| 摘要 |
A profile measuring instrument includes: a fixed member of which position relative to a workpiece having a surface to be profile-measured is fixed; a scanning member supported by the fixed member and movable in a scan direction along the surface of the workpiece relative to the fixed member; a laser interferometer that detects a displacement of the surface of the workpiece along the scan direction. The laser interferometer includes: a polarizing beamsplitter provided to the scanning member; a reference mirror fixed to the fixed member; a measurement optical path extending from the polarizing beamsplitter to the workpiece; and a reference optical path extending from the polarizing beamsplitter to the reference mirror. A difference between an optical path length of the measurement optical path and an optical path length of the reference optical path is a predetermined tolerable error or less. |
