HIGHLY ACCURATE ANGLE DETECTING SYSTEM WITH HIGH RESOLUTION

PURPOSE:To implement high resolution and high accuracy in angle detection and to implement a compact and light weight device, by projecting light from a light source on a diffraction grating, which can be rotated, and detecting the diffraction image by CCD line sensors, which are arranged in parallel. CONSTITUTION:Light from a light source L1 is made to be parallel light rays through an optical system L2. A diffraction image from a diffraction lattice 13, which can be rotated with a rotary shaft 13a as the center, is converged on CCD line sensors 15, which are arranged in parallel through a relay lens system 14. The diffraction image is moved in correspondence with the rotation of the lattice 13, and the output signals of the sensors 15 are changed in time. Based on the changing rate and the electric phase differences among the sensors, the change in angle can be detected highly accurately with high resolution. Therefore the device can be made compact and light-weight. By appropriately setting the sampling time, desired resolution or accuracy can be selected.