Fresnel imager

A fresnel imager is like a camera, but it doesn't have a lens. Instead, it uses special curved pieces called fresnel lenses to bend and focus light. Think of it like using a magnifying glass to make a small bug look bigger - the fresnel lenses do the same thing with light.

The fresnel imager works by using these fresnel lenses to focus light from different parts of a scene onto a detector, which records the brightness of each point of light. Then, all of these brightness measurements are put together to create a picture of the scene.

One advantage of the fresnel imager is that it can be made much thinner and lighter than a traditional camera, because it doesn't need a bulky lens. This makes it useful for things like drones, where weight is an important factor.

Overall, the fresnel imager is a nifty way to take pictures without needing a lens, thanks to its use of special fresnel lenses to focus and bend light.