It’s not. The mechanism by which it acts is quite different. The lens is a metasurface lens, which has small structures that cause the phases of light to constructively or destructively interfere. The result is caused by the fact that, by carefully picking how light interferes, one can form an image on the other side of the lens. This differs from a Fresnel lens (or other classical lenses), which essentially form images by having rays of light which emerge from one spot, on one side of the lens, converge to another spot on the other side.

(In particular, wave theory is not needed to predict the behavior of classical lenses.)

> [...] which has small structures that cause the phases of light to constructively or destructively interfere

This is slightly unclear. I meant more specifically:

[...] which has small structures that change the phase of the light, which, in turn, causes it to constructively or destructively interfere [...]

Well, a fresnel lense (or any lense) also just changes the phase of which in turn causes it...

But i will read the paper later.

Yeah, I should have said "subwavelength" structures, since I really didn't specify what "small" meant, but thought it was getting too technical.

>> this lens looks like a Fresnel lens taken to microscopic extremes:

Except I don't think it is. It's probably more like a diffraction grating or a hologram. You can actually make a flat lens by creating a hologram of a real lens and it will be flat.

That sounds like it would make it ridiculously easy to make VR headsets that are as thin as the prop glasses used in Westworld.

What are the downsides?

Wavelength specificity. You only get the original focal depth at the wavelength you used to make the hologram, and it changes proportional to the wavelength. When you consider that blue light is 2/3 the wavelength of red light, you can see that this is chromatic aberrations big brother.

Diffractive elements are very wavelength dependent so while something like this would only work for monochromatic light (like a laser), but not for multiwavelength light. For that you would need to do some colordiversity.