About These Images

I usually work with them at high resolution, sometimes painting each individual hair! They are shrunk and watermarked for the website.

Electron microscopes use a beam of electrons as their source of illumination; light microscopes use a beam of light. Light microscopes have glass lenses to control and focus the beam of light; electron microscopes have electromagnetic lenses to control and focus the beam of electrons. A beam of electrons has a shorter wavelength than a beam of light, so it is possible to see things at a higher magnification and resolution.

There are two primary types of electron microscopes - Scanning Electron Microscopes (SEMs) and Transmission Electron Microscopes (TEMs). There are also other types of microscopes and endless varieties of each!

Most of the images on this web site were taken with an SEM, which is generally used to image the surfaces of things. A beam of primary electrons is scanned rasterwise across the surface of a specimen. Those electrons interact with the specimen to kick off other particles. These include secondary electrons, commonly used to form an image, backscattered electrons with energies related to the element that gave them off, X-rays that also contain elemental information, Auger electrons, and photons, all of which contain some information about the specimen. Most of the images on this site were taken in secondary electron detection mode. Where lots of electrons were given off in the direction of the secondary electron detector, the image is bright. Where fewer reached the detector, the image is dark. In this way a black and white image is formed which gives information about the topography of the specimen. In other words, you can see lots of detail on these bugs!

In TEM the electrons are transmitted through a very thin specimen or an ultrathin section of a sample. Where the electrons get through to strike the screen or film the image is bright, and where the electrons are scattered away the image is dark. Sections and thin specimens can be stained in various ways to increase electron scattering and contribute to image contrast. The electrons that are scattered by the specimen also contain elemental information about the specimen, but I am just getting into that and so that is a story for another day!

For more about the electron microscopes I use, visit the Pacific Biomedical Research Center's Biological Electron Microscope Facility at the University of Hawaii.

So how do the black and white images get colored? I use Adobe Photoshop and "paint" the images with a mouse or digital pen and pad. The colors are a product of my imagination, especially the TEMs of cells, which usually have little or no color at all!

I hope you enjoy visiting my little world!

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Copyright © 1996-2000 Tina (Weatherby) Carvalho...MicroAngela This material may not be reproduced in any form without express written permission.