Spherical helical continuous scanning and reconstruction of luminous intensity distribution for near-field goniophotometric measurements

Near-field goniophotometric measurement is one of the commonly used methods to obtain the luminous characteristics of a light source and plays an important role in the design of light sources and optimization of performance indicators. However, the spherical grid scanning method currently widely used in near-field goniophotometric measurements suffers from problems of uneven spatial sampling and data redundancy. To solve these problems, this paper proposes a spherical helical continuous scanning method. The azimuth and zenith axes rotate continuously in coordination. The intersection points of the sampling directions and the scanning sphere are located on a helical line and are equally spaced, making the sampling direction as uniform as possible in space. The corresponding reconstruction method of luminous intensity distribution is also studied in this paper. The Delaunay triangulation algorithm is used to divide the sphere into surface elements with similar areas. The ray data in each sampling direction are calculated to obtain the full-space luminous intensity distribution. A near-field measurement device for the luminous characteristics of light sources was built. Traditional and proposed scanning measurements were carried out to reconstruct the full-space luminous intensity distribution of the same light sources. Experimental results show that the proposed method of spherical helical continuous scanning and reconstruction of luminous intensity distribution can achieve a similar matching index with much less sampling data and scanning time, providing a new approach for near-field goniophotometric measurements.