Led Lamps And Lanterns Of Inversion Optimization Design Method Of Nonimaging Optics Research

Since LEDs’lumen efficiency has increased rapidly in recent years, LEDs have begun to play an important role in many applications, such as, street and tunnel lighting, car headlamp projector luminaire and interior illumination. The research on nonimaging optical design method for LED is carried out by scholars in depth. There are mainly two design methods, which are tailored surface method and differential equation method. The shortcoming of the tailored surface method is time-consuming while that of the differential equation method is the difficulty in numerical computation of nonlinear partial differential equations and the limited applicability. The thesis aims to promote a universal nonimaging optical design method for LED through literature survey and nonimaging optical design experiments.The existing mathematical model of the differential design method for point source need to compute a sets of nonlinear PDEs which is always difficult. To overcome the disadvantages, A freeform reflector design method, which is mainly based on a first-order quasi-linear partial differential equation, is proposed in this article for uniform rectangular illuminance distribution in the field of LED illumination. The interaction between the freeform surface and the light beam is depicted based on the differential geometry theory and Snell’s Law. The energy topological relationship between the lambertian luminaire and the illuminated rectangular surface is established according to the LED luminous intensity distribution. Some nonimaging optical devices, such as freeform lens and reflectors for uniform rectangular and elliptical illuminance distribution on the target plane, are designed to verify the feasibility and the precision of the method. The design results are validated by ray tracing in some optical design software. And the results reveal that the illuminance uniformity on the target plane reach the expected goal. The time of the numerical computation is less than Is.In the field of near-field nonimaging optical design for LED, LED should not treated as point source because of its geometrical scale. The design model for extended source should be established. The energy topological relationship between the extended source with arbitrary luminance distribution and the target source with desire illuminance distribution is depicted by a set of topological expressions. After that the inverse optimal design method based on spline surface is promoted. In this section, the merit function is chosen according to the grid approximation, which is the comparison of the ideal illuminance and the optimal illuminance distribution. Then the interaction between the spline surface and the light beam is discussed and generalized in the form of mathematical derivation. Such discussions in this section provide some theoretical support for further research in inverse optimal design method for extended source.There are several points of innovation in this research. First, the mathematical description, in the form of first-order linear PDE with certain BCs, of the freeform surface is derived and this reduced the difficulty in numerical computation. Second, the continuity of the PDEs for point source id studied and this provides guidance for numerical computation. Third, the rationality and precision of the model is verified by different design experiments. Fourth, some theoretical problems in inverse optimal design method is discussed such as the energy topological relationship between the extended source and target plane, the choose of merit function and the mathematical description of spline surface.