Abstract: An optical information reading apparatus has an optical system which includes a concave mirror. The concave mirror has first and second concave portions and a planar portion. Reflection optical axes of the first and second concave portions are set offset relative to a reflection optical axis of the planar portion. This makes it possible to arrange a light source and a light-receiving sensor with a given proper interval therebetween in a longitudinal direction of the apparatus so that a thickness of the apparatus can be reduced. The first concave portion may form a portion of a first ellipsoidal surface of revolution and the second concave portion may form a portion of a second ellipsoidal surface of revolution. The first and second ellipsoidal surfaces share a rotation axis and focal points located at conjugate points on the rotation axis.

Abstract: An optical information reading apparatus comprises: a semiconductor laser (30); an optical scanning mechanism (50) for scanning bar code (90) using a laser beam emitted from the semiconductor laser (30); a photodetector (70) receiving a returning laser beam reflected at the bar code (90); information reading device (130, 140) for reading out information from the bar code on the basis of the returning laser beam received by the photodetector (70); sweep angle regulating mechanism (150, 180) for restricting a sweep angle of the laser beam used in a scanning operation of the optical scanning device (50) within a predetermined angle so as to scan only one bar code; an operational current detecting circuit (120) for detecting an operational current value of the semiconductor laser (30); and a deterioration judging device for making a judgement as to whether the semiconductor laser (30) is deteriorated or not on the basis of the operational current detected by the operational current value detecting circuit (120).

Abstract: An optical information reading method and device which prevents the generation of erroneous reading by specifying a reliable reading range for a bar code or like information. A microcomputer calculates the distance between the position of reflection of laser light from the bar code and a position at which the same laser light enters the scanning unit based on a time difference between the emission of the laser light and the reception of the reflected laser light. The microcomputer determines, through the calculation process, that the bar code is present within the suitable reading range only when the calculated distance is determined to be within the set reading range, and permits the scanning of the bar code.

Abstract: An optical information reading apparatus for optically reading information recorded on a recording medium with a laser light beam emitted from a light source. The apparatus comprises a hologram device for receiving at its center portion a laser light beam. The hologram diffracts the received light so as to produce a first diffracted light beam and is arranged to receive at its entire surface light to be reflected from the recording medium and to diffract the received light so as to produce a second diffracted light beam. This hologram device is arranged to be driven by a motor so as to move the first diffracted light beam for a scanning operation. Also included in the reading apparatus is a reflection assembly for reflecting the first diffracted light beam from the hologram device toward the recording medium and further for reflecting light reflected from the recording medium toward substantially the entire surface of the hologram device whereby the hologram device produces the second diffracted light beam.