1,720,967 research outputs found
Nonlinear Ptychographic coherent diffractive imaging
No full textPtychographic Coherent Diffractive Imaging (PCDI) is
a significant advance in imaging allowing the measurement of the full electric field at a sample without use of any imaging optics. So far it has been confined solely to imaging of linear optical responses. In this paper we show that because of the coherence-preserving nature of nonlinear optical interactions, PCDI can be generalised to nonlinear optical imaging. We demonstrate second harmonic generation PCDI, directly revealing phase information about the nonlinear coefficients, and showing the general applicability of PCDI to nonlinear interactions.
Data supports the paper "Odstrcil, Michal, Baksh, Peter, Gawith, Corin, Vrcelj, Ranko, Frey, Jeremy and Brocklesby, William (2016) Nonlinear ptychographic coherent diffractive imaging. Optics Express"</span
Ptychographic imaging of real biological samples using a high harmonic and synchrotron source
No full textVisualisation of nano structure is essential for rapidly evolving fields such as lithography,and to gain a greater understanding of mechanisms behind biological processes. This thesis focuses on using coherent diffraction imaging methods to resolve fine biological structures using a high harmonic generation source and a synchrotron source. The majority of work is focused on developing imaging using the ptychography technique using extreme ultraviolet radiation (EUV) at the University of Southampton.The state of the high harmonic generation imaging beam line is first improved. Flux, stability, and coherence have all been improved in order to meet the required beam characteristics for ptychography imaging. We present published experimental data that shows the first high resolution transmission polychromatic ptychography result from a high harmonic source. To the best of our knowledge we also show the first near field ptychography reconstruction on a high harmonic source. The very first images of real biological samples (chromosomes and hippocampal neurons) using high harmonic generation ptychography are presented. We can achieve 54nm resolution over 100 μm field of view of weakly scattering samples imaging both phase and amplitude. Our EUV microscope is compared to data collected using an established hard X-ray synchrotron source, where it is found far more information can be extracted from the inexpensive table-top source at the University of Southampton
XUV ptychographic imaging using a high harmonic source
No full textXUV ptychographic imaging using a high harmonic sourc
Ptychographic coherent diffractive imaging with orthogonal probe relaxation
No full textPtychography is a scanning coherent diffractive imaging (CDI) technique that relies upon a high level of stability of the illumination during the course of an experiment. This is particularly an issue for coherent sources where the beam intensity is usually tightly focused on the sample in order to maximize the photon flux density on the illuminated region of the sample. We present a method that includes limited stability of the illumination probe into the ptychography reconstruction. We have tested our reconstruction method in a proof of concept experiment, where the beam instability of a visible light source was emulated using a piezo driven mirror, and also in a short wavelength microscopy setup using a high harmonic generation source in the extreme ultraviolet range. Our work is showing a natural extension of the ptychography method that paves the way to use ptychographic imaging with any limited pointing stability coherent source such as free electron or soft X-ray lasers.</span
Wide-field broadband extreme ultraviolet transmission ptychography using a high-harmonic source
No full textHigh-harmonic generation (HHG) provides a laboratory-scale source of coherent radiation ideally suited to lensless coherent diffractive imaging (CDI) in the EUV and x-ray spectral region. Here we demonstrate transmission extreme ultraviolet (EUV) ptychography, a scanning variant of CDI, using radiation at a wavelength around 29 nm from an HHG source. Image resolution is diffraction-limited at 54 nm and fields of view up to ∼100 μm are demonstrated. These results demonstrate the potential for wide-field, high-resolution, laboratory-scale EUV imaging using HHG-based sources with potential application in biological imaging or EUV lithography pellicle inspection
Data for Lloyd’s mirror interference lithography with the EUV radiation from a high harmonic source
No full textWe demonstrate interference lithography using a high-harmonic source. Extreme ultraviolet (EUV) radiation is produced using high harmonic generation with 800 nm light from a femtosecond Ti:Sapphire laser (40 fs pulses, 1 kHz, 2W average power) in argon gas. Interference patterns created using a Lloyd’s mirror setup and monochromatized radiation at the 27th harmonic (29 nm) are recorded using ZEP-520A photoresist, producing features with < 200 nm pitch. The influence of the use of femtosecond pulsed EUV radiation on the recorded pattern is investigated. The capability of the high-harmonic source for high-resolution patterning is discussed.</span
Ptychographic coherent diffractive imaging with orthogonal probe relaxation
No full textPtychography is a scanning coherent diffractive imaging (CDI) technique that relies upon a high level of stability of the illumination during the course of an experiment. This is particularly an issue for coherent short wavelength sources, where the beam intensity is usually tightly focused on the sample in order to maximize the photon flux density on the illuminated region of the sample and thus a small change in the beam position results in a significant change in illumination of the sample. We present an improved ptychographic method that allows for limited stability of the illumination wavefront and thus significantly improve the reconstruction quality without additional prior knowledge. We have tested our reconstruction method in a proof of concept experiment, where the beam instability of a visible light source was emulated using a piezo driven mirror, and also in a short wavelength microscopy CDI setup using a high harmonic generation source in the extreme ultraviolet range. Our work shows a natural extension of the ptychography method that paves the way to use ptychographic imaging with any limited pointing stability coherent source such as free electron or soft X-ray lasers and improve reconstruction quality of long duration synchrotron experiments
Towards laser driven table-top coherent diffractive X-ray microscopy of cultured hippocampal neurons
No full textNeurodegenerative diseases such as Alzheimer’s disease have a huge impact on the world population; over 44 million people worldwide and 850,000 in the UK were recorded as living with dementia in 2013. There are numerous theories attempting to explain the cause of Alzheimer’s disease. Histology from the brains of people who had Alzheimer’s disease shows neurofibilliary tangles and amyloid plaques. Their role in the mechanism of disease is not yet completely understood but we envisage that novel imaging techniques may aid understanding. We present initial data collected using confocal fluorescence microscopy and hard X-ray scanning diffractive microscopy (ptychography) on cultured neuron samples plus high resolution large field of view imaging of test samples from a soft X-ray lab based high harmonic generation (HHG) source
Ultra-broadband ptychography with self-consistent coherence estimation from a high harmonic source
No full textWith the aim of improving imaging using table-top extreme ultraviolet sources, we demonstrate coherent diffraction imaging (CDI) with relative bandwidth of 20%. The coherence properties of the illumination probe are identified using the same imaging setup. The presented methods allows for the use of fewer monochromating optics, obtaining higher flux at the sample and thus reach higher resolution or shorter exposure time. This is important in the case of ptychography when a large number of diffraction patterns need to be collected. Our microscopy setup was tested on a reconstruction of an extended sample to show the quality of the reconstruction. We show that high harmonic generation based EUV tabletop microscope can provide reconstruction of samples with a large field of view and high resolution without additional prior knowledge about the sample or illuminatio
Lloyd's mirror interference lithography with EUV radiation from a high-harmonic source
No full textWe demonstrate interference lithography using a high-harmonic source. Extreme ultraviolet (EUV) radiation is produced by high-harmonic generation with 800 nm light from a femtosecond Ti:sapphire laser (40 fs pulses, 1 kHz, 2 W average power) in argon gas. Interference patterns created using Lloyd's mirror setup and monochromatized radiation at the 27th harmonic (29 nm) are recorded using a ZEP-520A photoresist, producing features with <200 nm pitch. The effect of the use of femtosecond pulsed EUV radiation on the recorded pattern is investigated. The capability of the high-harmonic source for high-resolution patterning is discussed
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