Features

• An interferometer is used to measure the radius of curvature of a small concave surface.
• There are two places where interference fringes can be observed reflecting on concave surfaces. The focal point of an achromatic lens is concave, and the center of curvature of the concave surface is at the focal point. By reading the distance between the two positions where the interference fringes of the concave sample can be observed with the micrometer of the stage on which the sample is placed, a precise radius of curvature can be obtained.