Application of Multilayer Diffractive Optical Elements in Micro-projection System

An image telecentric micro-projection system based on multilayer diffractive optical elements (MLDOE) has been designed for portable device. It consists of 0.26-inch Liquid Crystal on Silicon (LCOS), the polarization beam splitter (PBS) and hybrid refractive/diffractive eyepieces. The system has a focal length of 9.75 mm, a field of view of 40 degrees, an entrance pupil diameter of 4 mm, and works in the visible light. The diffractive structure contained in it is a double-layer separated diffractive optical elements with an angle-band integral average diffraction efficiency (ABIADE) of 98.9% at an incident angle of 0-15 degrees and working wavelength of 400-700 nm. The Modulation Transfer Function (MTF) of the system is better than 0.5 at 100 1p/mm, the distortion is less than 2%, the imaging quality is excellent, and the maximum diameter is 9.6 mm, the total length is 24.2 mm, and the weight is 2.37 g. It has the advantages of compact structure and light weight, and is satisfied with the miniaturization of the micro-projection system demand.