Abstract: A truncated triangular prism has an entrance and an exit face perpendicular to each other and a reflecting face inclined at an angle ? to the entrance face where ? is about 135°??B, and where ?B is the external Brewster angle for the material of the prism at the wavelength of radiation to be reflected by the prism. A beam of p-polarized radiation directed into the prism through the entrance face at the Brewster angle is totally internally reflected from the reflecting face and leaves the exit face at the Brewster angle and at an angle of ninety degrees to the direction at which the radiation enters the prism.

Abstract: An actively stabilized laser is disclosed which includes a temperature tunable etalon in the laser cavity for single frequency operation. The operation of the laser is actively monitored to detect variations induced by changes in the length of the resonator. These changes tend to cause the frequency of the selected longitudinal mode to shift so that it is no longer aligned with the peak of the transmission curve of the etalon. When this misalignment occurs, operation deteriorates. By monitoring laser performance, the misalignment can be detected and the temperature of the etalon can be changed to realign its transmission peak to the selected mode. In the preferred embodiments, either the laser output power or the current supplied to the laser is monitored. This approach substantially reduces mode hopping. An automatic initialization routine is also disclosed for selecting the starting etalon operating temperature in order to maximize the output power of the laser.

Abstract: An actively stabilized laser is disclosed which includes a temperature tunable etalon in the laser cavity for single frequency operation. The operation of the laser is actively monitored to detect variations induced by changes in the length of the resonator. These changes tend to cause the frequency of the selected longitudinal mode to shift so that it is no longer aligned with the peak of the transmission curve of the etalon. When this misalignment occurs, operation deteriorates. By monitoring laser performance, the misalignment can be detected and the temperature of the etalon can be changed to realign its transmission peak to the selected mode. In the preferred embodiments, either the laser output power or the current supplied to the laser is monitored. This approach substantially reduces mode hopping.