JPS61252539A - Image transfer multiple laser beam amplifying device - Google Patents

Abstract

PURPOSE:To improve beam opening utilization efficiency by providing a spatial filter consisting of a pair of lenses and a pin hole and an optical system for transferring and projecting the image of a laser beam on its input lens again onto the input lens. CONSTITUTION:A device is constituted of reflecting mirrors 1, 2, a laser medium 3, lenses 4, 5, a pin hole 6, switching elements 7, 8 for converting a polarizing direction and a polarizer 9. As for an incident laser beam, its deflecting direction is varied by operating a switching element 8 and it reciprocates between the reflecting mirrors 1, 2. While executing one reciprocating motion, the laser beam is amplified by passing through the laser medium 3 two times, and emitted in the direction opposite to an incident side from the polarizer 9, by operating the switching element 7, after several reciprocating motions. In this stage, in case of d1=d2=f, the image of the lens 5 is transferred to the lens 4 and subsequently, the image of the lens 4 is also transferred to the lens 5. In this way, diffracting effect of the laser optical beam is reduced and the beam opening utilization efficiency is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a laser device, and particularly to a laser light amplification device.

[Conventional technology]

Conventionally, multiplex laser beam amplification devices that obtain amplification efficiency by passing laser beams multiple times, as shown in FIGS. 3 and 4, remove high frequency components of the spatial intensity distribution of the laser beam.
A spatial filter consisting of a set of two lenses and a pinhole was incorporated.

[Problem that the invention seeks to solve]

However, in the conventional multiple laser beam amplification device, a diffraction pattern is generated in the laser beam due to the diffraction effect due to the aperture diameter of the optical element, which deteriorates the beam aperture utilization efficiency. ] The image transfer multiplex laser beam amplification device of the present invention includes a spatial filter consisting of a pair of lenses and a pinhole, and transfers the image of the laser beam on the input lens of the spatial filter onto the input lens again.・It has an optical system for projection.

〔Example〕

Next, two embodiments of the present invention will be described with reference to one drawing.

FIG. 1 shows an embodiment of the invention. 1.2 is a reflector, 3
is a laser medium, 4 and 5 are lenses, 6 is a pinhole, 7,
8 is a switching element that changes the polarization direction, 9 is a polarizer, Of is the focal length of the lenses 4 and 5, d is the optical distance between the reflecting mirror 1 and the lens 4, and d is the distance between the reflecting mirror 2 and the lens 5. is the optical distance of The solid line is the area in which the laser beam travels.

By operating the switching element 8, the incident laser beam changes its polarization direction and travels back and forth between the reflecting mirrors 11 and 1.degree.2. - The laser beam passes through the laser medium 3t-2 times during the round trip and is amplified. After going back and forth several times, the switching element 7t is operated, and the light is emitted from the polarizer 9 in a direction opposite to the incident side.

Here, if we set d, = d, = = f, the image of lens 5 will be transferred to lens 4. Next, the image of lens 4 will also be transferred to lens 5.
Due to this image transfer effect, the diffraction effect due to the aperture diameter of the optical element can be reduced, and the aperture utilization efficiency can be improved.

The second leg also represents an embodiment of the invention. 11,12゜13.1
4 is a reflecting mirror, 15 is a laser medium, 16° and 17 are lenses,
18 is a pinhole, 19 is a switching element that converts the polarization direction, 10 is a polarizer, Of is the focal length of the lens 17, s is the focal length of the lens 16, and / is the distance between the reflecting mirrors 11 and 12. The optical distance m-at' is the reflector 1
The optical distance between 2 and 14, dj' is the reflection f#11 and 1
The optical distance d4' between 3 is the optical distance between reflections @l1i13 and 14. The beam diameter expansion rate by lenses 17 and 16 is m = f * / f *. The solid line and the broken line indicate the area in which the laser beam travels. here,
In the configuration shown in Fig. 2, #:t, the image of the lens 17 goes back and forth once,
The arrangement satisfies the following conditions so that the images are transferred to the same position of the lens 17.

dl +d, +d, +d, = (m+1) (f
m + ft) The incident laser light is amplified by the laser medium 15. Next, by operating the switching element 19t, the polarization direction of the laser beam is changed and the laser beam reciprocates n1 times, and then the switching element 19 is operated again and the laser beam is emitted from the polarizer 1o. The configuration of the second stage shows the case where it makes two round trips. In FIG. 2, as in the example of FIG. 1, the image of the lens 17 moves back and forth once, and
It is transferred to the position of
The figures correspond to the respective part codes of the second factor.

〔Effect of the invention〕

As explained above, the present invention involves optimizing the focal length of a pair of lenses and the optical distance within the device to enable image transfer, reducing the diffraction effect of the laser light beam, This has the effect of improving beam aperture utilization efficiency.

[Brief explanation of drawings]

Fig. 1 is an optical path diagram showing an embodiment of the present invention, Fig. 2 is an optical path diagram showing an embodiment of the invention, and Fig. 3 is an optical path diagram showing an example of a conventional multiplex amplification device. FIG. 2 is an optical path diagram showing an example of a conventional multiplex amplification device. 1.2... Reflector, 3... Laser medium, 4.5... Kawa lens, 6 Kawakawa pinhole, 7, 8...
...Switching element, 9.10...Polarizer, 11,12゜13.14...Reflector, 1
5. Old... Laser medium, 16° 17... Lens, 18... Hinho Kaya, 19... Switching element, f... Kawa lens 7.8 focal length% dl
....Optical distance between reflector 1 and lens 4, d,
...Reflection @! 2 and lens 50 elemental distance s f
l... Focal length of lens 17 s t,...
... Focal length of lens 16, dl'... Optical distance between reflecting mirrors 11 and 12, d,'... Optical distance between reflecting mirrors 12 and 14% d Hatake'...
Optical distance between reflecting mirrors 11 and 13, d4""...
- Optical distance of 1 m between reflecting mirrors 13 and 14...Expansion rate of beam diameter by river lenses 17 and 16. Agent Susumu Uchihara, Patent Attorney, ``1. Kaede-1-1yPJ1 Figure 3

Claims (1)

[Claims] Image transfer characterized by comprising a spatial filter consisting of a pair of lenses and a pinhole, and an optical system that transfers and projects the image of the laser beam on the input lens of the spatial filter onto the input lens again. Multiple laser light amplification device.