Dual wavelength digital holography for improving the measurement accuracy
Asundi, Anand Krishna
Date of Issue2013
International Conference on Optics in Precision Engineering and Nanotechnology (2013 : Singapore)
School of Mechanical and Aerospace Engineering
In dual wavelength digital holography, a synthetic wavelength is obtained by using two lasers with different wavelengths to expand the measurement range of samples’ step heights from nanometers to micrometers. However, its measurement accuracy reduces along with the expansion of measuring range and significant noise is introduced at the same time. For cases where the sample’s height is smaller than the wavelength of illumination light, the measurement accuracy is very important. In this paper, a new approach of dual wavelength digital holography is presented. The synthetic wavelength is smaller than the wavelength of the two different lasers. Higher measurement accuracy can thus be achieved. The analysis and experimental results show the validity of this method.
© 2013 Society of Photo-Optical Instrumentation Engineers (SPIE). This paper was published in International Conference on Optics in Precision Engineering and Nanotechnology (icOPEN2013) and is made available as an electronic reprint (preprint) with permission of SPIE. The paper can be found at the following official DOI: [http://dx.doi.org/10.1117/12.2020394]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.