Optical Fresnel zone plate flat lens: colored photoresist through I-line stepper | Hacker News Reader

Optical Fresnel zone plate flat lens: colored photoresist through I-line stepper

nature.com

61 pointsbookofjoe14 comments

I had to do a lot of googling before I sort of understood this, so for future readers: these people figured out how to create tiny lenses using the same photolithography machines that are used currently used to create microchips (I-line stepper. I-line refers to a specific wavelength of UV light—365nm, and the stepper is the machine that focuses it on the silicon wafer)

That is only the context i.e. prior art of their method.

The novelty is in eliminating the etching and post-processing steps, by using a colored photoresist:

> In this study, we present a simplified method for fabricating visible Fresnel zone plate (FZP) planar lenses, a type of diffractive optical element, using an i-line stepper and a special photoresist (color resist) that only necessitates coating, exposure, and development, eliminating the need for etching or other post-processing steps.

More metamaterial lenses on the way?

Watch this space!

Not clear to me where the novelty is in this... people have been doing similar stuff for ages, and the performance of the optics here leaves a bit to be desired as well.

Sure we can mass produce these, but we can also mass produce wafer-scale lenses, and in any serious application, a normal metamaterial lens would justify the higher cost with its performance

it's a very narrow line of novelty, with a set of middling performance devices... not typically something I would expect from LSA.

That's just modern science no? The low hanging fruit has mostly been picked so advances are smaller and smaller, but we're doing more and more of them in parallel so the total advancement speed is still greater.

Seems like simpler fabrication but not sure why they can't just make a master and then stamp/pattern these at scale like how gratings are manufactured.

you definitely can and people definitely do this. There are arguments that stamp patterning is better suited for optics as well - specifically point defects seem to be less deleterious and that the feature shapes (not sizes) are more readily done via stamps. However, typically a lot of semiconductor manufacturing is viewed from an electronics perspective today, where stamping is definitely considered an inferior process.

Could diffractive optics be a decent alternative to reflective optics for EUV lithography? It has the same advantage of not needing a refractive material that works with EUV, but you can stick with optics that are 'inline'.

I guess the exposure just isn't going to be strong-enough because the actual aperture is just to small?

You still need a solid material which is transparent to EUV to build your lens onto - and isn't the lack of such a material the main reason why refractive EUV lenses aren't a thing?

A diffractive lens works by having small holes in a plate, at least as I understand it. The diffractive pattern then interferes constructively at the focal point. So the transparent material is just 'air' or more likely, vacuum. It doesn't need to be solid.

The problem I forsee is that it doesn't let much light through. Because most of the lens isn't holes, but instead solid non transparent material.

Do we possess the technology to place atoms sufficiently close enough to direct euv? Considering the fact euv is already close to the limit of our abilities

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