557,152 research outputs found
Advanced magneto-optical microscopy: Imaging from picoseconds to centimeters - imaging spin waves and temperature distributions (invited)
© 2016 Author(s).Recent developments in the observation of magnetic domains and domain walls by wide-field optical microscopy based on the magneto-optical Kerr, Faraday, Voigt, and Gradient effect are reviewed. Emphasis is given to the existence of higher order magneto-optical effects for advanced magnetic imaging. Fundamental concepts and advances in methodology are discussed that allow for imaging of magnetic domains on various length and time scales. Time-resolved imaging of electric field induced domain wall rotation is shown. Visualization of magnetization dynamics down to picosecond temporal resolution for the imaging of spin-waves and magneto-optical multi-effect domain imaging techniques for obtaining vectorial information are demonstrated. Beyond conventional domain imaging, the use of a magneto-optical indicator technique for local temperature sensing is shown
Nonlinear ptychographic coherent diffractive imaging
Ptychographic 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
Optically gated beating-heart imaging
The constant motion of the beating heart presents an obstacle to clear optical imaging, especially 3D imaging, in small animals where direct optical imaging would otherwise be possible. Gating techniques exploit the periodic motion of the heart to computationally "freeze" this movement and overcome motion artefacts. Optically gated imaging represents a recent development of this, where image analysis is used to synchronize acquisition with the heartbeat in a completely non-invasive manner. This article will explain the concept of optical gating, discuss a range of different implementation strategies and their strengths and weaknesses. Finally we will illustrate the usefulness of the technique by discussing applications where optical gating has facilitated novel biological findings by allowing 3D in vivo imaging of cardiac myocytes in their natural environment of the beating heart
Phase Retrieval with Application to Optical Imaging
This review article provides a contemporary overview of phase retrieval in
optical imaging, linking the relevant optical physics to the information
processing methods and algorithms. Its purpose is to describe the current state
of the art in this area, identify challenges, and suggest vision and areas
where signal processing methods can have a large impact on optical imaging and
on the world of imaging at large, with applications in a variety of fields
ranging from biology and chemistry to physics and engineering
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Advanced optical imaging methods for investigating manuscripts
This paper gives an overview of advanced optical imaging methods relevant to the study of manuscripts. While some of the methods covered are well established, others are very much in active development. ‘Optical’ in this context is loosely defined to cover the near ultraviolet, visible and the near infrared part of the electromagnetic spectrum. Optical imaging methods are in general non-destructive and can be applied in situ. They are non-invasive if care is taken to ensure a safe dosage of illumination during the imaging process. The examples given in this paper are biased towards work that the author has been involved in. This is by no means a comprehensive review. The aim of the paper is to illustrate how advanced optical imaging techniques can assist in the investigation of manuscripts
Electron beam profile imaging in the presence of coherent optical radiation effects
High-brightness electron beams with low energy spread at existing and future
x-ray free-electron lasers are affected by various collective beam
self-interactions and microbunching instabilities. The corresponding coherent
optical radiation effects, e.g., coherent optical transition radiation, render
electron beam profile imaging impossible and become a serious issue for all
kinds of electron beam diagnostics using imaging screens. Furthermore, coherent
optical radiation effects can also be related to intrinsically ultrashort
electron bunches or the existence of ultrashort spikes inside the electron
bunches. In this paper, we discuss methods to suppress coherent optical
radiation effects both by electron beam profile imaging in dispersive beamlines
and by using scintillation imaging screens in combination with separation
techniques. The suppression of coherent optical emission in dispersive
beamlines is shown by analytical calculations, numerical simulations, and
measurements. Transverse and longitudinal electron beam profile measurements in
the presence of coherent optical radiation effects in non-dispersive beamlines
are demonstrated by applying a temporal separation technique.Comment: 12 pages, 11 figures, submitted to Phys. Rev. ST Accel. Beam
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