In order to achieve a uniform illumination distribution confined to a given rectangular region, a feedback modification
strategy is introduced in the design of free-form optical surface. The whole process of this strategy includes two steps:
solving the initial structure and feedback process.
To solve the initial surface, we first divide the source space along its longitude and latitude direction with uniform angel.
Because the energy of each longitude and latitude micro-belt of free-form surface and each corresponding micro-belt on
the target plane is equal, the target plane can be divided into grids, and then the mapping relationship of source space and
target space is constructed. By using Snell’s Law and tangent plane iterative method, we obtain the coordinates of all grid
nodes and an initial free-form surface can be constructed. Afterwards we use specific feedback algorithm to improve the
illuminating performance. This method is proved to be efficient, the shape of illumination spot is dramatically improved
and the design result is satisfactory.
In light-emitting diode (LED) street lamp design, it has always been an obsession that how to achieve an
expected illumination distribution confined to a given region. To solve this problem, a new optimization strategy is
proposed. In view of the practicability of actual production, we select the relatively mature approach that is based
on both the Snell law and the energy conservation law which would obtain coordinate relations between the spaces
the light source and target plane owned respectively and a set of equations to establish the initial construction of
free-form lens. In addition, all the processes of simulation, analysis and optimization as well are accomplished in
software. Generally speaking, for construction method which is in the light of the set of equations, the major
improvement ideology focus on finding out the most suitable mapping relationship between the two coordinate
systems. So does our work.
In order to get better performance, the grid of control points must be modified. Then the core problem lies in
determining the direction and distance of every point’s movement contained in the grid. The rule of changing
direction has a bearing on energy relations while migration length is gained by direct search algorithm.We apply
the method in uniform illumination and get some effect. In short, the optimization strategy provides a practical and
simple way for street lamp design of LED illumination.