Abstract: An optical waveguide device usable as an optical wave-modulator and having a reduced DC drift includes a LiNbO.sub.3 substrate, an optical waveguide formed in a front surface portion of the substrate, a dielectric layer covering the front surface of the substrate and the optical waveguide surface, and an electrode system arranged on the dielectric layer, the dielectric layer comprising a matrix component consisting of an amorphous SiO.sub.2 and a doping element component consisting of Li and/or Nb; and having a refractive index lower than that of the amorphous SiO.sub.2 matrix free from the doping element component.

Abstract: A method of obtaining a correlation between a pattern to be identified and a number of reference patterns by irradiating and displaying the pattern to be identified and the reference patterns on an optical display plane, thereby producing a complex optical amplitude distribution. This distribution is Fourier-transformed to produce a first power spectrum corresponding to the light intensity distribution of its Fourier transformation patterns. The patterns are again irradiated based upon the first power spectrum and a second Fourier transform is performed to produce a second power spectrum which is the light intensity distribution of the second Fourier transformation pattern. The area of this distribution is restricted by controlling the transmittance or the reflectance of each of the portions of the display plane.

Abstract: An optical associative identifier is disclosed which is used to determine the closest match between an image to be identified and a plurality of reference images. The identifier includes a display area for displaying the various images, the display area additionally functioning as a spatial light modulator. First and second optical Fourier transform devices are included which are used to compare the reference images to the image to be identified. The output light intensity of each of the reference images is modulated in accordance with a two-dimensional intensity distribution corresponding to the correlation between the image to be identified in each of the reference images. Based upon a comparison of these output light intensities, a match between the image to be identified and one of the reference images can be made.

Abstract: An ultraviolet ray-shielding agent for selectively shielding ultraviolet rays while allowing a transmission of visible rays therethrough, comprising a visible ray-transmitting binder and extremely fine zinc oxide particles having an average size of 0.1 .mu.m or less in a mixing ratio of the zinc oxide particles to the binder of 1/10 to 10/1, and an ultraviolet ray-shielding tube for visible ray-irradiation luminescent lamps comprising a transparent substrate tube for sealing a light emission source therein, and a coating formed on a surface of the substrate tube and comprising the above-mentioned ultraviolet ray-shielding agent.