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Proceedings Paper

Homodyne displacement measuring interferometer probe for optical coordinate measuring machine with tip and tilt sensitivity
Author(s): Sam C. Butler; Michael A. Ricci; Chen Wang; Qun Wei; Jonathan D. Ellis
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Paper Abstract

In this proceedings, we present a 3DoF (one linear, two angular) optical probe for measuring freeform optics in conjunction with an optical coordinate measuring machine (OCMM). This probe uses homodyne interferometry in a Michelson configuration and position sensing detection to simultaneously measure displacement, tip, and tilt. The goal of this work is to investigate point-to-point methods for measuring freeform optics and establish a probing methodology that can perform self-alignment with respect to the local optical surface. We present the design and preliminary benchtop validation of the probe's performance. Benchtop validation shows successful measurements with 5 nm linear and 20 μrad angular noise levels, with a 15 μm spot size. A CMOS sensor is used for visual confirmation of proper focus on measurement surface to minimize initial defocus error. A PSD detects linear horizontal and vertical displacement of the reflected beam from the measurement surface using autocollimation. In-phase and quadrature signals are measured by two photodetectors and post-processed to obtain displacement information. Periodic error caused by polarization effects and beam mixing is compensated by FPGA-based signal processing.

Paper Details

Date Published: 12 October 2015
PDF: 7 pages
Proc. SPIE 9633, Optifab 2015, 96332E (12 October 2015); doi: 10.1117/12.2195966
Show Author Affiliations
Sam C. Butler, Univ. of Rochester (United States)
Michael A. Ricci, Univ. of Rochester (United States)
Chen Wang, Univ. of Rochester (United States)
Qun Wei, The Institute of Optics, Univ. of Rochester (United States)
Changchun Institute of Optics, Fine Mechanics and Physics (China)
Jonathan D. Ellis, The Institute of Optics, Univ. of Rochester (United States)

Published in SPIE Proceedings Vol. 9633:
Optifab 2015
Julie L. Bentley; Sebastian Stoebenau, Editor(s)

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