| 摘要 |
PROBLEM TO BE SOLVED: To provide a method that can obtain a sharp image of reflection light in measurement of parallelism of two planes facing each other.SOLUTION: The parallelism measuring method includes the steps of: arranging a semi-transmissive member of a reflection member such that a surface of the semi-transmissive member thereof forms an angle of almost 45 degrees with respect to a second measured plane; measuring an angle of a first reflection beam 25 in which an incident light beam 24 is reflected at an interface 10 of the semi-transmissive member of the reflection member, next reflected at the second measured plane, once again reflected at the interface of the semi-transmissive material and returned in an incident direction; measuring an angle of a second reflection beam 26 in which the incident light beam 24 is reflected at the interface 10 of the semi-transmissive member of the reflection member, next reflected at the second measured plane, next passes through the semi-transmissive member of the reflection member, next reflected at a first measured plane, once again passes through the semi-transmissive member of the reflection member, once again reflected at the second measured plane once again, reflected at the interface 10 of the semi-transmissive member and returned in the incident direction; and calculating an angle difference between the first measured plane and the second measured plane from the angles of the first and second reflection beams. |
