Abstract: To produce blue light by means of a laser, pumped light is coupled into a birefringent, nonlinear crystal (5) in a variable frequency laser (1) from a laser diode pumped light source (7, 8, 9) via an input mirror (3). Due to adjustment of the inclination of the crystal (5) or with the aid of tempering means (6) for the crystal, most of the pumped light is absorbed in the crystal (5)--upon suitable polarization of the pumped light--while the rest is available for a frequency mixture of the fundamental Wave of the laser and of the pumped light. Via an output mirror (4) blue laser light with a Wavelength of e.g. 459 nm is coupled out, with a fundamental wave of e.g. 1064 nm and pumped light with a wavelength of e.g. 806 nm.

Abstract: A frequency-doubled laser contains laser diodes as a pumped light source and a resonator (R) comprising in the stated order a first mirror (5), a laser medium (6), a Brewster plate (7) as a polarizer, a nonlinear crystal (8) for frequency doubling and a plane mirror (9) as an output mirror. The plane mirror ensures that shifts of rays taking place within the nonlinear crystal remain in the radiation area even when returning through the crystal, in contrast to the prior art which uses a concave mirror as an output mirror that causes shifted rays from the nonlinear crystal to be deflected out of the beam path. The inventive measure achieves a laser light that has high efficiency and is virtually free from intensity fluctuations.