Light intensity and colour modulating device

Abstract

Abstract 473,061. Light-valves. ROSENTHAL, A. H. March 5, 1936, No. 6634. [Class 40 (iii)] A device for varying the intensity, colour, or polarization of light comprises two finely dispersed substances in optical contact, their dispersion curves (i.e. refractive index n plotted against wavelength #) ao, #o, Fig. 1, intersecting at a wavelength #o, so that light of wavelength #o passes through the mixed medium, while light of other wavelength is scattered. An electrostatic or electromagnetic field is applied to the medium to split the dispersion curve of at least one of the substances, e.g. #o, into two dispersion curves #1, #2, corresponding to the ordinary and extraordinary beams which are plane polarized at right-angles. The wavelengths for which the medium is homogeneous are then #1, #2 and light of these wavelengths passes through the medium without scattering. The scattered light 11, Fig. 2, passing through is stopped by an aperture 8. The two wavelengths #1, #2, will vary with the magnitude of the applied field, and since they are plane polarized at right-angles, either may be extinguished by a Nicol prism so that the wavelength of the emergent light will vary with the applied field. This may be used in colour television, the applied field being derived from signals representing the colour of successive picture points. When used as an intensity modulator, light from a monochromatic source is used in conjunction with a filter passing the same wavelength, more or less light passing through in accordance with the applied field. When a magnetic field is used, it is applied in the direction of the light beam, and the two light beams of different colour are right and left-hand circularly polarized. The medium may be powdered glass in nitrobenzene, an emulsion of two liquids, a mixture of two solids ; however, at least one of the substances must exhibit the Kerr or Faraday effect. The device should be maintained at a constant temperature, which may be varied to adjust the intersection of the two dispersion curves.

Inventors

No inventors recorded.

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