Direct determination of focal length by using Talbot interferometry

Sriram, K. V.; Kothiyal, M. P.; Sirohi, R. S.

doi:10.1364/ao.31.005984

Cited by 48 publications

(8 citation statements)

References 9 publications

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“…The converging lens will produce a beat pattern as a result of the mismatch between the image of the first grating and the second grating. The focal length can be calculated with: (26) where is focal length, is the distance between gratings, is the pitch of the gratings, and is the pitch of the beat pattern.…”

Section: G Moiré Deflectometrymentioning

confidence: 99%

Measurement of spectacle lenses: A review

Mendoza-Villegas¹,

Trujillo-Schiaffino²,

Salas-Peimbert³

et al. 2014

Opt. Pura Apl.

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Spectacle lenses are the most commonly used solution for refractive errors of the eye, such as myopia, hyperopia, presbyopia and astigmatism. To correct a refractive error, the spectacle lens needs to have the correct lens power and an appropriate distribution of power along the surface of the lens, to measure these characteristics several methods have been developed, this paper presents a review of some of these methods and their optical principles.

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Section: G Moiré Deflectometrymentioning

confidence: 99%

Measurement of spectacle lenses: A review

Mendoza-Villegas¹,

Trujillo-Schiaffino²,

Salas-Peimbert³

et al. 2014

Opt. Pura Apl.

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“…There are a plurality of papers 5 – 37 describing different techniques for focal length measurement. For example, using Talbot imaging, Moire fringes, deflectometry, interferometry, imaging conjugates, and using gratings and holograms.…”

Section: Introductionmentioning

confidence: 99%

Simple and accurate method for determining lens focal length

Sasián

2023

Opt. Eng.

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A simple and accurate method for determining the focal length of a lens is presented.There is no need to know the distance between lens principal planes and can be performed with easily available and inexpensive hardware. Depending on the test lens (TL) f-number, the error on determining focal length can be in the order of 0.1% of the focal length. We discuss determining focal length with the Newton equation f 2 ¼ zz 0 , with the Bessel equation f ¼ ððL − PPÞ 2 − D 2 Þ∕4ðL − PPÞ, with equation f 2 ¼ y 0 ðy þ y 0 Þ, or with equation f ¼ ðy 2 − PP 2 Þ∕4PP.

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“…Many of these techniques, however, usually require rigorous alignment, which places a big impact on the measurement accuracy. There also exist other methods based on diffraction theory, such as Moiré deflectometry and Talbot interferometry [6], [7]. The measurement accuracy is mainly limited by fringe counting for Moiré deflectometry, and distance measurement between Moiré images for Talbot interferometry.…”

Section: Introductionmentioning

confidence: 99%

Inspection of Intraocular Lens With Dual-Side View Optical Coherence Tomography

Wang

Liu

et al. 2021

IEEE Photonics J.

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Intraocular lens (IOL) is widely used for cataract treatment. Its optical properties are crucial to obtain a good treatment efficacy and thus need to be evaluated and controlled. In this study, we propose a novel method based on optical coherence tomography (OCT) for noncontact and accurate in vitro measurement of thickness, refractive index and dioptric power of IOL implants. The OCT setup is specially designed to create two sampling optics, called dual-side view OCT (DSV-OCT), which allows for imaging IOL from the two opposite sides simultaneously in single OCT volume scanning. This can produce a three-dimensional surface contour without suffering image distortions due to the refraction of the curved surface. Then, the thickness and surface curvature can be easily computed from the surface contours. In addition, DSV-OCT is able to measure the refractive index. Three IOLs with different dioptric powers (5D, 20D and 28D) were chosen to evaluate this method. The results show that this method is capable to provide a comprehensive and accurate evaluation of IOLs from the aspects of thickness, refractive index and dioptric power, and hence can be potentially used as a quality assurance tool by IOL manufacturers.

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Direct determination of focal length by using Talbot interferometry

Abstract: A new and simple technique for the determination of the focal length of positive lenses and concave spherical surfaces by Talbot interferometry is described. Results of measurements are presented. We show that high measurement accuracy can be achieved with this technique.

Cited by 48 publications

References 9 publications

Measurement of spectacle lenses: A review

Measurement of spectacle lenses: A review

Simple and accurate method for determining lens focal length

Inspection of Intraocular Lens With Dual-Side View Optical Coherence Tomography

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