H. J. J. Seguin

Analysis of the CO2 TEA laser

A five‐temperature model for the CO2–N2–He system has been employed to predict the output‐power pulse shape from a TEA laser. Theoretical predictions are compared to experimental data for several gas mixtures, cavity configurations, and excitation levels with good agreement. This model should be useful in the evaluation of alternative pumping schemes and in the understanding of CO2 TEA laser dynamics when nonlinear media are placed in the optical cavity.

Beam propagation constants for a radial laser array

The beam quality of a radial laser array, quantified in terms of the M(2) propagation constant, is determined as a function of array element configuration. A lower bound on array M(2) is estimated for both phase-locked and nonphase-locked conditions. It is shown that, to achieve near-unity M(2) array, either aperture filling or spatial filtering is required in addition to phase locking. An aperture-filling method suitable for radial arrays of CO(2) slab lasers is presented.

Ultraviolet photoionization in TEA lasers

Measurements of UV photoionization parameters for TEA CO 2 gas lasers are presented. Electron density and ionization decay times are given as a function of pressure for several gases and gas mixtures. Penetration depth of ionizing radiation in the gases is determined. The effect of selected additives on photoionization is demonstrated. The results show that a significant enhancement in electron density can be achieved. The X -band microwave interferometer data provide additional insight into the mechanisms involved and further substantiate the effectiveness of the technique in high-powered CO 2 laser design.

Multichannel slab discharge for CO2 laser excitation

Experimental results on a unique multichannel slab‐type CO2 discharge system are presented. The interdigital discharge geometry incorporates both large‐area and multibeam laser array concepts into a single, compact package. Small signal gain and saturation intensity values indicate that this structure is well suited for use in a CO2 laser.

Photoionization parameters in the carbon dioxide laser gases

The data and results of an extended investigation of the more salient parameters associated with the application of ultraviolet (UV) photoionization processes in TEA CO 2 lasers are presented. The study encompasses emission spectra, wavelength dependence, and influence of circuit parameters for a typical UV spark source. This investigation and a companion study utilizing a specialized charge collection apparatus on a monochromator provides further insight into the primary mechanisms involved in these photoinitiated laser devices and has, in addition, provided design criteria for the development of more efficient photoionization sources.

Optimization studies of a multikilowatt PIE CO 2 laser

Details of an investigation of the operational performance of a 10 kW CW PIE CO 2 laser are presented. The results obtained from the experiment, successfully scaled by an order of magnitude from an earlier proof-of-principle device, clearly document that the PIE excitation process can be effectively utilized in the design of very large volume lasers. Optimization data further reveal that overall wallplug efficiency is commensurate with that obtained from E -beam sustained lasers; but at far less complexity and cost. As such, this relatively simple and reliable nonself-sustained excitation process appears attractive for the commercial development of very large and cost effective CW CO 2 lasers.

Phase-locking phenomena in a radial multislot CO 2 laser array

An investigation of phase-locking phenomena in a multichannel, slab-type electrode, CO2 laser array is presented. External and self-phase-locking percentages of 90% and 60%, respectively, have been demonstrated. Azimuthally distributed radial injection within the central region of this gain geometry has been identified as the principal phase-locking mechanism. Fundamental optical modes are initiated simultaneously within each individual discharge slot via injection from this central core-oscillator region.

High-power 24-channel radial array slab rf-excited carbon dioxide laser

A unique way of driving a multi-channel rf excited slab laser is presented. Resonant cavity techniques were employed to provide high power splitting and impedance transformation for the excitation of multiple discharge elements. Uniform and isolated power division was observed in 24 channels, stacked in a radial array referred to as the Zodiac geometry. Impedance matching networks were not necessary as the rf cavity splitter created a near ideal voltage source capable of driving any discharge impedance. With 24 channels driven, optical powers over 3 kW have been observed.

Phase locking in a multichannel radial array CO2 laser

Phase locking in an extended‐area, multichannel, radial array, carbon dioxide laser has been investigated. Preliminary self‐phase‐locking percentages as high as 62% were achieved with the device. The phase‐locking mechanism was determined to be the mutual optical coupling present within the central region of this geometry. As such, this region acted as a core oscillator to initiate a fundamental optical mode within each individual discharge slot.

uv photoionization density measurements in TEA lasers

Diagnostic measurements on uv photogenerated laser plasmas are presented. Ionization data obtained with an X‐band microwave interferometer show plasma density to be a function of both the gas mix and the irradiation source parameters. Electron density as a function of pressure is given for selected gases and mixtures. At atmospheric pressure the photoplasma density in the standard CO2 laser mix is found to be surprisingly low.