Simulation of a zero-dispersion filter monochromator for image-spectroscopic measurements

I propose a novel filter monochromator for image spectroscopic measurements. An aberration-corrected double monochromator that I reported on previously [Appl. Opt. 36, 7114-7118 (1997)] is modified for use in a zero-dispersion mode. An incident image on the entrance aperture is focused onto an imaging detector attached on the exit focal plane with a spectral bandwidth determined by the width of the intermediate slit. Unlike a conventional interference filter, the spectral bandwidth and its center wavelength are determined arbitrarily while both a low stray-light level and the sharp cutoff characteristics of the wavelength are maintained. To demonstrate the real capabilities, ray-tracing simulations are carried out. I also discuss the problem of wavelength purity in the spectroscopic image.