OPTICAL INFORMATION RECONSTRUCTING APPARATUS, OPTICAL INFORMATION RECODING/RECONSTRUCTING APPARATUS, METHOD OF MEASURING DIFFRACTION EFFICIENCY FOR OPTICAL INFORMATION PROCESSING APPARATUS

摘要

An optical information reproducer, an optical information recording/reproducing device, and a diffraction efficiency measurement method of an optical information processing device are provided to measure diffraction efficiency by detecting/comparing lightness of a reference beam before the reference beam is incident on an optical information storage medium and/with lightness of a beam which passes through the medium, thus faster and exacter diffraction efficiency is measured. A reproducing optical system(101) guides a beam scanned from a beam source(100) to an optical information storage medium(140). The first lightness detector(130) detects lightness of the beam by being positioned on the optical system(101). The second lightness detector(150) detects lightness of a beam which passes through the medium(140). An operator(170) compares the lightness of the detected beams to operate diffraction efficiency of the beams. An optical information detector(160) detects optical information reproduced by the beam which passes through the medium(140).