| 摘要 |
PROBLEM TO BE SOLVED: To allow detection of an information signal from a a part irradiated, contained in a scattering light or a refraction light by selecting an arranging position of a photodetector to a region outside the cofocal region of an optical system and being able to obtain a scattering light or a diffraction light from the part irradiated by laser light irradiation of a surface light-emitting laser to the part to be irradiated. SOLUTION: A constitution and a positional relation are so set up that a light-emitting element 2 consisting of a surface laser LD of a semiconductor laser of a vertical resonator type and an objective 3 are arranged on a semiconductor substrate 1 and a surface light-emitting laser LD and a part irradiated, that is a surface of a bar code B as a photorecording medium may be in the position of a cofocal point by the objective 3 respectively. Further, a photodetector 4 consisting of a photodiode or the like is arranged and formed on the cofocal position surface S of the semiconductor substrate 1 and outside the cofocal region. That is that the surface light-emitting laser and the photodetector are monolithically on a common semiconductor substrate with a prescribed positional relation. |
