17 results on '"LaserLaB - Biophotonics and Microscopy"'
Search Results
2. Tapered tip optical fibers for measuring ultra-small refractive index changes with record high sensitivity
- Author
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Chunyu Lu, Hamed Nikbakht, M. Yusuf Erdolu, Bob van Someren, B. Imran Akca, Biophotonics and Medical Imaging, and LaserLaB - Biophotonics and Microscopy
- Subjects
SDG 6 - Clean Water and Sanitation ,Atomic and Molecular Physics, and Optics - Abstract
Here we demonstrate an inexpensive, simple, and ultra-sensitive refractive index sensor based on a tapered tip optical fiber combined with a straightforward image analysis method. The output profile of this fiber exhibits circular fringe patterns whose intensity distribution dramatically changes even with ultra-small refractive index variations in the surrounding medium. The sensitivity of the fiber sensor is measured using different concentrations of saline solutions with a transmission setup consisting of a single wavelength light source, a cuvette, an objective lens, and a camera. By analyzing the areal changes in the center of the fringe patterns for each saline solution, we obtain an unprecedented sensitivity value of 24,160 dB/RIU (refractive index unit), which is the highest value reported so far among intensity-modulated fiber refractometers. The resolution of the sensor is calculated to be 6.9 ×10−9. Moreover, we measure the sensitivity of the fiber tip in the backreflection mode using salt-water solutions and obtained a sensitivity value of 620 dB/RIU. This sensor is ultra-sensitive, simple, easy to fabricate, and low-cost, which makes it a promising tool for on-site measurements and point-of-care applications.
- Published
- 2022
3. Ptychographic optical coherence tomography
- Author
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Kjeld S. E. Eikema, Mengqi Du, Stefan Witte, Lars Loetgering, ARCNL, LaserLaB - Physics of Light, Atoms, Molecules, Lasers, Amsterdam Neuroscience - Brain Imaging, and LaserLaB - Biophotonics and Microscopy
- Subjects
Computer science ,Physics::Optics ,02 engineering and technology ,01 natural sciences ,Signal ,010309 optics ,Mice ,020210 optoelectronics & photonics ,Optics ,Optical coherence tomography ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Medical imaging ,medicine ,Image Processing, Computer-Assisted ,Animals ,medicine.diagnostic_test ,business.industry ,Bandwidth (signal processing) ,Brain ,021001 nanoscience & nanotechnology ,Sample (graphics) ,Atomic and Molecular Physics, and Optics ,Ptychography ,Interferometry ,0210 nano-technology ,business ,Axial symmetry ,Tomography, Optical Coherence - Abstract
Ptychography is a robust computational imaging technique that can reconstruct complex light fields beyond conventional hardware limits. However, for many wide-field computational imaging techniques, including ptychography, depth sectioning remains a challenge. Here we demonstrate a high-resolution three-dimensional (3D) computational imaging approach, which combines ptychography with spectral-domain imaging, inspired by optical coherence tomography (OCT). This results in a flexible imaging system with the main advantages of OCT, such as depth-sectioning without sample rotation, decoupling of transverse and axial resolution, and a high axial resolution only determined by the source bandwidth. The interferometric reference needed in OCT is replaced by computational methods, simplifying hardware requirements. As ptychography is capable of deconvolving the illumination contributions in the observed signal, speckle-free images are obtained. We demonstrate the capabilities of ptychographic optical coherence tomography (POCT) by imaging an axially discrete lithographic structure and an axially continuous mouse brain sample.
- Published
- 2021
4. 70 μm diameter optical probe for common-path optical coherence tomography in air and liquids
- Author
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Marica Marrese, Davide Iannuzzi, Hidde Offerhaus, Erik Paardekam, Biophotonics and Medical Imaging, LaserLaB - Biophotonics and Microscopy, and Amsterdam Neuroscience - Brain Imaging
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Materials science ,genetic structures ,02 engineering and technology ,01 natural sciences ,010309 optics ,chemistry.chemical_compound ,Optics ,Optical coherence tomography ,0103 physical sciences ,medicine ,Fiber ,medicine.diagnostic_test ,business.industry ,High-refractive-index polymer ,021001 nanoscience & nanotechnology ,Atomic and Molecular Physics, and Optics ,Common path ,chemistry ,Barium titanate ,sense organs ,0210 nano-technology ,business ,SDG 6 - Clean Water and Sanitation ,Sensitivity (electronics) ,Refractive index ,Preclinical imaging - Abstract
We investigate and validate a novel method to fabricate ultrathin optical probes for common-path optical coherence tomography (CP-OCT). The probes are obtained using a 65 μm barium titanate microsphere inserted into an inward concave cone chemically etched at the end of a single-mode fiber. We demonstrate that the high refractive index (n 1.95) of the barium titanate microspheres allows one to maintain high sensitivity even while imaging in liquids, reaching a sensitivity of 83 dB. Due to its low cost, flexibility, and ease of use, the probe holds promise for the development of a new generation of ultrathin needle-based OCT systems.
- Published
- 2018
5. Compressive imaging through a multimode fiber
- Author
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Lyubov V. Amitonova, Johannes F. de Boer, Biophotonics and Medical Imaging, Amsterdam Neuroscience - Brain Imaging, and LaserLaB - Biophotonics and Microscopy
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Wavefront ,Materials science ,Multi-mode optical fiber ,Optical sectioning ,business.industry ,Image quality ,Image processing ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,010309 optics ,Speckle pattern ,Optics ,0103 physical sciences ,Fiber ,SDG 7 - Affordable and Clean Energy ,0210 nano-technology ,business ,Raster scan - Abstract
We propose and experimentally demonstrate a new concept of endo-microscopy: compressive multimode (MM) fiber imaging. We show that the speckle patterns generated in a MM fiber represent an excellent basis for compressive sensing. We demonstrate high-resolution compressive imaging through a fiber probe with the total number of measurements 20 times less than what is required for the standard raster scanning approach to endo-microscopy. Moreover, we show that the inherent optical sectioning of a MM fiber can help to overcome the main problem of compressive sensing and can be used for the imaging of bulk structures. Compressive MM fiber imaging does not require complex wavefront shaping and significantly increases the pre-calibration and imaging speed, creating a new approach to endo-microscopy.
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- 2018
6. Lensless phase contrast microscopy based on multiwavelength Fresnel diffraction
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Stefan Witte, Daniel W. E. Noom, Kjeld S. E. Eikema, Atoms, Molecules, Lasers, Biophotonics and Medical Imaging, LaserLaB - Physics of Light, Neuroscience Campus Amsterdam - Brain Imaging Technology, and LaserLaB - Biophotonics and Microscopy
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Image formation ,Microscope ,Materials science ,business.industry ,Phase-contrast X-ray imaging ,Resolution (electron density) ,Atomic and Molecular Physics, and Optics ,Ptychography ,law.invention ,Optics ,law ,Microscopy ,Phase retrieval ,business ,Fresnel diffraction - Abstract
We demonstrate a compact, wide-field, quantitative phase contrast microscope that does not require lenses for image formation. High-resolution images are retrieved from Fresnel diffraction patterns recorded at multiple wavelengths, combined with a robust iterative phase retrieval algorithm. Quantitative phase contrast images of living cultured neurons are obtained with a transverse resolution of
- Published
- 2014
7. Immersion photoacoustic spectrometer (iPAS) for arcing fault detection in power transformers
- Author
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Sheng Zhou, Davide Iannuzzi, Biophotonics and Medical Imaging, LaserLaB - Biophotonics and Microscopy, and Amsterdam Neuroscience - Brain Imaging
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Materials science ,Spectrometer ,Transformer oil ,business.industry ,Acoustics ,Linearity ,Response time ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Fault detection and isolation ,010309 optics ,Electric arc ,Optics ,0103 physical sciences ,Immersion (virtual reality) ,SDG 7 - Affordable and Clean Energy ,0210 nano-technology ,business ,Photoacoustic spectroscopy - Abstract
We report on the development of the first immersion photoacoustic spectrometer (iPAS) for arcing fault detection in power transformers. The spectrometer consists of a detection system and an all-optical photoacoustic sensing head mounted inside a small permeable chamber where dissolved C2H2 diffuses while the transformer oil is kept out. Our all-optical iPAS sensor can be placed directly inside an oil bath and measure dissolved C2H2 with the sensitivity and linearity needed for in situ arcing fault detection. Moreover, its fast response time holds great promise for extra-early fault diagnosis.
- Published
- 2019
8. Top-down approach to fiber-top cantilevers
- Author
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G.L. Gruca, D.C. Chavan, K. Heeck, J.H. Rector, Tjerk H. Oosterkamp, Davide Iannuzzi, Khashayar Babaei Gavan, Biophotonics and Medical Imaging, and LaserLaB - Biophotonics and Microscopy
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Cantilever ,Optical fiber ,Materials science ,Nanotechnology ,02 engineering and technology ,01 natural sciences ,law.invention ,010309 optics ,Optics ,law ,Fiber laser ,0103 physical sciences ,Sensitivity (control systems) ,Innovation ,Lithography ,Optical Fibers ,Microelectromechanical systems ,business.industry ,021001 nanoscience & nanotechnology ,Silicon Dioxide ,Atomic and Molecular Physics, and Optics ,Surface micromachining ,Microscopy, Electron ,and Infrastructure ,Microtechnology ,SDG 9 - Industry, Innovation, and Infrastructure ,Photolithography ,0210 nano-technology ,business ,SDG 9 - Industry - Abstract
Taking inspiration from conventional top-down micromachining techniques, we have fabricated a low mass gold fiber-top cantilever via align-and-shine photolithography. The cantilever is characterized by measuring its resonance frequency and mechanical quality factor. Our results show that the device grants mass sensitivity comparable to that reported for similar standard cantilevers. This proof-of-concept paves the way to series production of highly sensitive fiber-top devices for remote detection of biochemical substances.
- Published
- 2011
9. Demonstration of miniature all-optical photoacoustic spectrometer based on ferrule-top technology
- Author
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J.H. Rector, Davide Iannuzzi, K. Heeck, G.L. Gruca, LaserLaB - Biophotonics and Microscopy, and Biophotonics and Medical Imaging
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Time delay and integration ,Optical fiber ,Materials science ,Physics::Optics ,02 engineering and technology ,01 natural sciences ,law.invention ,Physics::Geophysics ,010309 optics ,Optics ,law ,0103 physical sciences ,SDG 7 - Affordable and Clean Energy ,Spectrometer ,business.industry ,Ferrule ,021001 nanoscience & nanotechnology ,Laser ,Pressure sensor ,Atomic and Molecular Physics, and Optics ,Computer Science::Other ,Interferometry ,Transducer ,0210 nano-technology ,business - Abstract
We present a miniaturized photoacoustic (PA) spectrometer obtained by carving a micromachined flexural pressure transducer directly at the top of a glass ferrule. The ferrule is equipped with two optical fibers, one for laser excitation of the gas and one for interferometric readout of the transducer. To demonstrate the working principle and assess the sensitivity of the device, we performed a set of measurements of C2H2 traces in an Ar buffer atmosphere. The data acquired show that our ferrule-top scheme allows one to increase the minimum detectable concentration by more than one order of magnitude with respect to the other miniaturized PA spectrometers reported in the literature, while decreasing the integration time by a factor of 10.
- Published
- 2013
- Full Text
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10. Collecting optical coherence elastography depth profiles with a micromachined cantilever probe
- Author
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Johannes F. de Boer, Davide Iannuzzi, Mattijs de Groot, Anna E. C. Meijering, Jianhua Mo, D.C. Chavan, Biophotonics and Medical Imaging, Physics of Living Systems, Student Lab and Education, and LaserLaB - Biophotonics and Microscopy
- Subjects
Cantilever ,Optical fiber ,Materials science ,medicine.diagnostic_test ,business.industry ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,law.invention ,010309 optics ,Interferometry ,Optics ,Optical coherence tomography ,law ,Deflection (engineering) ,Indentation ,0103 physical sciences ,medicine ,Elastography ,0210 nano-technology ,business ,Optomechanics - Abstract
We present an experimental setup that combines optical coherence elastography depth sensing with atomic force microscope indentation. The instrument relies on a miniaturized cantilever probe that compresses a sample with a small footprint force and simultaneously collects an optical coherence tomography (OCT) depth profile underneath the indenting point. The deflection of the cantilever can be monitored via optical fiber interferometry with a resolution of 2 nm. The OCT readout then provides depth profiles of the subsurface layer deformation with 15 nm resolution and depth range of a few millimeters. © 2013 Optical Society of America.
- Published
- 2013
- Full Text
- View/download PDF
11. In vivo depth-resolved birefringence measurements of the human retinal nerve fiber layer by polarization-sensitive optical coherence tomography
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Mark C. Pierce, Johannes F. de Boer, Teresa C. Chen, Barry Cense, B. Hyle Park, Biophotonics and Medical Imaging, and LaserLaB - Biophotonics and Microscopy
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Retina ,Birefringence ,Materials science ,medicine.diagnostic_test ,genetic structures ,business.industry ,Nerve fiber layer ,Glaucoma ,Retinal ,medicine.disease ,Atomic and Molecular Physics, and Optics ,eye diseases ,chemistry.chemical_compound ,medicine.anatomical_structure ,Optics ,chemistry ,Optical coherence tomography ,medicine ,Optic nerve ,sense organs ,Optical tomography ,business - Abstract
o our knowledge, this is the first demonstration of in vivo depth-resolved birefringence measurements of the human retinal nerve fiber layer (RNFL) by use of polarization-sensitive optical coherence tomography (PS-OCT). Because glaucoma causes nerve fiber layer damage, which may cause loss of retinal birefringence, PS-OCT is a potentially useful technique for the early detection of glaucoma. We built a fiber-based PS-OCT setup that produces quasi-real-time images of the human retina in vivo. Preliminary measurements of a healthy volunteer showed that the double-pass phase retardation per unit depth of the RNFL near the optic nerve head is 39 +/- 6degrees/100 mum. (C) 2002 Optical Society of America.
- Published
- 2002
12. Spectral shaping for non-Gaussian source spectra in optical coherence tomography
- Author
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Renu Tripathi, J. Stuart Nelson, Johannes F. de Boer, Nader Nassif, Boris Hyle Park, Biophotonics and Medical Imaging, and LaserLaB - Biophotonics and Microscopy
- Subjects
Physics ,Point spread function ,Quantum Physics ,Digital image correlation ,medicine.diagnostic_test ,business.industry ,Image quality ,Physics::Optics ,Optics ,Image processing ,Optical Physics ,Atomic and Molecular Physics, and Optics ,Spectral line ,Optical coherence tomography ,Modulation ,Electrical And Electronic Engineering ,medicine ,Optical tomography ,business - Abstract
We present a digital spectral shaping technique to reduce the sidelobes (ringing) of the axial point-spread function in optical coherence tomography for non-Gaussian-shaped source spectra. The spectra of two superluminescent diodes were combined to generate a spectrum with significant modulation. Images of onion cells demonstrate the improved image quality in a turbid biological sample. A quantitative analysis of the accompanying penalty in signal-to-noise ratio is given. (C) 2002 Optical Society of America.
- Published
- 2002
13. High-speed fiber-based polarization-sensitive optical coherence tomography of in vivo human skin
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B.H. Park, J.S. Nelson, CE Saxer, Zhongping Chen, Yonghua Zhao, J. F. de Boer, Biophotonics and Medical Imaging, and LaserLaB - Biophotonics and Microscopy
- Subjects
Optical fiber ,Birefringence ,Materials science ,medicine.diagnostic_test ,genetic structures ,business.industry ,Physics::Medical Physics ,Michelson interferometer ,Speckle noise ,Polarization (waves) ,Atomic and Molecular Physics, and Optics ,eye diseases ,law.invention ,symbols.namesake ,Optics ,Optical coherence tomography ,law ,symbols ,medicine ,Stokes parameters ,Optoelectronics ,sense organs ,business ,Phase modulation - Abstract
A high-speed single-mode fiber-based polarization-sensitive optical coherence tomography (PS OCT) system was developed. With a polarization modulator, Stokes parameters of reflected flight for four input polarization states are measured as a function of depth. A phase modulator in the reference arm of a Michelson interferometer permits independent control of the axial scan rate and carrier frequency. In vivo PS OCT images of human skin are presented, showing subsurface structures that are not discernible in conventional OCT images. A phase retardation image in tissue is calculated based on the reflected Stokes parameters of the four input polarization states. (C) 2000 Optical Society of America.
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- 2000
14. Phase-resolved optical coherence tomography and optical Doppler tomography for imaging blood flow in human skin with fast scanning speed and high velocity sensitivity
- Author
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Yonghua Zhao, Zhongping Chen, Christopher Saxer, Shaohua Xiang, Johannes F. de Boer, J. Stuart Nelson, Biophotonics and Medical Imaging, and LaserLaB - Biophotonics and Microscopy
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Physics ,medicine.diagnostic_test ,business.industry ,Phase (waves) ,Atomic and Molecular Physics, and Optics ,symbols.namesake ,Speckle pattern ,Optics ,Flow velocity ,Optical coherence tomography ,symbols ,medicine ,Optical Doppler Tomography ,sense organs ,business ,Phase retrieval ,Doppler effect ,Image resolution - Abstract
The invention is a fast-scanning ODT system that uses phase information derived from a Hilbert transformation to increase the sensitivity of flow velocity measurements while maintaining high spatial resolution. The significant increases in scanning speed and velocity sensitivity realized by the invention make it possible to image in vivo blood flow in human skin. The method of the invention overcomes the inherent limitations of the prior art ODT by using a phase change between sequential line scans for velocity image reconstruction. The ODT signal phase or phase shifts at each pixel can be determined from the complex function, {tilde over (Γ)}ODT(t), which is determined through analytic continuation of the measured interference fringes function, ΓODT(t), by use of a Hilbert transformation, by electronic phase demodulation, by optical means, or a fast Fourier transformation. The phase change in each pixel between axial-line scans is then used to calculate the Doppler frequency shift. Sequential measurements of a single line scan, measurements of sequential line scans or measurements of line scans in sequential frames may be used. Because the time between line scans is much longer than the pixel time window, very small Doppler shifts can be detected with this technique. In addition, spatial resolution and velocity sensitivity are decoupled. Furthermore, because two axial-line scans are compared at the same location, speckle modulations in the fringe signal cancel each other and, therefore, will not affect the phase-difference calculation.
- Published
- 2000
15. Simultaneous intensity, birefringence, and flow measurements with high-speed fiber-based optical coherence tomography
- Author
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Johannes F. de Boer, B. Hyle Park, Mark C. Pierce, Barry Cense, Biophotonics and Medical Imaging, and LaserLaB - Biophotonics and Microscopy
- Subjects
Birefringence ,Materials science ,medicine.diagnostic_test ,business.industry ,Blood flow ,Atomic and Molecular Physics, and Optics ,Intensity (physics) ,symbols.namesake ,Optics ,Optical coherence tomography ,symbols ,medicine ,Optical Doppler Tomography ,Fiber ,business ,Doppler effect ,Preclinical imaging - Abstract
We demonstrate that tissue structure, birefringence, and blood flow can be imaged simultaneously by use of techniques of polarization-sensitive optical coherence tomography and phase-resolved optical Doppler tomography. An efficient data-acquisition procedure is implemented that optimizes the concurrent processing and display of all three image types. Images of in vivo human skin acquired with a high-speed fiber-based system are presented. (C) 2002 Optical Society of America.
- Published
- 2002
16. Doppler standard deviation imaging for clinical monitoring of in vivo human skin blood flow
- Author
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J.S. Nelson, QM Shen, S. H. Xiang, J. F. de Boer, Yonghua Zhao, Zhongping Chen, CE Saxer, Biophotonics and Medical Imaging, and LaserLaB - Biophotonics and Microscopy
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congenital, hereditary, and neonatal diseases and abnormalities ,medicine.diagnostic_test ,business.industry ,nutritional and metabolic diseases ,Magnetic resonance imaging ,Human skin ,Blood flow ,Atomic and Molecular Physics, and Optics ,symbols.namesake ,Optics ,SDG 3 - Good Health and Well-being ,Optical coherence tomography ,symbols ,Medicine ,Optical Doppler Tomography ,Tomography ,business ,Doppler effect ,Image resolution - Abstract
We used a novel phase-resolved optical Doppler tomographic (ODT) technique with very high flow-velocity sensitivity (10 mu m/s) and high spatial resolution (10 mu m) to image blood flow in port-wine stain (PWS) birth-marks in human skin. in addition to the regular ODT velocity and structural images, we use the variance of blood flow velocity to map the PWS vessels. Our device combines ODT and therapeutic systems such that PWS blood flow can be monitored in situ before and after laser treatment. To the authors' knowledge this is the first clinical application of ODT to provide a fast semiquantitative evaluation of the efficacy of PWS laser therapy in situ and in real time. (C) 2000 Optical Society of America.
- Published
- 2000
17. zPIE: an autofocusing algorithm for ptychography
- Author
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Stefan Witte, Mengqi Du, Kjeld S. E. Eikema, Lars Loetgering, LaserLaB - Physics of Light, ARCNL, Atoms, Molecules, Lasers, Amsterdam Neuroscience - Brain Imaging, and LaserLaB - Biophotonics and Microscopy
- Subjects
Physics ,Microscope ,business.industry ,Phase (waves) ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Interference microscopy ,Ptychography ,law.invention ,010309 optics ,Optics ,law ,0103 physical sciences ,Metric (mathematics) ,Multislice ,Depth of field ,0210 nano-technology ,business ,Algorithm ,Fresnel diffraction - Abstract
An autofocusing algorithm for ptychography is proposed. The method optimizes a sharpness metric that would be observed in a differential interference microscope and is valid for both amplitude and phase modulating specimens. We experimentally demonstrate that the algorithm, based on the extended ptychographic iterative engine (ePIE), calibrates the sample–detector distance with an accuracy within the depth of field of the ptychographic microscope. We show that the method can be used to determine slice separation in multislice ptychography, provided there are isolated regions on each slice of the specimen that do not axially overlap.
- Full Text
- View/download PDF
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