Dennis Kunkel Microscopy, Inc.
Education Web Site
Light Microscopy (LM). Microscopy and photomicrography with the use of dissecting and compound microscopes. Light is transmitted through or reflected from a specimen to visualize its components. Magnifications of 5 to 1500 times can be achieved. Illumination techniques available:
Transmission Electron Microscopy (TEM). A transmission electron microscope transmits electrons through a specimen in a way that is similar to an optical light microscope passing light through a specimen. However, instead of glass lenses directing light wavelengths through a specimen, the electron microscope's electromagnetic lenses direct electrons through a specimen. Prior to this, the specimen must be prepared so it can be cut, or 'sectioned', in a thin, hard slice that will allow electrons to pass through it. Because the wavelength of electrons is much smaller than the wavelength of light, the resolution achieved by the TEM is many times greater than that of the light microscope. Thus, the TEM can reveal the finest details of structure - in some cases even individual atoms. Magnifications of 1,000 to 500,000 times are routine. If present in a biological sample, internal cell structures (nucleus, mitochondrion, etc.) can be imaged and photographed. With an electron microscope, micro-structural characterization of non-biological materials, including unit cell periodicity, can be readily determined using combinations of imaging and diffraction techniques. The TEM provides high resolution, two-dimensional views of a specimen. Three-dimensional reconstruction can be achieved with special software programs.
Scanning Electron Microscopy (SEM). A scanning electron microscope transmits electrons, as does a transmission electron microscope. However, rather than electrons passing through a thin slice of the specimen, they scan across the surface of a specimen, to create a high-resolution, three-dimensional image. Specimens must be carefully prepared and coated with a thin layer of gold metal to assist in image formation. Due to the energy and wavelength of the electrons that create the image, greater depth of field and higher resolution are achieved when compared to conventional light microscopy. Very fine details of the exterior morphology and topography of biological and non-biological samples can be photographed. Magnifications of 10 to 300,000 times are routine. The SEM provides three-dimensional views of a specimen to facilitate information important in interpreting structural organization.
Photomicrography and Image Applications
Microscopy and photomicrography have important applications in many scientific, medical, industrial and commercial areas. The following is a selected list where microscopy and photomicrography services can be utilized.
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