Angle-resolved measurements of optical material properties

Purpose and goal

A new system for measuring angular resolved transmittance (BTDF) has been developed. Using flexible optics and two different detectors, the automated system can be adapted to materials with different scattering properties. In addition, an existing measuring equipment for reflectance (BRDF) has been improved, which means that the Swedish national laboratory for photometry and radiometry at RISE AB can now offer evaluations of optical materials in line with the needs of the industry, which was the main goal with the project.

Expected results and effects

The two well-functioning and flexible measuring systems for evaluating BTDF and BRDF complement the National laboratory’s traditional services for optical materials. The interest from the industry for more advanced characterization of surfaces and materials is expected to continue to increase in the coming years, and with the two new measurement systems the laboratory will continue to be able to offer relevant evaluations. With some additional validations there is also good possibilities to add the quantities BTDF and BRDF to the laboratory’s scoop of traceable services.

Planned approach and implementation

With largely existing equipment, a cost-effective measurement system for BTDF has been developed based on a fiber-coupled light source of the Xenon type, a robust rotation table and two different detectors. With a high degree of automation and flexible data collection, the system can be adapted to objects with different properties and sizes. In addition, a monochromator-based system for BRDF has been improved and evaluated. Primarily, the detector part has been redesigned, which means that BRDF measurements in the range 350-900 nm can now be performed with the desired accuracy.