Abstract: An optical chamber for use in a laser or other optical device includes a hollow container with holes at opposite ends. A fixed mirror is sealed to the housing and overlies one hole, whereas a movable mirror is sealed to the housing by a flexible seal such as an O-ring interposed between the mirror and the housing. A variable force actuator such as a piezoelectric element biases the movable mirror against the seal. By varying the force applied by the actuator, the movable mirror can be moved towards and away from the fixed mirror to vary the path length through the chamber. The chamber can provide a low cost tunable gas laser.

Abstract: In an optogalvanic spectroscopy system, a plasma is exposed to light at a wavelength associated with a particular species in the analyte. The light is amplitude modulated. The amplitude of a modulated component in the signal representing electrical impedance of the plasma is detected in a phase independent manner, so that the detected amplitude is substantially independent of the phase of the modulated component in the impedance signal relative to the amplitude modulation of the light. The system has reduced sensitivity to changes in the spectrum of the applied light.