GB2313472A - Mirror mount for a laser resonator - Google Patents

Abstract

A laser mirror 4 is held by a spring pressure plate 7 against a platform 2 formed on a body 1. A collar 5 is located about the mirror 4 and the platform 2. The mirror is inserted in an aperture 23 in the end plate 21 of a sealed gas laser, secured to the plate 21 by screws 11. A seal 27 prevents gas from leaking between the collar 5 and the wall of the aperture 23 whilst a further seal 6 prevents leakage between the interior of the collar and the mounting body 1. Jacking screws 12 are screw-threaded through the body 1 to bear against the plate 21 and allow the alignment of the mirror 4 to be accurately adjusted. Such a mount allows replacement of the mirror from outside of the resonator.

Description

lASER RESONATORS TECHNICAL FIELD OF THE INVENTION This invention relates to laser resonators, and particularly to the mounting of mirrors for use therein.

BACKGROUND Mirrors are commonly used in laser resonators. These are generally held by an adhesive, but changes in ambient temperature can often result in movement of the mirror causing changes in laser power.

The present invention seeks to provide a form of mirror mount which is patentably different from any known mounting assembly.

SUMMARY OF THE INVENTION The present invention proposes a mirror mounting assembly for use in a laser resonator comprising: - a mirror; - a mounting body including a platform adapted to provide firm support for said mirror; and - an apertured clamping member located about the mirror and secured to the mounting body such that the mirror is firmly held between the clamping member and the platform.

The mounting body is preferably secured in the resonator by adjustable mounting means.

The mirror is preferably laterally located by a locating collar which is received over the mirror and the mounting body. The collar is preferably held by the clamping member.

BRIEF DESCRIPTION OF THE DRAWINGS The following description and the accompanying drawings referred to therein are included by way of non-limiting example in order to illustrate how the invention may be put into practice. In the drawings: Figure 1 is an exploded side elevation of a mirror mounting assembly in accordance with the invention, and Figure 2 is a plan view of the assembled mounting assembly.

DETAILED DESCRIPTION OF THE DRAWINGS The assembly is used to mount a mirror in a laser resonator, e.g. a carbon dioxide gas laser. In a typical laser the gas is held in a tube 20 which is sealed to an end plate 21 by an O-ring seal 22 or similar means. The plate 21 contains an aperture 23 for receiving the mirror in registration with the tube 20.

The mirror mounting assembly comprises a generally disc-shaped mounting body 1 which is formed from a solid metal block (in this case a disc) with a central upstanding circular platform 2. In some cases the platform 2 may have a central aperture which passes completely through the block 1 to pass the laser output beam. The upper face 3 of the platform is lapped (smoothed flat) to support a flat, high quality mirror 4.

Lateral location of the mirror is achieved by an annular locating ring 5 which fits closely over the platform 2 and mirror 4. The ring has an external annular groove 26 to receive a resilient sealing ring 27, and a similar O-ring seal 6 is also interposed between the ring 5 and the body 1. A circular clamping spring 7 is dimensioned to be superimposed on the locating ring 5 with a further O-ring gas seal 8 interposed between the ring 5 and the underside of the spring 7. Four clamping screws 9 are inserted through the spring 7 and ring 5 and are threaded into the body 1 to clamp the locating ring 5 between the spring 7 and the body 1. In addition, the spring 7 has small projections 19 on its underside which press against the mirror 4 and thereby hold it firmly against the platform 2.

The mounting body 1 is itself mounted externally on the end plate 21 of the laser resonator by means of three headed fixing screws 11. The ring 5 is received in the aperture 23, sealed by the ring 27, and the body 1 is held by the three screws 11 which are inserted through the mounting body and threaded into the end plate 21. Three jack screws 12 are threaded through the body 1 to bear against three pads (not shown) mounted on the end plate.

The jack screws 1 2 are used to accurately align the mirror with the resonator cavity. The mounting screws 11 are tightened or slackened as required, to permit fine adjustments to be made to the angle of the mirror by means of the jack screws 12. When the correct alignment has been achieved the fixing screws 11 are tightened to firmly clamp the mounting body against the jack screws 12.

The seal 21 prevents the escape of gas (carbon dioxide in this example) between the plate 21 and the collar 5, whereas the seal 6 maintains the laser seal by preventing gas inside the ring 5 from escaping between the ring and the body 1. A different arrangement of seals may be used, for example, when the body 1 is apertured for the output beam. A seal may also be interposed between the mirror 4 and the ring 5.

With the mounting assembly described, the mirror is less likely to undergo movement with ambient temperature changes so that the power output of the laser is maintained over a much greater range of operating temperatures.

Should the mirror become damaged the whole mounting assembly can be quickly and easily changed without requiring extensive re-building and realignment of the laser.

Whilst the above description lays emphasis on those areas which, in combination, are believed to be new, protection is claimed for any inventive combination of the features disclosed herein.

Claims (12)

1. A laser resonator having a wall which contains an aperture and in which a laser mirror is held in a mounting assembly which is mounted in registration with said aperture from the outside of the resonator.

2. A laser resonator according to Claim 1, in which the mounting assembly is provided with adjustment means for aligning the mirror.

3. A laser resonator according to Claim 2, in which said adjustment means comprises screw adjustment.

4. A laser resonator according to Claim 3, in which said screw adjustment comprises jacking screws acting between the mounting assembly and said wall.

5. A laser resonator according to any preceding claim, in which the mounting assembly comprises a mounting body which includes a platform for supporting the mirror.

6. A laser resonator according to Claim 5, in which an apertured clamping member is secured to the mounting body such that the mirror is firmly held between the clamping member and the platform.

7. A laser resonator according to Claim 5 or 6, in which a collar is located about the mirror and the platform.

8. A laser resonator according to Claim 7 as appended to Claim 6, in which the collar is held between the clamping member and the mounting body.

9. A laser resonator according to Claim 7 or 8, in which the collar is located within the aperture in the laser wall.

10. A laser resonator according to Claim 9, in which a seal is interposed between the collar and the wall of the aperture.

11. A laser resonator according to Claim 9 or 10, in which sealing means is interposed between the collar and the mounting body.

12. A laser resonator according to any preceding claim, in which the laser comprises a sealed gas laser.

1 3. A laser resonator substantially as described with reference to the drawings.