Two Imphys papers published in the same issue of Optics Express

News - 18 October 2016

In the Optics Express issue 21 two publications of ImPhys are published. One from CPO and one from QI.
1.) "Image resolution and deconvolution in optical tomography" by Jelle van der Horst and Jeroen Kalkman
2.) "Time-resolved cathodoluminescence microscopy with sub-nanosecond beam blanking for direct evaluation of the local density of states" by Robert J. Moerland, I. Gerward C. Weppelman, Mathijs W. H. Garming, Pieter Kruit, and Jacob P. Hoogenboom.

"Image resolution and deconvolution in optical tomography"

Jelle van der Horst and Jeroen Kalkman

Abstract:
We present a frequency domain analysis of the image resolution of optical tomography systems. The result of our analysis is a description of the spatially-variant resolution in optical tomographic image after reconstruction as a function of the properties of the imaging system geometry. We validate our model using optical projection tomography (OPT) measurements of fluorescent beads embedded in agarose gel. Our model correctly describes both the radial and tangential resolution of the measured images. In addition, we present a correction of the tomographic images for the spatially-varying resolution using a deconvolution algorithm. The resulting corrected tomographic reconstruction shows a homogeneous and isotropic pixel-limited resolution across the entire image. Our method is applied to OPT measurements of a zebrafish, showing improved resolution. Aside from allowing image correction and providing a resolution measure for OPT systems, our model provides a powerful tool for the design of optical tomographic systems.

Link paper

"Time-resolved cathodoluminescence microscopy with sub-nanosecond beam blanking for direct evaluation of the local density of states"

Robert J. Moerland, I. Gerward C. Weppelman, Mathijs W. H. Garming, Pieter Kruit, and Jacob P. Hoogenboom

Abstract:
We show cathodoluminescence-based time-resolved electron beam spectroscopy in order to directly probe the spontaneous emission decay rate that is modified by the local density of states in a nanoscale environment. In contrast to dedicated laser-triggered electron-microscopy setups, we use commercial hardware in a standard SEM, which allows us to easily switch from pulsed to continuous operation of the SEM. Electron pulses of 80–90 ps duration are generated by conjugate blanking of a high-brightness electron beam, which allows probing emitters within a large range of decay rates. Moreover, we simultaneously attain a resolution better than λ/10, which ensures details at deep-subwavelength scales can be retrieved. As a proof-of-principle, we employ the pulsed electron beam to spatially measure excited-state lifetime modifications in a phosphor material across the edge of an aluminum half-plane, coated on top of the phosphor. The measured emission dynamics can be directly related to the structure of the sample by recording photon arrival histograms together with the secondary-electron signal. Our results show that time-resolved electron cathodoluminescence spectroscopy is a powerful tool of choice for nanophotonics, within reach of a large audience. 

Link paper

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