| 摘要 |
PROBLEM TO BE SOLVED: To accurately and easily detect the focusing position of coherent light by providing a light quantity characteristic output means which outputs variation characteristics of a detected light quantity when a body is displaced relatively to an optical system as characteristics including at least a maximum or minimum value. SOLUTION: Laser light 2 as coherent light from a laser light source 1 is passed through a half-mirror 3, and converged by an objective 4 to t irradiate the surface of a sample 5. A sensor 6 detects the quantity of part of the laser light transmitted through the halfmirror 3. The signal from the sensor 6 is inputted to an arithmetic processor 13, which calculates variation characteristics of the detected light quantity. Its arithmetic output C is outputted from an output device 14 such as a display. When the height of the sample 5 is adjusted to the position (height) where the quantity of the laser light that the sensor 6 receives varies to the largest value, the laser light can accurately be converged on the surface of the sample 5. Namely, the laser light is in focus. |
