Pro-Lite has introduced Labsphere's HMS-series of "Half Moon" integrating hemisphere systems which are novel spectroradiometers that are ideally suited to measuring the forward flux from solid state lighting. By mounting the sample and its drive electronics outside of the sphere, thermal management problems are much reduced and measurement speed and accuracy are improved compared with a traditional integrating sphere.
Integrating spheres have been used since 1894 to collect the 4p steradian output of lamps and other sources of light placed in their geometric centre. The combination of spherical surface and diffuse high reflectance coating creates a uniform radiance field within the sphere which can be sampled by a photodetector. The Labsphere Half Moon systems comprise half an integrating sphere and a plane mirror bisecting the equator. From within the "sphere" one would see a real hemisphere looking in one direction and a mirror image of the real hemisphere looking in the opposite direction. The result is a uniform radiance field with higher brightness, faster measurement times and half the footprint of a full sphere.
A Half Moon spectroradiometer provides an ideal solution for measuring the forward (2p) flux from solid state lighting (SSL). The device under test is placed at a port in the centre of the plane mirror which means that the body of the luminaire, the heat sink and any drive electronics remain outside of the chamber and don't absorb light. This results in improved accuracy compared with placing the sample within a full sphere. With the sample placed outside of the sphere, stabilisation times are reduced, as the device under test will reach thermal equilibrium more quickly.
The Half Moon systems are available with hemispheres of 31cm (12-inches), 50cm (20-inches) and 103cm (40-inches) diameter. A Half Moon spectroradiometer system comprises the integrating hemisphere, a high CCD array spectrometer and Labsphere’s LightMtrX application software which takes care of the photometric and colorimetric computations, providing lumens, chromaticity, colour temperature and colour rendering data in an instant.