COMPACT FLOWING GAS SYSTEM FOR LASERS

SYSTEME COMPACT DE CIRCULATION DE GAZ POUR LASER

English Abstract

Abstract of the Disclosure

A miniature air actuated vacuum transducer is connected on the down-
stream side of a laser and is disposed for creating a vacuum suction for
exhausting gas from a flowing gas laser system. Specifically, a compact flow-
ing laser is disclosed in combination with a specific pulp or vacuum trans-
ducer. A small high pressure gas cylinder is provided such that applicant's
laser can operate in a miniaturized environment.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A compact flowing gas laser having pumping-means associated there-
with, said laser comprising:
(a) a body having a transverse optical resonant cavity therein and
a pair of inlet passages and an outlet passage connected to said cavity in
said body;
(b) an active laser medium connected to said inlet passages for
flow into said cavity through said inlet passages;
(c) regulating means for regulating the flow of said active medium
into said cavity; and,
(d) vacuum transducer means for directing said active medium to the
atmosphere, said vacuum transducer means including a housing enclosing a body
having an orifice therein, an air inlet connected with said body through a
first side of said housing, a high pressure source of gas connected to said
inlet for flow through said orifice, an enlarged exhaust port opening through
a second side of said housing for directing said gas from said orifice to the
atmosphere and a port in said housing connected to said outlet passage in said
body of said laser, whereby a low pressure area is created in said port as a
result of said high pressure gas being expanded in said orifice and said active
medium is drawn into said housing and directed to the atmosphere through said
exhaust port.

2. Apparatus as in claim 1, wherein said high pressure gas is air.

3. Apparatus as in claim 1, wherein said high pressure gas is N2.

Description

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Miniature gas lasers ~uch as waveguide C02 systems utilize internal
gas mixtures at partial atmospheric pressures~ Longitudinally excited
lasers typically are operated at low pressures on the order of 35 to 200
Torr. The transversely excited (TE) waveguide lasers are operated at some-
what higher pressures (50 to 300 Torr typically), and although pressures as
high as 4 atmospheres have been reported, numerou6 limitations still exist
in the development of positive pressure tranversely excited (TEA) lasers in
waveguide configurations.
Successful operation of low power, longitudinally excited C02 wave-
guide lasers has been obtained with sealed off gas reservoirs, and commercial
versions of CW waveguide lasers are now available from at least two sources.
However~for higher power, pulsed, and TE configurations, flowing gas systems
at partial atmospheric pressures are generally employed with some sort of
vacuum pumping. The trip]e requirements of relatively low absolute pressure
(lOO Torr), capable of starting at atmospheric pressure, and capable of exhaus-
ting into atmospheric pressure cannot be met by most of the lighter and smaller
classes of vacuum pumps.
; To overcome many of these limitations and to provide a more compact, -~
portable gas handling system, the present invention utilizes a miniature air -
operated vacuum pump which works on the principle of the venturi tube in which
a high pressure source of air or other gas is rapidly expanded in an enlarged
chamber downstream of a small orifice. This creates a very low pressure area
within the venturi chamber J which provides a vacuum suction at a side port
located backstream of the rapidly expanding gas. The downstream side of the
laser resonator is connected to thi~ port.
A flowing gas laser systen) utilizing internal gas mixture~ at partial
atmospheric pressure. A regulated active medium supply directs the gas (C02~ ~le,
N2) into the laser cavity. A vacuum transducer i~ connected on the downstream
side of the laser cavity to exhaust the gas from the laser cavity. A high
pressure source of air is directed through a small orifice and is rapidly
expanded in an enlarged chamber do~mstream of the small orifice and is rapidly
expanded in an enlarged chamber downstream of the small orifice creating a


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low pressure area within the venturi charnber to provide a vacuum suction at
a side port which is connected to the laser cavity.
Figure 1 i8 a diagra~natic vlew of the ilowing gas la~er system oi
the present invention.
~igure 2 is a pictorial view of a miniature vacuum pump used in the
laser system.
Figure 3 is a graph illustratLng the absolute pressure and the air
supply pressure in a particuLar application of the device.
As shown in Figure 1, a waveguide laser 10 includes a body 12 having
a pair of mirrors 13 and 15 forming a resonant optical cavity 17. Mirror 15
is partially transmissive to form an energy abstracting means. A pair of
electrodes l9 and 21 are connected to a high voltage power source 23 and mounted ~-
in body 12. A pair of inlets 14 and 16 connect into an axial cavity 18. A
regulated gas supply 20 (C02, He, N2) is connected through a valve 22 to inlets
i 14 and 16. An outlet port 24 i8 in communication with cavity 18.
A vacuum transducer 26 is provided with a port 28 which i9 connected
to outlet port 24 of the laser. Pressure is monitored via a vacuum gage, 29.
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The housing of transducer 26 includes an inlet port 39 and an exhaust port 32.
The transducer includes a body 34 having a small orifice 36 therein disposed
in communication with an enlarged chamber or exhaust port 32. A gas supply 38 ~ -
(N2~or air) is connected through a valve 40 to inlet port 30 of the transducer.
In operation, gas from supply 38 is directed into the transducer
through inlet 30, and through orifice 36 and is rapidly expanded in chamber 32. -
A low pressure area is created in Port 26 to provide a vacuum suction through
port 24 to draw the ilowing laser gas tberethrough where it is drawn into the
transducer to be directed to the atmosphere.
In one example an ALr-Vac Modcl AVR-046 vacuum transducer (dimensions
on the order of 6 cm x 2.5 cm x 1.5 cm and a mas~ about 0.06 kg) was utiliæed
with a pulsed wavegulde T~ la~er whic~l had been previously optimlzed Eor a
cavity pressure of about 250 Torr, and a relatively high ga~ flow rate of
1300 cm3/minO Figure 2 indicates thatatmaxlmum supply pressure this flow
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rate can be maintained even with the cavity pressures as low as 200 Torr~ so
the transducer has some margin above that needed for this particular applica-
tion. The air supply pressure ~7as then reduced to 4~2 kgm/cm2~ and performanceof the laser was found to meet the noted requirements.




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