WO1981001348A1

WO1981001348A1 - A laser assembly

Info

Publication number: WO1981001348A1
Application number: PCT/GB1980/000190
Authority: WO
Inventors: R Fraval; H Fraval
Original assignee: Sinar Ets Dev Ltd; R Fraval; H Fraval
Priority date: 1979-11-03
Filing date: 1980-11-03
Publication date: 1981-05-14
Also published as: EP0038813A1; JPS56501744A

Abstract

A laser assembly requires a very stable and rigid base. This is provided by concrete or other solidified material into which is set, while it is still in a liquid or semi-liquid state, the laser tube (1) itself or mountings (21, 22) therefor. The material is preferably fibre reinforced. When the tube (1) is directly set into the base (4), cavities (5, 6, 7) for cooling fluid can be provided by a dissolvable former which is set into the material with the tube. When the material has solidified, the former can be dissolved out. The technique is applicable to lasers with a folded optical path as well as lasers with a single straight tube.

Description

"A Laser Assembly" This invention relates to the construction of lasers. It is primarily concerned with gas lasers, CO₂ lasers in particular, but there is no reason why the same principles should not be applied to liquid and solid lasers.

An essential requirement for most optical apparatus, and lasers in particular, is a strong, rigid and stable mounting. The provision of a laser cavity has hitherto been technically difficult and expensive (involving machining precision components and cavities), and the aim of this invention is to provide a much simpler and cheaper method of making one.

According to one aspect of the invention there is provided a laser assembly comprising a base, ar.d a laser tube and associated optical elements mounted on the base, wherein the base is a solid-setting material into which are set other components of the assembly.

According to another aspect of the invention there is provided a method of constructing lasers wherein the laser tube and associated optical elements are supported in a mould which is then filled with a solidsetting initially liquid or semi-liquid material, and a substantially complete laser head assembly is removed from the mould when the material is set. According to a further aspect of the invention there is provided a method of constructing lasers wherein mountings for the laser tube and associated optical elements are supported in conjunction with a mould, the mould is filled with a solid-setting initially liquid or semi-liquid material which sets around parts of said mountings, and the laser tube and associated elements are secured to other parts of said mountings. The preferred solid-setting material is cement based (herein referred to as concrete) and may be fibre reinforced. The aggregate used with the cement may be natural (for example sand) or may be a manufactured material. This can provide greater strength and better insulating properties than sand. Various admixtures such as fly-ash, polymers or plasticisers can also be included for particular results. The fibres are conveniently glass fibres, although other reinforcement can be adopted.

Gas lasers require cooling, and ducts for a fluid cooling medium, generally water, can be moulded into the tube mounting.

Concrete is one of the most suitable materials for use as an optical bench or table, and the additon of fibres only improves its quality in this respect. The use of a mould means that the operation can be repeated accurately for an indefinite number of times, and of course with mass production and such a material as glass reinforced cement (GRC) the expense can be considerably reduced.

For a better understanding of the invention, some embodiments will now be described, by way of example with reference to the accompanying drawings, in which: Figure 1 is a longitudinal section of a laser head assembly constructed by the method of this invention,

Figure 2 is a similar section, in more diagrammatic form, of a laser head assembly with a folded optical path, Figure 3 is a longitudinal section of a further laser head assembly,

Figure 4 is an end view of the assembly of Figure 3, and

Figure 5 is a diagrammatic section of another laser head assembly with a folded optical path. The assembly of Figure 1 has a laser tube 1 with branches 2 and 3 near its ends for the input and outlet of. gas. The tube is supported in a solid block 4 moulded as described below, the support zones being near the branches 2 and 3 and being separated by a water cavity 5. This has inlet and outlet ducts 6 and 7 respectively. The ends of the tube 1 emerge into cavities 8 into whose mouths are set mirror supports 9. The mirrors are shown at 10, and are held by clamping rings 11 adjustable by screws 12. Electrodes 13 axe housed in chambers 14 opening into the branches 2 and 3, and their power leads 15 extend through the block 4 to exterior terminals 16.

The construction of this assembly is effected by mounting the tube 1 with the mirror supports 9 in a mould. The central portion of the tube 1 is encased in a jacket with two arms corresponding to the cavity 5 and the ducts 6 and 7. This jacket is made of a substance, such as expanded polystyrene, which can be dissolved out to create the cavity. The electrodes 13 and the leads 15 are also set in position. The concrete mix may then be poured or sprayed over the laser tube assembly until the mould cavity is filled. The mix will generally be vibrated or vacuum drawn to consolidate it. When it is set, the assembly is removed and the water cavity can be created by dissolving out the material of the jacket. Since the block 4 is to act as a water duct, the mix will have additives that will make it water-proof, such as polymers or plasticisers, and/or a water-proofing agent can be flowed through the cavity to line its surface.

Figure 2 shows a similar construction for a "folded" laser. Here the optical path of the laser is reflected at two intermediate points 17 in order to reduce the physical length of the laser assembly, although the optical length will be approximately three times that dimension, enabling greater power.

In the embodiment of Figures 3 and 4 there is less direct mounting of the tube on a concrete base, which is an open-ended trough 20. Into this are set, near each end, glass plates 21 forming transverse bulkheads, and between them two "adjust-and-lock" tube mounts 22 are set into the trough base. The plates 21 and mounts 22 are held by a jig while the trough is moulded and sets. A plasma tube 23 is encased by a water jacket 24 over most of its length and is held in place by the mounts 22 embracing the water jacket. The tube is then aligned with apertures 25 in the plates 21 and is connected with mirror assemblies 26 by flexible vacuum tight couplings 27 extending through those apertures. Such couplings would only be used for a non-sealed plasma tube.

Each mirror assembly 26 has a mount plate 28which extends over most of the outer side of the associated plate 21 and which can be adjusted relative thereto by dynamic mounts 29 and micro-position adjusters 30. The mirror 31 is carried by a holder 32 central of the plate 28.

This construction may be adopted when a separate resonator cavity from the plasma tube is required, and it will allow the use of sealed plasma tubes. It can also be employed for a through-flow system where more accurate and adjustable mirror mounts are required, and it will be seen from the Figures that they are readily accessible. The concrete trough forms a stable base for the mirrors, via the rigidly held plates 21, the positional stability of the mirrors being limited largely by the integrity and stability of the dynamic mounts 29 and the micro-position adjusters 30. Except for the elements set into the concrete, all parts are easily replaceable.

Figure 5 illustrates how this form of construction can be applied to a folded beam system. A concrete substrate 33 has set into it mirror mounts 34 and adjustand-lock mounts 35 for the tube/water jacket assemblies. As before, the laser would derive its stable performance from the mechanical and thermal stability of the concrete used. In this specification reference is made to lasers, It should be understood that the invention could equally well be applied to other optical apparatus requiring great stability and accuracy, and the term laser is to be construed in the following claims as embracing such apparatus.

Claims

1. A laser assembly comprising a base, and a laser tube and associated optical elements mounted on the base, wherein the base is a solid-setting material into which are set other components of the assembly.

2. An assembly as claimed in Claim 1, wherein the material is cement based.

3. An assembly as claimed in Claim 1, wherein the material is fibre reinforced.

4. An assembly as claimed in Claim 1, 2 or 3, wherein the base is set around the tube itself.

5. An assembly as claimed in Claim 4, wherein the base has moulded-in ducts for cooling fluid.

6. An assembly as claimed in Claim 1, 2 or 3, wherein the material is set around parts of mountings for the tube and optical elements, which are secured to other parts of said mountings.

7. A method of constructing lasers wherein the laser tube and associated optical elements are supported in a mould which is then filled with a solidsetting initially liquid or semi-liquid material, and a substantially complete laser head assembly is removed from the mould when the material is set.

8. A method as claimed in Claim 7, wherein ducts for cooling fluid are moulded into the base formed by the set material.

9. A method as claimed in Claim 8, wherein the ducts are formed by a second material around which the first material flows and sets and which is subsequently dissolved out.

10. A method of constructing lasers wherein mountings for the laser tube and associated optical elements are supported in conjunction with a mould, the mould is filled with solid-setting initially liquid or semi-liquid material which sets axound parts of said mountings, and the laser tube and associated elements are secured to other parts of said mountings.

11. A method as claimed in Claim 7, 8, 9 or 10, wherein the solid-setting material is cement based and fibre reinforced.