Stability of the reference flat used in Fizeau interferometer and its contribution to measurement uncertainty

Abstract

To calibrate a squareness standard and a height micrometer, the Korea Research Institute of Standards and Science (KRISS) has built a new linear measuring machine moving vertically. The main requirement on design of the machine is to achieve the flexibility to calibrate several kinds of standards such as square master, cylindrical square, height micrometer and linear height gauge which are positioned vertically on the surface plate. The system consists of a precision granite column with an air bearing state, a laser interferometer and two electronic probes. In order to calibrate the squareness standards, the granite beam is used as a reference of squareness and a guide of vertical movement. The instrument incorporates a frequency stabilized He-Ne laser. The vertical movement is measured by a laser interferometer whose operation is based on the heterodyne measurement technique. Positioning for calibrating the height micrometer is undertaken by using a vertical state and a horizontal stage, and its measurement range of 0-700 mm. The paper gives a description of the system and a preliminary measurement results.