Condenser Aperture Reduction Phase Contrast: A New Technique for Improved Imaging in Light Microscopy
Abstract:Conventional phase contrast images are affected with some typical limitations, e.g., halo artifacts, small depth of field and constancy of contrast amplification. In this paper, a new technical modification of phase contrast illumination is presented leading to improved results in examinations of transparent specimens. Based on technical modifications in the normal optical design, the condenser aperture iris diaphragm can be used in phase contrast observations in the same way as usual and well known in bright-field examinations. When the condenser is fitted with an additional second iris diaphragm which can be horizontally shifted in optional direction, the illuminating light can be collimated furthermore, and oblique illumination can be achieved. By this 'condenser aperture reduction phase contrast,' several quality determining parameters can be influenced. Thus, the visible depth of field can be enhanced (circa doubled or quadrupled), the intensity of contrast and contour sharpness of fine details can be amplified and regulated with the help of the condenser aperture diaphragm. Moreover, the planarity of field can be improved, and halo-artifacts may be reduced in some specimens. In specimens affected with a high vertical dimension, existing three dimensional structures can be examined and documented in a superior clarity. The article describes all relevant optical basics, the experimental implementation of a technical prototype and practical evaluations and experiences with this new technique.
Document Type: Research Article
Publication date: April 1, 2010
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- Journal of Advanced Microscopy Research (JAMR) provides a forum for rapid dissemination of important developments in high-resolution microscopy techniques to image, characterize and analyze man-made and natural samples; to study physicochemical phenomena such as abrasion, adhesion, corrosion and friction; to perform micro and nanofabrication, lithography, patterning, micro and nanomanipulation; theory and modeling, as well as their applications in all areas of science, engineering, and medicine.
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