| 摘要 |
PROBLEM TO BE SOLVED: To provide a small sized optical encoder with good accuracy in which a light source emits light stably. SOLUTION: A surface emitting laser 1 is installed on a photodetector 3 being arranged approximately parallel to a scale 2 and is arranged so that a light beam with a desired shape can be projected toward an optical pattern surface of the scale 2. The primary axis 100 of the light beam emitted from the surface emitting laser 1 is approximately perpendicular to the photodetector 3, and a beam spot is formed on the optical pattern surface of the scale 2. The emitting section of the light source 1 is disposed in an area other than a region where only zero order diffraction light and one order diffraction light interfere with each other or only the zero order diffraction light and minus one order diffraction light interfere with each other in a section where the zero order diffraction light exists. Furthermore, a light blocking metal 18 is disposed so as to surround the periphery of a light receiving section 4 and also disposed in a region between the surface emitting laser 1 and the inner edge of the light receiving section 4.
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