JPH0458890B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a laser power measuring method for measuring laser power.

(Prior art) As shown in FIG. 3, a conventional laser power meter for measuring laser power has a blackened absorption surface 3 provided on the surface of a thermally conductive substrate 1 on the side irradiated with the laser beam 2 to be measured. The structure was such that a thermocouple 4 and a cooling jacket 5 were provided on the substrate 1 concentrically with respect to the blackened absorption surface 3. In such a laser power meter, the laser beam 2 to be measured is converted into thermal energy by the blackened absorption surface 3,
The power of the laser beam 2 to be measured was measured by electrically detecting the temperature rise of the substrate 1 with a thermocouple 4.

(Problem to be solved by the invention) However, with this method of measuring laser power, as the power level increases, a large amount of heat is handled, and there are structural constraints, cooling constraints, and blackening absorption. The design was difficult due to the durability of surface 3, and there were problems in that it was difficult to perform stable measurements.
For example, when a cooling jacket 5 with an inner diameter of 69 mm is provided on a substrate 1 made of copper with a thickness of 10 mm, and a laser beam 2 to be measured with a beam diameter of 40 mm and a power of 5 kW is incident on the blackened absorption surface 3, the center of the substrate 1 The temperature rise will be 280℃,
There was a problem that the blackened absorbing surface 3 was damaged. If the thickness of the substrate 1 is increased, the temperature rise will be reduced, but errors will occur, and the cooling jacket 5 cannot be made too thick due to the design considerations.

An object of the present invention is to provide a laser power measuring method that can easily measure even high-output laser power while avoiding problems such as a blackened absorption surface.

(Means for solving the problems) The means of the present invention for achieving the above object are as follows:
The present invention will be explained with reference to FIGS. 1 and 2, which correspond to embodiments. The present invention transmits the laser beam 2 to be measured, absorbs the measurement control laser beam 7, and reflects the laser beam 2 to be measured at that portion. Using a semiconductor substrate 6 having a characteristic of The measurement control laser beam 7 is characterized in that the time for which the measurement control laser beam 7 is applied is controlled by controlling the irradiation time of the measurement control laser beam 7.

(Function) When measurement is performed in this way, the irradiation time of the laser beam 2 to be measured that is incident on the sensor 8 is limited to a short time according to its energy, and therefore the temperature rise of the sensor 8 is suppressed. . Therefore, even high output power can be measured without any problem.

(Example) Examples of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a first embodiment of the present invention. In this embodiment, the semiconductor substrate 6 is placed obliquely in the optical path of the laser beam 2 to be measured. This semiconductor substrate 6 has a property of transmitting the laser beam 2 to be measured, absorbing the measurement control laser beam 7, and generating free electrons in that portion to reflect the laser beam 2 to be measured. As such a semiconductor substrate 6, for example, a germanium plate is used. Germanium has absorption characteristics at a wavelength of 0.5 to 1.5 um, and generates a large amount of free electrons, and has transmission characteristics at a wavelength of 3 to 15 um. Therefore, as the laser beam 2 to be measured, CO,
As the CO ₂ laser light and the measurement control laser light 7, Lewy laser light and YAG laser light are suitable. The measurement control laser beam 7 is made to strike the same position of the semiconductor substrate path 6 where the laser beam 2 to be measured hits, with a beam spot that is the same as or larger than the beam spot of the laser beam 2 to be measured. The laser beam 2 to be measured is reflected by the semiconductor substrate 6, and a sensor is placed at a position on the optical path through which the reflected light passes to receive the light, electrically detect the power, and amplify and display it on the amplification/display unit 9. I'm starting to let them do it. A blackening absorber/cooler 10 is disposed on the optical path along which the laser beam 2 to be measured passes through the semiconductor substrate 6 to absorb unnecessary laser beams.

In this state, the measurement control laser beam 7 is repeatedly irradiated onto the semiconductor substrate 6 in a pulsed manner. The same position on the semiconductor substrate 6 is continuously irradiated with the laser beam 2 to be measured. Thus, when the measurement control laser beam 7 is irradiated, free electrons are generated in the semiconductor substrate 6 at that portion, and the semiconductor substrate 6 has a reflective property and reflects a part of the laser beam 2 to be measured. This reflected laser beam 2 to be measured is detected as an average value by a sensor 8, and the value is displayed on an amplification/display device 9. When the measurement control laser beam 7 is not irradiated, the laser beam 2 to be measured passes through the semiconductor substrate 6,
It is absorbed and cooled by the blackening absorption/cooler 10. By shortening the irradiation time of the measurement control laser beam 7, the average power of the laser beam 2 to be measured that enters the sensor 8 can be reduced, so that the sensor 8 for low power can stably measure high power. You will be able to do this. By measuring the reflectance of the semiconductor substrate 6 by the measurement control laser beam 7 in advance, the sensor 8 is irradiated with a power proportional to the power of the laser beam 2 to be measured. Correct measurement of the laser beam 2 to be measured can be performed by multiplying by a constant or the like.

FIG. 2 shows another embodiment of the invention. In this embodiment, a sensor 8 is placed on the optical path through which the laser beam 2 to be measured passes through the semiconductor substrate 6, and a blackening absorber/cooler 10 is placed on the optical path through which the laser beam 2 to be measured is reflected. are doing.

In this state, the laser beam 2 to be measured is applied to the semiconductor substrate 6.
is applied continuously, and the measurement control laser beam 7 is repeatedly applied in a pulsed manner to the application point. Thus, when the measurement control laser beam 7 is irradiated,
The laser beam 2 to be measured is reflected, absorbed and cooled by a blackening absorption/cooler 10 . When the measurement control laser beam 2 is not irradiated, the laser beam 2 to be measured passes through the semiconductor substrate 6 and is repeatedly incident on the sensor 8 and is detected as an average value, which is displayed on the amplification/display unit 9.

(Effects of the Invention) As explained above, in the laser power measurement method according to the present invention, the incident time of the laser beam to be measured that is incident on the sensor via the semiconductor substrate is determined by the measurement control laser beam that irradiates the semiconductor substrate. Since it is controlled, it is possible to perform measurements while suppressing the temperature rise of the sensor. Therefore, even at high output, stable measurements can be made with a low power sensor.

[Brief explanation of the drawing]

1 and 2 are schematic configuration diagrams of the first and second embodiments of the apparatus for implementing the laser power measurement method according to the present invention, and FIG. 3 is a longitudinal section of the main part of the conventional laser power measurement method. It is a diagram. 2... Laser light to be measured, 6... Semiconductor substrate, 7
...Measurement control laser light, 8...sensor.

Claims (1)

[Claims] 1 Using a semiconductor substrate that has a property of transmitting the laser beam to be measured, absorbing the measurement control laser beam, and reflecting the laser beam to be measured, and placing the measurement control laser at the position where the laser beam to be measured is irradiated. A method for measuring laser power, comprising: irradiating light, and controlling the time during which the measured laser beam passes through the semiconductor substrate and enters the sensor by controlling the irradiation time of the measurement control laser beam.