JPS60153023A - Beam splitter device for high output laser - Google Patents

Abstract

PURPOSE:To obtain an inexpensive beam splitter device for a high-output laser which divides regular single-lateral-mode laser light into plural beams without using any partial transmission mirror and has high reliability and light resistance by dividing the laser light into numbers of laser beams through a total reflecting mirror. CONSTITUTION:Regular high-output laser light 12(5') in single lateral mode such as TM01 emitted from a laser oscillator 1 travels straight as shown by an arrow 13 through a pipe-shaped optical path cover 4 to strike the small-sized total reflecting mirror 9 and is split into two at a wave trough, and the lower half part is reflected as shown by an arrow 14 and made incident on a condenser lens 8. The upper half part, on the other hand, is reflected by a total reflecting mirror 3 as shown by an arrow 16 to enter the condenser lens 8. Consequently, the beam splitter device for high-output laser light which attain plural-beam splitting without any expensive partial transmission mirror and has high reliability and light resistance is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a beam snorniter device for a high-power laser that divides a high-power laser beam into two or more parts.

[Technical background of the invention]

Up until now, attempts have been made to divide high-power Raded light into two parts and use them in two places.
It is configured as shown in the figure.

That is, Rade light 5 emitted from Rade oscillator 1 passes through optical path cover 4 and is split into reflected light 7 and transmitted light 6 by partially transmitting mirror (beam sinter) 2. The reflected light 7 is used at the first station, and the transmitted light 6 is further reflected by the total reflection mirror 3 and used at the second station. In the figure, 8 is a condenser lens.

Furthermore, in the case of two or more divisions, for example, in the case of three divisions, the configuration is shown in FIG. 2, and the same parts as in FIG. 1 are given the same reference numerals. As is clear from this example, when dividing into n using partially transmitting mirrors 2, n-1 partially transmitting mirrors 2 are required.

[Problems with background technology]

When splitting the laser beam as described above, the partially transmitting mirror 2 is always required. This partially transmitting mirror 2 is generally expensive. For example, in order to divide IKW's CO and LED into two parts, a partially reflective coating (
(partially transparent coating) is used. In this case, the partially transmitting mirror 2 is approximately 6 times as expensive as the total reflecting mirror made of a metal substrate.

In addition, since it is a partially transmitting mirror 2, the laser beam is absorbed by its reflective coating surface, the inside of the substrate, and the transmitting coating surface, causing the temperature of the mirror itself to rise and the properties of the mirror to change, resulting in the commonly referred to thermal lens effect. (Effect of similar being subjected to optical thermal distortion due to thermal changes such as temperature rise)
This causes optical distortion to the laser beam.

[Purpose of the invention]

The purpose of this invention is to provide two
It is an object of the present invention to provide a beam splitter device for a high-power laser, which can be divided into more than 10 parts, is inexpensive, has high reliability of optical components, and has improved light resistance.

[Summary of the invention]

The present invention is a beam sintering device for a high-power laser, which splits a beam into a large number of parts using a total reflection mirror without using a partially transmitting mirror, and does not give almost any optical distortion to the Raded light.

[Embodiments of the invention]

The beam splitter device for high power laser of this invention is the third
It is constructed as shown in the figure, and a diagram illustrating its principle is shown in FIG.

The same parts as in the conventional example (Fig. 1) are given the same reference numerals, and the laser beam 5' emitted from the laser oscillator 1 passes through the optical path cover 4 for protection and safety, and is directed downward as described later. Only half of the beam is guided to a small total reflection mirror 9 for beam bending.

Then, the lower half portion of the Radhe light 5' is bent by 90 degrees by this total reflection mirror 9, and this bent reflected light 10 is guided to the condenser lens 8.

On the other hand, the upper half of the Rede light 5' travels straight through the optical path cover 4 as transmitted light 11 without touching the total reflection mirror 9, and is guided to the total reflection mirror 3 of a normal size.

Then, due to this total reflection mirror 3, the transmitted light 11 becomes 90
This bent transmitted light 11 is guided to a condenser lens 8.

Now, the laser beam 5' in FIG. 3 is a TEMo mode laser beam 12 (see FIG. 4) which has been adjusted to use the beam snorrit method according to the present invention. An arrow 13 in FIG. 4 indicates the direction in which the laser beam 12 travels. Then, the small total reflection mirror 9, which is a beam f IJ knotler, reflects half of the laser beam 12 in the Radhe optical path and changes the optical path in the direction of the arrow 14. The unreflected portion travels straight in the direction of arrow 15, is reflected by total reflection mirror 3, and has its optical path changed in the direction of arrow 16.

In this way, the laser beam 12 is divided into its upper half and lower half and can be used at two locations.

Next, the principle of this invention will be described. This invention is based on the following characteristics of laser light.

That is, in general, laser light travels in a straight line very well, and the wavefronts of the laser light are aligned. Therefore, unless a large disturbance is caused to the wavefront of the laser beam, its characteristics will not change.

Now, we will focus on the oscillation transverse mode of the laser beam, and in the valley part of the oscillation transverse mode, we will
Divide into. At that time, in the valley part of the oscillation transverse mode of the laser beam, the energy is almost zero (theoretically zero), so splitting the laser beam in that part has a large effect on the wavefront of the laser beam. not give.

An explanatory diagram of the principle and the results of theoretical calculation are shown in FIG. That is, FIG. 5(a) shows the Rade oscillation transverse mode TEMo, where ■○ is the direction of the electric field. Also, in Fig. 5(b),
This oscillation transverse mode is converted into a fast Fourier transform (F
FT) and show the results. This result has been proven to correspond to the state of light at an infinite distance according to the principle of Fourier optics, or to the state (energy distribution) of light at the focal plane when focused by a lens.

Therefore, as shown in FIG. 5(c), the above TEMo.

Assume that only one of the modes is used. The results of fast Fourier transform in that case are shown in FIG. 5(d).

As is clear from this result, as long as the 18M0□ mode is divided at the valley portion of its energy distribution, it will not be subjected to much disturbance, and its mode pattern will be close to a Sigaussian distribution. This means that even when the laser beam is divided and used in this way, the convergence of the laser beam is not significantly impaired. This has been confirmed in experiments as well.

An example of an inappropriate application of the invention is shown in FIG. 6(,).

This is the TEM mentioned above. , mode, if we divide the energy at the peak part of its output, i.e. T EM
o. An example is shown in which the central part of the mode is extracted and half is taken, and the result is shown in FIG. 6(b). This result means that the spread is extremely large at the υ angle, and the light is scattered with a large beam tupple. Therefore, such light has lost its original property of Rede light. Therefore, even when light is focused by a lens, its light focusing ability is very poor.

[Modifications and application examples of the invention]

The above principle of laser beam splitting can be applied to all laser oscillation transverse modes. That is, if the oscillation transverse mode is divided at the zero energy value, those modes will not be disturbed so much.

Therefore, TEMo2, TEM, ,3, TEMo4・
...or TEM, 1.18M2m, TEM, 2.
If it is a single mode such as ..., it can be divided at the valley part. FIGS. 7 and 8 respectively show an example of dividing into three in TEMo mode and an example of dividing into four in TEMo4 mode. ■ to ■ in the figure are the numbers of divisions.

In addition, when actually performing these divisions, it is possible to use a plane mirror as shown in Fig. 4, but as shown in Fig. 9 (,)
, (b) and (C) may also be used.

Furthermore, here, the square mode (T E Mvtan )
This method focuses on the circular mode (TEMP
It can also be applied to A'). In that case, the first
A cylindrical mirror 20 as shown in FIG. 0 may be used.

〔Effect of the invention〕

According to this invention, one or more so-called Raded lights can be divided into two or more parts without using the partially transmitting mirror 2. As a result, the cost of the device can be reduced and the reliability of the optical components can be increased. In addition, since a metal mirror can be used as the total reflection mirror 9, the light resistance against laser light is improved, and it can be applied to dozens of locations, making it very effective for splitting the laser beam of a high-power laser. It is.

[Brief explanation of drawings]

1 and 2 are schematic configuration diagrams showing a conventionally used multi-division beam splitter device, and FIG. 3 is a schematic diagram showing a beam splitter device for a high-power radar according to an embodiment of the present invention. A configuration diagram, FIG. 4 is an explanatory diagram of the operation in the beam snoritzer device of FIG. 3, and FIGS. 5(a) to (d)
6(a) and (b) are characteristic curve diagrams showing inappropriate application examples of this invention, and FIGS. 7 and 8 are characteristic curve diagrams showing the principle of division and theoretical calculation results in this invention. The figure shows a suitable application example of the present invention, and FIGS. 9(a), (b), (C), and 10 are schematic configuration diagrams showing modified examples of the total reflection mirror used in the present invention. 1...Laser oscillator, 2...Partial transmission mirror, 3.
... Total reflection mirror, 4... Optical path cover, 5... Rede light, 6... Partially transmitted light, 7... Partially reflected light, 8...
...Condensing lens, 9...All-search mirror, 10.°° reflected light, 11..Transmitted light, 12.. Rade output distribution,
13... Laser beam traveling direction, 14... Reflection direction, 1
5... Passing direction, 16... Reflection direction. Applicant's representative Patent attorney Takehiko Suzue Figure 3 Figure 4 Figure 5 (a) Figure 5 (b) -EI O+8 Blueness Figure 5 (C) Figure 5 (d) 1θ +e Negative Le Figure 6 (a) Figure 6 Isamu Exhibition Figure 7 Figure 9 Figure 10 Figure 8

Claims (1)

[Claims] Of one or more types of high-power radar light, TEM, ..., TEM
. , , or TEM1, , TEM, etc. In a beam splitter device that splits the laser beam having a normal single transverse mode into two or more, A beam snoritter device for a high-output laser, characterized by dividing the beam into two or more directions.