Patent ID: 7505137
Filing Date: 2009-03-17
Classification: G01J

Abstract:
1. An optical wavelength meter for measuring an optical wavelength of an optical beam comprising: a) coarse optical filter means and first optical power measurement means for measuring output of the coarse optical filter means and second optical power measurement means for measuring an unfiltered reference beam for coarse wavelength measurement; b) fine optical filter means comprising first and second periodic optical filters in quadrature having a finesse of substantially 2 and free spectral range of substantially 100 GHz, such that peaks and troughs of the first filter coincide with substantially linear ranges between peaks and troughs of the second filter, and third and fourth optical power measurement means for measuring output of the first and second periodic optical filters in quadrature for fine wavelength measurement, respectively; c) beam splitting means for splitting the optical beam between the unfiltered reference beam and the coarse and fine optical filter means; d) synchronized clock signal measurement means for synchronized measurement of the output of the first, second, third and fourth optical power measurement means; e) processing means for determining the optical wavelength of the optical beam from a predetermined transmissivity-wavelength relationship of the coarse filter and the first and second optical power measurement means for coarse wavelength measurement and from predetermined transmissivity-wavelength relationships of the first and second periodic optical filters and at least one of the third and fourth optical power measurement means for fine wavelength measurement; and f) calibration filter means comprising an etalon filter and calibration filter output power measuring means; wherein free spectral range of the etalon filter differs just sufficiently from the free spectral range of the periodic optical filters that the etalon filter is in phase only at top, middle and bottom wavelengths of a range of measurements of interest to obtain co-incident or Vernier-like maximum power at those wavelengths.