Ocean Optics SpectraSuite - Manual (Page 162)

A: Experiment Tutorials
150 000-20000-300-02- 201110
Note
If you change any sampling variable (integration time, averaging, smoothing, fiber size,
etc.), you must store a new reference and dark spectrum.
Reflection Experiments
Reflection is the return of radiation by a surface, without a change in wavelength. Reflection can be:
 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.
Reflection is expressed as a percentage (%R

) relative to the reflection from a standard reference
substance:
S

- D

%R

=
R

- D

x 100%
Where:
S

= the sample intensity at wavelength 
D

= the dark intensity at wavelength 
R

= the reference intensity at wavelength 
The following figure shows a typical reflection setup. A light source sends light via the input leg of a
reflection probe onto a sample. 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,
which is connected to the computer.