| 摘要 |
PURPOSE:To easily measure the parallelism of a parallel surface with high precision and to scan and measure undulations of the parallel surface by arranging a reflecting mirror at right angles to the optical axis of a laser light source and detecting deviation in the incidence position of reflected light which is transmitted through a sample. CONSTITUTION:When a light beam is incident on a nearly parallel surface 17 with a fine angle theta at an angle theta1, the angle epsilon between the incident light beam and projection light beam is fixed even when the surface 17 is rotated by a fine angle. The sample 20 which transmits light and has a nearly parallel surface with a fine angle theta is inserted into the optical path between the laser light source 18 and reflecting mirror 19. The light beam transmitted through the sample 20 changes in traveling direction by the angle epsilon and is reflected at a point A on the mirror 19 and then transmitted through the sample 20 again to travel at an angle 2epsilon to the projection light and reaches a point B. The extent (d) of deviation is obtained from d= 2(l1+l2)(n-1)theta, where l1 and l are distances between the sample 20, and light source 18 and mirror 19 and (n) is the refractive index of the sample 20. For the purpose, a beam splitter 21 and a qarter-wavelength plate 22 re provided on the optical path, and the reflected light is made incident on a beam position detecting element 23 to read the output signal of the extent (d) of deviation, so that a measurement is easily taken only by placing the sample on the optical path. |
