Abstract: The present invention reads out track addresses written onto ID sections of a recording medium, for example, from five, tracks of the plurality of tracks read out simultaneously, to execute demodulation and error correction. In case where the addresses are multiple-written onto the ID sections, the optical spot judges the track address of the desired track on the basis of the plurality of read-out track addresses until the optical spot passes through the remaining track address. Further, in case where there is only a single one of the track addresses written on said ID sections, the track addresses are read out one by one, are demodulated and are error-corrected. The track address of the desired track is judged on the basis of the plurality of read-out track addresses, prior to the fact that the optical spot enters an information recording area.

Abstract: An electronic endoscope having a light emitting unit for emitting illuminating light from the tip of the insertable part, a solid state imaging device at the tip for receiving an illuminated light image, a sample-holding circuit for sample-holding an output signal from the solid state imaging device, a light source for such light emitting unit and an iris device in such light source, the iris device comprising a diaphragm device for preventing the spectral characteristics of the endoscope from being changed due to the amount of light reduction which consists of a diaphragm assembly consisting of two dimensionally diaphragm units which consists of light passing openings with small sectional area and light shading parts formed by tubular surfaces surrounding the side surfaces of the openings, positioned in the beam emitted from illuminating lamp, and provided with means for turning diaphragm assembly from a position where the tubular surfaces are in parallel with the axis of the illumination beam to a position

Abstract: The optical recording and reproducing apparatus comprises a magnetic field applying section, a movable mechanism for moving the magnetic field applying section, a distance detecting section for detecting a distance between magnetic poles of the magnetic field applying section and the surface of a recording medium, and a distance control section for maintaining the above distance constant in response to an output of the distance detecting section. The distance between two magnetic pole ends of the magnetic field applying section can be minimized. Further, on the basis of the tracking control of either one of the recording and erasing light beams, it is possible to enable a high-precision tracking control to the other of the two light beams.