 If you have a sensor that has a time resolution comparable to the speed of light, then you can actually do some crazy things to camera optics. Nobody has looked at the optics itself. So in this project we wanted to really think about what will happen to the design of optics and optics of a camera when your sensor has time resolution that is comparable to the speed of light. We have used a cavity that is two semi-transparent mirrors to trap the light inside this space. You can use a cavity to fold an optical path in time. Now cavity is basically a trap for light. So when you have a trap that light gets trapped in and wants to escape, you can call it a cavity. Imagine you have a room and you place a mirror at one end and a mirror at the other end. And now if I were to stand in that cavity and turn on a flashlight, think about where those photons go. They'll go to the front of the room, bounce off the wall, and then come right back. Now if I exited that room, those photons would just bounce back and forth forever. Now what we're working with is very similar to that. The only difference is when it hits one wall, a little bit of the light passes through. And that's what we end up measuring with our sensor. But now that your sensor becomes very high time resolution or ultra-fast, you can actually use each of these round trips to create the image that you desire. One of the interesting applications of time-folded imaging is the ability to measure multi-spectral signatures off our scene. Measuring multi-spectral information is very important for industrial applications. We want to classify objects based on their spectral signature. We turned this huge 30 centimeter lens into a tiny 3.1 centimeter lens. Reducing the size of a camera lens is an important problem. If you look at iPhones nowadays, there's a little bump at the bottom, and that's because we can't make the lenses any smaller. So you can imagine using techniques like this to reduce the sizes even further. Now that the cameras are everywhere and the sensors are becoming faster and faster, time-folded optics can enable these cameras to not only capture the scene, but capture more and more information about what's in front of them.