Abstract

The differential heterodyne interferometer (DHI) is suitable for precise measurement of step height and line width, since its differential configuration can significantly reduce disturbances from the environment [1,2]. Like most phase measuring interferometers, however, the DHI is limited, in that it can obtain only the phase from 0 to 2π, because of the sinusoidal nature of the optical interference involved. Thus, the measurable step height is limited to one quarter of the wavelength of the light source. This study describes a confocal differential heterodyne interferometer (CDHI) for measuring step heights of several micrometers, with a high resolution and line width with high repeatability. The CDHI has a simple structure and rapid measurement speed.

© 2005 Optical Society of Korea

Differential wavelength-scanning heterodyne interferometer for measuring large step height

Sheng-Hua Lu, Ching-I Chiueh, and Cheng-Chung Lee
Appl. Opt. 41(28) 5866-5871 (2002)

Dual-wavelength heterodyne differential interferometer for high-precision measurements of reflective aspherical surfaces and step heights

H. J. Tiziani, A. Rothe, and N. Maier
Appl. Opt. 35(19) 3525-3533 (1996)

High-precision laser transverse differential confocal radius measurement method

Shun Tang, Yanhong Li, Lirong Qiu, Yin Song, Weiqian Zhao, and Shuai Yang
Opt. Express 29(19) 29960-29971 (2021)

Precise optical surface profilometry using innovative chromatic differential confocal microscopy

Liang-Chia Chen, Duc Trung Nguyen, and Yi-Wei Chang
Opt. Lett. 41(24) 5660-5663 (2016)

Compact scanning confocal chromatic sensor enabling precision 3-D measurements

Daniel Wertjanz, Thomas Kern, Ernst Csencsics, Gerhard Stadler, and Georg Schitter
Appl. Opt. 60(25) 7511-7517 (2021)