| 摘要 |
PURPOSE:To improve the accuracy of a size without measured errors, by adding an auxiliary circuit to a light detector, and obtaining the size of a part, where effects are small even though the beam diameter of parallel scanning light or the detecting sensitivity of the light detector is changed. CONSTITUTION:The detected voltage VP of parallel scanning light 1 by a light detector 4 is inputted to a divider 6. The detected voltage VP is obtained when the parallel scanning light 1 is converged by a condensor lens 3 and inputted to the light detector 4 under the state a material to be measured 2 is not present. The voltage VP is made to one half by the divider 6 and the result is inputted to a sample and hold circuit 7. A holding signal from a terminal 9 is added to the sample and hold circuit 7 when the light detector 4 detects the detected voltage VP. Therefore, the sample and hold circuit 7 holds the value of one half the detected voltage VP. From a comparator 8, an output is sent out in a range of a size Ls, in which the detected voltage V becomes one half the VP. By adding the auxiliary circuit, the measuring accuracy of the size of a part, in which the effects are small even though the beam diameter or the detecting sensitivity is changed, can be improved. |
