Abstract

Achromatic optical systems forming phase shifters and phase modulators are presented and shown to impart phase angle shifts in incoming waves which are independent of wavelength over extremely broad spectral ranges. Three major classes of achromatic phase shifter are described including the triangle, close cascade, and imaged grating configurations. When constructed utilizing volume holographic optical elements, very high diffraction efficiencies may be achieved over the large bandwidths used. These systems may similarly be utilized to impart achromatic frequency shifts and frequency modulations which are wavelength independent over extreme spectral ranges and usually do not disturb the spatial form of the input waves. These devices may be used in ac interferometers and allow such interferometers to be operated in white light. Achromatic phase shifts of 0, +ϕ, −ϕ, +2ϕ, −2ϕ,…, may be simultaneously obtained.

© 1987 Optical Society of America