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Programmable Illumination and High-Speed, Multi- Wavelength, Confocal Microscopy Using a Digital Micromirror

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posted on 12.06.2013, 14:40 by Franck P. Martial, Nicholas A. Hartell
Confocal microscopy is routinely used for high-resolution fluorescence imaging of biological specimens. Most standard confocal systems scan a laser across a specimen and collect emitted light passing through a single pinhole to produce an optical section of the sample. Sequential scanning on a point-by-point basis limits the speed of image acquisition and even the fastest commercial instruments struggle to resolve the temporal dynamics of rapid cellular events such as calcium signals. Various approaches have been introduced that increase the speed of confocal imaging. Nipkov disk microscopes, for example, use arrays of pinholes or slits on a spinning disk to achieve parallel scanning which significantly increases the speed of acquisition. Here we report the development of a microscope module that utilises a digital micromirror device as a spatial light modulator to provide programmable confocal optical sectioning with a single camera, at high spatial and axial resolution at speeds limited by the frame rate of the camera. The digital micromirror acts as a solid state Nipkov disk but with the added ability to change the pinholes size and separation and to control the light intensity on a mirror-by-mirror basis. The use of an arrangement of concave and convex mirrors in the emission pathway instead of lenses overcomes the astigmatism inherent with DMD devices, increases light collection efficiency and ensures image collection is achromatic so that images are perfectly aligned at different wavelengths. Combined with non-laser light sources, this allows low cost, high-speed, multi-wavelength image acquisition without the need for complex wavelength-dependent image alignment. The micromirror can also be used for programmable illumination allowing spatially defined photoactivation of fluorescent proteins. We demonstrate the use of this system for high-speed calcium imaging using both a single wavelength calcium indicator and a genetically encoded, ratiometric, calcium sensor.

History

Citation

PLoS One, 2012, 7 (8), e43942

Author affiliation

/Organisation/COLLEGE OF MEDICINE, BIOLOGICAL SCIENCES AND PSYCHOLOGY/School of Biological Sciences/Department of Cell Physiology and Pharmacology

Version

VoR (Version of Record)

Published in

PLoS One

Publisher

Public Library of Science

issn

1932-6203

eissn

1932-6203

Copyright date

2012

Available date

12/06/2013

Publisher version

http://www.plosone.org/article/info:doi/10.1371/journal.pone.0043942

Language

en

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