Positive Light Inc.

Positive Light Inc. designed the Indigo-DUV all-solid-state 193-nm laser source to fill the need for an optical metrology tool for at-wavelength characterization of deep-UV optics and detectors. The device enables precision optical metrology and calibration of 193-nm lithography stepper lenses and deep-UV spectrometers.

The Los Gatos, Calif., company's design includes a Ti:sapphire oscil-lator pumped by the Evolution laser, a diode-pumped solid-state Nd:YLF laser as well as a fourth-harmonic frequency-conversion package.

The Evolution laser offers power stability with less than 1 percent rms fluctuation, resulting in power stability of less than 3 percent rms from the Indigo-DUV at 193 nm, and in diode lifetimes of more than 10,000 hours.

The Ti:sapphire oscillator is injection-seeded by a tunable narrow-linewidth external-cavity diode laser, allowing near-transform-limited linewidths for 40-ns, 772-nm output. An analog, kilohertz closed-loop control circuit provides the frequency stability, and a high-precision wavelength option controls the long-term frequency drift to subpicometer performance. Indigo-DUV produces The laser's near-transform-limited linewidth operation results in a coherence length of >3 m, enabling the precision interferometry of lens assemblies with greater than 1 m in optical path length.

Complete with a close-loop chiller, Indigo-DUV operates on 110/220 VAC and requires only a low-flow nitrogen purge.