The CF-LCoS Micro Optical Engine With LED Illumination

A review of the traditional design methods of rectangular illumination system for Pico-Projector optical engine is first carried out, then the analysis method of Fly-eye lens array based on Fourier optics theory is proposed, and the uniformity condition of Fly-eye system is given based on the analysis method. By reviewing the traditional free-form lens design methods for rectangular illumination, the shortcomings of the traditional methods are indicated, and a series of complete free-form lens design methods for rectangular illumination is proposed. Based on these methods, the problems of surface normal deviations and illumination figuration aberration in traditional methods are for the first time resolved.The novel ideas of this paper are listed as follow:(1) Adaptive grid control method. This method is proposed to reduce the human factors in the design of freeform lens system and increase the possibility of physical realization for the free-form lens system. The problems of surface normal deviations and illumination configuration aberration are resolved with this method for the first time.(2) Free-form surface construction method with surface-emitting source model. Free-form lens constructed with this method can be used in surface-emitting source systems without source extension optimization, and the method increases the possibility of obtaining the optimal solution compared with traditional point source approximation method.(3) Lens system design method based on real ray tracing. This method is proposed for lens system design, to control the incident ray angle of display chip and to increase the contrast ratio.(4) Dynamic tessellation method of effective source solid angle region. This method is proposed to tessellate almost any kind of source effective solid angle region and to eliminate the dependent of source radiation energy structure while designing.(5) Analysis of directional derivative continuity and curvature distribution for free-form surface. Based on the analysis, the defects of illumination are eliminated. Higher projection quality can be obtained.(6) Based on the free-form surface construction method with surface-emitting source model, an initial parameters optimization method is proposed. With this method, the designer can optimize the system using fewer parameters, and these parameters have clear physical meaning so that the optimization gets more efficient.Based on the series of methods above, a design example of CF-LCoS Pico-Projector optical engine and its simulated results are presented. The collection efficiency reaches67.7%. while using a LED source of1101m(1W), the total flux on the screen reaches7.371m, and the ANSI nine points uniformity reaches98.6%, performance indicators of CF-LCoS Pico-Projection optical engine are fully upgraded compared with traditional systems.