A NOVEL METHOD FOR THE PHOTOMETRIC EVALUATION OF SEARCHLIGHTS

A novel technique is described for testing searchlights and other high ly collimated luminaires. The proposed method, which uses a modified d etector assembly to compute the luminance at all positions in a measur ement plane close to the luminaire and for all beam angles, does not r equire a long test range or complicated calibration techniques and the refore reduces significantly the time needed for testing. Computer sim ulations are presented which demonstrate the failure of the inverse sq uare law inside the beam cross over distance when measuring the intens ity on a standard screen, the validity of the proposed method within t he beam cross over distance and the effects of a smoothing technique w hich is used to reduce noise. Results are also presented for a searchl ight that has been tested with an experimental implementation of the m ethod and these show good agreement with predicted data.