| 摘要 |
PURPOSE:To elevate the measuring accuracy by measuring phase difference between two wave surfaces at points in the interference region by a fringe scanning method each time the reference wave surface is shifted to specify the origin of the offset amount accurately. CONSTITUTION:A laser light from a laser light source 1 proceeds to a beam splitter 2 through a collimator lens L1 and the reflected component is incident into an object O to be measured through a converter lens L2. The light reflected from the object O is focused on flat mirrors M1 and M2 through a condenser L3. The light reflected on the flat mirrors M1 and M2 is incident onto a light receiving surface of an area sensor 5 through an image formation lens L4. Here, the reference wave surface is repeated several times at a specified very small interval with respect to the wave surfaces being measured. Each time the reference wave is shifted, the phase difference between the two wave surfaces at points in the interference region is measured by a fringe scanning method to specify the origin of the offset amount. |
