Interference modulo and the interferometer null which for aspheric surface measurement are by the optical three-dimensional phase modulation component which uses

摘要

PURPOSE:To modulate the space phase of luminous flux passing through an optical path by arranging a liquid crystal layer in the optical path of an optical system forming a plane of a standard or test wave and controlling the space distribution of the electric field crossing the liquid crystal layer to control the space distribution of the refractive index of the liquid crystal layer. CONSTITUTION:An optical space phase modulation element 1 is composed of the liquid crystal layer 4 held between two glass plates 2, 3 and electrodes 5, 6 are respectively provided to the glass plates 2, 3 and the electrodes 6 of one glass plate 3 are composed of small electrodes and the voltages of the respective small electrodes are variable individually. A large number of the respective small electrodes 6 are densely arranged in a matrix form and electric fields can be applied thereto individually by a scanning electrode driving circuit 7 and a signal electrode driving circuit 8. The small electrodes 6 are placed in 160X120 pixels arranged in a rectangular shape and the respective electronic circuits 7, 8 are mounted so as to be capable of modulating the electric field distribution crossing the liquid crystal layer 4 according to an external video signal. The inner surfaces of the glass plates 2, 3 are treated so as to become a nematic mode twisted at a twist of 0-360 deg..