Patent ID: 6852988

Claim:
A gap adjustment apparatus comprising: a first holder for holding a first object having a first measurement surface; a second holder for holding a second object having a second measurement surface, in a manner such that the second measurement surface faces the first measurement surface; a first displacement gauge for measuring a distance extending from the first displacement gauge to the first measurement surface; a target whose relative position with respect to the first displacement gauge is fixed, the target having a target measurement surface orientated in the same direction as the second measurement surface; a second displacement gauge for measuring distances extending from the second displacement gauge to the second measurement surface and to the target measurement surface; and a moving mechanism for moving the first holder and the second holder to alter a gap between the first measurement surface and the second measurement surface, wherein when the gap between the first measurement surface and the second measurement surface is altered, a gap between the second displacement gauge and the target measurement surface is not altered.