| 摘要 |
PURPOSE:To measure wave front aberration with high precision by employing such a coherent light source that a supply current and projection light vary in specific relation, and controlling the current and modulating the phase of coherent light. CONSTITUTION:Light projected from a semiconductor laser as the coherent light source 1 is split into two by a beam splitter 3, and one beam is passed through an optical path 11 to be detected to illuminate a body 5 to be measured. Light reflected by this body 5 to be measured and the other split light beam as reference light are guided to an interference pattern generating optical path 13 and interference fringes produced by the two pieces of luminous flux are obtained as two-dimensional information by a photodetecting element 9. In general, the semiconductor laser has a region where the wavelength lambda0 varies linearly with the current I, so that current supplied to the semiconductor laser is controlled in this region to cause variation in optical laser wavelength, modulating phase of interference light. Then, phases of respective addresses of the element 9 where the interference fringes are projected and image-formed are detected. This constitution, therefore, eliminates the need to provided a phase-modulating means on the optical path and facilitates the phase modulation, thereby measuring the wave front aberration with high presision. |
