Integrating spheres collect reflected light from samples over a full hemisphere. The sphere, by nature of its internal diffuse (lambertian) reflection and integration of the energy, is insensitive to directional reflectance features coming from the sample, and therefore, gives a very repeatable “averaged” response to the reflectance of the sample placed in the beam at the sphere port. Sample placement and incidence beam/collection alignment are less critical to the measurement results because the integrating sphere looks at representative averaged energy from all angles at the same time.
The RTS-3ZC Integrating Sphere features a 13º/D geometry to allow near normal incidence at 13º, and diffuse collection via the instrument’s fiber optic bundle. The interior of the integrating sphere is made of Zenith diffuse polymer material, a solid, machined form of PTFE. Zenith® is a highly reflective (>95%) and Lambertian reflector over the broad spectral range of 350-2500 nm, which provides maximum efficiency and optical performance. A specially designed collimated tungsten light source, included with the sphere, delivers close to solar irradiance levels at the sample.