| 摘要 |
PROBLEM TO BE SOLVED: To make an optical system simple, low-cost and compact, by forming a mirror member of a photodiode, mounting the mirror member onto a substrate, constituting a deflection face of the mirror member to be a mirror face passing a part of a light projected from a light-emitting element, and detecting the light passing the mirror face by the photodiode. SOLUTION: A mirror member 3 of a trapezoidal section is fixed onto a semiconductor substrate 1. The mirror member 3 has an inclined side face 3a of an acute angle to a front face of the substrate 1, and an upper flat face. The mirror face 3a is faced to the side where a light is projected from a light- emitting element 2. The mirror member 3 is constituted of a semiconductor material such as silicon or the like. A PIN-junction photodiode is formed at the semiconductor material to take outside a power monitor signal. A metallic film that can reflect, e.g. 90% or more of the light projected from the light- emitting element 2 is formed at the mirror face 3a of the mirror member 3 by vapor deposition, etc. |
