In one embodiment the disclosure relates to a method and a system for determining the corrected wavelength of a photon scattered by a sample. The method includes the steps of determining a wavelength of a photon scattered from a sample exposed to illuminating photons and passed through a tunable filter and correcting the determined wavelength of the photon as a function of the temperature of the tunable filter and as a function of the bandpass set point of the tunable filter. The step of correcting the determined wavelength can further include determining an offset and adding the offset to the determined wavelength of the photon.