Abstract: A high output level is maintained in power supplies having multiple cells in each leg. Failed cells in any leg are bypassed to provide a current path through the respective leg. All of the unfailed cells are utilized while maintaining equal magnitude between phases and a balance phase relationship in the line-to-line output voltage. The invention may be utilized in conjunction with a peak voltage reduction circuit, and a by-pass switch.

Abstract: A stable single-frequency laser interferometer comprises a Michelson interferometer having a power stabilized single-frequency laser and a dual light sensor comprising two closely spaced very small sensor surfaces mounted in substantially the same plane. Devices rotate the plane of the dual light sensor and/or elements of the interferometer to adjust the effective convergent angle of the recombining beams to have a sufficiently large effective convergent angle to promote stability and so that the output signals of the two sensors are in phase quadrature.

Abstract: A single frequency adapter for a gas laser comprises a jacket for engaging and being secured to the casing surrounding the gas laser. An induction coil is fixed within the jacket and positioned to surround the hollow mirror mount at one end of the laser tube while being outwardly spaced from the hollow mount. A power supply and modulator apply an alternating current to the induction coil.