Variable transmission output coupler and tuner for ring laser systems

Operation and characteristics of a novel variable transmission output coupler for ring laser systems are reported. It also provides tuning of the laser wavelength with negligible deviation of the output beam. The transmission coefficient can be changed continuously from 0 to greater than about 80 percent. The tuning capability is from the ultraviolet to the near infrared, and depends only on the material of the prisms. No optical coatings are used, and all beams enter and exit the coupler at Brewster angle with minimal loss.