- Bright field microscopy
Bright field microscopy is the simplest of all the
optical microscopy illuminationtechniques. Sample illumination is transmitted (i.e., illuminated from below and observed from above) white light. The most common use of the microscope involves the use of an organism mounted to a glass microscope slide.
* Base - Supporting structure that usually contains an electrical light source or illuminator.
Objective lens(es)- Magnify the image.
* Oculars - Magnify the image from the objective lens. A microscope with one ocular lens is often called a monocular, a microscope with two oculars is called a binocular.
* Arm - The support structure that connects the lens systems to the base.
* Body tube - Sends light to the ocular lens.
* Condenser lens - Directs light to pass through the specimen.
* Stage - Platform that allows mechanical movement of a microscope slide.
* Adjustment knobs - Course and fine focus adjustment.
The magnification of an optical microscope is only limited by the magnifying power of the lens system. However, the limit of
magnificationfor most light microscopes is 1000x which is set by an intrinsic propertyof lenses called resolving power.
* Simplicity of setup with only basic equipment required.
* No sample preparation required, allowing viewing of live cells.
* Very low
contrastof most biological samples.
* Low apparent
optical resolutiondue to the blur of out of focus material.
* Reducing or increasing the amount of the light source via the
* Use of an
oil immersion objectivelens and a special immersion oil placed on a glass cover over the specimen. Immersion oil has the same refractionas glass and improves the resolution of the observed specimen.
* Use of sample staining methods for use in
microbiology, such as simple stains ( Methylene blue, Safranin, Crystal violet) and differential stains (Negative stains, flagellar stains, endospore stains).
* Use of a colored (usually blue) or polarizing filter on the light source to highlight features not visible under white light. The use of filters is especially useful with
# Advanced Light Microscopy vol. 1 Principles and Basic Properties by Maksymilian Pluta, Elsevier (1988)
# Advanced Light Microscopy vol. 2 Specialised Methods by Maksymilian Pluta, Elsevier (1989)
# Introduction to Light Microscopy by S. Bradbury, B. Bracegirdle, BIOS Scientific Publishers (1998)
# Microbiology: Principles and Explorations by Jacquelyn G. Black, John Wiley & Sons, Inc. (2005)
# [http://ourworld.compuserve.com/homepages/pvosta/pcrref.htm Microscopy and Imaging Literature]
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