Reflective autofocus image system with MEMS deformable mirror and freeform design

摘要

In this paper, we proposed a miniature auto-focus image system without moving components. We had previously presented a 2-Mega-Pixel auto-focus module by combining reflective optics, refractive optics and MEMS deformable mirror. This configuration can be further improved. We expanded 2-Mega-Pixel image plane to 8-Mega-Pixel image plane and corrected the aberration by adding one more lens as a stop. For the concern of the cost, we distributed the optical power of the adding lens to the fixed reflecting mirror and the deformable mirror, and we designed them as freeform surfaces to compensate aberrations. Finally, an 8M pixel auto-focus image system that FOV is ±26° can be achieved. The MTF at half spatial frequency is above 25% , and the thickness of the system is 8.2mm.