Integrating Sphere Radiometry and Photometry
Radiometers and Photometers measure optical energy from many sources including the sun, lasers, electrical discharge sources, fluorescent materials, and any material which is heated to a high enough temperature. A radiometer measures the power of the source. A photometer measures the power of the source as perceived by the human eye.
All radiometers and photometers contain similar elements. These are an optical system, a detector, and a signal processing unit. The output of the source can be measured from the ultraviolet to the mid-infrared regions of the electromagnetic spectrum.
Proprietary diffuse reflectance coatings developed by Labsphere allow the use of integrating sphere radiometers in outer space, vacuum chambers, outdoors and in water (including sea water) for extended periods of time. Two factors must be considered when using an integrating sphere to measure radiation:
1) getting the light into the sphere, and 2) measuring the light.
The integrating sphere is a simple, yet often misunderstood device for measuring optical radiation. The function of an integrating sphere is to spatially integrate radiant flux. Before one can optimize a sphere design for a particular application, it is important to understand how an integrating sphere works.