I.E. Protsenko

Efficiency of light emitting devices based on light emitting diodes (LED) is determined by not only efficiency of LED themselves but also by optimum formation of light beams from LED arrays. Such formation may be made with the help of light panels well-known in computer monitors, commercial light emitting devices and TV. However similar panels for lightening are not so well-developed. This work is dedicated by the development of light panels based on LED. Two-dimension light panel for lightening with side introduction of light is considered. The work light emitting side of the panel and the opposite side of the panel are shaped as the sequence of elliptic lenses. These lenses are placed such that certain light power comes outside from the work side of the panel at each reflection, which provides homogeneous light beam from the work surface. The light does not go outside the panel from the surface opposite to the work surface. Phenomena of total internal reflection and «optical» property of the ellipse are used. «Optical» property means that the beam coming from the point source in one focus of the ellipse arrives to its other focus after reflection from the surface of the ellipse. The panel made of the sequence of focusing and defocusing lenses is a waveguide, where the light beam aperture does not exceed some maximum. It lets to control the beam, for example, only certain part of the light power can go outside at each reflection of the beam from the work surface, while the light does not go outside at all from the opposite surface of the panel because of the total internal reflection. The method of the calculation of parameters of panel is presented in the paper. The example of the panel design is given. Equal light power goes outside at each reflection of the light from the work surface, which provides homogeneity of lightening. The advantage of the panel is that no diffusion scatters present, which lets one to achieve high efficiency of the transportation of the light. Efficiency of the panel considered in the example exceeds 90 %, which lets one to use such panels for external lightening with powerful light sources. Possibilities of making pre-determined directions and angular distributions of the output light beam are shown. The panel decreases the brightness of LED souses several times - proportional to the number of reflections of the light beam.