Zoomable lens without any moving parts | Hacker News Reader

Zoomable lens without any moving parts

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168 pointssimonebrunozzi55 comments

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Interesting, looks like the last big lens tech, liquid lenes are finally here.

The First Smartphone to Use a Liquid Lens is the Xiaomi Mi Mix Fold

https://petapixel.com/2021/03/30/the-first-smartphone-to-use...

Liquid Lens Features, Applications, and Technology

https://www.edmundoptics.com/knowledge-center/application-no...

[The] camera uses a liquid lens powered by a motor that uses precision manipulation on that packet of fluid to switch between a 3x telephoto zoom and a macro mode [..]

If I understand correctly, the lens in the Xiaomi Mi Mix Fold does require a mechanical movement to be adjusted (it's also clearly visible in the video), so I'm not sure what is the point.

It's a much more compact mechanical movement than a traditional focusing system, allowing them to use the same sensors for two different zoom levels on the phone. Right now this is otherwise being done by using multiple sensors and lenses instead.

I remember prior literature on liquid lenses used electric charges. It is possible the ones in the phones use mechanical movements to get around patents.

I think I also remember something like that. It might have been an interface between silicon oil and a saline solution that was deformed by applying an electric field.

You can change the zoom/focus by a lot more if the lens can be made to change shape, kind of like the eye. You would need to have a much greater degree of movement to replicate it with hard lenses.

You could also do things like use different patches of the sensor to focus different parts of the scene. Depending on how much the lens can morph, it could provide for bifocal functionality or limited fly eye.

Another new(?) type of lens: https://www.polight.com/technology-and-products/how-does-it-...

The glass is deformed rather than moved. The main selling points compactness and very fast change of focus.

It's impossible to deform something without moving parts of it. Still, fast focus is good.

What happens to a liquid lens at -60 F / -51 C?

To me this kind of sounds like turning a bug into a feature. And that's great. I would not doubt if they were having a problem with phase shift with temp and thought, "Hey, what if we did this intentionally?"

Usually engineers hate the electromagnetic phase shift that comes from temperature change, or worse, temp changed caused physical shifts in phase of the material. One notable example of this is the PTFE dielectric material for coaxial cables which has become notorious for the "teflon knee" in it's temperature vs phase plot.

Hey, phase shift is great for radars and radar-like processing. If you can control or calibrate it it somehow, you're gold.

We actually engineered the material specifically for its optical/IR behavior. See: https://www.nature.com/articles/s41467-019-12196-4

This is essentially a zone plate reflector which has two states, and thus switchable focal points.

The images shown lead me to suspect this is a binary zone plate, which has a much narrower bandwidth over which it would be effective.

However, this is all prototypes, if they can indeed make a zone plate that can be addressed as pixels, with finer control over phase shift at each pixel, there are quite a few places where it would be quite useful, in spite of the narrower bandwidth.

https://en.wikipedia.org/wiki/Zone_plate

That's incorrect, metalenses are not diffractive lenses. They continuisly change the local refractive index through subwavelength structures. There's a brief introduction and discussion about differences with diffractive lenses here: https://www.nature.com/articles/s41467-020-15972-9

Why is "meta" in the name?

It's a general category of assemblies / structures that mimic a material with unusual or even impossible properties: https://en.wikipedia.org/wiki/Metamaterial

Co-author here, Not a binary zone plate.

How wide of a bandwidth could this handle? Do you think it will be possible to cover the entire visible light spectrum some day?

It’s theoretically possible; this is a very active field of research.

Co-author here: link to the journal article: https://www.nature.com/articles/s41467-021-21440-9

I love the idea of these electro-optic (or in this case electo-thermal) configurable lenses. and fourier optics in general.

What range of optical wavelengths did this lens operate well over, or could a similarly constructed system operate. My experience with electron beam exposed PMMA grating/lenses was that they were OK over the optical range, but did show noticeable dispersion, while for filtered (or laser) optics they worked extremely well to replace much thicker/heavier system solutions.

This was designed for the mid-IR (5.2um). I don’t recall its bandwidth but is was small on order of 100nm. The dispersion of this material in the mid-IR is relatively flat. There is active research on dispersion engineering via more complex geometry of the ‘meta-atoms’ to broaden the bandwidth for achromatic metalens optics. Other research is actively looking to design materials that could have this phase change functionality in the visible wavelength range. All stable phase change materials to my knowledge strongly absorb in the visible range.

Thanks a lot for the quick response! I read enough to see it was designed for multi-micron, but was hoping it would still work down to near-IR. It will be hard to use this for depth imagers or standard CMOS at those longer wavelengths, but for true IR cameras it could be amazing.

https://web.archive.org/web/20210403031009/https://www.extre...

This reduces ghost effects as well, of which was taken advantage by an attacker who eventually inject stop signs, for instance, into the imager:

https://www.usenix.org/system/files/raid20-man.pdf

Bah, Caltech can top that. Why bother with a lens? How about an optical phased array? :)

https://www.caltech.edu/about/news/ultra-thin-camera-creates...

I’d also wager on computation vs moving parts, even if those moving parts are microscopic.

Possibly faster, more reliable.

> When heated, the atomic structure of the material rearranges

So it does move, just on a smaller scale.

before even opening the thread, i knew someone would make this comment.

come on guys, we all know what the title means

It's a valid observation. A lens that could somehow do that without moving at all would be pretty magical, and the headline plays on this to get your attention. The headline could have been "MIT Creates Zoomable Lens That Works Using Heat" which is still cool, but not as sensational.

Or better yet, "MIT Creates Zoomable Lens That Works by Moving More or Less".

By this definition of movement absolutely nothing would do anything. If there was electric current you could say, "but the electrons are moving in the material". It's like saying your stove moves when you cook.

By any reasonable definition without moving parts means without any macroscopic (mechanical) parts that move.

Well, I actually thought this was going to be about phased array optics, so I guess there is some distinction here.

This is quite close to phased array optics actually.

I think on sites like HN - even with non-controversial subjects - you have to say "improbable" instead of "impossible" and stay away from absolutes.

Maybe "zoomable lens with no conventional moving parts", or "non-mechanical zooming" or solid-state zoom lens or...

Atomic structure shifts are not conventionally considered ‘moving’. Most people wouldn’t call water turning to ice a ‘movement’.

Not until the glaciers show up.

A glacier is compacted snow, not ice

Snow is ice.

> Snow comprises individual ice crystals

https://en.wikipedia.org/wiki/Snow

I can warrantee you compacted snow is ice. Just go to Greenland, Argentina or Switzerland and see a glacier by yourself. You see ice and bubbles(bubbles could grow and become caves and over time they go up).

Icebergs are called ICE- berg for a reason, not snow-bergs.

If you had a snow that is 1/10 the density of water, just 10 meters of snow means 1 atmosphere of pressure. That pressure compresses the snow, making 10 meters hold more water and more pressure.

There are places in the world with glaciers higher than three kilometers(1.8 miles).

Just wait til you hear about supersolids

I was thinking of when water gets over boiling point and then is disturbed:

https://en.wikipedia.org/wiki/Superheating#Occurrence_via_mi...

I think that the point is that there is nothing that you could really "separate as a part", everything being fused into a single piece impossible to disassemble without destroying it.

This is to put in perspective with a Zoom Lens where moving parts are designed to be assembled and disassembled: https://www.lensrentals.com/blog/2021/01/the-secret-of-the-b...

Also, a heated metal bar dilates and thus moves, not sure it is considered having "parts".

If the phase change causes the whole lens to stretch or shrink, then it would fit my definition of "move"

Define ‘move’. All matter ‘moves’ on some scale even at absolute zero temperature.

No magic photon teleportation happening here: it moves. Just not with gears.

Always thought that camera lenses the way they are, are the already obsolete technology. I mean we can fit billions of transistors on a fingernail, but we need this mechanical contraption to zoom things? I think this invention is still not it, but I am glad the tech in that space is finally going somewhere. Don't get me wrong, I love lenses but it feels like using something from a last century, even though it was just made.

Lenses are like rockets in that way. The physics of light and space are unforgiving and hard to solve.

So at what scale do we call movement movement? Because things are moving inside this lens, but at a molecular/atomic level.

> It’s just a proof of concept right now, but it’s a very cool concept.

Though metalens need to be heated, it's a very cool concept!

It looks like the material is organized on a grid. Imagine a lense + algorithm that conforms to the depth map of the FOV. You could get super focus (there's probably more appropriate term) in a single shot.

What you're describing is a light field camera.

It's cool tech, there was a company called Lytro that tried to commercialize them a while back.

No, they are describing a lens that can change the effective focus for different regions of the image, so that you can get multiple parts in focus at the same time. There are no light field tricks here.

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