With metal lenses, camera telephoto lenses become ultra-flat

It is a technology that is revolutionizing optics. It makes it possible to design telephoto lenses a few millimeters thick and telescopes a few centimeters long.

Imagine a telescope that fits in the palm of your hand. This is what engineers from the Faculty of Science at Harvard University have just presented. They have developed an ultra-thin lens, barely two millimeters thick. But this lens is capable of showing you the craters of the moon with as good definition as 50 or 70 cm telescopes.

This feat is made possible thanks to a completely new way of designing objectives. Instead of stacking dozens of lenses (concave, convex, divergent, etc.), we take a thin plate of glass. And we engrave a microscopic pattern inside which will accomplish the same job, that is to say guide the light, but in two millimeters thickness. This is what we call metalens and it is revolutionizing optics.

The ambition is really to replace any current optic. Researchers have been working on this for several years and in recent months, they have made considerable progress. For a long time, metalens were limited to black and white, now they work in color. We also get wide-angle and several zoom levels. So it would be great for phones, we would no longer have these three or four lenses sticking out at the back.

The same quality as a paparazzi megazoom

The problem is that the metalens created so far were not very bright and the colors were not always faithful. This should change with what Harvard engineers have just presented. We could have ultra-thin lenses with the same quality as large traditional optics.

The good news is that they’re not going to cost more. To engrave them, we use the same technique as for microprocessors, so the cost price should be similar (a few tens of euros on average). A paparazzi megazoom easily costs over 10,000 euros. So if the quality keeps up, maybe one day we will have the same thing, fully integrated into our cell phones for cheap.