Abstract: An optical phase standard includes a coupler dividing an applied optical signal between a measurement interferometer and a frequency reference branch. Resulting signals at the outputs of the measurement interferometer and the frequency reference branch are sampled. The samples acquired at the output of the frequency reference branch are mapped to optical frequencies that are traceable to a frequency standard provided by an absorption cell. This mapping determines the optical frequencies at which the samples acquired are at the output of the measurement interferometer. From the acquired samples at the output of the measurement interferometer, phase characteristics of a device under test (DUT) are extracted. Aspects of the optical phase standard are alternatively implemented according to an optical phase standardization method.

Abstract: An optical phase standard includes a coupler dividing an applied optical signal between a measurement interferometer and a frequency reference branch. Resulting signals at the outputs of the measurement interferometer and the frequency reference branch are sampled. The samples acquired at the output of the frequency reference branch are mapped to optical frequencies that are traceable to a frequency standard provided by an absorption cell. This mapping determines the optical frequencies at which the samples acquired are at the output of the measurement interferometer. From the acquired samples at the output of the measurement interferometer, phase characteristics of a device under test (DUT) are extracted. Aspects of the optical phase standard are alternatively implemented according to an optical phase standardization method.

Abstract: An optical frequency discriminator includes an interferometer cascaded with an absorption cell that provide a composite signal. A receiver samples a composite signal and maps to the sample positions of the acquired samples, corresponding optical frequencies of an applied optical signal.

Abstract: A thermal regulator stabilizes the temperature within an internal cavity of an instrument. The thermal regulator includes a circulator that draws ambient medium surrounding the instrument and recirculated medium within the internal cavity, into a duct. The circulator forms a mixture of the drawn ambient medium and recirculated medium. An adjustable heater intercepts the mixture and controls the temperature of the mixture to be within a temperature range that is less than a temperature range of the ambient medium in which the instrument is surrounded.

Abstract: Measurement and correction of encoder errors in a servo loop. By driving the servo system on a predetermined trajectory such that encoder errors occur at frequencies outside the servo loop response, these errors are sampled. Sampled encoder error data is filtered to produce correction data, which may be applied inside or outside the servo loop.