| 摘要 |
PURPOSE:To attain to enhance the measuring accuracy of refractive index and to make it possible to perform measurement without using a movable part, by illuminating a lens to be inspected by a spot-like state while using a plurality of divided elements as a position detecting element. CONSTITUTION:Each image of light sources 11A-11C is formed to the position of a lens 15 to be inspected in a spot like state by providing lens 12 and, when there is no lens 15 to be inspected in a light path, the luminous flux passed through an iris 13 is subjected to the quantitative division of light on divided elements 17A-17D as shown by a stopped-down image 13'. When the lens 15 to be inspected is present in the light path, the distribution of light quantity to the divided elements becomes unequal as shown by the stopped-down image 13''. From the shift direction and the shift amount thereof, the displacement of the center position of the received luminous flux due to the lens 15 to be inspected is detected and the displacement thereof is large as the refractive index of the lens 15 to be inspected becomes higher. By this method, the refractive index is automatically measured with high accuracy by using electric output from a plurality of the divided elements. |
