Fast phase unwrapping algorithm for interferometric applications

Schofield, M. A.; Zhu, Yimei

doi:10.1364/ol.28.001194

Cited by 383 publications

(325 citation statements)

References 29 publications

Supporting

Mentioning

319

Contrasting

Order By: Relevance

“…4, and can also clearly see that there are significant artifacts in the unwrapped phase map for the random binarization technique which are induced by the local phase unwrapping approach [8]. We also compare the residual errors obtained through recovering the phase map using both a local and global [9] phase unwrapping technique and compare their relative merits. Figure 5 shows the growth of residual error for two different binarization techniques with two distinct phase unwrapping approaches.…”

Section: Resultsmentioning

confidence: 99%

Traceable interferometry using binary reconfigurable holograms

2014

View full text Add to dashboard Cite

The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. We describe the characterization of a ferroelectric-liquid-crystal-on-silicon (FLCOS) spatial light modulator (SLM) in the production of holograms for use in interferometric metrology. It has already been shown that such a device can be used in producing small-amplitude arbitrary reference surfaces with small but appreciable errors due to the contaminating effect of higher-order structures being propagated through the spatial filter. Here we further quantify the size of these residuals for increasingly large aberrations up to nine waves rms Zernike astigmatism, showing a Zernike-corrected rms wavefront error of roughly 0.06 waves with high vibrational stability. We also present measurements of a vacuum window element using the FLCOS device to drastically reduce interferometric fringe density, showing a residual wavefront error of 0.046 waves rms with dominant components originating from test piece structure rather than holographic errors.

show abstract

Section: Resultsmentioning

confidence: 99%

Traceable interferometry using binary reconfigurable holograms

2014

View full text Add to dashboard Cite

show abstract

“…Because a facet's height of the mFLL is higher than one half of the wavelength (0.555 um) of the laser source, a phase ambiguity occurs in PSI. That is a wellknown ambiguity problem in PSI [30,31]. In this specimen, correcting points are shown as inflection points in the profile.…”

Section: Correcting Wrongly Unwrapped Phases With Thementioning

confidence: 87%

Unambiguous 3D Surface Measurement Method for a Micro-Fresnel Lens-Shaped Lenticular Lens Based on a Transmissive Interferometer

Yoon¹,

Kim²,

Kim³

et al. 2014

Journal of the Optical Society of Korea

View full text Add to dashboard Cite

The use of a laser interferometer as a metrological tool in micro-optics measurement is demonstrated. A transmissive interferometer is effective in measuring an optical specimen having a high angle slope. A configuration that consists of an optical resolution of 0.62 micron is adapted to measure a specimen, which is a micro-Fresnel lens-shaped lenticular lens. The measurement result shows a good repeatability at each fraction of facets, however, a reconstruction of the lens shape profile is disturbed by a known problem of 2π-ambiguity. To solve this 2π-ambiguity problem, we propose a two-step phase unwrapping method. In the first step, an unwrapped phase map is obtained by using a conventional unwrapping method. Then, a proposed unwrapping method based on the shape modeling is applied to correct the wrongly unwrapped phase. A measured height of each facet is compared with a profile result measured by AFM.

show abstract

“…The Laplacian of the unwrapped phase data, , was estimated from the wrapped phase information (Schofield and Zhu, 2003),…”

Section: Qsm Reconstructionmentioning

confidence: 99%

Probing neuronal activation by functional quantitative susceptibility mapping under a visual paradigm: A group level comparison with BOLD fMRI and PET

et al. 2016

View full text Add to dashboard Cite

Dynamic changes of brain-tissue magnetic susceptibility provide the basis for functional MR imaging (fMRI) via T2*-weighted signal-intensity modulations. Promising initial work on a detection of neuronal activity via quantitative susceptibility mapping (fQSM) has been published but consistently reported on ill-understood positive and negative activation patterns (Balla et al., 2014;Chen and Calhoun, 2015a). We set out to (i) demonstrate that fQSM can exploit established fMRI data acquisition and processing methods and to (ii) better describe aspects of the apparent activation patterns using fMRI and PET as standards of reference. Under a standardized visual-stimulation paradigm PET and 3-T gradient-echo EPI-based fQSM, fMRI data from 9 healthy volunteers were acquired and analyzed by means of Independent Component Analysis (ICA) at subject level and, for the first time, at group level. Numbers of activated (z-score>2.0) voxels were counted and their mean z-scores calculated in volumes of interest (occipital lobe (Nocc_lobe), segmented occipital gray-matter (NGM_occ_lobe), large veins (Nveins)), and in occipital-lobe voxels commonly activated in fQSM and fMRI component maps. Common but not entirely congruent regions of apparent activation were found in the occipital lobe in z-score maps from all modalities, fQSM, fMRI and PET, with distinct BOLD-negatively correlated regions in fQSM data. At subject-level, Nocc_lobe, NGM_occ_lobe and their mean z-scores were significantly smaller in fQSM than in fMRI, but their ratio, NGM_occ_lobe/Nocc_lobe, was comparable. Nveins did not statistically differ and the ratio Nveins/NGM_occ_lobe as well as the mean z-scores were higher for fQSM than for fMRI. In veins and immediate vicinity, z-score maps derived from both phase and fQSMdata showed positive and negative lobes resembling dipole shapes in simulated field and phase maps with no correlate in fMRI or PET data. Our results show that standard fMRI tools can directly be used for fQSM processing, and suggest that fQSM may have the potential to detect gray-matter activation distant from large veins, to improve detection of veins with stimulus-induced venous oxygen saturation (SvO2) variations, and to better localize areas of activation. However, our results seem to clearly expose issues that phenomenologically resemble an incomplete dipolar inversion and that need to be subject to further investigation. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. fMRI. In veins and immediate vicinity, z-score maps derived from both phase and fQSM-data showed positive and negative lobes resembling dipole shapes in simula...

show abstract

Fast phase unwrapping algorithm for interferometric applications

Cited by 383 publications

References 29 publications

Traceable interferometry using binary reconfigurable holograms

Traceable interferometry using binary reconfigurable holograms

Unambiguous 3D Surface Measurement Method for a Micro-Fresnel Lens-Shaped Lenticular Lens Based on a Transmissive Interferometer

Probing neuronal activation by functional quantitative susceptibility mapping under a visual paradigm: A group level comparison with BOLD fMRI and PET

Contact Info

Product

Resources

About