| 摘要 |
PURPOSE:To measure the fine displacement of the surface of a body to be measured at plural measurement positions at the same time by passing laser luminous flux through a unidirectional optical element and an objective, reflecting it by a body to be measured, and guiding the luminous flux to a divided photodetector through an optical means for defocusing detection. CONSTITUTION:The luminous flux emitted by a laser light source 10 is passed through the unidirectional optical element 11 and objective 12 and then converged on the surface of the body 13 to be measured. Return light which is reflected by the body 13 to be measured is passed through the optical means 14 for defocusing detection and then reaches the divided photodetector 16. Here, when the return light which is reflected at a point A is considered as to image formation 17 on the body 13 to be measured, the return light from the point A reaches a photodetection part 16A'. The fine displacement or surface roughness at the point A of the body 13 to be measured can be measured from the output signal of the detection part 16A through the operation of the optical means 14 for defocusing detection. Similarly, the surface shapes at points B, C - are measured by detection parts 16B', 16C' - corresponding to other points B, C - of the body 13 to be measured. |
