Abstract

Line scan based microscopy methods for deep tissue imaging

Nanguang Chen, Associate Professor, National University of Singapore

Focal Modulation microscopy (FMM) is an emerging technique for molecular imaging in deep tissues. By combining spatial filtering with focal modulation, we are able to drastically improve the signal-to-background ratio. As a result, a penetration depth three times greater than confocal microscopy can be achieved. Recently we have been working on further improving FMM in terms of image acquisition speed. We have developed line scan focal modulated microscopy, a proprietary technique highly suitable for zebrafish and mouse brain imaging. It features parallel illumination and parallel detection, leading to much improved imaging speed. A prototype line scan FMM has been built and we have demonstrated an imaging speed of 100 frames per second with enhanced optical sectioning. Optical coherence tomography (OCT) is an established morphological imaging method with a penetration depth up to 3 mm. In most existing OCT setups, A-lines are recorded sequentially when the weakly focused sample beam is scanned laterally. While a galvanometer is usually employed as the scanning device, the typical resonant frequency of high-end galvanometers is a few kilohertz. It is therefore very challenging for existing OCT techniques to go beyond 20 thousand frames per second. We have developed a novel OCT technique, which does not need a scanning mechanism for two-dimensional cross-sectional imaging. The image acquisition time can be reduced to a few nanoseconds and more than one million frames can be obtained in one second.