INTEGRATING SPHERE ARRANGEMENT FOR PRODUCING SIZE - CORRECTED COLOR SIGNALS

In order to color sort objects such as peas or sweets, they are dropped in succession through two integrating spheres. In the first sphere, the object absorbs infra-red radiation and the peak reduction in infra-red flux is detected in order to provide a signal responsive to the size of the object. In the second sphere, the object is illuminated with white light and the peak reduction in flux is detected by at least three detectors for three colors determined by filters. To make the illumination more uniform in the sphere, there is a step around the sphere almost half way down, with light sources equi-spaced around the step. The size signal is divided into the respective color signal in a micro-processor to produce a size-corrected color signal.