Abstract

As an alternate method of creating a total flux scale, a method using an integrating sphere with an opening and two baffles and the spectral irradiance standard placed outside the sphere is proposed. Theoretical analysis was made by computer simulation on several models of the above-mentioned integrating sphere whose geometry was not axially symmetric. The window illuminance was analyzed for varying conditions of sphere geometry such as size and location of the baffles, internal source, and wall reflectance, and an optimum geometry was predicted. Based on the results of the theoretical analysis, an integrating sphere of 20-in. diameter was actually built, and measurements were made in varied conditions, and the experimental results were compared with the results of the simulation. The effect of baffles with various sizes and varied location was first tested on relative bases, and the results were in good agreement with the results of the simulation. Second, absolute comparisons were made using four miniature lamps to compare the flux data obtained by this integrating sphere method and the data obtained by goniophotometry. The data of the two methods agreed within 0.5%.

© 1987 Optical Society of America