An arrangement for the resonant frequency doubling of multimode laser
radiation with resonators is provided, including mirrors and an optically
nonlinear material. The arrangement ensures a dispersion-free tuning of
the length of a passive resonator, and enables the frequency doubling of a
multimode laser, which is resonant simultaneously for all modes of the
laser radiation, and which is achieved by pairs of mutually oppositely
disposed movable elements of an optically transparent material, such as
prisms (P1, P2). The prisms are brought into the beam path of the
resonator (R), formed from mirrors (M1 to M4) and optically nonlinear
material (BBO). The prisms are movable elements (P1, P2) which are
connected to adjusting elements such as piezoactuators, so that the
optical length of the resonator (R) can be tuned and compensation for
dispersion attained.