Method and system for stabilizing and demodulating an interferometer at quadrature
US6597458B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 2, 2001 |
| Grant date | Jul 22, 2003 |
| Priority date | — |
| Expiry date | Jul 28, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B9/02067
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and system for stabilizing and demodulating an interferometer at quadrature are described. In response to receipt of a signal indicative of optical power of the interferometer, an interferometer control system determines an optical path length correction required to stabilize the interferometer at quadrature utilizing signal amplitudes appearing at multiple harmonics of the signal. In a particularly preferred embodiment, the signal amplitudes are calculated utilizing the Goertzel algorithm, a computationally efficient discrete Fourier transform. The interferometer control system then outputs an error signal indicative of the optical path length correction. In a preferred embodiment, the error signal forms the DC component of a composite stabilization signal, whose AC component is the reference modulation signal utilized to excite a transducer to modulate the optical path length of the interferometer. With the interferometer stabilized at quadrature, the interferometer control system determines a first signal amplitude of a particular harmonic without target oscillation and a second signal amplitude of the same harmonic with target oscillation. Based upon the relative magni…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.