FR2504744A1 - CO2 LASER SCELLE - Google Patents

Abstract

THE INVENTION RELATES TO A CO-SEALED LASER. THE DISCHARGE CAVITY 320 OF THIS LASER IS BOUNDED BY SIDE WALLS 306, 304 AND TOP AND BOTTOM COVERS 332, 334 RESPECTIVELY. INSIDE THE ENCLOSURE THUS FORMED, ARE MOUNTED ELECTRODES 301, 302 CONSTITUTING RESPECTIVELY THE CATHODE AND THE ANODE OF THE LASER EXCITATION DISCHARGE CIRCUIT. THE INVENTION IS USED TO IMPROVE THE VIBRATION RESISTANCE AND SHELF LIFE OF LASERS, AS WELL AS TO REDUCE THEIR SENSITIVITY TO VARIATIONS IN THE INPUT ELECTRIC CURRENT.

Description

The present invention relates to a laser

  with CO 'sealed, robust and simple excited transverse-

  under atmospheric pressure and in which a corona discharge preionization technique is adopted. In U.S. Patent No. 4,207,540 issued to GJ Ernst, as well as an article by Ernst and Boer titled "Construction and Performance Characteristics of a Rapid Discharge TEA C 02 Laser" and published in "Optics Communications ", Volume 27, No. 1, October 1978, page 105, there is described a C 02 gas flow laser in which one adopts

  a corona discharge preionization technique.

  This discharge technique involves using an intense electric field to initiate a discharge at

  inside the bore of the laser, this

  charge generating ultraviolet light which pre-

  ionizes the gas in the laser's main discharge zone Figure 2 of the above-mentioned article and Figure 3 of the patent mentioned above illustrate the details of

  relevant construction of this laser The invention de-

  written and claimed in this patent is a com-

  characterizing a particular discharge circuit and a particular electrical connection to the electrode preionization system In these two references,

  the gas flows continuously through the volume

  tif, thus producing a different ambient

that of a sealed laser.

  The present invention relates to a C 02 laser

  301 perfected excited transversely under atmospheric pressure

  pheric and preionized by discharge discharge, this laser

  being designed to operate under conditions of

  have a long shelf life, the mechanical construction of the cavity of this laser being

  :; odified vis-à-vis the devices of the prior art

  in order to improve its efficiency under long-lasting sealing conditions and to reduce the over-coordination of the device of the prior art to a circuit

particular electric.

  In the accompanying drawings Figure 1 illustrates a detail of the prior art laser described in the aforementioned article;

  FIG. 2 is a reproduction of FIG.

  re 3 of the aforementioned patent; Figure 3 is a cross-section of a laser constructed in accordance with the present invention; and FIG. 4 is an exploded view of a laser

  constructed according to the present invention.

  In FIG. 3, a section is shown

  cross-section, a laser cavity designed according to the

  invention, in which the volume 320 is the cavity

  laser discharge tee which is delimited by

  side kings 306 and 304, as well as lids

  332 and 334 at the top and at the base respectively.

  The optical axis of the laser is perpendicular to the plane of the drawing, while the transverse axes 350 and 351 pass through the covers 332, 334 and the walls 304,

  306 respectively In the illustrated embodiment

  The walls and covers consist of a dielectric material such as "MACOR" which is a machinable ceramic glass made by "Corning Glass Works", while the seals 309 and 311 formed between the walls and the covers are sealed. hermetically by welding by means of a glass frit or by adopting

  an equivalent sealing technique

  of the enclosures thus formed, have mounted electri-

  trodes 301 and 302 which are respectively the cathode and

  the anode of the laser excitation discharge circuit.

  These electrodes are connected via lids 334

  and 332, by members 307 and 308 respectively, the

  3 S * 'e are shaped so as to have a low inductance

  * facilitate the formation of a tight seal between

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  the conductive metal member and the cover The seal formed between the connecting members and the covers is sealed by means of an epoxy resin

  or by welding with a glass frit

  S figurations of the electrodes 301 and 302 are studied

  according to the process given by Chang (see

  Ernst, lines 54-56), in which the parameters are as follows: K = 0.02, '= arc cosine (-K), the spacing between the electrodes 301 and 302 being, at

  As an illustration, one centimeter.

  Inside the wall 304 of the cavity of the

  laser, is machined a reentrant volume 314, to a depth

  calculated so that the remaining wall thickness between the electrode and this incoming volume

  a critical value, for example, 2 millimeters, which

  it will depend on the material chosen for the wall 304.

  In the cavity thus defined 314, is introduced a

  electrode 310 which is electrically connected to the housing

  thode 301 by means of a low inductance path (not shown in the diagram) The electrode 310 is

  arranged in the cavity 314 so that its former

  upper tremity is located in the vicinity of the tran-

  created in the surface of electrode 302 between

  the curved surface 321 facing the cathode and the sur-

  2 '5 flat face 322 coming into contact with the edge of the pa-

  king 304 The transition zone 312 o these two surfaces meet, is not angular, but rounded with

  a radius of at least 0.076 mm The electrode 310 is dis-

  parallel to the transverse axis 350, such that its upper edge is located substantially at

  the same height as the transition zone 312 of the elec-

  trode 302 and that the shortest distance between

  frro Jes 310 and 302 passes through at least a portion of

  without a cavity 320 without completely crossing the pa-

  As a result of this separation, the distance

  and, therefore, the field of greatest intensi-

  are not located inside the wall 304, which could tend to promote a rupture of the material of which this wall 304 is made, but

  they are located partly in the area of

  The intense electric field created at the angle where the surface 321 joins the wall 304 detaches electrons from the material of the latter and generates a corona discharge which descends along the surface of the wall. the wall 304 towards

  electrode 301, thereby producing ultraviolet radiation

  violets The ultraviolet radiation thus created crosses the entire zone 320, which has the effect of

  subject the gas to a preionization.

  FIG. 4 illustrates, by an exploded view, a

  embodiment of the invention in which a

  402 forms the walls and ends of the body of the laser cavity, which is traversed by an axis 400 which passes through a lens 420, an opening 404, the main cavity, an opening 405 and a lens

  422 Lenses 420 and 422 are hermetically sealed

  openings 404 and 405 in order to maintain them in

  alignment in an environment subject to high levels of

  The opposite sides of the body can be

  born by classical techniques for them to be

  parallel and smooth, thereby ensuring alignment

  In one side (304) of the body 402, an insert 314 is machined which holds an electrode 310. This electrode 310 is held in alignment by conventional fasteners (not shown) on the top and base of the body. 402, are adapted lids 332 and 334 which are welded in place by means of a glass frit or by another hermetic sealing technique The electrodes 301 and 302 are attached to their corresponding lids as illustrated by the cross section of the figure 3 who

  taken as arrows 3-3 in Figure 4.

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  According to an advantageous characteristic of the in-

  vention, the body 402 of FIG. 4 has only four sealed joints, namely those formed on the

  top and bottom covers, as well as those

  on the lenses A lid seal

  could possibly be eliminated by sinking the

  by hot isostatic pressing or by means of

  than equivalent, thus eliminating a seal near the electrode under tension (anode) According to another advantageous characteristic of the invention, it is used

  a single material for the body of the laser, contrary

  the prior art in which several materials with thermal characteristics are employed.

  According to another characteristic which is

  still of the invention, although the course of

  between the electrode 302 and the electrode 310 is

  necessarily short, in order to generate the high intensity

  required field, the route established outside the

  between the connectors of the electrodes 302 and 310 or

  their surfaces is quite long, thus eliminating a

  major ficulty of the devices of the prior art

re.

  On the other hand, a device built

  the teachings of the prior art are

  illustrated in Figures 1 and 2; in Figure 1, the cavity

  tee is defined by members 18, 17, 19 and 5, two of these members being made of brass and the other two of glass,

  thus forming four joints between dissem-

  Another difficulty with the provision

  of the prior art, lies in the fact that a short direct path is established between the electrode

  of mass 31 and the brass member 18, which is in contact with

  electrical contact with the anode 2 A device constructed in accordance with this technique has undergone a series of electrical short circuits between the electrode located in

  outside the cavity and the anode In Figure 2, elec-

  trodes 118 and 119 which are in electrical contact with the anode 2 and the cathode 3, extend over a long distance maintaining a minimum spacing between them by means of an insulating medium 105. In accordance with the prior art, this This device gives rise to a very short rise time of the Marx generator due to the low inductance, which is a feature of the prior art system, which is an integrated laboratory instrument designed for time.

  fastest climb (about 15 nanoseconds).

  The present invention uses the same principle

  the physics of a discharge induced by dielectricity

  that to develop an instrument generating

  portable field designed to tolerate prejudicial conditions

  It can be determined by vibration and thermal expansion, while being insensitive to variations in electrical parameters. A laser constructed in accordance with the present invention has a voltage pulse rise time of greater than 30 nanoseconds and a pulse voltage of more than 18 kilovolts for a gap of

1 centimeter between electrodes.

  A modified version of the invention has a second electrode similar to the electrode 310 and which is pressed into the wall 306 to provide a

  more uniform preionisation and redundant

  In another version of the invention, the end pieces and the covers

  332, 334 are combined to form a unitary unit.

  In yet another version, the sides 304, 306 and the covers 332, 334 are combined to form a

monobloc unit.

Claims (5)

CLAIMS I   1 C02 laser excited transversely under   atmospheric pressure, comprising an amplification medium   cation and confined in a sealed enclosure having a   optical axis and a transverse axis, this enclosure com-   carrying first and second end members disposed perpendicularly to the optical axis, first and second side members, and first and second   second cover, the side members and the covers   keys being arranged parallel to the optical axis,   say that all these bodies are made up of the same   characterized in that it comprises: anode and cathode electrodes disposed on opposite sides of the enclosure and inside thereof, parallel to the optical axis and along the transverse axis being separated from each other by the side members, the anode electrode having a curved surface facing the cathode electrode,   as well as flat wall surfaces   tact with the side members, said curved surface and said flat wall surfaces joining in a transition zone having a radius of curvature of at least 0.076 mm;   this laser also comprising at least one electro-   disposed outside the laser cavity and electrically connected to the cathode electrode by means of a low inductance conductor, while being mounted along the outer surface of one of the side members by overlapping the anode electrode along the transverse axis, so that the shortest straight line between the anode and this electrode passes through a   part 4 in the middle of the laser and also a layer of   insulation consisting of part of the wall quoted from the letter;   the scope also incorporating   placed along the optical axis to resonate   optic radiations inside the medium   amplification, as well as elements intended to   plodding a high pulsed voltage to the anodic electrodes   and cathodic, this voltage having a time of   at least 30 nanoseconds; and a peak value calculated such that an electric field of at least 18 kV / cm is created between these electrodes, thereby generating between the anode and   the electrode located outside the cavity, an   geometry with effluvium which conditions the medium of GO 2 between   anodic and cathodic electrodes.   Laser according to claim 1, characterized   rised in that the end members and the lateral members   are one continuous organ.   Laser according to claim 1, characterized   rised in that the end members and the lids form a single continuous organ.   Laser according to claim 1, characterized   rised in that the side members and lids form a single continuous organ.   Laser according to any of the claims   cations I to 4, characterized in that the sealed enclosure extends without discontinuity between the electrode located outside the cavity and the anode, along the surface flat wall.