ADJUSTING TYPE RANGE FINDER AND DISTANCE MEASURING METHOD THEREOF

PROBLEM TO BE SOLVED: To provide an adjusting type range finder and a distance measuring method thereof.SOLUTION: The adjusting type range finder and a method thereof causes a first light beam having an object video to pass through an optical deflection element and generates a second light beam having an object video. The optical deflection element includes a liquid crystal layer and a transparent type Blaze diffraction grating, and the liquid crystal layer is electrically connected to a voltage device. A first voltage is provided to the liquid crystal layer by the voltage device. The second light beam is projected to an optical image formation apparatus to form an M-th order diffracted video in which energy is concentrated. The voltage device is adjusted and the second voltage is provided to the liquid crystal layer. The second light beam is caused to form an N-th order diffracted video in the optical image formation apparatus. The M-th order diffracted video and the N-th order diffracted video forms a set of video series. An actual distance of the object from the optical deflection element is calculated, based on deviation amount of an image formation position of an object, in the set of video series.