintaining a stable base energy level. When returning to the original position, a coherent laser beam is emitted, and the mirrors at both ends strengthen each other due to the optical bombing effect, creating laser beam resonance. That is, the laser 4 consists of an internal laser reciprocating reflected light 4b and a l/- laser output light 4a which is partially emitted from the output mirror 5 to the outside. The output of 4a is determined by the 1t-III reflective coating rate of output @5.

Here, the mirrors are fixed to the optical system mount 3 so that the optical axes of the mirrors at both ends do not shift, and thermal expansion deformation due to the laser beam and ambient temperature is absorbed by the bellows 18 and the bare link 2, and the reflecting mirror 6 and Structural measures are taken to prevent the output mirror 5 and the optical axis from misaligning.

However, since a strict optical axis deviation of θ=0.5 to 1 radian is required, the mirrors were adjusted at all times. This will be explained with reference to FIGS. 2 and 3. FIG. 2 illustrates the empty optical axis condition, and shows the discharge tube 8 (inner diameter D1
If the center is set at the center, then 5.6 mm is placed at both ends via apertures 26 (inner diameter J]2). The size of the aperture 26 is determined by the beam thickness of the laser beam 4, and the aperture 26 is provided to limit the effective light receiving area of the mirror and prevent thermal damage due to the deviation of the optical axis shown in FIG.
This is a condition for D2.

If only the reflection mirror 6 is shifted by θ for some reason, the reflected light of the laser beam 4b will partially hit the aperture 26b and not all of it will reach the output mirror 5, so that the optical bombing l will be It is attenuated and also cuts off the laser output light 4a.

The present invention focuses on this phenomenon, and by arranging an inner diameter heat detection element 25 between the mirror and the aperture, the deviation of the laser optical axis can be detected by converting the optical temperature. (When a laser beam hits an object, the object becomes thermal energy and is balanced.) Hereinafter, an embodiment of the present invention will be explained with reference to FIG. This is the temperature distribution of the heat detection element 25b on the side.

FIG. 5 shows an embodiment of the sharp movement mechanism section 27.

With the optical system frame 3 as a reference, the reflecting mirror 6 is temporarily fixed via a mirror mounting head 15 for fixing it and a spring 22 for fixing the screw pole I/20 and the variable position.

The rotational force of the reverse rotation drive unit 24 (for example, a pulse motor) fixed to the screw thread 3 is converted into linear displacement (in the horizontal direction in the figure) by the gear 23 and the end gear of the screw bolt 20.
The screw bolt 20 rotates with the fixed side as the fixed side, resulting in left and right displacement. At this time, mirror mounting base] 5 and screw bolt 2
0 and iIj: Since they rub against each other, a thrust bearing 21 is provided between 15 and 20 in order to reduce the loss of driving force.

Although only one screw bolt 20 is shown in FIG. 5, there are two to three bolts for 360-degree transformation, so they are not shown.

On the other hand, the reflection mirror 6 is hit by the laser beam 4b and a reflection loss of several percent occurs, but all of this is converted into heat, so the reflection mirror 6
A hollow water cooling gap 16 is provided at the inner end of the tube to cool it and prevent thermal damage. Cooling water is supplied to the hollow water cooling gap 16 at a location not shown. There is a bellows 18 on the right side of the mirror mounting base 15, which is fastened with a bolt 19 across a hollow cylindrical aperture 26. The gasket 17 is for preventing water leakage or leakage of the sealed gas 13.

In addition, between the reflecting mirror 6 and the aperture 26, a heat detection element 25a- is installed in an insulating hollow cylinder 25-1 as shown in FIG.
The heat detection element 25 embedded in d2 is mounted on the mirror base 15, and serves as the tip for measuring the temperature of the laser beam 4b.

In addition, since only the reflector 6 is generally made of an extra material, a heat detection element 25 (for example, a CC thermocouple) is embedded on the back side (left side in the figure) to measure the heat transfer distribution due to reflection loss of the laser beam. It's okay.

The second structure makes it possible to detect the temperature due to the deviation of the laser beam 41, and if a drive command is sent from the first part to the reversible rotation part 24, the screw bolt 20
The displacement is transmitted to and the reflecting mirror 6 becomes movable. Total reflection mirror 5
Although not shown in the figure, since they are the same mechanism, their explanation will be omitted.

Based on the following, an embodiment of the egg weight system 1 for automatic alignment will be described with reference to FIG.

The temperature measurement data from the heat detection element 25 is amplified by n (4 in FIG. 6) to obtain 4 temperature values, and the calculation unit 29 calculates the n difference between the average value and the maximum and minimum temperature values. Calculate by

A reference data storage unit 31. which has the calculation results and reference value data of the temperature distribution and sharp movement pattern shown in FIG. A sharp motion signal is obtained from the sharp motion generation signal 32 by the comparison calculation section 30, which drives the reversible rotation drive section 24 and the boundary motion mechanism section 27, and detects the heat detection element 25 using the laser beam 41).
Set the purpose so that the four temperature data are the same. The key point of this method is to obtain the data in the standard data storage section 31 unique to the product, but when there is an uneven temperature distribution as shown in FIG. We obtained data on whether to use pulse drive through experiments and obtained good results.

As described above, according to the present invention, the following foundations have been established.

(1) As a result of detecting alignment deviations by temperature and being able to understand changes in laser beam diameter from changes in temperature distribution,
Detection elements for automatic control have been established.

(2) We have completed the structure of an electric-mechanical system that can precisely control the position of the mirror.

(3) The deviation of the laser beam diameter was stopped by a change in temperature distribution, and as a result, we were able to obtain basic data that gives the number of pulses to excite the mirror position regulating drive unit.

As described above, according to the present invention, optimal alignment for laser output is automated, and laser output can be opened and closed always under desired alignment conditions.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a high-speed axial flow type carbon dioxide laser device, FIGS. 2 and 3 are schematic side sectional views of the alignment, FIG. 4 is a temperature distribution characteristic diagram of the heat detection element according to the present invention, and FIG.
The figure is a sectional side view of the boundary movement mechanism section in which it is mounted, FIG. 6 is a sectional view of the heat detection element, and FIG. 7 is an overall control block diagram. 6...Reflector, 24...Reversible rotation drive unit, 25...
Heat detection element, 26... Aperture, 27... Boundary movement mechanism section, 28... Alignment automatic control section, 31.
・・Kibe (stem vice-class figure 4)

Claims (1)

[Claims] 1. In a mirror for a laser oscillator with an aperture attached, a heat detection element attached to the aperture, a processing unit that compares the detected value of the heat detection element with a reference temperature of the laser beam, and a processing unit. 1. A laser oscillation device comprising: a mirror layer movement mechanism section that drives a mirror position based on a processing result from the section.