Controllable Fabrication of Au Nanocups by Confined-Space Thermal Dewetting for OCT Imaging.

Here, this study reports a novel confined-space thermal dewetting strategy for the fabrication of Au nanocups with tunable diameter, height, and size of cup opening. The nanocup morphology is defined by the cup-shaped void space created by a yolk-shell silica template that spontaneously takes an eccentric configuration during annealing. Thermal dewetting of Au, which is sandwiched between the yolk and shell, leads to the desired nanocup morphology. With strong scattering in near infrared, the Au nanocups exhibit superior efficiency as contrast agents for spectral-domain optical coherence tomography imaging. This confined-space thermal dewetting strategy is scalable and general, and can be potentially extended to the synthesis of novel anisotropic nanostructures of various compositions that are difficult to produce by conventional wet chemical or physical methods, thus opening up opportunities for many new applications.

Imaging of optic nerve head drusen: improvements with spectral domain optical coherence tomography.

OBJECTIVE: To demonstrate a new algorithm that can determine the shape, location, and volume of optic nerve head drusen (ONHD), which were imaged with spectral domain optical coherence tomography (SDOCT). METHODS: One exenteration patient and 4 glaucoma patients with bilateral ONHD were recruited from the Massachusetts Eye and Ear Infirmary and from a private practice office. Images were obtained using an experimental SDOCT system developed at the Wellman Center for Photomedicine, Massachusetts General Hospital. With axial resolutions of about 6 mum, SDOCT can obtain 2-dimensional images in 1/29 of a second, compared with commercially available time domain OCT instruments with 10 mum resolution images in 1.28 seconds. The volumes of ONHD were calculated with a new algorithm and were then correlated with visual field mean deviation. RESULTS: SDOCT can display 2-dimensional images comparable with histology and 3-dimensional videos of ONHD. ONHD are signal-poor regions with high-signaled borders. Larger ONHD volumes are directly correlated with larger mean deviation absolute values on Humphrey visual field testing. CONCLUSIONS: SDOCT is a potentially better technique for ONHD imaging and may improve the diagnosis and management of patients with both OHND and glaucoma.

Spectral shaping for non-Gaussian source spectra in optical coherence tomography.

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.