Time-Folded Imaging Systems; Spatial Involution of Paraxial Optics Using Time


The inventors of this technology have developed novel optics that expand the design possibilities and capabilities of ultrafast, depth-sensitive cameras. This invention has wide applications in industries and fields that utilize ultrafast photography, including medical imaging and remote sensing.

Problem Addressed

Imaging speed and depth of cameras have advanced significantly, including the development of ultrafast cameras. Despite these developments, ultrafast camera systems are limited by the design constraints of conventional imaging optics. This places major restrictions on the size and capabilities of these imaging systems. The inventors have developed novel optic systems in which images are captured based on the timing of reflecting light within cavities. This invention enables new designs and capabilities of ultrafast cameras, including multi-zoom capture and multi-color imaging.


Currently, ultrafast cameras are restricted by the optics of conventional low-speed cameras, e.g., the lens must be placed at a certain distance away from the sensor. To address this limitation, the inventors utilize a technique called “time-folding optics” in which light is reflected within a cavity consisting of two partially reflective mirrors. An ultrafast sensor captures an image at specific time intervals, resulting in a set of time-resolvable images. Importantly, this system allows ultrafast cameras to be designed compactly because the focal point moves closer to the lens with each reflection of light inside the cavity. In addition, rearrangement of the cavity and lens enables multi-zoom capabilities, as focused images of objects placed at different distances can be captured within a single acquisition. Furthermore, addition of spectral filters to this optical configuration allows for ultrafast, high-resolution, multi-color imaging.


  • Allows for compact design of ultrafast cameras
  • Expands capabilities of ultrafast cameras, including multi-zoom and multi-color imaging