Currently, I am looking for a way to measure the total reflection of a reflective film. I am using an UV instrument equipped with a reflection mode and it measures the absolute reflection of the film. Absolute reflection is more like a specular reflection from the surface. In my knowledge, I know that it is necessary to measure both the specular and diffuse reflection of the film in order to get the total reflection value. Now, can I measure the diffuse reflection of the film? And I could not find any option in the present instrument that I am using to determine the diffuse reflection. Any suggestions?
An integration sphere is usually used to measure diffuse reflection. It can be added as an optional accessory to some spectrometers.
An integration sphere is usually used to measure diffuse reflection. It can be added as an optional accessory to some spectrometers.
You can find the principle of measuring diffuse reflection with an integrating sphere on Wikipedia: https://en.wikipedia.org/wiki/File:Integrating_sphere_principle.svg.
If you are not equipped with such a sphere, you can make the integration yourself by moving the detector at different location and tracing the intensity according to the angle.
There are setups like "Praying Mantis" used as an alternative for integrating spheres on Varian-Agilent spectrometers. If you don't have access to any such equipment, you hardly can obtain a reliable measument of total reflectance. In any case, if you need to measure the net reflactance of the film without the reflection from the front and rear surfaces of the substrate, consider using a black strongly absorbing substrate.
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