A thin camera with a zoom function using reflective optics

We propose a camera that can maintain its thin dimension even when it utilizes a lens with a large focal length to zoom in. Large focal length have made the structure of a conventional camera thick. In this paper, we show how reflective optics prevents a camera from requiring significant thickness. Reflective optics is an inclusive term for optical systems consisting of mirror reflectors or a combination of lenses and mirrors. To demonstrate the concept, we fabricated a double-focus lens. Since this lens has a wide-angle lens inside and a telescopic lens outside, two views from different focal lengths can be obtained by deciding which part of the lens is to be used. We fabricated a micro-mirror structure that has flexible hinges and is actuated by external magnetic fields. The mirror that reflects light through the outside lens also takes the role of a shutter, by blocking light passing through the inside lens when the camera is utilizing the outside lens. By shifting the mirror, the camera can allow light to pass through the inside lens. Thus, the view with the double-focus is selected by actuating the mirror. We demonstrated switching between the two views with our prototype camera.