Colorized SEM Images

The images in this library were all obtained using the scanning electron microscope (SEM). The SEM forms images of the external surfaces of objects. In this context, it is the analog of the "dissecting" or "stereo" microscopes with which you may be familiar with from school (the microscope that DIDN'T use glass slides).

In a nutshell, the SEM functions by scanning a tightly focused beam of high-energy electrons across the surface of a sample. At every point in this scan (usually referred to as the "raster") the interaction of the beam and the sample produces a "signal" which can be detected. The signal produced at each point in the raster is then mapped onto a video screen whose area has a one-to-one correspondence to the SEM raster area (i.e. each point on the SEM raster corresponds to a single picture element on the screen). The brightness of a particular video picture element is governed by the amount of signal produced at the corresponding point in the microscope raster.

60-watt light bulb filament (75x)

The first question everyone asks upon seeing these images is: "What is it?". The second question is: "How much is it magnified?". While the first question is relatively easy to answer (usually), the answer to the second gets a little complex - especially because you're viewing the images on YOUR monitor and not on mine. Initially, magnification in the SEM is a function of both the size of sample raster and the size of the viewing monitor.

Since the raster area is very small and the monitor area is (comparatively) very large, this mapping arrangement leads to the production of a magnified image on the monitor. If you use a LARGER monitor the image is magnified more. The same holds true for stored images. If you view the images full-screen on a standard 14" monitor (like my PACKARD BELL) the magnifications listed will be correct (more or less). If your monitor is larger than 14", and you fill the screen with the image, the magnification that YOU see will be greater than the listed mag. The same holds true of viewing in a window -- the smaller the window, the lower the magnification that YOU see.

( more info on SEM imaging)

integrated circuit (400x)
This is a portion of a semi-conductor device showing several printed circuits.
Each color represents a different material, and in this case
a vacuum problem during the deposition of aluminum (cyan)
caused this layer's "lumpy" appearance, and rendered the device useless.
©Ron Barber (1995). All rights reserved.

magnesium oxide crystals (1350x)

These crystals are the "sparks" that result when magnesium metal is burned in air.

sodium chloride crystal (300x)
A single grain of salt shows the expected cubic structure common to di-ionic compounds.
The mechanisms that formed the little "swirl" on the surface of the crystal is a bit of a mystery.
©Ron Barber (1995). All rights reserved.

desmids (3000x)
Desmids are a very common type of fresh water algae.
These were imaged on the filter paper which removed them from their watery home.
©Ron Barber (1995). All rights reserved.

leaf (1300x)
The varied forms and structures of leaves make them excellent subjects for pictures.
In addition, there is often all kinds of junk on the surfaces of leaves
which can be as interesting as the leaf itself.
©Ron Barber (1995). All rights reserved.

bread mold (1200x)

Penicillium is the stuff the antibiotic is made from and grows not only on bread but on citrus fruits as well. The moldy spots are generally composed of a number of different fungal species.

microshells in sand

These tiny shells are found in sand and the ones imaged here and below are about double the size of salt grains.