JPH0234468B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a laser output control device that controls laser output at high speed.

[Prior art]

FIG. 3 is a schematic configuration diagram showing a laser output control device in a conventional carbon dioxide laser device disclosed in, for example, Japanese Patent Application No. 160656/1988 filed by the applicant of the present application. In the figure, 1 is a container filled with laser medium gas containing carbon dioxide gas, 2A and 2B are containers 1
A pair of electrodes provided inside, 3 is electrode 2A, 2B
4 is a power supply of 2A,
The discharge generated by applying a high voltage to 2B, 5 reflects most of the laser light, but only about 1%.
6 is a total reflection mirror that has the property of transmitting light, and 6 is a partially transmitting mirror. The above container 1, electrodes 2A, 2B,
A power source 3, a laser medium gas (not shown) for generating discharge 4, a total reflection mirror 5, and a partial transmission mirror 6 constitute a laser oscillator. 7 is a partially transmitting mirror 6
8 is a detection laser beam output from the total reflection mirror 5;
The intensity is proportional to the intensity of the laser beam 7. 9 is an integrating sphere whose inner surface is a completely diffusing surface, 10 is an input port for inputting the detected laser beam 8 into the integrating sphere 9, 11 is an output port for outputting the laser beam diffused within the integrating sphere 9, and 12 is an output A micro laser detector made of, for example, a thermopile installed at port 11, 13 an output command value output from an output setting device (not shown), 1
4 is a comparator, and 15 is an amplifier.

A laser output control device in a conventional carbon dioxide laser device is configured as described above, and has an integrated electrode 2.
A high voltage is applied to A and 2B from a power source 3 to generate a discharge 4 to excite the laser medium gas and emit a laser beam with a broken length of 10.6 μm. This emitted laser light causes laser oscillation by repeating reflection between the total reflection mirror 5 and the partial transmission mirror 6 provided in parallel.
A laser beam 7 is outputted from the partially transmitting mirror 6 to the outside.
On the other hand, the total reflection mirror 5 outputs a detection laser beam 8 of about 10 to 50 W, which is proportional to the intensity of the laser beam 7 output from the partial transmission mirror 6. Input port 10 to integrating sphere 9
Inject it inside. The detection laser beam 8 incident on the integrating sphere 9 undergoes numerous reflections on the inner surface of the integrating sphere 9, is uniformly diffused and attenuated, and is incident on a minute laser detector 12 installed at the output port 11. The attenuation rate of the integrating sphere 9 for the micro laser detector 12 is
Assuming that the diameter of is approximately 100 mm and the diameter of the light receiving surface of the micro laser detector 12 is approximately 1 mm, it is approximately 1/10000,
For example, when the detection laser beam 8 of about 50 W is input to the integrating sphere 9, the input to the micro laser detector 12 is about 5 mW.
becomes. The laser light input to the micro laser detector 12 is converted into an electrical signal, this electrical signal is compared with a predetermined laser light output command value 13 by a comparator 14, and the deviation signal is amplified by an amplifier 15. By controlling the output voltage or output current of the power source 3, the excitation intensity of the laser medium gas is controlled, and the intensity of the laser beam 7 is kept approximately constant.

However, since the micro laser detector 12 is composed of a thermopile or the like, its sensitivity changes when the ambient temperature changes, and this causes the problem that laser output control cannot be performed accurately when the temperature changes significantly, such as in summer and winter. It was hot.

Furthermore, as described above, since the detection laser beam 8 of 10 to 50 W is incident on the integrating sphere 9, the temperature of the integrating sphere 9 increases, and the temperature of the micro laser detector 12 also increases due to heat conduction from the integrating sphere 9. As a result, the output characteristics of the micro laser detector 12 vary. For example, when a detection laser beam 8 of about 50 W is incident on an integrating sphere 9 with a diameter of about 100 mm, the temperature of the integrating sphere 9 increases by about 100°C. Now, when measuring the integrating sphere input and the output of the minute laser detector using a minute laser detector 12 with a sensitivity, that is, an output voltage/input light intensity of 12 mV/1 mW and a temperature coefficient of sensitivity of -0.36%/°C, the result is shown in Figure 4. As shown by the broken line 16, the output of the micro laser detector 12 decreases by about 10% compared to the case where there is no temperature rise as shown by the solid line 17, and therefore the output of the laser beam 7 differs from the output command value 13. There was also the problem that it got hot.

[Summary of the invention]

This invention was made for the purpose of improving the above-mentioned problems, and in a laser output control device having an integrating sphere and a micro laser detector, the micro laser detector is provided with a case in which heat can be transferred to the micro laser detector. We propose a laser output control device that prevents fluctuations in the output characteristics of a micro laser detector due to temperature changes by housing the micro laser detector in a heat transfer case and controlling the temperature of the micro laser detector at a constant temperature via the heat transfer case.

[Embodiments of the invention]

FIG. 1 is a schematic configuration diagram showing one embodiment of the present invention, and in the figure, 1, 2A, 2B, and 4 to 1
2 is the same as the conventional device described above. 18 is a heat transferable case made of aluminum or copper. The case 18 accommodates the micro laser detector 12 in close contact with its side surface, has an opening 12A on the light receiving surface of the micro laser detector 12, and is installed so that the opening 12A is located at the output port 11 of the integrating sphere 9. do. Further, constant temperature control means for the micro laser detector 12 is connected to the case 18, and a heater 19 and a temperature sensor 20 such as a thermistor or thermocouple, which form part of the means, are attached. 21 is an output line of the micro laser detector 12, 22 is a comparator that compares the output signal of the temperature sensor 20 and the temperature setting signal 23, 24 is amplified the signal from the comparator 22,
An amplifier 26 that controls the operation of the relay 25 is a power source that supplies power to the heater 19 through the contacts of the relay 25. Comparator 22 and amplifier 2
4. The relay 25 and power supply 26 also constitute constant temperature control means.

In the laser output control device configured as described above, the temperature setting signal 23 is set to the ambient temperature and the integrating sphere 9.
For example, at a high temperature that is not affected by the temperature rise of
By setting the temperature to 50° C. and applying heat to the micro laser detector 12 through the heat transferable case 18, constant temperature control is performed so that the micro laser detector 12 is always maintained at a constant high temperature. Therefore, the output characteristics of the micro laser detector 12 can be maintained constant, and the output of the laser beam 7 can be accurately controlled by the stable output signal of the micro laser detector 12.

FIG. 2 is a schematic configuration diagram showing another embodiment of the present invention, and 27 is an electronic cooler as an element of constant temperature control means using the Peltier effect.

In this embodiment, the temperature sensor 20 is used in case 1.
8 is detected, the difference between this output signal and the temperature setting signal 23 set at a constant temperature, for example, 25°C, is determined by the amplifier 28, and the direction of the current flowing to the electronic cooler 27 is determined by the amplifier 28 according to this difference. By heating and cooling the case 18 at a constant temperature, the output characteristics of the micro laser detector 12 are stabilized.

In the above explanation, we have described the case where a thermopile is used as a detection element as a micro laser detector, but carbon dioxide lasers can also use gold/germanium elements, mercury/cadmium/telluride elements, pyroelectric effect elements, and YAG lasers can also use silicon photo sensors, etc. Needless to say, it can be used.

〔Effect of the invention〕

As explained above, this invention is capable of controlling the temperature of a minute laser detector at a constant temperature through a heat transferable case, so that the output characteristics of the minute laser detector are not affected by ambient temperature changes or temperature rises of the integrating sphere. is stabilized, so the laser output can be controlled accurately and at high speed. Furthermore, since the temperature of the micro laser detector is always maintained constant, it is possible to use a detection element whose temperature characteristics are not very good, which also has the effect of reducing the cost of the device.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention;
FIG. 2 is a schematic configuration diagram showing another embodiment of the present invention, FIG. 3 is a schematic configuration diagram showing a conventional laser output control device, and FIG. 4 is a characteristic diagram of integrating sphere input and output of a micro laser detector. . 1... Container, 2A, 2B... Electrode, 3, 26...
...power supply, 5...total reflection mirror, 6...partial transmission mirror, 9
... Integrating sphere, 12 ... Microscopic laser detector, 14,
22... comparator, 15, 24, 28... amplifier,
18... Case, 19... Heater, 20... Temperature sensor, 25... Relay, 27... Electronic cooler. Note that the same reference numerals in each figure indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] 1. A laser output control device having an integrating sphere into which a laser beam derived from a laser oscillator is incident, and a minute laser detector that detects the laser beam diffused by the integrating sphere, wherein the minute laser A laser output control device comprising: a case that houses a detector and is capable of transmitting heat to the micro laser detector; and constant temperature control means connected to the case. 2. The constant temperature control means of the micro laser detector includes a temperature sensor attached to the case, and a heater attached to the case to control the constant temperature at a temperature higher than the ambient temperature. The laser output control device according to item 1. 3. Claim 1, characterized in that the constant temperature control means for the micro laser detector includes a temperature sensor and an electronic cooler, which are respectively attached to the case.
Laser output control device as described in .