| 摘要 |
PURPOSE:To detect the extent of inclination of an objective lens to easily discriminate whether it is within an allowable value by providing a specular surface on the upper face of a flange of the objective lens and irradiating the specular surface with test light and measuring the spot position of the reflected light. CONSTITUTION:An objective lens 17 is attached to an actuator 5, and this actuator 5 is set on a head 19 of an inspecting machine. Parallel rays 23 for test are thrown at an angle alpha to a flange 17b of the lens 17 and are reflected on a specular surface 18 on the upper face. When the lens 17 is not inclined, light 23 is reflected at the angle alpha on the specular surface 18 and passes mirrors 20 and 2 and is projected to a point F on a projection face 22. When the lens 17 is inclined, light 23 is reflected at an angle alpha+DELTAalpha and is projected to a point F' DELTAalpha off the point F. Consequently, the spot position of the reflected light is measured to detect the extent of inclination of the objective lens without contacting with the actuator, and it is easily discriminated whether this extent is within the allowable value or not. |
