An arc lamp is an optical source used in many kinds of
instruments to provide high levels of brightness. Arc
lamps are often filled with gases, such as krypton, mercury,
or xenon. Developed in Germany during World War II for
use in high-powered search lights, the particularly bright
and penetrating xenon arc lamps are now used in both SPFs
and IMAX theaters.
Assaying is the process of determining how much of a
certain substance is present.
A cuvette is a small transparent tube (often rectangular)
that holds a solution or a sample.
Diffraction gratings are closely spaced, straight, parallel
grooves on an aluminum surface which are able to separate
(or diffract) white light into its component wavelengths.
By the early 1950s they were rare but available, so
Dr. Bowman was able to use one in his prototype SPF.
An electron is a negatively charged subatomic particle.
Fluorescence is the glow made by some materials when
they are "excited by" (react to) light in
the visible or invisible (ultraviolet) range. Molecules
absorb photons (the smallest possible bits of light)
at one wavelength of color and become excited. The molecules
change slightly as they store the energy of the photons.
As they change, they leak some of the energy to surrounding
molecules. Using the remaining energy, the molecules
emit new photons in different colors. This creates a
fluorescent glow. (Click on film icon to watch an
animation on the physics of fluorescence).
A monochromator selects light from a narrow band of
wavelengths using either a prism or a diffraction grating.
High quality but very expensive monochromators were
just beginning to be produced in the United States in
the 1950s when Dr. Bowman used them in his instrument.
chemical compound released by one neuron that acts as
a messenger to another neuron.
fluid ground substance of whole blood.
Light radiation having wavelengths that places it
outside the violet end of the visible spectrum, invisible
to the human eye.