The problem of focusing light flux into an arbitrary curve in 3D space arises in the design of different laser or illumination systems. Using a diaphragm with a curved hole is not efficient and does not work for any 3D pattern. In this study, we propose a numerical analytical approach for designing reflective surfaces that efficiently produces the prescribed intensity distribution on the arbitrary curve in 3D space. The method consists of two steps: computation of the eikonal function on the curve and reconstruction of the reflective surface using the precomputed eikonal function. In the first step, we use the iterative technique for obtaining the eikonal function in the set of points on the curve. After that, we compute the continuous eikonal function by interpolation of the obtained values of the eikonal in points and reconstruct the reflective surface using continuous eikonal distribution. As examples, the reflectors generating spiral lines on the inclined plane and illumination system module are computed and simulated. Simulation data show the high quality of the produced illuminance distributions.
Design of LED optical elements producing uniform illumination in rectangular regions is one of the most actual and challenging problems in development of lighting devices. As a rule, LED optical element has at least two surfaces (inner and outer) that leads to computational complexity of design process and requires application of different optimization techniques. We present a new rapid computational method for automatical design of optical elements with two free-form surfaces which generate uniform irradiance distribution in the rectangular region. Such optical elements have high lighting efficiency (about 92 %) and can be produced by injection molding.
The method for computation of LED optical elements with two aspherical surfaces and the highest possible efficiency is
presented. The series of optical elements producing uniformly illuminated circle regions were computed and simulated
with point light source. The simulation data shows that such optical elements have good performance for all angular
sizes of the illuminated region (from 0° to 160°) including cases of full collimation and illumination of wide regions. The
proposed design method works well with extended light sources too. The optical element with height of 7 mm generating
uniformly illuminated region with angular size of 60° was simulated with extended light source 1x1 mm. The light
efficiency decreased by 1-2 % only and the irradiance distribution remained the same. Taking into account the small
dimensions of the proposed optical elements they can compete with TIR-optics in cases of generation narrow-angle light
A method is suggested for design of refractive optical surface intended for generation of the prescribed irradiance
distribution. The method is based on the gradient optimization of the refractive surface represented as a bicubic spline in
spherical coordinates. An optical element for direct-type backlight system was designed. The element produces
uniformly illuminated hexagonal region with angular size of 143° at the distance of 15 mm from the Luxeon® Rebel
Cool-White LED. The RMS error of generated irradiance distribution from the constant value is 3-4% with an energy
efficiency greater than 81%. The simulation data shows that a large, uniformly illuminated region can be formed by
means of a system of the indicated elements, located at the nodes of a rhombic grid.