Creation of an optical xyz coordinate system using bidirectional blazing from a symmetric triangular-groove grating in a conical diffraction mount

Abstract

An xyz beam splitter is described that uses a diffraction grating upon which light is incident in a plane parallel to the grating grooves to produce symmetric conical diffraction into the ±1 orders, with all higher orders being suppressed or evanescent. The ±1 orders are mutually orthogonal when the wavelength/grating period ratio λ/Λ=1/2, independent of the angle of incidence ϕ. Orthogonality of, the ±1 orders with the direction of incidence occurs at ϕ=arctan(1/2)=35.264°. By choice of a symmetric triangular-groove profile (isoceles with a 120° apex angle), bidirectional blazing occurs into the desired ±1 orders, with little or no light appearing in the vestigial 0 order.