Active optical systems with a helium-strontium recombination amplifier

For the first time, tests have been made of an active optical system with a conjugate resonator in which the discharge tube of a recombination helium-strontium laser emitting in the blue region (430 nm) is used as an amplifier. A high-contrast enlarged image, convenient for observation was obtained. Active generation of images can be achieved not only with high-gain lasers but also with lasers of comparatively low gain (5 m^–1), with appreciable inversion lifetimes (150–200 ns).