Integrating spheres offer unique functions which makes them very useful in reflectance, transmittance and absorbance applications. The Lambertian emittance characteristic of uniform light sources incorporating integrating spheres provides a hemispherical diffuse and uniform illumination of test samples e.g. such as light panels used for backlighting of displays. In this case the luminance contrast of the light panels can be measured using an additional luminance meter viewing through an additional port. The large acceptance angle of integrating sphere based light detection systems is the main reason for using spheres in reflectance and transmittance applications.
Any light that is reflected by a diffuse material or passing through a diffuse material must be completely detected. This should be independent of the angle of reflected or transmitted light and also from any increase in spot size. Flat field detectors do not meet this requirement. The port frame will not interfere with the acceptance angle if it is designed with a knife-edge. Besides acceptance angle, larger measurement apertures can be made, an other argument for the integrating sphere. A precisely collimated light beam is a prerequisite for accurate reflectance and transmittance measurements. The collimated beam must not only precisely target the sample area but also not contain any diffraction rings which can produce an offset light level inside the sphere limiting measurement resolution.
Additional information from our Products section: consider the UP series integrating spheres for reflection, transmission, absorbance and other applications where more precise port positioning is critical. Gigahertz-Optik can also offer service measurements in its calibration laboratory.
Additional information from our Products section: consider the 