Instead of the traditional approach that relies on the arrangement of optical components, researchers have developed novel photography optics that capture images based on the timing of reflecting light inside the optics. According to the researchers, these new principles open the door to new capabilities for time- or depth-sensitive cameras that are impossible with conventional photography optics.
The researchers created new optics for an ultrafast sensor known as a streak camera, which resolves images from ultrashort pulses of light. Among other things, streak cameras and other ultrafast cameras have been used to create a trillion-frame-per-second video, scan through closed books, and provide a depth map of a 3-D scene. These cameras have relied on traditional optics, which have a variety of design constraints.
The researchers describe a method for making a light signal reflect back and forth off carefully placed mirrors within the lens system. At each reflection time, a fast-imaging sensor captures a separate image. The result is a series of images, each corresponding to a different point in time and distance from the lens. Each image can be accessed at a different time. This technique has been dubbed “time-folded optics” by researchers.
A set of semireflective parallel mirrors in the new optics architecture reduces, or “folds,” the focal length every time light reflects between the mirrors.