PR-680/680L User Manual
33
C
LEANING AND
H
ANDLING
I
NSTRUCTIONS FOR THE
RS-3
(
AND
SRS-3)
Use the following procedure to maintain the unique optical and reflectance properties of the
Reflectance Standard. If the material becomes soiled, use a jet of clean dry air to blow the soil off, or
rinse with distilled water. A soft bristle brush may be used.
OR
1a)
If the material becomes grossly contaminated or scratched, restore its original optical condition
by sanding the surface under a stream of running water using a 220-240 grit waterproof emery cloth.
Sand until the surface is totally hydrophobic (water beads and runs off the material immediately).
Rinse with distilled water.
Note:
If the emery cloth grit is too fine the finish will be inadequate as the surface may become too
smooth and reflect a high level of specular component (mirror image). Also, if the SRS-3 is
refinished, it will be necessary to recalibrate if the standard for optimum accuracy.
L
UMINOUS
/
R
ADIANT
I
NTENSITY
Luminous Intensity is the luminous flux per unit solid angle in a given direction and is calculated from
Radiant Intensity (watts/steradian)
. It can be easily thought of as luminous flux (lumens) traveling
through a cone (solid angle) in a given direction (for example the forward 180°). Luminous intensity is
given in
candelas (lumens / steradian)
or
millicandelas
(1 candela = 1000 millicandelas).
FIGURE 76 - ILLUSTRATION OF LUMINOUS INTENSITY
Solid Angle