ESAD Shearing Deflectometry: A Primary Flatness Standard with Sub-Nanometer Uncertainty

Abstract:

Article Preview

To overcome the limitations of conventional interferometry, a technique has been developed which allows the absolute topography measurement of near-plane and slightly curved optical surfaces of arbitrary size with low measurement uncertainty. The Extended Shear Angle Difference (ESAD) method combines deflectometric and shearing techniques in a unique way to minimize measurement errors and to optimize measurand traceability. A device for the topography measurement of optical surfaces up to 500 mm in diameter, achieving sub-nanometer repeatability, reproducibility and uncertainty, was built at the Physikalisch-Technische Bundesanstalt (PTB). The ESAD method is optimally suited for creating a primary standard for straightness and flatness with highest accuracy by which the three-flat test or liquid mirrors can be replaced as starting points of the traceability chain in flatness measurement. In the following, the improved ESAD device which uses optimized opto-mechanical components is presented. Central aspects of the proper design and use of deflectometric systems are highlighted, including the optimal use of pentaprisms.

Info:

Periodical:

Key Engineering Materials (Volumes 381-382)

Edited by:

Wei Gao, Yasuhiro Takaya, Yongsheng Gao and Michael Krystek

Pages:

543-546

DOI:

10.4028/www.scientific.net/KEM.381-382.543

Citation:

R. D. Geckeler "ESAD Shearing Deflectometry: A Primary Flatness Standard with Sub-Nanometer Uncertainty", Key Engineering Materials, Vols. 381-382, pp. 543-546, 2008

Online since:

June 2008

Authors:

Export:

Price:

$35.00

In order to see related information, you need to Login.

In order to see related information, you need to Login.