Inspection of freeform intraocular lens topography by phase measuring deflectometric methods

Speck, Alexis; Zelzer, Benedikt; Kannengießer, Marc; Langenbucher, Achim; Eppig, Timo

doi:10.1364/ao.52.004279

Cited by 15 publications

(7 citation statements)

References 15 publications

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“…The measurements were done parallel with all three cameras. Stereo-deflectometry requires at least a second camera (cam1) to determine the absolute position in space, also referred to as absolute phase measuring deflectometry [11,17]. Therefore each camera picture (from cam2 and cam3) in combination with the camera for absolute position measurement (cam1) was used to calculate the slope data.…”

Section: Accuracymentioning

confidence: 99%

Quality control of injection molded eyewear by non-contact deflectometry

Speck

Zelzer

Langenbucher

et al. 2014

J. Eur. Opt. Soc.-Rapid Publ.

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Occupational eye wear such as safety spectacles are manufactured by injection molding techniques. Testing of the assembled safety spectacle lenses in transmission is state of the art, but there is a lack of surface measurement systems for occupational safety lenses. The purpose of this work was to validate a deflectometric setup for topography measurement, detection of defects and visualization of the polishing quality, e.g. casting indentations or impressions, for the production process of safety spectacles. The setup is based on a customized stereo phase measuring deflectometer (PMD), equipped with 3 cameras with f'1,2 = 16 mm and f'3 = 8.5 mm and a specified measurement uncertainty of ± 3 µm. Sixteen plastic lenses and 8 corresponding injection molds from 4 parallel cavities were used for validation of the deflectometer. For comparison an interferometric method and a reference standard (< λ/10 super polished) was used. The accuracy and bias with a spherical safety spectacle sample was below 1 µm, according to DIN ISO 5725-2.2002-12. The repeatability was 2.1 µm and 35.7 µm for a blind radius fit. In conclusion, the PMD technique is an appropriate tool for characterizing occupational safety spectacle and injections mold surfaces. With the presented setup we were able to quantify the surface quality. This can be useful and may optimize the quality of the end product, in addition to standardized measuring systems in transmission.

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Section: Accuracymentioning

confidence: 99%

Quality control of injection molded eyewear by non-contact deflectometry

Speck

Zelzer

Langenbucher

et al. 2014

J. Eur. Opt. Soc.-Rapid Publ.

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show abstract

“…As a low-cost, full-field three-dimensional shape measurement technique with a high dynamic range, the phase measuring deflectometry (PMD) method was first introduced in 2004 and improved to be a flexible and effective approach to inspect specular reflecting surfaces [12]. It could be used to accurately measure the surface shape of a single optical element with the unique advantages of a high dynamic range, full field of view, and non-null measurement [13] on the basis of the triangulation law [14], Scheimpflug principle [15], and diffuse-versus-specular reflections principle [16]. Based on the synergy between deflectometry and ray-tracing, the PMD method was employed for the on-site evaluation of the free-form mirrors with a high speed, high accuracy, and cost reduction [17][18][19].…”

Section: Introductionmentioning

confidence: 99%

“…In 2018, the phase measuring deflectometry system combined with a laser resonator was designed to achieve a high-precision online thermal distortion measurement of crystals in the high-power laser [27]. However, limited by the wavefront reconstruction principle and algorithm, the screen of the liquid crystal display (LCD) has to be placed in parallel with the surface of the mirror under test, which takes up a large measurement space [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]. Thus, these mentioned methods are primarily constrained in offline tests and not applicable for real-time measurement in the enclosed laser facility.…”

Section: Introductionmentioning

confidence: 99%

Surface Shape Distortion Online Measurement Method for Compact Laser Cavities Based on Phase Measuring Deflectometry

et al. 2022

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Conventional phase measuring deflectometry (PMD) takes up a large measurement space and is not suitable for compact online measurement, as the liquid crystal display (LCD) has to be placed in parallel with the mirror under test. In this paper, a compact online phase measuring deflectometry (COPMD) with the LCD screen set perpendicular to the mirror under test is presented for surface shape distortion real-time measurement. The configuration of the COPMD in an enclosed laser cavity is proposed, and the principle of the method is theoretically derived by using the vector-form reflection law. Based on the analysis model, the fringe modulation regulation of the LCD is revealed, and the measurement errors caused by misalignments of the components are illustrated. The validity and flexibility of the COPMD method are verified in the experiment by using a single-actuator deformable mirror as the mirror under test and the PMD method as the comparison. The proposed COPMD method remarkably expands the application range of the conventional PMD method, as it could make efficient use of compact space and is applicable for real-time measurement in enclosed laser facilities and assembled laser systems.

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“…2 However, the application of the freeform surface in the imaging community is not as wide as in the illumination fields such as the LED industry, 3,4 because the former requires higher fabrication and measurement precision. 7 However, its micron level precision is not sufficient for measuring imaging freeform optics. 5 In recent years, much research has been focusing on finding effective methods of testing a freeform surface with high precision.…”

Section: Introductionmentioning

confidence: 99%

Assessment of optical freeform surface error in tilted-wave-interferometer by combining computer-generated wave method and retrace errors elimination algorithm

et al. 2015

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Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 08/17/2015 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx Assessment of optical freeform surface error in tilted-wave-interferometer by combining computer-generated wave method and retrace errors elimination algorithm Abstract. As is well-known, optical testing has begun to emerge as a limiting factor in the application of freeform surfaces. In all kinds of published freeform optical metrology, the tilted-wave-interferometer (TWI) is the precise and flexible method for testing a freeform surface as it can compensate the local surface's deviation from its best fit sphere by using a set of tilted waves. In the process of measurement with TWI, accurate assessment of the test surface error from the fringes plays a key role. We present a method for evaluation and characterization of surface aberrations in TWI by combining computer-generated wave technology and a retrace errors elimination algorithm. The feasibility of the method is proved by the simulation and experimental results.

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Inspection of freeform intraocular lens topography by phase measuring deflectometric methods

Cited by 15 publications

References 15 publications

Quality control of injection molded eyewear by non-contact deflectometry

Quality control of injection molded eyewear by non-contact deflectometry

Surface Shape Distortion Online Measurement Method for Compact Laser Cavities Based on Phase Measuring Deflectometry

Assessment of optical freeform surface error in tilted-wave-interferometer by combining computer-generated wave method and retrace errors elimination algorithm

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