Presentation + Paper
20 August 2020 Solutions for environmentally robust interferometric optical testing
Erin M. McDonnell, Leslie L. Deck
Author Affiliations +
Abstract
Optical interferometry is widely used for surface metrology, and phase-shifting interferometry (PSI) remains the “gold standard” for measuring surface form and texture. In the past, the environmental sensitivity of PSI relegated its use to dedicated metrology labs with well-controlled environments. As metrology requirements have expanded beyond the lab, advances in metrology techniques now enable high-precision optical testing in places previously considered inappropriate for interferometric techniques. A class of environmentally-robust methods preserve the gold-standard accuracy of PSI by measuring and accounting for rigid-body motions from vibration and large-scale airflow during the PSI acquisition. These methods, including model-based PSI, use a physical model of the interference to measure cavity rigid body motion and accommodate a wide variety of measurement geometries, surface shapes, surface departure, reflectivities, and environmental conditions without changing the user’s measurement process. For more extreme environments, spatial carrier methods analogous to off-axis holography extract the surface phase fast enough to “freeze” vibration and air turbulence in a single camera frame. The price paid for single-frame acquisition is a loss of lateral resolution as well as a modest increase in sensitivity to optical aberrations, requiring calibration for compensation. This paper will describe current techniques and methods, as well as provide examples and results for practical measurement scenarios in the manufacture of high-precision optical components and systems.
Conference Presentation
© (2020) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Erin M. McDonnell and Leslie L. Deck "Solutions for environmentally robust interferometric optical testing", Proc. SPIE 11487, Optical Manufacturing and Testing XIII, 114870J (20 August 2020); https://doi.org/10.1117/12.2569458
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KEYWORDS
Environmental sensing

Metrology

Wavefronts

Interferometry

Interferometers

Motion models

Turbulence

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