Multifocus tomographic algorithm for measuring optically thick specimens

Yablon, A.D.

doi:10.1364/ol.38.004393

Cited by 32 publications

(11 citation statements)

References 12 publications

(41 reference statements)

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“…Last, the reconstructed hexagonal lattice structure of the photonic-crystal fiber shown in Fig. 10(c) highlights TDPM's capability, and the results may be compared directly with a recently published state-of-the-art optical fiber tomographic algorithm which is based on ODT in the Rytov approximation [54]. In addition to the lattice structure, RI features resulting from the modification residual stresses in the fiber, such as the ring surrounding the air-hole lattice, are visible in Fig.…”

Section: Resultsmentioning

confidence: 99%

Three-dimensional quantitative phase imaging via tomographic deconvolution phase microscopy

Jenkins¹,

Gaylord²

2015

Appl. Opt.

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The field of three-dimensional quantitative phase imaging (3D QPI) is expanding rapidly with applications in biological, medical, and industrial research, development, diagnostics, and metrology. Much of this research has centered on developing optical diffraction tomography (ODT) for biomedical applications. In addition to technical difficulties associated with coherent noise, ODT is not congruous with optical microscopy utilizing partially coherent light, which is used in most biomedical laboratories. Thus, ODT solutions have, for the most part, been limited to customized optomechanical systems which would be relatively expensive to implement on a wide scale. In the present work, a new phase reconstruction method, called tomographic deconvolution phase microscopy (TDPM), is described which makes use of commercial microscopy hardware in realizing 3D QPI. TDPM is analogous to methods used in deconvolution microscopy which improve spatial resolution and 3D-localization accuracy of fluorescence micrographs by combining multiple through-focal scans which are deconvolved by the system point spread function. TDPM is based on the 3D weak object transfer function theory which is shown here to be capable of imaging "nonweak" phase objects with large phase excursions. TDPM requires no phase unwrapping and recovers the entire object spectrum via object rotation, mitigating the need to fill in the "missing cone" of spatial frequencies algorithmically as in limited-angle ODT. In the present work, TDPM is demonstrated using optical fibers, including single-mode, polarization-maintaining, and photonic-crystal fibers as well as an azimuthally varying CO2-laser-induced long-period fiber grating period as test phase objects.

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Section: Resultsmentioning

confidence: 99%

Three-dimensional quantitative phase imaging via tomographic deconvolution phase microscopy

Jenkins¹,

Gaylord²

2015

Appl. Opt.

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“…While all of the results shown here concern measurement of refractive index with the aid of transverse interferometry, the algorithm is quite general and suitable for any tomographic measurement technique in which the imaging depth-offield is substantially smaller than the transverse dimension of the object 12 . For this reason the new tomographic algorithm described here is applicable to measurement of refractive index using techniques other than transverse interferometry such as Quantitative Phase Microscopy (QPM) 1,7-9 , Diffraction Tomography 3 , or Differential Interference Contrast (DIC) microscopy 4 as well as measurement of fiber residual elastic stress 5,7-9 , or measurements of the transverse distribution of rare-earth dopant 11 . Three-dimensional measurements of optical fiber samples 4,8,9 are obtainable by repeating the fundamental two-dimensional measurement along a length of optical fiber.…”

Section: Discussionmentioning

confidence: 99%

“…The inverse Radon transform 10 , or a mathematically analogous algorithm, is used to synthesize the onedimensional projections into a single two-dimensional cross section. Typically the refractive index is measured 1-4,7-9 , although residual stress 5,[7][8][9] or the transverse distribution of rare-earth dopant 11 may also be measured. While twodimensional measurements can be made at a cleaved fiber end-face, two-dimensional tomographic reconstructions from one-dimensional transverse projection data is preferable because such transverse measurements are inherently nondestructive, and therefore they can be used to map out variations along the length of a fiber, for example near a fusion splice 8,9 , a physical taper, or even a fiber grating.…”

Section: Motivationmentioning

confidence: 99%

Novel multifocus tomography for measurement of microstructured and multicore optical fibers

Yablon¹

2014

SPIE Proceedings

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A novel multifocus tomographic algorithm for reconstructing an optical fiber's cross sectional refractive index distribution from transverse projections is described. This new algorithm is validated against measurements of both microstructured and multicore optical fibers, which were not previously measurable. Optical fiber tomographic measurements recently made by several research groups using different technologies have all suffered from the same limitation, namely that typical fiber diameters (several hundred microns) exceed the imaging depth-of-field (approximately one micron) by several orders of magnitude. The new algorithm combines data acquired from a multiplicity of focal planes to overcome this limitation, yielding measurements with extremely fine spatial resolution over large transverse dimensions, thereby providing the first-ever high quality measurements of microstructured and multicore fibers. This new measurement approach is broadly applicable to any tomographic problem in which the depthof-field is greatly exceeded by the transverse dimension of the specimen. Many types of transverse optical fiber measurement technologies, including interference microscopy, quantitative phase microscopy (QPM), residual stress measurement, differential interference contrast (DIC) microscopy, and spontaneous emission tomography will benefit from this new algorithm, which will greatly facilitate characterization of optical fibers for high-power applications.

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“…In order to achieve fine spatial resolution, a fiber sample must be imaged with high numerical aperture objective lenses whose depth of field is approximately two orders of magnitude smaller than the transverse width of typical fibers. In the presence of this constraint, conventional filtered backprojection produces significant measurement artifacts, especially for features far from the fiber's center axis [5]. A newly described multifocus tomographic algorithm overcomes this limitation and achieves fine spatial resolution (~1 µm) over large transverse distances (~100 µm) [5,6].…”

Section: Tomographymentioning

confidence: 99%

“…In the presence of this constraint, conventional filtered backprojection produces significant measurement artifacts, especially for features far from the fiber's center axis [5]. A newly described multifocus tomographic algorithm overcomes this limitation and achieves fine spatial resolution (~1 µm) over large transverse distances (~100 µm) [5,6]. In this case, projection data is acquired at a multiplicity of focal positions and also at a multiplicity of angular orientations.…”

Section: Tomographymentioning

confidence: 99%