High-Pulse-Rate Sources for Active Imaging Systems

75787S In support of systems to detect the proliferation of nuclear weapons, Los Alamos National Laboratory (LANL) has developed a photon-counting, Remote Ultra-Low Light Imaging sensor that has many advantages over conventional range-imaging devices. However, the photon-counting design requires a laser with unique characteristics: namely, a pulse rate in the 1 kHz-1 MHz range with a pulsewidth less than 1 ns. This project will develop compact seed lasers, to generate the needed pulse format, along with a compact power amplifier capable of power levels of 10 W or higher. The seed lasers will use 1064-nm, short-cavity, diode-pumped solid state lasers with either passive or active Q-switches. The amplifier will be an adaptation of a commercial product, configured for this particular application. Phase I designed the passively Q-switched seed laser; designed, constructed, and tested a short-cavity, actively Q-switched laser; tested an amplifier stage; and conducted an initial design of the packaging for the entire laser source. Both spreadsheet and rate-equation models for the passively and actively Q-switched lasers were developed and verified against experimental data. In Phase II, the semiconductor-based, passive Q-switches, will be fabricated; a breadboard facilty to test the lasers and the power amplifier will be built; system output will be converted into a green wavelength; and the entire system will be packaged into a ruggedized, modular configuration. At the end of Phase II, the system will be delivered to LANL for testing and system integration. Commercial Applications and Other Benefits as described by the awardee: Beyond the application to non-proliferation sensors, the Remote Ultra-Low Light Imaging sensor should be applicable to: NASA, for precision landing sensors; the DoD for intelligence on and tactical imaging of areas of interest; and various environmental agencies in need of accurate imaging data for, say, crop and vegetation analysis. The high-pulse rate laser source also should find use in Geiger-mode detectors, micromachining, and laser display systems.