Carbon dioxide laser photodetector

Abstract

To provide an inexpensive and fast-responding detector for carbon dioxide laser light output. [Solution] The device comprises an absorber 10 that absorbs and diffusely reflects carbon dioxide laser light 100, and temperature sensors 20-30 located symmetrically on the front and back surfaces of the absorber. By detecting the difference between the front temperature sensor 20 and the back temperature sensor 30, the infrared radiation 102-103 due to the heat of the absorber is canceled out, and the device can be used as a detector to measure the output of the carbon dioxide laser light by detecting only the diffuse reflection 101 of the laser light.

Description

Technical Field

[0001] The present invention relates to a carbon dioxide laser light detector for detecting the output of carbon dioxide laser light.

Background Art

[0002] Carbon dioxide lasers are used in a wide range of fields, such as industrial fields like cutting metals and resins, and medical fields like surgical treatment and dental treatment.

[0003] In general, to measure the output of carbon dioxide laser light, a laser output measuring device using a thermopile method, such as that in Non-Patent Document 1, is used.

[0004] As an element capable of detecting carbon dioxide laser light at high speed, it is possible to detect by using an HgCdTe (mercury cadmium telluride) element like that in Non-Patent Document 2. Also, when using this element, it is common to use an integrating sphere to homogenize the laser light and detect a part of it.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Non-Patent Documents

[0006]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

[0007] While laser power measuring instruments like the one described in Non-Patent Document 1 are suitable for high-power measurements, they have a slow response time and require laser irradiation for at least one second.

[0008] HgCdTe elements like those described in Non-Patent Document 2 have a fast response time but are very expensive. Furthermore, integrating spheres require an integrating sphere with a gold coating on its inner surface, which also increases costs.

[0009] As mentioned above, it has been difficult to obtain an inexpensive detector with a fast response time for carbon dioxide laser light.

[0010] This invention has been made in view of the above-mentioned problems, and aims to provide an invention that solves the above-mentioned problems. [Means for solving the problem]

[0011] In order to solve the above problems, the present invention has the following configuration. The carbon dioxide laser photodetector of the present invention is a detector for measuring the output of carbon dioxide laser light, characterized in that it comprises an absorber that receives carbon dioxide laser light and a temperature sensor arranged on the front and back surfaces of the absorber. The carbon dioxide laser photodetector of the present invention is characterized in that the absorber is an absorber that absorbs carbon dioxide laser light and also emits infrared radiation due to diffuse reflection on the front surface of the absorber and heat absorbed. The carbon dioxide laser photodetector of the present invention is characterized in that the temperature sensor has sensitivity in the infrared range and is equipped with a fast response time. The carbon dioxide laser photodetector of the present invention is characterized by comprising a plurality of temperature sensors in order to reduce the influence of beam diameter and mode changes. The carbon dioxide laser photodetector of the present invention is characterized by a structure that can detect only the diffuse reflection of carbon dioxide laser light on the surface of the absorber by taking the difference between the temperature sensors on the front and back surfaces. [Effects of the Invention]

[0012] With the above configuration, the present invention can detect the output of a carbon dioxide laser beam at low cost and with a fast response time. [Brief explanation of the drawing]

[0013] [Figure 1] This figure shows the basic configuration of a carbon dioxide laser photodetector according to an embodiment of the present invention. [Figure 2] This diagram shows the configuration of the temperature sensor section of a carbon dioxide laser photodetector according to an embodiment of the present invention. [Figure 3] This figure shows the configuration of a carbon dioxide laser photodetector according to an embodiment of the present invention. [Figure 4] This figure shows the configuration of the electronic circuit of a carbon dioxide laser photodetector according to an embodiment of the present invention. [Figure 5] This figure shows the time variation of the voltage output obtained from a carbon dioxide laser photodetector, which is an embodiment of the present invention. [Modes for carrying out the invention]

[0014] The following describes a carbon dioxide laser photodetector according to an embodiment of the present invention. This carbon dioxide laser photodetector uses an absorber that receives carbon dioxide laser light and a temperature sensor that is sensitive to the infrared region. It also uses an electronic circuit for differential and amplification of the voltage output obtained from the temperature sensor.

[0015] Figure 1 shows the basic configuration of a carbon dioxide laser light detector. It consists of an absorber that receives carbon dioxide laser light and a temperature sensor, and the output of the carbon dioxide laser light is detected based on the output of the temperature sensor.

[0016] The carbon dioxide laser light 100 is irradiated onto the absorber 10, and a part of the laser light is reflected as diffuse reflection 101 on the surface of the absorber. The remaining laser light is absorbed by the absorber and converted into heat. The absorbed heat is emitted from the absorber as infrared radiation 102 - 103.

[0017] The front and back temperature sensors have sensitivity in the infrared region, and a non-contact type temperature sensor such as that in Non-Patent Document 3 can be used. Since both the diffuse reflection 101 and the infrared radiation 102 - 103 are wavelengths in the infrared region, the front temperature sensor 20 detects the diffuse reflection 101 and the infrared radiation 102. The back temperature sensor 30 detects the infrared radiation 103.

[0018] Figure 2 shows an example of the configuration of the temperature sensor. Three temperature sensors are installed at 120° intervals on a donut-shaped printed circuit board. Also, the detection surface of the temperature sensor is installed with an inclination towards the center of the absorber. When importance is attached to factors such as laser output, beam diameter, and incident position dependence, the number of temperature sensors can be configured to be even more.

[0019] Figure 3 shows an example of the configuration with the printed circuit board of Figure 2 installed. The printed circuit board is installed at an equal distance from the absorber. The absorber uses an aluminum alloy (A5052) as the base material, and its surface is coated with a matte black heat-resistant synthetic resin paint. This surface treatment is to promote appropriate absorption and diffuse reflection due to the rough surface.

[0020] Figure 4 shows an example of the configuration including the electronic circuit of the carbon dioxide laser light detector. The front and back temperature sensors 20 - 30 are connected in series respectively and input to the amplifier circuit 50. In the amplifier circuit 50, the front temperature sensor 20 and the back temperature sensor 30 are input to a differential amplifier, the diffuse reflection component of the front temperature sensor is extracted, and the signal is amplified by the main amplifier. At this time, the main amplifier adds zero point adjustment and gain adjustment functions for the front and back of the absorber This allows for compensation of temperature differences and individual differences in the sensitivity of temperature sensors. [Examples]

[0021] The following describes the results of actually irradiating the CO2 laser detector with CO2 laser light using the CO2 laser photodetector described above. The CO2 laser light to be irradiated has an oscillation wavelength of 10.6 μm, an output of 1 W, and a beam diameter of Φ3 mm, and is irradiated near the center of the CO2 laser photodetector.

[0022] Figure 5 shows the results of measurements taken by connecting to an oscilloscope under the above conditions. The response time was 22.7 ms at 0-95% voltage and 35.6 ms at 0-100% voltage.

[0023] This carbon dioxide laser photodetector uses an inexpensive temperature sensor, the same type used in non-contact thermometers, as its temperature sensor, and the absorber is made of surface-treated metal. As a result, it has a faster response time and is less expensive than conventional laser power meters. [Explanation of Symbols]

[0024] 10 absorbent material 20 Front temperature sensor 30 Rear temperature sensor 40 Printed circuit boards 50 Amplifier Circuit 100 Carbon dioxide laser light 101 Diffuse reflection 102-103 Infrared radiation

Claims

1. A carbon dioxide laser light detector for measuring the output of a carbon dioxide laser light, characterized by comprising an absorber that receives carbon dioxide laser light and temperature sensors located on the front and back surfaces of the absorber.

2. A carbon dioxide laser photodetector characterized in that the absorber comprises an absorber that has been treated to absorb and diffusely reflect carbon dioxide laser light.

3. The aforementioned temperature sensor is a carbon dioxide laser photodetector characterized by having sensitivity in the infrared range and a fast response time.

4. The aforementioned temperature sensor is a carbon dioxide laser photodetector characterized by comprising multiple temperature sensors, taking into consideration the laser output and the sensitivity of the temperature sensors.

5. The aforementioned temperature sensor is a carbon dioxide laser photodetector characterized by detecting only the diffuse reflection of carbon dioxide laser light by taking the difference between the temperature sensor outputs on the front and back surfaces, thereby canceling out infrared radiation due to the heat of the absorber.

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