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MICROSCOPY APPLICATIONS | Biomedical
MICROSCOPY APPLICATIONS / Biomedical 41
pinhole is collected by a detector, and the output may be used to modulate the brightness of a television tube scanned in unison with the raster on the specimen. Images are normally digitized and stored in computer memory, and may be combined and manipulated to present information about the specimen as required. In contrast to this electronic system, there is another approach to confocal imaging, the tandem scanning microscope, which uses a spinning disc to scan the specimen with a large number of beams simultaneously, and presents its image directly to the eye or photographic camera. This system may provide faster scanning than the single-beam electronic system, and thus has applications in studying dynamic events. Advantages and Limitations of Light Microscopy
The light microscope has many advantages over other forms of microscope. Light microscopes are extremely versatile instruments. They can be used to examine a wide variety of types of specimen, frequently with minimal preparation. Light microscopes can be adapted to examine specimens of any size, whole or sectioned, living or dead, wet or dry, hot or cold, and static or fast-moving. They offer a wide range of contrast techniques, providing information on the physical, chemical, and biological attributes of specimens. The image from a light microscope is presented in color. It can be observed with the eye directly, recorded by photographic, video or computer techniques, and image components can be analyzed. And the instruments themselves are
(relatively) inexpensive, small, require no vacuum, and are undemanding of operating conditions, services and maintenance. The principal limitation of the light microscope is its resolving power. Using an objective of NA 1.4, and green light of wavelength 500 nm, the resolution limit is B0.2 mm. This value may be approximately halved, with some inconvenience, using ultraviolet radiation of shorter wavelengths. By good fortune, however, the resolving power of the light microscope is adequate for many areas of work in the biological and physical sciences. See also: Microscopy Techniques: Light Microscopy.
Further Reading Bradbury S and Bracegirdle B (1998) Introduction to Light Microscopy. Oxford: Bios Scientific Publishers and Royal Microscopical Society. Murphy DB (2001) Fundamentals of Light Microscopy and Electronic Imaging. New York: Wiley-Liss, Inc. Pluta M (1988) Advanced Light Microscopy. Vol. 1 – Principles and Basic Properties. Warsaw: Polish Scientific Publishers. Pluta M (1989) Advanced Light Microscopy. Vol. 2 – Specialized Methods. Warsaw: Polish Scientific Publishers. Pluta M (1993) Advanced Light Microscopy. Vol. 3 – Measuring Techniques. Warsaw: Polish Scientific Publishers. Richardson JH (1991) Handbook for the Light Microscope: A User’s Guide. New Jersey, USA: Noyes Publications. Robinson PC and Bradbury S (1992) Qualitative Polarized-Light Microscopy. Oxford: Oxford University Press and Royal Microscopical Society.
MICROSCOPY APPLICATIONS Contents
Biomedical Food Forensic Environmental Liquid Crystals Semiconductors Proteins and Nucleic Acids
Biomedical A Warley, King’s College, London, UK & 2005, Elsevier Ltd. All Rights Reserved.
Introduction Microscopic techniques are primarily used to determine the structural characteristics of a specimen under study. Light microscopy is used to show the overall distribution of different cell types and tissues
pinhole is collected by a detector, and the output may be used to modulate the brightness of a television tube scanned in unison with the raster on the specimen. Images are normally digitized and stored in computer memory, and may be combined and manipulated to present information about the specimen as required. In contrast to this electronic system, there is another approach to confocal imaging, the tandem scanning microscope, which uses a spinning disc to scan the specimen with a large number of beams simultaneously, and presents its image directly to the eye or photographic camera. This system may provide faster scanning than the single-beam electronic system, and thus has applications in studying dynamic events. Advantages and Limitations of Light Microscopy
The light microscope has many advantages over other forms of microscope. Light microscopes are extremely versatile instruments. They can be used to examine a wide variety of types of specimen, frequently with minimal preparation. Light microscopes can be adapted to examine specimens of any size, whole or sectioned, living or dead, wet or dry, hot or cold, and static or fast-moving. They offer a wide range of contrast techniques, providing information on the physical, chemical, and biological attributes of specimens. The image from a light microscope is presented in color. It can be observed with the eye directly, recorded by photographic, video or computer techniques, and image components can be analyzed. And the instruments themselves are
(relatively) inexpensive, small, require no vacuum, and are undemanding of operating conditions, services and maintenance. The principal limitation of the light microscope is its resolving power. Using an objective of NA 1.4, and green light of wavelength 500 nm, the resolution limit is B0.2 mm. This value may be approximately halved, with some inconvenience, using ultraviolet radiation of shorter wavelengths. By good fortune, however, the resolving power of the light microscope is adequate for many areas of work in the biological and physical sciences. See also: Microscopy Techniques: Light Microscopy.
Further Reading Bradbury S and Bracegirdle B (1998) Introduction to Light Microscopy. Oxford: Bios Scientific Publishers and Royal Microscopical Society. Murphy DB (2001) Fundamentals of Light Microscopy and Electronic Imaging. New York: Wiley-Liss, Inc. Pluta M (1988) Advanced Light Microscopy. Vol. 1 – Principles and Basic Properties. Warsaw: Polish Scientific Publishers. Pluta M (1989) Advanced Light Microscopy. Vol. 2 – Specialized Methods. Warsaw: Polish Scientific Publishers. Pluta M (1993) Advanced Light Microscopy. Vol. 3 – Measuring Techniques. Warsaw: Polish Scientific Publishers. Richardson JH (1991) Handbook for the Light Microscope: A User’s Guide. New Jersey, USA: Noyes Publications. Robinson PC and Bradbury S (1992) Qualitative Polarized-Light Microscopy. Oxford: Oxford University Press and Royal Microscopical Society.
MICROSCOPY APPLICATIONS Contents
Biomedical Food Forensic Environmental Liquid Crystals Semiconductors Proteins and Nucleic Acids
Biomedical A Warley, King’s College, London, UK & 2005, Elsevier Ltd. All Rights Reserved.
Introduction Microscopic techniques are primarily used to determine the structural characteristics of a specimen under study. Light microscopy is used to show the overall distribution of different cell types and tissues