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Proceedings Paper

Imaging of small particles using wide-field confocal microscopy
Author(s): Stephen P. Morgan; N. B. E. Sawyer; Michael G. Somekh; Chung Wah See; B. Y. Shekunov; E. Astrakharchik
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Paper Abstract

Particle measurement is important in many applications such as the manufacture of drugs and paints, and aerosols. In bioimaging there is interest understanding the imaging of nanoparticles and subcellular scatterers. We present in this paper a wide field, phase measuring confocal microscope that can be used for such measurements. The wide field confocal response is obtained by illuminating both sample and reference arms of an interferometric microscope with nominally identical speckle patterns. When the speckle patterns are highly correlated the interference is significant. Contributions from out of focus planes result in uncorrelated speckle patterns and no interference. This provides a wide field confocal response. High speed measurements are enabled by parallel phase stepping using polarization optics. We have also developed a vector diffraction microscope model, using Mie theory as a scattering function, to validate the images of small particles. Correctly scaling the amplitudes of the unscattered and scattered electric fields enables co-polar transmission imaging to be modeled. Finally it is demonstrated that the phase is a more sensitive measurement of particle size than the amplitude.

Paper Details

Date Published: 13 October 2003
PDF: 8 pages
Proc. SPIE 5068, Saratov Fall Meeting 2002: Optical Technologies in Biophysics and Medicine IV, (13 October 2003); doi: 10.1117/12.518774
Show Author Affiliations
Stephen P. Morgan, Univ. of Nottingham (United Kingdom)
N. B. E. Sawyer, Univ. of Nottingham (United Kingdom)
Michael G. Somekh, Univ. of Nottingham (United Kingdom)
Chung Wah See, Univ. of Nottingham (United Kingdom)
B. Y. Shekunov, Univ. of Bradford (United Kingdom)
E. Astrakharchik, Univ. of Bradford (United Kingdom)


Published in SPIE Proceedings Vol. 5068:
Saratov Fall Meeting 2002: Optical Technologies in Biophysics and Medicine IV
Valery V. Tuchin, Editor(s)

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