Scattering light distribution models are indispensable to describe the scattering characteristics of optical surfaces as precisely as possible. Standard models such as Harvey, Lambertian or Phong, are available in the database of ray tracing and rendering programs. 

For example, to describe a metallic surface such as gold or semi-transparent optical materials using a ray tracer or rendering software, it is common to use one of the standardized models mentioned above. In many cases, the type of description of the scattering characteristic using standard models is accurate enough. However, more recently, a precisely description of the scattering -distribution of the models are required, particularly by developing systems using sunlight as a source of renewable energy.

We developed such a modular laboratory system that measures the scattering characteristics of metallic surfaces and semi-transparent layers.

Next, the measurement results and mathematical descriptions obtained were incorporated into a ray-tracing software for the design of a solar thermal system for horticulture.

Results:

The direct measurement of the scattered light characteristics of materials, contributes to obtain better results for a precise design of complex solar systems.

Conclusions:

The measurement of scattering light distribution of metallic and semitransparent surfaces, improves the knowledge of light distribution of many optical surfaces. Nevertheless, more measurements are necessary to ensure reproducibility. The developed mathematical models also need to be adjusted to provide a more accurate description furthermore.