Talbot interferometry for measuring the focal length of a lens

Nakano, Yoshiaki; Murata, Kazumi

doi:10.1364/ao.24.003162

Cited by 115 publications

(36 citation statements)

References 14 publications

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“…Here the distance d is called the Talbot distance if the beam is collimated. For converging or diverging beams, the Talbot distance would be modified slightly [1]. It is important to have a sharp (de)magnified-image to form an optimal image with an accurate measurement of the distance between the grating and detector for a focal length determination.…”

Section: Determination Of Focal Lengthmentioning

confidence: 99%

“…zand the (de)magnified period is 0.1969 mm (=20.48/104), whereas the precise corresponding value is 0.1977 mm, as calculated by Eq. (1). If the coarse (de)magnified period is used to determine the focal length of the lens, Eq.…”

Section: Accurate Determination Of the (De)magnified Periodmentioning

confidence: 99%

“…Moiré interferometry is the most commonly used method for examining long focal lengths and is based on the Talbot effect and Moiré fringe analysis [1][2][3]. When a plane wave is incident upon a periodic transmission grating, a self-image of the grating is formed at regular distances from the grating, the so-called Talbot distance and its multiples, and a similar phenomenon occurs when a grating is placed in a converging or diverging beam.…”

Section: Introductionmentioning

confidence: 99%

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Talbot Interferometry for Measuring the Focal Length of a Lens without Moiré Fringes

Lee¹

2015

Journal of the Optical Society of Korea

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A simple method to determine the focal length of a lens using the Talbot image is presented. This method uses only one grating, requiring neither Moiré fringe analysis nor the angle between the gratings. The original Fourier transform was used to access the spectrum beyond the limitation set of the usual fast Fourier transform to determine the (de)magnification accurately enough to be used for the focal length. A set of Talbot images simulated numerically with the Fresnel diffraction integral was used to demonstrate the method. For focal lengths between 5550 mm and 5650 mm, the mean difference between the focal lengths determined from the Talbot images and the true values was 3.3 mm with the standard deviation of the difference being 3.8 mm. The true focal lengths can be recovered with an accuracy of 0.06%.

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Section: Determination Of Focal Lengthmentioning

confidence: 99%

Section: Accurate Determination Of the (De)magnified Periodmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Talbot Interferometry for Measuring the Focal Length of a Lens without Moiré Fringes

Lee¹

2015

Journal of the Optical Society of Korea

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“…To determine the location of the nodal point, the nodal slide technique serves as a standard method [2], and several methods exist for determining the focal length, the Talbot effect approach being one such example [3]. However, it appears that no report exists on the determination of the GIP location, which is the focus of this paper.…”

Section: Introductionmentioning

confidence: 99%

Alternative Description for Gaussian Image Plane

Kim¹,

Lee²

2015

Journal of the Optical Society of Korea

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An alternative description for the Gaussian image plane (GIP) of an optical system for a given object is presented, which applies to both aberration-free and non-aberration-free systems. We extend the definition of transverse magnification (TM) to the image plane (IP) displaced from the GIP and find that the TM depends linearly on the locations of both an aperture stop placed in front of the system and the IP. Hence, we redefine the GIP as the location at which the slope of the TM variance changes sign. The definition is deterministic and self-consistent and, therefore, no other parameters or measurements are needed. The derivation of this definition using a set of paraxial ray tracings and supporting experimental data for a thick bi-convex lens system is presented.

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“…Because of the complexity in accurately locating the principal focal planes that usually lie within the focusing element, various indirect methods for focal length measurement are conventionally used, such as image magnification, autocollimation, nodal slide, Bessel's method, Moiré deflectometry, and Talbot interferometry. [3][4][5][6][7][8][9] The effectiveness of most of these methods is often limited with regard to high accuracy, dynamic range over which measurements can be performed (for both positive and negative dioptric powers), spatial sample alignment, and subjectively image observation. Recently, [10][11][12] we have demonstrated a fibre-optic-based backreflectance technique for testing focusing optical elements with relatively large numerical apertures and short positive focal lengths.…”

Section: Introductionmentioning

confidence: 99%

A simple confocal fibre-optic laser method for intraocular lens power measurement

Ilev

2006

Eye

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IK Ilev AbstractPurpose To develop novel confocal fibreoptic laser method (CFOLM) for accurate and objective measuring of the dioptric power of both positive and negative intraocular lenses (IOLs). Methods The CFOLM principle of operation is based on a simple apertureless single-mode fibre laser confocal design. The key element is a single-mode fibre coupler that serves simultaneously as a point light source (3-5 lm fibre diameter) used for the formation of a collimated Gaussian beam, and as a confocal point receiver that is highly sensitive to spatial displacements of the focused backreflectance laser emission. The basic CFOLM systems include IOL testing set-ups for the measurement of both positive and negative IOLs. Results The CFOLM designs provide high accuracy (r1 lm) in spatially locating the IOL focal point and in measuring the focal length in a broad range of both positive and negative powers including high-magnification IOLs with power greater than 720 D. We have tested various IOL samples with both positive ( þ 5 to þ 30 D) and negative (À5 to À20 D) powers and we have obtained high levels of power testing repeatability estimated by a SD in the interval of 0.004-0.06/0.003-0.013 D and a relative error in the interval of 0.015-0.3/0.02-0.16%, for positive/negative IOLs, respectively. Conclusions The presented IOL power testing method offers a simple, accurate, objective, quick, and relatively inexpensive approach for dioptric power measurement of positive and negative IOLs. It provides an independent source of IOL power measurement data and information for evaluating the effectiveness and safety of novel IOL products.

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Talbot interferometry for measuring the focal length of a lens

Cited by 115 publications

References 14 publications

Talbot Interferometry for Measuring the Focal Length of a Lens without Moiré Fringes

Talbot Interferometry for Measuring the Focal Length of a Lens without Moiré Fringes

Alternative Description for Gaussian Image Plane

A simple confocal fibre-optic laser method for intraocular lens power measurement

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