Interferometric Synthetic Aperture Microscopy: Computed Imaging for Scanned Coherent Microscopy

Abstract

Three-dimensional image formation in microscopy is greatly enhanced by the use of computed imaging techniques. In particular, Interferometric Synthetic Aperture Microscopy (ISAM) allows the removal of out-of-focus blur in broadband, coherent microscopy. Earlier methods, such as optical coherence tomography (OCT), utilize interferometric ranging, but do not apply computed imaging methods and therefore must scan the focal depth to acquire extended volumetric images. ISAM removes the need to scan the focus by allowing volumetric image reconstruction from data collected at a single focal depth. ISAM signal processing techniques are similar to the Fourier migration methods of seismology and the Fourier reconstruction methods of Synthetic Aperture Radar (SAR). In this article ISAM is described and the close ties between ISAM and SAR are explored. ISAM and a simple strip-map SAR system are placed in a common mathematical framework and compared to OCT and radar respectively. This article is intended to serve as a review of ISAM, and will be especially useful to readers with a background in SAR.

Transfer of optogenetic vectors into the brain of neonatal animals to study neuron functions during subsequent periods of development

“…Коммер-ческие компании (Neuronexus, Neuralynx, Omnetics, Atlas Neuroengineering, IMTEK, Multichannel system, Intan Blackrock) предлагают различные многоканальные полу-проводниковые (с микроусилителем для каждого канала на плате) оптотроды (оптоволокно + электрод), при по-мощи которых возможны одновременные стимуляция светом и запись локальных потенциалов клеток (Davis et al, 2008;Tan et al, 2008). Плотность печати микроплат позволяет вести запись до 256 каналов, регистрируя попу-ляционные спайки малого количества нейронов (Buzsaki et al, 2015).…”

Approximate wavenumber domain algorithm for interferometric synthetic aperture microscopy

“…ISAM reconstruction of OCT image provides same transverse resolutions at different depths [9]. However, there is the requisition for high precision because of the Stolt interpolation in the frequency domain just like the precise wavenumber domain algorithm or xKA in Synthetic Aperture Radar (SAR) [10].…”

Computational optical coherence tomography [Invited]

“…The resampling step Just as the name suggests, ISAM has much in common with SAR in both the physics and mathematics of the problem [74]. A heuristic illustration in Fig.…”

“…Interestingly, as the digital computational power at that time was far from sufficient for processing radar data, Fourier optical methods were used for radar data processing [77][78][79]. Further insightful comparisons and connections between SAR and ISAM were discussed in Ref [74]. In addition to SAR, ISAM also shares a broad commonality with other systems applying computational imaging to multi-dimensional data collected using both spatial multiplex and time-of-flight measurements from a spectrallybroad temporal signal, such as synthetic aperture sonar [80], seismic migration imaging [81], and certain modalities in ultrasound [82] and photoacoustic imaging [83].…”

“…ISAM is a reconstruction technique that solves the inverse scattering problem for OCT and directly manipulates the 3D spatial frequencies, which brings all the depths into focus simultaneously and rearranges the 3D energy distribution of the data set (Fig. 4 and [74]). Digital refocusing, in contrast, only deals with one 2D en face plane at a time, and cannot concentrate the energy spreading along the axial direction, which is caused by the quadratic phase migration.…”