Has anyone on this list used a holographic grating for spectroscopy? I
was asked to test an inexpensive thin film type holographic grating for
slitless meteor spectroscopy. Trying to measure a spectrum it appears that
dispersion is non linear. Is this a characteristic of a holographic grating
type? I would have thought linearity would be the same as with a blazed
precision transmission diffraction grating!!!!!! Any comments?

Ed Majden