Abstract: A calibration method and apparatus is disclosed that includes a power stabilized laser diode to generate a laser beam that is passed through the hologon scanner to be calibrated and a mechanism for measuring the power intensity of the laser beam at a plurality of positions at an exposure plane for each facet of the hologon scanner. The measured light levels are converted to correction factors that are stored in a corresponding programmable read only memory (PROM) as a function of facet number and scan position. The hologon scanner and its corresponding programmable PROM are then installed in a laser scanning apparatus. The laser scanning apparatus adjusts the output of its light source in accordance with the correction factors stored in the PROM in order to compensate for variations in the light transmission efficiency of the facets of the hologon scanner.

Abstract: A head-up display for a vehicle, including a primary image reflection hologram supported by a transparent substrate located in the vehicle operator's field of view for the ambient scene in front of the vehicle, a light source for providing playback illumination to the primary image hologram, and a guard hologram in front of the primary image hologram for substantially reflecting ambient illumination that otherwise could spuriously turn on the first reflection hologram, the guard hologram having an angular bandwidth and a spectral bandwidth that are greater than the angular bandwidth and the spectral bandwidth of the primary image hologram, and having an optical density of 2.0 or greater. The guard hologram can be parallel fringe reflection hologram or a slant fringe reflection hologram.

Abstract: In spectacles, the lens is to be mounted on the frame in an especially simple manner and for this purpose hooks are arranged at the lower sections of the frame and additional hooks are provided on the lens below the upper cross piece which are arranged on opposite sides of the rod connecting cross piece and nose piece. The sections of the upper cross piece extending on either side of the rod being elastically deformable to the point of the release of the additional hooks provided on the lens. Protrusions arranged on the lens abut against opposite sides of the rod.

Abstract: An optical sensor comprising a light detector, a converging lens located between the light detector and a light source, the light rays from which are detected by the light detector, and a light shielding means provided on a part of the converging lens, the shielding means shielding light rays emitted from the light source, thereby reducing dependence of the amount of light rays to be detected upon angles of incidence with which the light rays enter into the converging lens of the optical sensor.