Abstract: A rapidly tunable low pressure laser comprised of a one electrode pair low ressure CO.sub.2 gas laser gain cell and intra-cavity quarterwave plate and Q-switch. The cell has a fixed laser output coupled at one end of the laser cavity and at the other end of the cavity a wavelength switching device which changes laser lines in less than 1.times.10.sup.-3 .mu.sec, i.e. changes the wavelengths in less than 1 millisecond within the low pressure laser, to produce at least two quick pulses of different wavelengths at a separation of 1 millisecond. The wavelength switching device is comprised of a fast rotating mirror on the laser optical axis and a fixed grating, or a rotating grating on the optical axis.

Abstract: The optical cavity of the present laser has a folded optical path with a pair of reflective diffraction gratings and a gain cell in it. A disk with radially distributed perforations rotates in the optical path between the gratings and the gain cell. The laser wavelength depends upon which perforation is aligned with the slot in a slotted plate also in the optical path. The laser output consists of a sequence of different wavelength but colinear rays.