Deflectometry challenges interferometry: the competition gets tougher!

Christian Faber; Evelyn Olesch; Roman Krobot; Gerd Häusler

doi:10.1117/12.957465

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13 September 2012 Deflectometry challenges interferometry: the competition gets tougher!

Christian Faber, Evelyn Olesch, Roman Krobot, Gerd Häusler

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Proceedings Volume 8493, Interferometry XVI: Techniques and Analysis; 84930R (2012) https://doi.org/10.1117/12.957465
Event: SPIE Optical Engineering + Applications, 2012, San Diego, California, United States

Abstract

Deflectometric methods that are capable of providing full-field topography data for specular freeform surfaces have been around for more than a decade. They have proven successful in various fields of application, such as the measurement of progressive power eyeglasses, painted car body panels, or windshields. However, up to now deflectometry has not been considered as a viable competitor to interferometry, especially for the qualification of optical components. The reason is that, despite the unparalleled local sensitivity provided by deflectometric methods, the global height accuracy attainable with this measurement technique used to be limited to several microns over a field of 100 mm. Moreover, spurious reflections at the rear surface of transparent objects could easily mess up the measured signal completely. Due to new calibration and evaluation procedures, this situation has changed lately. We will give a comparative assessment of the strengths and – now partly revised – weaknesses of both measurement principles from the current perspective. By presenting recent developments and measurement examples from different applications, we will show that deflectometry is now heading to become a serious competitor to interferometry.

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Christian Faber, Evelyn Olesch, Roman Krobot, and Gerd Häusler "Deflectometry challenges interferometry: the competition gets tougher!", Proc. SPIE 8493, Interferometry XVI: Techniques and Analysis, 84930R (13 September 2012); https://doi.org/10.1117/12.957465

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