Coherent light generators – Particular resonant cavity – Mirror support or alignment structure
Patent
1987-12-07
1988-07-19
Scott, Jr., Leon
Coherent light generators
Particular resonant cavity
Mirror support or alignment structure
372 61, 372 65, H01S 308
Patent
active
047590319
DESCRIPTION:
BRIEF SUMMARY
This invention relates to lasers and particularly to mounting means for laser reflectors.
In the design of gas lasers there is a need to provide for accurate alignment of the cavity reflectors and location of the reflectors in a fixed, permanent manner such that the alignment is not disturbed. The reflectors must generally be aligned parallel within the order of 10 micro-radians and must then be fixed to the laser in a way which is vacuum tight and mechanically robust. The alignment tolerance and vacuum integrity must be maintained through subsequent exposure to vibration, shock and temperature cycling; the reflection must also not be susceptible to misalignment over prolonged times, in or out of use.
The usual manner in which this is achieved is to seal each of the reflectors into a tunable mirror mount. The mount generally incorporates a deformable, usually metal, member which is foricbly adjusted for tuning. Such arrangements are susceptible to long term creep and are generally difficult to incorporate in the laser design, in such a way that an expansion match is achieved throughout the cavity.
In an alternative arrangement, an outer, vacuum-tight housing is provided for the laser so that the reflector mount is adjustable but not vacuum tight.
An object of the invention is to provide a laser with reflector mounting means which is at the same time easy to adjust very accurately, mechanically strong and inherently vacuum tight.
According to one aspect of the invention, a laser comprises mounting means for controlling the attitude of a laser cavity reflector with resepct to the laser cavity housing, the mounting means comprising a pair of ring members each having first and second non-parallel optically flat surfaces, the ring members being connected to each other by optical contact between the first surfaces and respectively connected to the reflector and an end face of the housing by optical contact with the second surfaces, the ring members being orientated with respect to each other and to the reflector to determine the attitude of the reflector with respect to the end face, and the optical contacts providing a mechanically strong mounting for the reflector and a vacuum tight optical seal to the cavity housing.
The reflector may be composed of a different material from the ring members, there then being a third ring member interposed between the mounting means and the reflector, the third ring member being composed of the same material as the pair of ring members and being optically sealed to the adjacent ring member and metallurgically sealed to the reflector.
The ring members, the cavity housing and the reflector may be composed of a low expansion glass ceramic.
There may be two mounting means one in respect of each laser reflector. Alternatively, there may be only one mounting means, the other reflector of the laser being fixed to the cavity housing by metallurgical sealing.
According to another aspect of the invention a method of manufacturing a laser includes the steps of mounting at least one reflector of the laser on the laser cavity housing by interposing between optically flat surfaces associated respectively with the reflector and an end face of the housing, mounting means comprising a pair of ring members each having first and second non-parallel optically flat surfaces, the first surfaces being in contact, rotating the ring members independently and in unison until the laser reflectors are parallel, and producing an optical seal between abutting ones of the optically flat surfaces.
A volatile lubricating liquid may be interposed between abutting ones of the surfaces to permit, temporarily, independent rotation of the rings.
Two embodiments of the invention will not be described, by way of example, with reference to
FIGS. 1 and 2 of the accompanying drawings, showing, diagramatically, axial sections of a laser body.
Referring to FIG. 1, a laser comprises a body or housing 1, and a reflctor 6 positioned at each end of the optical cavity. Only one end is shown here, the other being similar exce
REFERENCES:
patent: 3855547 (1974-12-01), Kirk
patent: 4638486 (1987-01-01), Dost et al.
patent: 4653060 (1987-03-01), Barth et al.
patent: 4653063 (1987-03-01), Acharekar et al.
patent: 4672626 (1987-06-01), Koseki
Price Henry T.
Syers Peter J.
GEC--Marconi Limited
Jr. Leon Scott
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