| 摘要 |
PURPOSE:To simplify the measuring method and to enhance accuracy, by detecting the amount of reflected light from the end surface of a matter to be measured, making the diameter of the light spot on the end surface of the matter to be measured variable, and computing the diameter of a minute hole. CONSTITUTION:A laser beam 10 from a semiconductor laser 1 is projected on a matter to be measured 20 on a finely moving stage 9 through light polarizing beam splitter 3, a 1/4 wave length plate 4, a condenser lens 5, and the like. The reflected light is supplied to a light receiving device 7 through the splitter 3, a condenser lens 6, and the like. The diameter of the light spot on the end surface of the matter to be measured 20 is made variable. The relationship between the amount of reflected light and the amount of movement of the stage 9 is obtained from two circular cylinders, whose outer diameters are known, beforehand. The expression of relation between the amount of movemet of the stage 9 and the size of the outer diamter is obtained. Then the matter to be meausred 20 is measured, and conversion to the size of the diameter of the hole is performed. |
