Retinal projection display system based on MEMS scanning projector and conicoid curved semi-reflective mirror

Abstract

Retinal projection display (RPD) is a research hotspot in the field of near-eye display (NED), which has a long depth of field and is able to overcome the vergence-accommodation conflict (VAC) because of the principle of Maxwellian view. However, the existing problems of RPD, such as small field of view (FOV) and large volume heavy weight, restrict its application and development. In this paper, an RPD system based on micro-electro-mechanical system (MEMS) and conicoid curved semi-reflective mirror is proposed in order to realize a large FOV with compact structure and light weight. The MEMS used is a kind of biaxial scanning mirror, which works in coordination with RGB laser diodes for the sake of scanning a two-dimensional image in a specific direction with high illuminance and high resolution. The conicoid curved semi-reflective mirror is used to project the image onto the retina and form a large FOV with a suitable eye relief distance (ERF), meanwhile to keep the external object visible. The combination of MEMS, RGB laser diodes and conicoid curved semi-reflective mirror retains compact size factor suitable for wearable function. The performance of the proposed RPD is quantitatively analyzed. And the key performance is set forth in detail as follows. The FOV is 70° horizontal (H) × 40° vertical (V), ERF is 30mm. And the MTFs are discussed as well. The proposed RPD system realizes a large FOV, a long depth cue and high performance with compact size, which can be further applied in the next-generation optical see-through NED.