JPS63226089A - Laser output controller - Google Patents

Abstract

PURPOSE:To make the division ratio of a laser beam constant and obtain a stable laser output by a method wherein the parts which are coated with gold and reflect the laser beam and the parts which are not coated with gold and transmit the laser beam are provided on the surface of a derivative substrate and the laser beam transmitted through or reflected by the optical device is detected and converted into an electric signal by a photosensor. CONSTITUTION:In case of a carbon dioxide laser oscillator, the surface of a substrate 18 made of ZnSe, Ge, GaAs, Si, KC, NaC, ZnS or the like is so finished as to have a highly accurate mirror surface and masking of, for instance, parallel lines is applied to the mirror surface which is coated with gold (Au) by evaporation or the like to form the parts 19 which are coated with gold and the parts 20 which are not coated with gold. The division ratio of a laser beam 8a which is the monitor input of a beam power sensor 9 can be exclusively determined by the beam diameter A of the laser beam 7 entering a beam splitter 17 surface, i.e. by the incident area at the beam splitter 17 surface and the total area of the parts 20 which are not coated and transmit the laser beam 8a and is not influenced by the variation of the reflectivity of the mirror surface caused by the temperature of the beam splitter 17 surface so that the dividing ratio can be always constant.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a laser output control device for controlling laser light output from a laser oscillator.

[Prior Art] FIG. 8 is a schematic diagram showing a laser output control device in a conventional carbon dioxide laser device. In the figure, 1 is an oscillator container filled with a laser medium gas containing carbon dioxide, 2A and 2B are a pair of electrodes provided in this container 1,
3 is a power source for applying high voltage to the electrodes 2A and 2B; 4
is electrode 2A.

2B, 5 is a total reflection mirror, 6 is a partial reflection mirror, and 7 is a laser beam output from the partial reflection mirror 6 to the outside.

22 to 26 are pend mirrors that reflect and transmit the laser beam 7; 17 is an optical element for splitting the transmitted laser beam 7; a beam splitter consisting of a partial reflecting mirror whose reflectance is controlled by a dielectric multilayer film; 8 a.
8b is a laser beam split by the beam splitter 17, and is branched and transmitted to the beam power sensor 9 and the processing lens 28, respectively. 13 is an output command value from an output setting device (not shown), 14 is a comparator, and 15 is an amplifier.

In a laser output control device for a conventional carbon dioxide laser device configured as described above, a pair of electrodes 2A, 2
A high voltage is applied to B from a power source 3 to generate a discharge 4 to excite the laser medium gas and emit a laser beam with a wavelength of 10.6 μm. The emitted laser beam is repeatedly reflected between the total reflection mirror 5 and the partial reflection mirror 6 whose mirror surfaces are arranged in parallel, thereby causing laser oscillation, and the partial reflection mirror 6 outputs the laser beam 7 to the outside.

The output laser beam 7 propagates along a predetermined optical path while reflecting off pend mirrors 22 to 26 and enters the beam splitter 17, where it is divided into a transmitted laser beam 8a and a reflected laser beam 8b. Laser light 8a enters beam power sensor 9 and is converted into an electrical signal. This electric signal and a predetermined output command value 13 are compared by a comparator 14, the deviation signal is amplified by an amplifier 15, and the excitation intensity of the laser medium gas is controlled by controlling the output of the power supply 3, and the laser beam is 7 is held constant.

[Problems to be Solved by the Invention] In the conventional laser output control device as described above, the temperature of the beam splitter 17 increases due to the laser light 7 incident on the beam splitter 17, and the multilayer coating on the surface that determines the reflectance increases. changes occur. This causes a problem in that the reflectance and transmittance of the beam splitter 17 fluctuate, making it impossible to accurately monitor the output of the laser beam 7.

The present invention has been made to solve this problem, and a sensor always detects a fixed ratio of transmitted laser light or reflected laser light to the output laser light in an optical element. The purpose of this invention is to obtain a laser output control device that performs stable control based on values.

[Means for Solving the Problems] A laser output control device according to the present invention uses an optical element that splits laser light to reflect the laser light onto the surface of a dielectric substrate having a transparent property. A gold-coated part and a non-gold-coated part that transmits laser light are provided, and a sensor detects the laser light that passes through the optical element or the laser light that is reflected by the optical element and converts it into an electrical signal. This is what I did.

[Function] In the present invention, the optical element, that is, the beam splitter is determined by the ratio of the incident area of the beam diameter incident on the beam splitter to the total area of the portion without gold coating or the portion with gold coating. Transmitted laser light or reflected laser light is incident on the sensor at a constant division ratio.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

First, a case will be described in which a laser beam transmitted through an optical element is used as a monitor input of a sensor. In this case, the schematic configuration of the laser output control device according to the embodiment of the present invention is the same as the configuration shown in FIG. 8 showing the conventional example. However, the configuration of the beam splitter 17 in the figure is different in the present invention from the conventional example, and FIGS. 1(a) and 1(b) are a front view and a side sectional view, respectively, showing an example of the configuration of the beam splitter 17.

In the figure, 18 is a substrate, which in the case of a carbon dioxide laser oscillator is ZnSe, Ge, or GaAs.

The surface of the substrate 18 made of Si, KCI, NaCl, ZnS, etc. is formed into a highly accurate mirror surface, and this mirror surface is masked, for example, in a parallel straight line, and then gold (Au) is coated by vapor deposition or the like. A portion 19 coated with gold (hereinafter referred to as a “coated portion”) and a portion 20 not coated with gold (hereinafter referred to as a “non-coated portion”) are formed. The incident laser beam 7 is reflected by the coated portion 19 of the surface of the beam splitter 17 and transmitted by the non-coated portion 20 .

The ratio of the total area of the non-coating portion 20 in the portion of the laser beam 7 irradiated to the beam splitter 17 and the irradiation area of the laser beam 7 to the beam splitter 17 is determined by the characteristics of the beam power sensor 9, comparator 14, amplifier 15, etc. It is determined by taking into consideration the loss rate of power due to the beam light 8a incident on the beam power sensor 9, etc., and is usually selected in the range of about 0.5 to 10%.

In the output control device shown in the schematic configuration diagram of FIG. 8, which includes the beam splitter 17 according to the present invention configured as described above, the laser medium gas excited by generating the discharge 4 between the electrodes 2A and 2B, The operation until the laser beam 7 outputted by laser oscillation caused by repeated reflection between the total reflection mirror 5 and the partial reflection mirror 6 is incident on the beam splitter 17 is completely the same as in the conventional example.

FIG. 2 is a detailed diagram of the beam splitter 17 and beam power sensor 9 according to the present invention shown in the schematic configuration diagram of FIG. The beam light 7 incident on the splitter 17 is a laser beam 8a that is transmitted through the non-coated portion 20 on the mirror surface made of a gold (Au) coating layer.
The transmitted laser beam 8a enters the beam power sensor 9 as a monitor power, and the reflected laser beam 8b becomes machining energy and is propagated to a machining head, etc. .

The division ratio of the laser beam 8a that passes through and becomes the monitor input of the beam power sensor 9 is determined by the beam diameter (A in the figure) of the laser beam 7 incident on the beam splitter 17 surface, that is, the incident area on the beam splitter 17 surface and the laser beam diameter. light 8a
is uniquely determined by the total area of the non-coated portion 20 through which the beam is transmitted, and is always constant without being affected by fluctuations in the reflectance of the mirror surface caused by changes in the temperature of the beam splitter 17.

Note that in the above embodiment, the substrate 18 of the beam splitter 17
2 shows a case in which the coating portion 19 is applied so that the non-coating portion 20 forms a large number of parallel lines,
For example, as shown in FIG.
may be in the form of a mesh such as a lattice, or may be in a radial, concentric, or spider web pattern (not shown in the figure). It can be arbitrarily determined according to the division ratio.

Furthermore, in the above embodiment, an example has been described in which the laser beam 8a transmitted through the non-coating portion 20 of the beam splitter 17 is made incident on the laser power sensor 9 and used as a monitor input, but as shown in FIG. Even if the laser beam that enters the integrating sphere 31 and is diffused within the integrating sphere 31 is detected by the micro laser intensifier 32 and its output is transmitted to the controller, the same effect as in the above embodiment can be obtained. play.

Next, FIG. 5 shows an embodiment in which the laser beam reflected by the optical element is used as a monitor input of a sensor, and FIGS. 6(a) and (b) show an example of the configuration of this beam splitter 17. It shows. This FIG. 6 corresponds to FIG. 1 in which the coated portion 19 is a non-coated portion and the non-coated portion 20 is a coated portion.

However, even in this case, the ratio of the total area of the coating portion 19 in the portion of the laser beam 7 irradiated to the beam splitter 17 and the irradiation area of the laser beam 7 to the beam splitter 17 is usually 0.5 to 10 as described above. It is set within a range of about %.

FIG. 7 is a detailed diagram of the beam splitter 17 and the beam power sensor 9.

Therefore, in this embodiment, the beam light 7 is
The mirror surface made of the gold (Au) coating layer splits the laser beam 8a that passes through the non-coated part 20 and the laser beam 8b that is reflected by the coated part 19 at a constant ratio, and the reflected laser beam 8b is used as the beam power sensor. The laser beam 8a that enters the laser beam 9 as a monochrome input and passes therethrough becomes machining energy and is propagated to a machining head or the like.

Also in this embodiment, an integrating sphere as shown in FIG. 4 can be used.

[Effects of the Invention] As described above, according to the present invention, as a laser beam splitting element, a reflective element having a part coated with gold in an appropriate pattern and a part not coated with gold on a substrate that is transparent to laser light is used. Since a mirror is used, the division ratio of the laser beam remains constant and stable laser output can be obtained.

[Brief explanation of drawings]

1(a) and 1(b) are a front view and a side sectional view showing a beam splitter according to an embodiment of the present invention, respectively, and FIG.
3 is a front view showing another embodiment of the beam splitter according to the present invention, and FIG. 4 is a diagram showing a beam splitter and a laser power sensor for explaining the present invention in detail. FIG. FIG. 5 is a block diagram showing another embodiment in which the laser light transmitted through the splitter is detected by an integrating sphere and the laser light diffused within the integrating sphere is detected by a minute laser detector. 6(a) and 6(b) are a front view and a side sectional view of the beam splitter in FIG. 5, and FIG. 7 is an explanatory diagram of the operation of the beam splitter and laser power sensor in FIG. FIG. 8 is a schematic configuration diagram of a laser output control device in a normal carbon dioxide laser device. In the figure, 7 is a laser beam, 8a is a laser beam, 9 is a laser power sensor, 17 is a beam splitter, 18 is a substrate, 19 is a coated part, 20 is a non-coated part, 3
1 is an integrating sphere, and 32 is a minute laser detector. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. Agent Patent Attorney Muneharu Sasaki Figure 1 (a) (b) Loop 8c: Laser light 17 Himusarig Figure 2 Figure 3 Figure 4 Figure 5

Claims (10)

[Claims] (1) Divide the laser beam output from the laser oscillator,
In a laser output control device that enters one of the divided laser beams into a sensor as a monitor input and controls the output of the laser oscillator according to the output of the sensor, the optical element that divides the laser beam is made of a dielectric material. It consists of a substrate made of a substance, a part on the surface of the substrate to which the laser beam is irradiated, a part coated with gold so as to reflect the laser beam, and a part not coated with gold so as to transmit the laser beam. Features a laser output control device. (2) The laser output control device according to claim 1, wherein the laser light transmitted through a portion of the optical element that is not coated with gold is used as a monitor input of the sensor. (3) The laser output control device according to claim 1, wherein the laser light reflected by the gold-coated portion of the optical element is used as a monitor input of the sensor. (4) The laser output control device according to claim 1, wherein the portion of the optical element coated with gold or the portion not coated with gold is formed in a linear or mesh shape. (5) The laser output control device according to claim 1, wherein the gold-coated portion of the optical element is formed by a large number of points. (6) Dielectric material is ZnSe, Ge, GaAs, Si,
The laser output control device according to claim 1, which is made of any one of KCl, NaCl, or ZnS. (7) The laser output control device according to claim 1, wherein the gold coating is applied by ICB gold vapor deposition. (8) The laser output control device according to claim 1, wherein the sensor is a laser power sensor that converts incident laser light into an electrical signal. (9) The laser output control device according to claim 1, wherein the sensor comprises an integrating sphere and a minute laser detector that detects laser light diffused within the integrating sphere. (10) The laser output control device according to claim 1, wherein the laser oscillator is a carbon dioxide oscillator.