Abstract
By the microinterferometers employing fringes of constant thickness, it is found that the angle of incidence to the reference mirror and the specimen is normal or very nearly so. Therefore, the difference of height corresponding to the fringe spacing obtained is λ/2. (λ is the wave length of the monochromatic light employed.)
In this method, the fringes are obtained by employing the oblique incidence to the reference mirror and the specimen, and are observed by a microscope in the light of the regular reflection. The fringe spacing is accepted as equivalent to λ/2 cos θ by the simple computation which is confirmed by experiment (θ is the angle of the incidence or the reflection. 0°<θ<90°)
Since the fringe spacing is 1/cosθ times as large as λ/2, the measurement of the surfaces rougher than those which can be measured by normal incidence type is possible.
