Patent ID: 7082145

Claim:
A laser cavity for generating a pulsed laser output, comprising: a gain medium including a light transmission axis; at least one first optical element disposed on one side of the gain medium to return laser light emitted from the one side of the gain medium back through the gain medium; a polarization selective element disposed on the light transmission axis to the other side of the gain medium; at least one second optical element arranged to define a first optical path from the polarization selective element along which laser light of one polarization is in use directed; at least one third optical element arranged to define a second optical path from the polarization selective element along which laser light of other polarization is in use directed; and at least one electro-optical element disposed in one of the first and second optical paths and being operable to switch the polarity of the laser light transmitted therethrough such as to generate a pulsed laser output; wherein the at least one first optical element comprises a reflective element; wherein the polarization selective element comprises a polarizer; wherein the polarizer includes a first optical surface which includes a dielectric film coating and is in optical communication with the other side of the gain medium and the at least one third optical element, a second optical surface which is in optical communication with the at least one second optical element, and a third optical surface which is the surface through which laser output pulses are in use dumped; and wherein the second and third optical surfaces of the polarizer are arranged such that the laser light transmitted therethrough is not more than ten degrees from a direction normal to the respective optical surface.