Calibration for Spectroscopic Analysis

A spatial light modulating mask for an optical analysis system, the optical analysis system having a dispersive optical element for spatially separating spectral components of an optical signal in a first direction, the spatial light modulating mask comprising:

• an intensity modulating pattern for modulating at least one spectral component of the optical signal,
• at least a first calibration segment at a first position, the first position being fixed with respect to the intensity modulating pattern, the at least first calibration segment being at least partially transparent for a reference optical signal.

An optical analysis system for determining a principal component of an optical signal, wherein the system comprises:

• a calibration segment at a first position;
• a detector for detecting at least a portion of a reference optical signal transmitted through the calibration segment;
• means for modifying the analyzing the detected portion of the reference optical signal in order to make one or more adjustments to one or more spatial light manipulation means.