| 摘要 |
PURPOSE:To minimize obscuration of a spot light image at the photoelectric sensor and increase accuracy by a device wherein the photoelectric sensor is arranged such that an angle made by the photoelectric sensor of light receiving means crossing the light receiving optical axis substantially equals to an angle made by the light projecting optical axis of light projecting means crossing the light receiving optical axis. CONSTITUTION:Light projecting means to project a spot light and light receiving means to detect a spot light image projected on the measured objective from the light projecting means are provided. A photoelectric sensor 5' is arranged such that an angle theta made by a light projecting optical axis 7 crossing a light receiving optical axis 8 becomes substantially equal to an angle theta made by the photoelectric sensor 5' crossing the light receiving axis 8. With this arrangement, the spot light image is focused substantially on the photoelectric sensor 5' as an image A'', B'' with no obscuration. Thus, when using a PSD or CCD element as the photoelectric sensor, sensitivity and accuracy of positional detection can be improved drastically. |
