Method of spectrally tuning a filter

A method for tuning a dielectric filter comprises determining filter characteristics of a filter including a cut-on wavelength and a cut-off wavelength taken at a selected gain level. The filter is rotatably attached to a collimator assembly and a light source having a wavelength approximately equal to the cut-on frequency is applied to the filter and rotated to adjust the filter to the cut-on wavelength, and the spectral performance is measured and compared with a cut-on rating value. The method further includes applying a light signal having a wavelength set to a cut-off wavelength, to the filter rotating the filter relative to the collimator assembly, measuring spectral performance, and comparing the measured spectral performance with a cut-off rating value. The light source having a wavelength set to the cut-on wavelength is reapplied to the filter, and the difference in measured spectral performance with the rating values for each of the low cut-on wavelength and high cut-off wavelength are compared to determine if the difference is within an acceptable range. The steps are repeated until the difference is within an acceptable range and the filter is thus fixedly attached to the collimator assembly to complete the resultant filter.