US Patent 7230761 High-dispersion grisms

A grism based upon a grating with a given line frequency is configured such that a design wavelength will undergo either a specific total bend angle, a zero-degree total bend without lateral displacement, or a zero-degree total bend with a lateral displacement. Each configuration exhibits the same dispersion characteristics. Other design wavelengths, bend angles and displacements are possible through appropriate adjustment of grating frequency, prism geometry, and/or material(s). A specific design is disclosed using light with a +/−delta wavelength around a design wavelength of 795 nm. The invention may be used to disperse light at different wavelengths, including wavelengths associated with optical communications bands.