Stray Light From Diffraction Gratings

摘要: Stray Light From Diffraction GratingsGeorge I. GeikasBall Aerospace Systems DivisionP.O. Box 1062, Boulder, Colorado 80306AbstractVarious types and sources of grating stray light are described. A format for straylight measurements is presented so that made by differentinvestigators can be directly compared. Finally an investigation to determinean order magnitude Bidirectional Reflectance Distribution Function input into thestray programs APART GUERAP the narrow field interference (holograph -ically recorded) gratings.IntroductionGrating spectrometers have been in existence since astronomer David Rittenhouse (1786)experimented with parallel hairs held fine watch screws. Since time spectra havebeen observed finer detail. Today many cases resolution spectrais limited more focal plane than theoretical theinstrument.The three practical aspects a grating's performance are:Spectral PurityResolving PowerEfficiencyAll above influenced some degree light. As result thetypes need identified minimized achieve satisfactoryinstrument.Stray perfect gratingStray arising spectrometer not arise from imperfec-tions grating. Many workers overlapping spectral orders whenthe free range instrument exceeded. "perfect"grating as follows:Overlapping orders.Diffraction secondary maxima uniformly illuminated grating.Edge scatter overfilled grating.Spectral broadening underfilled grating.Aberrations optics, exclusive grating.Double diffraction grating.Surface scattering optics.Surface grating.Wood anomalies.In above, except surface scattering, careful engineering minimize