UV-Vis Frequently Asked Questions - Relative Diffuse Reflectance
What is relative diffuse reflectance?
Relative diffuse reflectance is measured by using an integrating sphere to measure the diffuse reflected light with specular reflected light excluded, as shown in the top diagram. This is used to measure samples with a rough surface, such as paper. The picture at bottom left shows an integrating sphere attachment used to measure relative diffuse reflectance. When using an integrating sphere, a material such as barium sulfate or specialized fluorine-based polymer is used as the reference plate (sometimes referred to as a white reference plate).
Attach a barium sulfate or other white reference plate at position (1) in the integrating sphere shown here. Perform baseline correction. The sample beam shines on the white reference plate.
Remove the white reference plate from position (1) and place the measurement sample in its place. Measure the sample to obtain the diffuse reflectance. Specular reflected light is reflected out of the integrating sphere via the sample beam inlet port and, therefore, is not detected.