JPH08327810A - Optical mirror and laser beam splitting device using the same - Google Patents

Abstract

PURPOSE: To divide a laser beam and to distribute it with a prescribed ratio on a prescribed place by providing a sectorial hole for passing the laser beam on a reflection mirror for deflecting the laser beam and making the pivot of the sector of the sectorial hole coincident with the center of the mirror. CONSTITUTION: An optical mirror 1 is composed of a circular reflection mirror provided with a sectorial hole 2, a number of the sectorial holes 2 may be arbitrary, and may be either even numbers or plural numbers. The pivot of the sectorial hole 2 is provided at the center of the optical mirror 1 so as to coincide with the center of a laser beam LA. The sectorial holes 2 is formed by setting its radius of circular arc to be larger than the predicted maximum diameter of the laser beam LA and the expanding angle of the sector is arbitrary. The reflection surface 1a of the optical mirror 1 is coated with aluminum. When a laser beam is reflected by such an optical mirror, since the sectorial hole 2 is provided on the optical mirror 1, a part of laser beams is reflected and the other is passed through the sectorial hole 2. Consequently, by properly setting the area of the sectorial hole 2, the desired dividing ratio of laser beam is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical mirror which accurately deflects a laser beam in a wide wavelength range by a predetermined amount and allows the rest to pass therethrough, and divides a predetermined amount of laser beam into a predetermined number of places using the optical mirror. The present invention relates to a laser beam splitting device for transmitting by transmitting.

[0002]

Lasers, especially free electron lasers (FELs)
Has a feature different from other types of lasers in that the wavelength of the generated laser light is variable by changing the energy of the electron beam or the strength of the wiggler magnetic field. In recent years, various advantages such as laser processing, isotope separation, semiconductor physical properties, medical applications, etc.
Applied research in various fields such as the development of new material catalysts is being attempted.

When conducting such application research, one F
It is necessary to divide the FEL light generated by the EL device into several places and transmit it because it is limited to various researches and developments if the FEL light is transmitted to only one place. A beam splitter using a ZnSe plate, a SiO ₂ (quartz) plate, or the like is known as a technique used for such FEL light splitting. In such a beam splitter, the transmitted laser light and the reflected laser light are split at a fixed ratio determined by the material.

[0004]

However, when a laser beam is split by such a beam splitter, it is strongly reflected at a specific wavelength determined by the mirror material used for polarization and is absorbed in other regions, so that the usable wavelength range is limited. Be restricted.

Further, the ratio of the reflected laser light is also determined by the material, and therefore the deflection ratio also has a large wavelength dependency. When the laser light is deflected over a wide wavelength range, the ratio of the deflectable beam is arbitrary. Cannot be divided into proportions.

In view of the above-mentioned state of the art of the conventional laser beam splitting technique, the present invention is an optical system capable of splitting a monochromatic laser beam into any desired ratio using a deflection mirror having a simple structure having a fan-shaped hole. The challenge is to provide a mirror.

Further, the present invention provides a laser beam splitting device capable of sequentially splitting a laser beam at an arbitrary ratio using the deflecting mirror having the above-mentioned simple structure and distributing it to a predetermined place at a predetermined ratio. This is an issue.

[0008]

As a means for solving the above-mentioned first problem, the present invention provides a reflecting mirror for deflecting a laser beam with a fan-shaped hole for passing a laser beam, and the fan of the fan-shaped hole is the main part of the mirror. The optical mirror is provided so as to be aligned with the center.

This optical mirror may be provided with a plurality of fan-shaped holes for passing laser beams of the same shape.

As a means for solving the above second problem, the third invention is an optical mirror in which a fan-shaped hole is formed in a reflecting mirror for deflecting a laser beam so that the center of the fan is aligned with the center of the mirror. Combining multiple mirrors with a holeless mirror,
The fan-shaped mirror is a laser beam splitting device in which fan-shaped holes having areas that are sequentially reduced from the upstream side of the laser light are overlapped.

[0011]

According to the optical mirror of the first invention having the above structure,
If the area of the fan-shaped hole is provided in a desired ratio, the laser light is reflected in the area other than the fan-shaped hole, and the laser light corresponding to the fan-shaped hole passes as it is, so that the laser light can be divided into any ratio. . In this case, the laser light has one kind of wavelength, and by laminating, for example, an aluminum coat thin film on the reflection surface, the laser light has a wide wavelength range (0.2 μm to several tens μ).
Even if it changes in m), it can be divided into a desired division ratio.

As in the second invention, when a plurality of the fan-shaped holes are provided for one optical mirror, it is possible to divide the laser light into a finer division ratio according to the increase in the number.

In the laser splitting device of the third invention using the optical mirror of the first invention, the number of laser beams to be split is set by appropriately setting the number of mirrors with fan holes and the overlapping of the fan hole shapes. Then, each beam intensity ratio can be divided into a desired ratio.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic perspective view of the optical mirror of the first embodiment, and FIG. 2 is a side view and a sectional view thereof. As shown,
The optical mirror 1 of this embodiment is composed of a circular reflecting mirror provided with fan-shaped holes 2. In FIG. 2A, two fan-shaped holes 2 having the same shape are provided, and in FIG. 2B, four fan-shaped holes 2 are provided. An example is shown. The number of the fan-shaped holes 2 is arbitrary and may be even or odd.

The third part of the fan-shaped hole 2 is the incident laser light L _A.
It is provided at the center of the optical mirror 1 so as to coincide with the center of.
The fan-shaped hole 2 is formed by setting the arc radius thereof to be larger than the maximum diameter of the expected laser beam L _A , and the fan-shaped spread angle is arbitrary. The reflecting surface 1a of the optical mirror 1 is coated with aluminum.

In the optical mirror of this embodiment having the above structure, the laser light is split as follows. When the reflecting surface of the optical mirror 1 is coated with aluminum, the optical mirror 1 has a high reflectance (0.9 or more) with respect to laser light in a wide wavelength range of 0.2 μm to several tens of μm.

When the laser beam is reflected by such an optical mirror 1, since the optical mirror 1 is provided with the fan-shaped hole 2, a part of the laser beam is reflected and the other part passes through the fan-shaped hole 2. Therefore, if the area of the fan-shaped hole 2 is appropriately set, a desired laser light division ratio can be obtained. In this case, the division ratio of the laser beam does not depend on the material of the reflective thin film coated on the reflective surface, but only on the area ratio of the holes.

If it is desired to change the splitting ratio of the laser light, a thin reflecting plate (having a reflecting film formed on the surface of aluminum coat) which can be slid is provided so that the area of the fan-shaped hole 2 can be changed. If the laser light is split as described above by rotating it to freely change the area ratio, for example, in the example of FIG. 1, the reflected laser light becomes two thin laser beams. These may be used as separate beams as they are, or if it is desired to combine the two beams into one, they may be combined into one via a condenser lens in the middle.

Next, FIG. 3 shows a laser beam splitting device of a second embodiment, which splits the laser beam split by using the above-mentioned optical mirrors into a predetermined number of places.

In the illustrated example, the laser beam splitting device comprises a combination of three reflecting mirrors, fan-shaped holed mirrors 1A and 1B and holeless mirror 1C. When it is desired to increase the number of split beams, the number of fan-shaped holes in each reflecting mirror may be increased, or the number of fan-shaped holed mirrors may be increased. In the illustrated example, one beam is divided into three laser beams by two fan-shaped mirrors with holes.

A fan-shaped mirror 1 of this laser beam splitting device.
A and 1B are 1A with the radial center of the fan-shaped hole on the same line.
The hole areas of 1B are successively reduced so that the hole area of 1B is smaller than the hole of 1B. Therefore, in order to obtain a desired splitting ratio when splitting the laser beam by the fan-shaped holed mirrors 1A and 1B, the hole areas of 1A and 1B may be set to a predetermined ratio.

FIG. 3 (b) shows the above three reflection mirrors as one.
The overlapping of the fan-shaped holes when viewed from the side A is shown. (C) is a sectional view.

A laser beam splitting device having such a configuration is shown in FIG.
Needless to say, when the laser light is sent from the laser device X shown in (a), the laser light is divided into a predetermined ratio according to the area ratio of the fan-shaped holes. In this case, it is premised that the laser light used is monochromatic light having one wavelength.

In this embodiment, an aluminum coat was used as an example of the reflection film of each reflection mirror, but other than this, various metal thin films such as gold, silver, etc. were used to make the laser light of a wide wavelength range variable. At times, it is advisable to stack a thin film having the maximum reflectance in each wavelength range as a multilayer film.

[0025]

As described above in detail, in the optical mirror of the first invention, the shape and area of the fan hole provided in the reflection mirror are appropriately set so that the ratio of the reflected light to the light passing through the fan hole is reduced. Since the ratio is set to the predetermined ratio, there is an advantage that the laser light can be split at any desired ratio even when the wavelength of the laser light changes.

In the second invention, since a plurality of fan-shaped holes having the same shape are provided, this has the advantage that the division ratio can be set more finely.

Further, in the third invention, since a plurality of optical mirrors of the first invention and a mirror without holes are combined and the size of the fan-shaped holes is gradually reduced from the upstream side, the laser beam is desired. It is possible to divide into a predetermined number of places and a division ratio, and there is an advantage that a predetermined amount of laser light can be distributed to a predetermined number of places.

[Brief description of drawings]

FIG. 1 is a schematic perspective view of an optical mirror according to a first embodiment.

FIG. 2 is a side view of the same as above and a side view of a partially deformed side.

FIG. 3 is a schematic perspective view of a laser beam splitting side view of the second embodiment, and a side view and a sectional view of the laser beam splitting side view seen from one side.

[Explanation of symbols]

1 optical mirrors 1a reflective surface 2 sector hole 3 sector of main L _A laser beam

Claims (3)

[Claims] 1. An optical mirror comprising a reflecting mirror for deflecting a laser beam, wherein a fan-shaped hole for passing a laser is provided, and the center of the fan of this fan-shaped hole is aligned with the center of the mirror. 2. The optical mirror according to claim 1, wherein a plurality of fan-shaped holes for passing a laser having the same shape are provided. 3. A fan-shaped mirror is formed by combining a plurality of optical mirrors, each having a fan-shaped hole formed in a reflecting mirror for deflecting a laser beam so that the center of the fan is aligned with the center of the fan, and a holeless mirror. A laser beam splitting device in which holes having areas that are successively narrowed from the upstream side of the laser beam are overlapped.