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Proceedings Paper

Edge enhancement of weak-phase object in laser scanning confocal microscope
Author(s): Masahide Itoh; Shin Uematsu; Hiroshi Ishiwata; Toyohiko Yatagai
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Paper Abstract

In the image of laser scanning confocal microscope, an edge of a weak phase object is sometimes enhanced as bright and/or dark line. This phenomenon is thought to be caused by the interference effect of diffractive light from the edge. The imaging characteristics of this type of microscope are regarded as a product of the optical sectioning characteristics (I-Z response) and the optical property of its imaging system. The I-Z curve decreases monotonically with depth (Z) which is determined by a diameter of pinhole and a numerical aperture (NA) of imaging system. Analyzing partially coherent imaging system under the weak phase approximation, we found that intensity image generated with increasing a defocus in observing weak phase only object of step-like figure. Accordingly the peak in optical transfer function (OTF) arose at some point of specific defocused depth in response to the spatial frequency of an observing object, so we observe an edge enhancement in this type of microscope. In experiment, we used OLS1100 laser scanning microscope (Olympus Co., Ltd.) with NA=0.95 in 100-power objective. Light source is Ar-ion laser of 488nm. We prepare rectangular samples which have 5.0 micron in width, and 50 nm in depth. We observed edge enhancement in auto-focus mode for the above samples. After measuring defocus characteristics of I-Z response we evaluate our theory in good agreement for the edge enhancement on the image of laser scanning confocal microscope.

Paper Details

Date Published: 13 June 2005
PDF: 8 pages
Proc. SPIE 5856, Optical Measurement Systems for Industrial Inspection IV, (13 June 2005); doi: 10.1117/12.612481
Show Author Affiliations
Masahide Itoh, Univ. of Tsukuba (Japan)
Shin Uematsu, Univ. of Tsukuba (Japan)
Hiroshi Ishiwata, Olympus Corp. (Japan)
Toyohiko Yatagai, Univ. of Tsukuba (Japan)

Published in SPIE Proceedings Vol. 5856:
Optical Measurement Systems for Industrial Inspection IV
Wolfgang Osten; Christophe Gorecki; Erik L. Novak, Editor(s)

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