Abstract: Recording and reproduction are performed on an information recording medium at high density. Marks having front and rear edges deviated in M levels in accordance with multilevel data are recorded at predetermined mark intervals. In information reproduction, adjoining front and rear edges are read at the same time to generate read data in succession when a spot area of a reading light beam falls on mark reference positions and space reference positions. Approximate analysis such as Viterbi decoding is performed to compare the read data with predetermined expected value data. Based on the result, the deviations of the front and rear edges of each mark are determined to decode the multilevel data. Here, a row of reference marks having front and rear edges corresponding to combinations of M levels of deviation is recorded as if the foregoing marks are. The row of reference marks is read as if the foregoing marks are, so that the expected value data for the approximate analysis is obtained.

Abstract: An optical pickup device for reading information recorded on an optical disc, the device having a semiconductor laser, a half mirror and a light-receiving element. The semiconductor laser and the half mirror are attached to each other via a grating, and the light-receiving element is attached on the surface of the half mirror.

Abstract: A display apparatus having: an inputting device for inputting a first image signal generated for a first display device having a first coloring characteristic defined by a first color range shown in a chromaticity diagram; a converting device for converting the inputted first image signal into a second image signal for a second display device having a second coloring characteristic defined by a second color range shown in the chromaticity diagram, the second color range and the first color range are different from each other; a driving device for generating a driving signal on the basis of said second image signal; and the second display device for displaying an image on the basis of the driving signal.

Abstract: A light modulation apparatus includes: a light modulation device including first light transmission control elements each for controlling the amount of transmission of a light beam, for generating and applying a modulation light beam representing a modulation signal by controlling the amount of transmission of the light beam in each of the first light transmission control elements in accordance with the modulation signal; and a detection light beam generating device that always allows transmission of a part of the light beam for generating and applying a detection light beam for detecting a displacement of the irradiation position of the modulation light beam.