| 摘要 |
PURPOSE:To expand measuring range by arranging a collimator lens between half mirrors on the observation optical axis and an object lens on the base optical axis to eliminate changes in the reading of the angle in the scale depending on the multiplication of the object lens. CONSTITUTION:A collimator lens 30 is arranged at the position between half mirrors 16 and 22 on the observation optical axis 20. An object lens 32 is arranged at the position between the mirror 16 and a reflector 18 on the base optical axis 10. Then, the image of a target 26 is formed in relay on the optical axis 10 on the side opposite to the object lens 14 viewed from the mirror 16. This enables the expansion of the measuring range while eliminating changes in the reading of the angle of eccentricity in the scale 24 depending on the multiplication of the lens 14. |
