Coherent light generators – Particular pumping means
Patent
1988-11-14
1990-09-04
Gonzalez, Frank
Coherent light generators
Particular pumping means
372 70, 372 87, H01S 309
Patent
active
049550357
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a microwave-pumped, high-pressure, gas-discharge laser, in particular, an excimer laser, with an optical resonator, with a resonator gas volume arranged therein and extending along an optical axis thereof, with a microwave coupling structure enclosing the resonator gas volume within it and with a microwave generator connected to the microwave coupling structure.
Such high-pressure, gas-discharge lasers operate with pressures greater than or equal to 100 mbar, an electric power density greater than or equal to 1 kilowatt per cm.sup.3 in relation to an active resonator gas volume and a frequency greater than or equal to 100 MHz, in particular, in the microwave range. Excimer lasers are a particularly preferred type of these high-pressure, gas-discharge lasers.
In such high-pressure, gas-discharge lasers, the active resonator gas volume is enclosed in a tube which extends coaxially with the optical axis and is positioned in an area of maximum electric field intensity within the microwave coupling structure. A high-pressure gas discharge is ignited and maintained in the resonator gas volume by the microwave excitation. Laser action occurs by gas particles which have been excited to their laseractive levels by the high-pressure gas discharge emitting coherent light. However, a precondition of optimal laser action is that this emission occur near the optical axis of the resonator.
Owing to the high pressure and the resulting high electron density in such a high-pressure gas discharge, however, a phenomenon referred to as wall breakdown and constituting a spatial instability of the discharge occurs. In this wall breakdown, the energy of the electrons contained in the gas discharge and hence also the emission of the gas particles in the area of wall surfaces of the tube is substantially greater and decreases towards the center, i.e., towards the optical axis. The emission even frequently has a minimum in the area of the optical axis.
Such effects are known, for example, from the paper presented by R. W. Waynant, D. P. Christensen and W. M. Bollen, Jr., entitled "Design Considerations for RF Pumping of Rare Gas Halide Lasers", published in Topical Meeting on Excimer Lasers 1/83 in Incline Village, Nev..
Heretofore, in order to avoid such a wall breakdown, a tube with a diameter which is as small as possible has been chosen so that the effect of the emission minimum in the area of the optical axis is only insignificant.
Aside from adjustment problems resulting from such small diameters of the resonator gas volume, such a decrease in the resonator gas volume is unacceptable, in particular, in commercial laser applications. Also, in spite of the reduction in the cross-section of the tube, the wall breakdown adversely affects the laser power and also the mode purity for these are known to always be optimal in the case of stable resonators when the emission is greatest in the area of the optical axis.
Proceeding from this prior art, the object underlying the invention is to so improve a high-pressure, gasdischarge laser of the generic kind that a wall breakdown is substantially suppressed.
This object is accomplished in accordance with the invention in a high-pressure, gas-discharge laser of the kind described at the beginning by a central area with an electric field intensity being above a threshold value for a high-pressure gas discharge being disposed within the resonator gas volume in a transverse direction to the optical axis and being adjoined on both sides thereof by outer areas with a field intensity being below the threshold value for the high-pressure gas discharge.
The field structure created by the inventive solution enables substantial suppression of a wall breakdown as the high-pressure gas discharge transversely to the optical axis is no longer bounded on all sides by wall surfaces and so a typical wall breakdown with a maximum emission in ring-shaped arrangement around the optical axis can no longer be formed because the laser gas in the resonator gas volume carrying out the high
REFERENCES:
patent: 3748594 (1973-07-01), Pugh
patent: 3753152 (1973-08-01), Pettipiece
patent: 4004249 (1977-01-01), Kikuchi
patent: 4393506 (1983-07-01), Laakmann et al.
patent: 4414488 (1983-11-01), Hoffmann et al.
patent: 4513424 (1985-04-01), Waynant et al.
patent: 4618961 (1986-10-01), Sutter, Jr.
patent: 4631732 (1986-12-01), Christensen
patent: 4780881 (1988-10-01), Zhang et al.
Article "Design Considerations for Pumping of Rare Gas Halide Lasers", by ynant, Christensen and Bollen, Jr., Topical Meeting on Excimer Lasers, 1/83, pp. MA4-1-MA4-5.
Article "Improved Performance of the Microwave-Pumped XeCl Laser", by Wisoff, Mendelsohn, Harris and Young, IEEE Journal of Quantum Electronics, vol. OE-18, No. 11, Nov. 1982.
Article "Microwave-Excited Ionized Laser with External Magnetic Field", by Katsurai and Sekiguchi, Electronics and Communications in Japan, vol. 54-B, No. 1, 1971.
German Article entitled " ", Archiv Fur Elektrotechnik, Published in XII. Band, 1923, by W. Rogowski.
Article entitled "A Novel Analytical Design Method for Discharge Laser Electrode Profiles", by E. A. Stappaerts, Published in Applied Physics Letters, 40(12), 15 Jun., 1982.
Article entitled "Improved Uniform-Field Electrode Profiles for TEA Laser and High-Voltage Applications", by Chang, The Review of Scientific Instruments, vol. 44, No. 4, Apr. 1973.
Article entitled "Excimer Laser Pumped by an Intense Relativistic Microwave Source", by Didenko et al., Soviet Technical Physics Letters, 12(10), Oct. 1986.
NRL Memorandum Report 5432 entitled "The Effects of Surface Waves on RF Discharge Pumped Lasers", By Waynant, Christensen and Bollen, Jr., published in DD Form 1473, of Office of Naval Research, Jan. 30, 1985.
Deutsche Forschungs -und Versuchsanstalt fuer Luft- und Raumfanr
Gonzalez Frank
LandOfFree
Microwave-pumped, high-pressure, gas-discharge laser does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Microwave-pumped, high-pressure, gas-discharge laser, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Microwave-pumped, high-pressure, gas-discharge laser will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-447049