This paper presents a test method, which uses 'light-point figures' to calculate light distribution solids from vehicle headlamps. This method is based on the theory of elementary reflections, which enables the calculation of the luminous intensity of a headlamp consisting of several parts, each of which is described by a mathematical equation. The mathematical modelling and calculation are very complicated, and must assume many simplifications. The model used here has components representing: (1) the reflector, based on parabolic or ellipsoidal surfaces; (2) the filament, assumed to be cylindrical; (3) the optical elements of dissipative glass or lens; and (4) the test-beam path. The flow chart of the general calculation algorithm is given. The computer program using the algorithm works in two modes: (1) observation of the light-point figure for a given direction, allowing designers to estimate which parts of a reflector and dissipative glass are useful; or (2) presentation of information on the progress of calculation only. The results of the calculation are very satisfactory, allowing for the complexity and requirements of the system being analysed.
Abstract