| 摘要 |
PURPOSE:To facilitate the adjustment of both light path lengths of a reference wave front and a matter wave front when a wave front state to be inspected is observed and to enable the stable measurement of an interference fringe, by using a converting means such as a corner or a cube in a part of an interference system. CONSTITUTION:The plane wave from the wave front to be inspected of a CD head 4 is divided into two waves by a beam splitter 27 and the reflected plane wave is not only converted by 180 deg. in the advance direction thereof by a corner cube 18 but also shifted laterally and, thereafter, the diameter of luminous flux is magnified by a magnifier 20 and the aberration of the front wave of the superposed part with the other plane wave of two-split plane waves is improved to form a reference wave front 30. The plane wave transmitted through a splitter 17 is extincted so as to be made same to the wave front 30 in luminous intensity by a density filter 21 and converted by 180 deg. in the advance direction by a corner cube 19 and shifted laterally. Optical wedges 22, 23 are properly rotated around the optical axes to incline a passing plane wave to form a matter wave front 31 having a predetermined relative angle so as to form an interference fringe through the superposition with the wave front 30. The wave fronts 30, 31 are superposed by the splitter 17 to be guided to observation system 24, 25 and a wave front state is measured by measuring the interference fringe.
|
