Wavefront Aberration Measurement Deflectometry for Imaging Lens Tests

Yu, Linzhi; Li, Dahai; Ruan, Yilang; Zhang, Xinwei; Wang, Ruiyang; Xu, Kun

doi:10.3390/app12157857

Cited by 5 publications

(1 citation statement)

References 27 publications

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“…However, most schemes assume very small deflection angles (or, equivalently, small variations of the refractive index) and therefore apply only to simple object shapes and/or require that the studied object be immersed in an index-matching fluid. Alternative (large-deflection) approaches often simplify the problem and, e.g., assume that the refractive index inside the object is constant and only recover its shape (Petz et al, 2009) or focus on selected (application-specific) optical parameters of samples (such as "refractive power") (Knauer et al, 2008;Vargas et al, 2010;Yu et al, 2022). The traditional schlieren technique, a form of deflectometry (Toepler, 1864;Greenberg et al, 1995), has also been studied in combination with moiré (L'Esperance and Buckner, 2017) and phase-shifting methods (Joannes et al, 2003;Beghuin et al, 2009;Antoine et al, 2019) in order to characterize optical components in direct transmission or tomographically (Foumouo et al, 2010;González et al, 2011).…”

Section: Deflectometry In Transmissionmentioning

confidence: 99%

Deflectometry for specular surfaces: an overview

et al. 2023

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Deflectometry as a technique to assess reflective surfaces has now existed for some 40 years. Its different aspects and variations have been studied in multiple theses and research articles; reviews are available for certain subtopics. Still a field of active development with many unsolved problems, deflectometry now encompasses a large variety of application domains, hardware setup types, and processing workflows for different purposes, and spans a range from qualitative defect inspection of large vehicles to precision measurements of microscopic optics. Over these years, many exciting developments have accumulated in the underlying theory, in the systems design, and in the implementation specifics. This diversity of topics is difficult to grasp for experts and non-experts alike and may present an obstacle to a wider acceptance of deflectometry as a useful tool for research and industrial applications. This paper presents an attempt to summarize the status of deflectometry and to map relations between its notable branches. Its aim is to provide a communication basis for experienced practitioners and also to offer a convenient entry point for those interested in learning about the method. The list of references introduces some prominent trends and established research groups in order to facilitate further self-directed exploration.

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Section: Deflectometry In Transmissionmentioning

confidence: 99%

Deflectometry for specular surfaces: an overview

et al. 2023

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Evaluation of the aspherical surface of a plano–convex lens by refraction using an LCD

Huerta-Carranza,

Granados-Agustín,

Santiago-Alvarado

et al. 2024

Review of Scientific Instruments

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We present a simple method to evaluate the curved surface of a plano–convex aspheric lens using an incoherent light source. We implement an exact ray trace to obtain analytical expressions for designing a set of geometric objects, placed within a plane, to produce by refraction a regular array of either circles or straight lines in the plane of detection when the optical system under test works in accordance with the nominal design. An innovative geometrical test is implemented to calibrate the position of each element involved in the measurement system. As part of the calibration process, we considered that the camera lens can be affected by the distortion aberration; therefore, we proposed a straightforward method to compensate for the defects introduced in the experimental images. Finally, we used the measured values of the slopes to recover the shape of the surface under test using an iterative algorithm; as a result, we obtained the geometric parameters describing the surface with a percentage error less than 1.7%.

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Height reconstructions from geometric wavefronts using vision ray metrology

Ramirez-Andrade,

Falaggis

2024

Appl. Opt.

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A recently reported vision ray metrology technique [Opt. Express 29, 43480 (2021)OPEXFF1094-408710.1364/OE.443550] measures geometric wavefronts with high precision. This paper introduces a method to convert these wavefront data into height information, focusing on the impact of back surface flatness and telecentricity errors on measurement accuracy. Systematic errors from these factors significantly affect height measurements. Using ray trace simulations, we estimate reconstruction errors with various plano-concave and plano-convex elements. We also developed a calibration technique to mitigate telecentricity errors, achieving submicron accuracy in surface reconstruction. This study provides practical insights into vision ray metrology systems, highlighting validity limits, emphasizing the importance of calibration for larger samples, and establishing system alignment tolerances. The reported technique for the conversion of geometric wavefronts to surface topography employs a direct non-iterative ray-tracing-free method. It is ideally suited for reference-free metrology with application to freeform optics manufacturing.

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Wavefront Aberration Measurement Deflectometry for Imaging Lens Tests

Cited by 5 publications

References 27 publications

Deflectometry for specular surfaces: an overview

Deflectometry for specular surfaces: an overview

Evaluation of the aspherical surface of a plano–convex lens by refraction using an LCD

Height reconstructions from geometric wavefronts using vision ray metrology

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