Ocean Optics OOIBase32 - Manual (Page 103)

A: Experiment Tutorials
Reflection Experiments
Reflection is the return of radiation by a surface, without a change in wavelength. Reflection can be either
of the following:
• Specular (the angle of incidence is equal to the angle of reflection)
• Diffuse (the angle of incidence is not equal to the angle of reflection)
Every surface returns both specular and diffuse reflections. Some surfaces may return mostly specular
reflection, while others may return mostly diffuse reflection. Specular reflection increases proportionately
with the amount of gloss on a surface.
We express reflection as a percentage (%R λ ) relative to the reflection from a standard reference
substance:
S λ - D λ
%R λ =
R λ - D λ
x 100%
Where:
S
λ = Sample intensity at wavelength
λ
D
λ = Dark intensity at wavelength
λ
R
λ = Reference intensity at wavelength
λ
Typical reflection setup: A light source (far right) sends light via the input leg of a reflection probe onto a
sample (bottom center). A reflection probe holder holds the probe in either a 90 or 45-degree angle from
the surface. The output leg of the reflection probe carries light from the sample to the spectrometer (top
center) connected to the PC (far left).
Common reflection applications include measuring the properties of mirrors and coatings. Other
applications include measuring the visual properties of the color in paints, plastics, and food products.
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