K. E. Leopold

Continuously tunable high‐pressure CO2 laser with uv photopreionization

The operation of a uv photoinitiated tranverse‐discharge CO2 laser has been investigated at pressures up to 15 atm. Preliminary studies of a device having an active volume of [inverted lazy s] 13 cm3 have yielded a maximum output of [inverted lazy s] 1 J in 30 nsec, while the use of a grating‐tuned resonator has resulted in continuously tunable operation over frequency intervals of [inverted lazy s] 20 cm−1.

Dependence of the damage and transmission properties of fused silica fibers on the excimer laser wavelength

The damage and transmission properties of selected commercially available fused silica fibers have been measured as a function of excimer laser wavelength. Two-photon absorption and color center formation in fused silica currently limit the use of these fibers at the excimer wavelengths of 193 nm (ArF) and 248 nm (KrF).

Dependence of the nonlinear transmission properties of fused silica fibers on excimer laser wavelength

The nonlinear transmission properties of commercially available fused silica fibers have been determined as a function of excimer laser wavelength. Accurate two‐photon absorption coefficients have been measured and the influence of color center formation is discussed. Two‐photon absorption and color center formation dominate the ArF and KrF transmission at high intensities while both of these effects are negligible at the XeCl and XeF laser wavelengths.

Ultralong optical‐pulse corona preionized XeCl laser

A simple corona preionization scheme together with magnetic spiker and pulse forming line technology has resulted in the production of 100‐mJ, 1‐μs duration as well as 500‐mJ, 0.5‐μs duration XeCl laser pulses.

The effect of debris formation on the morphology of excimer laser ablated polymers

A study of the distribution of the debris formed by the XeCl laser ablation of polyimide and polyethylene terephthalate and the KrCl laser ablation of polyimide shows that it is the redeposition of debris rather than impurities which accounts for the cone structures commonly seen in the surface morphology.

Magnetically induced pulser laser excitation

A novel excitation scheme has been developed for excimer discharge lasers. The technique uses pulse transformer technology to induce a fast, high voltage pulse directly onto a ground potential laser electrode resulting in the breakdown of the laser gas mix. Saturation of the pulse transformer core inductance then permits efficient energy transfer from the main energy storage circuit into the discharge. When this excitation technique was used in a XeCl laser an output energy density of 2.5 J/l and an overall electrical to optical efficiency of 2% were obtained. The technique appears promising for the development of high energy, high average power excimer lasers.

Spatially resolved gain measurements in UV preionized homogenous discharge XeCl and KrF lasers

Spatially uniform avalanche discharges of relatively long duration have been obtained in a UV‐preionized, high‐pressure, rare‐gas–halide laser. In the case of XeCl pulse durations as long as 70 ns have been observed. The spatial distribution of the small‐signal gain in a plane transverse to the laser axis has been measured. The active discharge cross sections with better than 90% gain uniformity were 2.8×3.0 and 2.8×2.5 cm2 for XeCl and KrF, respectively. The use of neon rather than helium as a buffer gas increased the discharge cross section, and the laser pulse duration resulting in improved laser output energy densities of 4.5 J/l in XeCl and 2.8 J/l in KrF.

Damage measurements of fused silica fibres using long optical pulse XeCl lasers

Abstract UV-preionized XeCl lasers with optical pulse durations in the range 7.5 ns to 300 ns were used to measure the front surface damage thresholds of fused silica substrates and commercially available fused silica fibres. The maximum energy that could be transmitted through the fibres increased approximately with the square root of the laser pulse duration.

A Simple Laser‐Triggered Spark Gap with Subnanosecond Risetime

The construction and operating characteristics of a pressurized laser‐triggered spark gap capable of switching voltages exceeding 10 kV with a risetime of less than 300 psec are described. Other desirable features are its low delay and jitter times (∼1 nsec), the ability to deliver rectangular pulses with less than 10% ripple during and after the pulse, and its simplicity of construction. The gap has been investigated using the output of either a single mode ruby laser or a mode‐locked neodymium‐glass laser as a trigger.

Microsecond duration optical pulses from a UV‐preionized XeCl laser

XeCl laser pulse durations of 1.5 μs (full width at half‐maximum) have been obtained using a recently developed UV‐preionized magnetically induced pulser laser excitation scheme.