Visual method of measuring reflection-type characteristics of holographic optical elements

A highly diverging laser beam is used to measure angular and spectral selec tivities and grating vector direction for reflection-type holographic optic al elements (HOE's). The intensity distribution of the beam transmitted fro m the HOE's reveals dark, ring-shaped patterns. Since these ring patterns a re formed as a result of the beam diffracted by the HOE's, the thicknesses and the diameters of the ring patterns convey information on both the angul ar and the spectral selectivities of the HOE's. In addition the deviation o f the ring centers relative to the center of the intensity distribution rev eals the grating vector direction. Determination of values related to the r ing patterns permits highly accurate measurement of HOE characteristics, su ch as the upper limit of the diffraction wavelength, the angular and the sp ectral selectivities, and the grating vector direction. This is proved expe rimentally. (C) 1998 Optical Society of America.