S. K. Nikumb

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.

Toric unstable CO 2 laser resonator: an experimental study

The output characteristics of a toric unstable resonator fitted to a multichannel stripline excitation system are presented. The resonator is shown to possess the usual advantages of a conventional unstable resonator plus the ability to modify the profile of the output beam by a simple change in the coupling aperture. Laser output parameters have been studied as a function of coupling fraction, magnification, and internal loss factors. Variations in the focal spot size as a function of the coupling aperture as well as resonator alignment sensitivity and polarization properties have been investigated.

Annular-coupled concave–convex stable resonator for large-volume high-quality energy extraction

A theoretical investigation of a stable concave-convex resonator configuration, which appears suitable for single-mode high-power energy extraction from large volume gain media, is presented. The design features annular output coupling with a surprisingly uniform near-field intensity distribution. The computer-based analysis, supported by preliminary experimental results, suggests that acceptable alignment tolerances are provided along with an unusually small beam divergence. With proper design, a far-field divergence of 0.5 mrad, encompassing near 80% of the total laser energy, appears feasible. Operational data, recently obtained with this optical extraction approach, have revealed a further important practical advantage over an unstable resonator, being far less prone to mode degradation and hot spot formation on optical component misalignment.

Electronic mode and power control of a high-power CO/sub 2/ laser

An electronic supervisory system has been developed which allows long-term mode and power stability to be obtained from a high-power CO/sub 2/ laser, without any form of mechanical compensation. The system is shown to be capable of stabilizing the total output power of the laser to within 3% of the desired level. Mode stability is evaluated by measuring the power level in each quadrant of the laser output. Individual quadrant power is shown to vary by no more than 2%, with the system in operation. The relatively simple and inexpensive controller appears suitable for retrofitting to any medium- or high-powered laser, whether repetitively pulsed or CW. >

Performance characteristics of a high power CO 2 laser with computer vision mode and power control

An electronic laser controller, based on a computer vision system, has been developed for automatic mode and power control of a high powered CO(2) laser. The cross-sectional image of a sample of the output beam is continually analyzed and used to servo regulate both the laser cavity and the excitation level of the discharge. The technique stabilizes average laser output power to within 4%, while maintaining the best output power distribution achievable by the particular laser. Control system design also provides important on-line beam intensity profile data to assist in maximization of operating efficiency.

A multi-channel slot discharge CO2 laser employing a toric unstable resonator

Abstract Experimental results on a unique multi-channel slot-type CO 2 laser system fitted with a toric unstable resonator are presented. The discharge structure combines both large-area and multi-beam laser array concepts into a single, compact package. The unstable toric resonator has the unique property that optical radiation is extracted from the center of the system. Experiments have indicated that output beam characteristics are a function of the coupling aperture in the secondary mirror. Output power levels of 35 W per channel in a near diffraction limited beam have been obtained with 10% power conversion efficiency.

Gain characteristics of a MAGPIE coaxial CO 2 laser system

Gain coefficient measurements of a MAGPIE (magnetically stabilized, photoinitiated, impulse-enhanced, electrically excited) coaxial CO 2 laser discharge are presented. The effects of gas composition, input power, pulser ionization, and magnetic field on gain are examined. Measurements of the radial gain profile and saturation intensity are also discussed. A maximum small-signal gain of 0.30 m-1is observed, along with a saturation intensity of 190 W/cm2.

Mode stabilization of a high power laser via computer vision

Abstract A computer vision system which performs real-time mode control of a high powered CO 2 laser has been developed. The device continuously monitors the output beam to derive alignment data for the primary resonator optic. The technique ensures that the lasers intensity distribution is as uniform as possible. Valuable profile data and beam diagnostics are also generated by the system.

Multiple pass unstable resonator for an annular gain CO2 laser.

The design, construction, and operational characteristics of an optical resonator for an annular gain media are described. The system, developed for laser power extraction investigations in a new type of coaxial discharge geometry, features a folded multipass unstable resonator concept, fabricated from lightweight uncoated diamond-turned aluminum substrates. The resulting cw CO2 device incorporates excitation aspects of the nonself-sustained PIE excitation process in addition to a new magnetic discharge stabilization technique. Laser performance and output beam characteristics are presented.

Multichannel laser resonators - an experimental study

The output characteristics of several large-area multichannel unstable resonators are presented. The conventional unstable resonator and a novel toric unstable resonator, in both confocal and nonconfocal configurations, have been studied. Output beam profiles, optical energy extraction, beam focusability, resonator alignment properties and polarization states of the various resonators have been analysed in depth.