Design of Optical Engine Based on Laser Source and SELFOC Lens for Micro Projector

摘要

A novel structure of optical engine based on Laser sources and SELFOC lens array for single-plate DLP micro projector is proposed. Under the strict consideration of light utilization rate, illumination uniformity and the shape of projection light spot, we simulated the characteristics of this optical engine by means of 3D modeling and ray tracing using the software TracePro. The optical parameters and the volume of optical engine are also evaluated. The key component of this optical engine is a SELFOC lens array, which consists of 2×2 single unit SELFOC lenses with the square cross section. The lenses are in same physical dimension, optical characteristics and mechanical accuracy, and the lens material is zero dispersive. Thus by using the one-to-one coupling between unit and the tricolor laser sources in the form of fiber Ethernet, the projection light spots of RGB tricolor out of SELFOC lens array are sequentially produced, and then modified to the shape of 4:3 rectangular before utilized by DMD. The image information modulated by DMD is reflected to projection lens while the irrelevant light is dispelled. Thus, only by using a single-stage lens array, we successfully actualize the expansion, collimation and uniformity of tricolor laser Gaussian beams, and afford high luminous efficiency back light to DMD. The light spot completely covered the 5.4mm×4.05mm region restricted by 0.3" DMD. And the results show that the total light utilization rate of optical engine is 43.3%, the illumination uniformity is above 90.2% and the volume is less than 15 cm3. Not only does the SELFOC lens array improve the light utilization rate, but it also achieves the illumination uniformity and greatly simplifies the structure of optical engine for micro projectors as well.