Patent ID: 8759744

Claim:
A method of operating a spectrometer to determine the wavelength of an optical signal, for determining the resonant wavelength of an optical fibre Bragg grating, wherein the spectrometer comprises an array of photosensitive pixels each of which generates an output signal in response to the intensity of light incident on the pixel, the output signal being communicated to a switch matrix, and the output of the switch matrix being received by an integrator to determine the strength of the pixel output signal; and a refractive element arranged to direct light to a particular position in the array depending on the wavelength of the light, the method comprising: selecting a first group of pixels in the array by reference to a wavelength distribution of the optical signal, monitoring the output signals from the first group of pixels; on the basis of the output signals from the first group of pixels, selecting a second group of pixels; and determining the wavelength of the optical signal from the output signals of the second group of pixels.