| 摘要 |
PURPOSE: To obtain an optical sensor which blocks out inessential light efficiently by providing a head part which is composed of a light-emitting element and of a photodetector, an optical means by which a radiated luminous flux is returned to the head part and a spacer member which regulates the interval between the light- emitting element and the photodetector and the optical means. CONSTITUTION: A luminous flux which is radiated from a light-emitting element 1 is transmitted and diffracted by a diffraction grating G1 so as to be divided into zero-order diffracted light and±first-order diffracted light. A zero-order luminous flux which has traveled straight in the grating G1 is reflected and diffracted by a diffraction grating G2 so as to be divided into±first-order diffracted light, and it is phase-modulated so as to be incident on a diffraction grating G3. The light which is incident on the grating G3 is divided into±first-order diffracted light and other luminous fluxes, and only a luminous flux which has been transmitted and diffracted in a direction perpendicular to the grating G3 is utilized. When the luminous flux is transmitted through the grating G3, diffracted light other than a required luminous flux perpendicular to the grating G3 is generated. A member A which holds the gratings G1, G3 is a light-transmitting member which comprises window parts w1, w3 for light-receiving, light is cut effectively, and it is possible to prevent the quality of an output signal from being degraded.
|
