22/08/2010

3D optical microscopy

As a scientist primarily researching in structural biology, I'm always interested in techniques in which the data is visual - whether they be direct microscopic or telescopic images, or derived, such as electron density maps or tomographic reconstructions.


Recently, I read a very interesting article in Physics World about how techniques from "adaptive optics", which has been very successful in improving astronomical images from ground-based telescopes, can be applied to optical microscopy. This leads immediately to a range of possible applications for cell biology. Unfortunately the article is only available to subscribers (oh how I hate that), but I found the web-page of the author, Alan Greenaway, which I'd like to share.

The particular technique that caught my attention was the use of a diffraction grating to split light after focusing by an objective lens, but prior to image formation. This diffraction grating has been constructed in such a way that three images are formed next to each other, corresponding to three separate focal planes in the specimen. Amazingly, this allows three-dimensional information in the form of a "z-stack" to be recorded simultaneously and live, with a single microscope. So, living, mobile cells such as swimming sperm can be imaged in a pseudo-3D movie. In combination with fluorescence imaging, it is possible to record depth information for single particles and vesicles during live biological processes.

This is a fascinating idea, and somehow all the more pleasing that it came from academic interdisciplinary research rather than from the R&D department of a large technology company.

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