
22
Application Notes—Photoconductive Cells
APPLICATION NOTE #1
Light-SomePhysical Basics
Light is produced by the release of energy fromthe atoms of a material
when they are excited by heat, chemcal reaction or other means. Light
travels through space in the formof an electromagnetic wave.
A consequence of this wave-like nature is that each “color” can be
completely defined by specifying its unique wavelength. The
wavelength is defined as the distance a wave travels in one cycle.
Since the wavelengths of light are very short they are normally
measured in nanometers, one nanometer being equal to 1 x 10
-9
meters.
The spectral response of PerkinElmers photoconductors are specified
by lots of relative response versus wavelength (color) for various
material types.
Natural Illumnance
RoomIllumnation
Ultraviolet
(To X-rays and Gamma Rays)
Infrared
(To Radar Waves)
Visible Light
400
700
Violet
Red
Wavelength
Violet
Below 450 nm
Blue
450 - 500 nm
Green
500 - 570 nm
Yellow
570 - 590 nm
Orange
590 - 610 nm
Red
610 - 700 nm
Sky Condition
Light Level (Typical)
Direct Sunlight
10000 fc
Overcast Day
1000 fc
Twilight
1 fc
Full Moon
0.1 fc
Clear Night Sky (moonless)
0.001 fc
Lighting Condition
Light Level (Typical)
Candle - Lit Room
5 fc
Auditorium
10 fc
Classroom
30 fc
Inspection Station
250 fc
Hospital Operating Room
500 - 1000 fc