Patent ID: 9594014
Date: 2017-03-14
CPC Classifications: G01B,G01N,G03F

Claim:
1. An installation structure of a length meter for measuring a displacement of an object placed in vacuum, comprising: a vacuum chamber A having the object installed therein; a vacuum chamber B provided separately from the vacuum chamber A, the vacuum chamber B having the length meter stored therein; an installation base integrally mounted to a surface plate and installed on a side portion of the vacuum chamber A, the surface plate supporting the vacuum chamber A and/or the object and a vacuum chamber C installed under a lower surface of the installation base with the installation base interposed therebetween, wherein the vacuum chamber B is installed on the installation base, and a side wall of the vacuum chamber B is overlapped with a side wall of the vacuum chamber A with a first vacuum sealing portion interposed therebetween, wherein laser light axis holes are provided at corresponding positions on the overlapping side walls of both the vacuum chambers A and B and the first vacuum sealing portion respectively, and a laser light incident from the length meter stored in the vacuum chamber B enters into the vacuum chamber A through the laser light axis holes, and a laser light reflected from the object in the vacuum chamber A enters into the length meter in the vacuum chamber B through the laser light axis holes, wherein the vacuum chamber B includes a space portion that stores the length meter, and a lower end portion of the vacuum chamber B is joined to an upper surface of the installation base to which the length meter is fixed so as to store the length meter on the installation base, and wherein the vacuum chamber B is installed on the upper surface of the installation base via a third vacuum sealing portion provided along the lower end portion of the vacuum chamber B so as to allow a displacement in a direction parallel to the upper surface of the installation base, a connection portion of the vacuum chamber C between the vacuum chamber C and the lower surface of the installation base is provided to have substantially the same shape as the lower end portion of the vacuum chamber B, and a fourth vacuum sealing portion having substantially the same vacuum sealing area as the third vacuum sealing portion of the vacuum chamber B is provided along the connection portion, and the vacuum chamber C is mounted to the lower surface of the installation base immediately below the vacuum chamber B via the fourth vacuum sealing portion provided along the connection portion.