Large scale photometric capabilities

Measurements of total luminous flux of an illuminating structure have traditionally employed goniophotometric techniques , which require measurement of either the luminous intensity distribution or the illuminance distribution at many different angles. While we have developed these capabilities within our laboratory, these types of measurements are extremely time consuming, generate large amounts of data, and require a sophisticated data collection and control apparatus. For a simple approach to measure the light output, an integrating sphere is typically used. As part of our research program, we designed and constructed a new integrating measurement instrument, which we call the Isotropic Reflective Integrating Sphere (IRIS). The key to the IRIS detector is the use of not a single detector, but rather 176 detectors that are distributed uniformly around the sphere. Each fibre contributes equally to the output signal, which greatly improves the measurement accuracy compared to traditional integrating spheres. This new instrument is capable of performing detector-referenced measurements of total luminous flux using a multiple detector system that eliminates the need for baffling.