Abstract: An optical system may include an optical radiation source, an optical device, an optical reference device, an optical detector, and a processing module. The optical radiation source may provide an optical input signal. The optical device may provide one or more of a first band-pass output associated a first band-pass wavelength response and a first band-stop output associated with a first band-stop wavelength response. The optical reference device may provide one or more of a second band-pass output associated with a second band-pass wavelength response and a second band-stop output associated with a second band-stop wavelength response. The optical devices may be coupled together and may provide an optical output signal. The optical detector may convert the optical output signal into an electrical measurement signal. The processing module may evaluate deviations between the band-pass responses and the band-stop responses.