Light modulation system Patent #: 4091281
ApplicationNo. 07/043124 filed on 04/27/1987
US Classes:359/15, Using a hologram as an optical element359/285, Acousto-optic359/573Variable grating
ExaminersPrimary: Arnold, Bruce Y.
Attorney, Agent or Firm
International ClassesG01D 5/38 (20060101)
G01D 5/26 (20060101)
G02B 26/00 (20060101)
G02B 26/06 (20060101)
G02B 27/44 (20060101)
G02B 27/42 (20060101)
AbstractAchromatic optical systems forming phase shifters and phase modulators are presented and shown to impart (temporal) phase-angle shifts in incoming waves which are independent of wavelength over extremely broad spectral ranges (achromatic or white light). Three major classes of achromatic phase shifters 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 with white light. The devices are also useful in switching between spatial sine and cosine optical transforms in optical pattern recognition systems.