A feedback-control circuit for color calibration of a diffraction light device includes at least one diffractive light device (DLD) having a gap distance defined by opposing plates, at least one sensor configured to convert light modulated by the DLD device into a light signal indicative of the gap, a controller configured to calculate a voltage correction value based on a difference between the gap as indicated by the light signal and a designer-specified gap value and being further configured to apply a corrected voltage corresponding to the voltage correction value to the DLD device.