momoschili

UV-C radiation is so rare in our lives and even in specific work environments that unless you have a very special need for it, you don't need to detect it. As far as I know, it's mostly just germicidal lamps and arc lamps that generate enough UV-C to be of any real concern, and in that case the operator knows about it.

what other general computing task leverages the wide bandwidths that optical transceivers provide as well as AI?

I get that AI washing is annoying, but this seems like such a petty thing to be mad at.

A key here for western users is that it does not include Ge, which is notably a material that China has a stranglehold on.

good point, I didn't read closely enough! The geometry of the GAAFET is definitely changes the physical model a lot (among the most important factors probably?)

Well I think both commentators are valid- the effect of shrinking a transistor but keeping the same geometry is probably well captured by this model. Going from a "10 nm" DUV finFET to a "7 nm" EUV finFET, this model probably works quite well whether you're manufacturing using EUV or DUV.

I think the crux of the matter is the transition from 7 nm down to our modern nodes, where the major change was not only going from DUV to EUV, but perhaps more importantly the change from finFET to multi-gate or gate-all-around FET (GAAFET), where this model probably needs significant updates to be still valid.

This might be changing with the slowdown in node advancements, but I think it's unlikely you are going to get anything truly "state-of-the-art" in publication research. Academia has trailed industry in this kind of transistor level semiconductor physics for years now. The majority of the state-of-the-art models are closely held in your usual suspects (Intel, TSMC, etc), and are likely considered significant trade secrets.

only the non-stereo realsense was killed. The stereo device was kept along for the ride

These have been around since at least 2016 and haven't really made any real waves... it's another technology Intel held out to dry. Stereo is a reliable tech that is relatively simple to implement but for the most part it seems to be have been left behind by other methods that are better suited for compact form factors in consumer like time of flight, or even LIDAR. Intel itself tried its hand at LIDAR, but shuttered the LIDAR real sense cameras in the early 2020s after no success.

I think the only consumer application where I know of stereo 3D being used is in hobbyist 3D scanners. I'm sure there's some machine vision applications in industrial QC, but besides that not really much else. Maybe in AR/VR but even there it seems ToF is a better match.

the foreman grills gets a lot of flack but it's a damn good cooking utensil and if not for him I'm not sure it would have been as publicized as it was.

also a great dad, christian, and boxer

RIP

yup, I bought a 13 mini and was happy that Apple was one of the companies that supported this form factor. That being said, the 13 mini sales numbers speak for themselves and I understand why this kind of phone isn't released every year. I'm holding out that Apple recognizes that most of the users of the 13 mini aren't serial upgraders and will continue refreshing the segment every 5 years or so

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

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.

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 is a solution to increase density, but this introduces significant integration complexity in addition to just increasing the overall cost. I think if this optical analog computer takes off, this kind of routing will likely be necessary

most people in the field believe his research isn't even capable of being wrong

definitely

Information in an electric circuit travels along that circuit at ~0.9c. The physical light pulses that are running through the optical waveguides are more or less traveling at around ~c/n, where n is the refractive index of the material (in this case silicon, so n ~ 3.5).

the actual optical "packet" of information is traveling slower than the electric "packet". The key here is that the electric packet can a few bits, while the photonic packet in theory has a much larger bandwidth.

It's a really smart idea to try to leverage the inherent scalability of semiconductor photonics. I think the use of a linear optical resonator to amplify a weak optical nonlinearity is quite genius, and something the relatively small nonlinear photonics community has been trying to do forever. That they showed this kind of 'all-optical-ish' nonlinearity on a relatively mature process in a foundry is nothing to scoff at, and likely one of the biggest results in semiconductor photonics in a while. At the single device level I think it makes so much sense, but what concerns me in general is how well this scales from a few perspectives:

1. resonators and device-to-device variance: in general it's pretty hard to get these resonant effects to line up with each other from a production POV, especially with large arrays. Silicon photonics has come far, but I don't think it has approached the level of uniformity as electronics. They have demonstrated some level of electro-optic tunability, which is the traditional solution, but they still need to leverage that for their nonlinear effects too.

2. area and space: the 'minimum' trace size of these planar photonics circuits is still quite large (~200 nm minimum feature size typically for these waveguides). This is essentially due to a minimum size needed to confine light within a waveguide which depends generally on the waveguide's refractive index and target wavelength. These are currently all integrated on a planar manner, so each channel becomes quite large, especially if now you also need a relatively large ring resonator, which in this case is at least ~100 micrometers or so in diameter

3. the combination of 1 and 2: high device-to-device variation, along with a large planar footprint means that these things are quite expensive and difficult to manufacture, without some kind of miniaturization benefit that you would typically get with electronics (at least not yet). This effect appears to be more than the sum of 1 + 2.

light speed isn't really all that good when you remember that information in your electrical circuit is traveling as fast (if not faster) than light in the medium in this case. Sounds good in marketing, but the key here is bandwidth, not 'speed'

who out there actually has a consumer spectral imager these days? Cheapest ones I can find are ~10k USD....

Simply speaking, "l" describes the number of nodes. In the same sense that a particle in a box with sin(nx) wave function has more nodes the higher energy (or momentum) state it is in.

As for why l==0 has no rotation going on at all, one would say that this should be expected. Qualitatively, the symmetric sphere does not change with rotation, so how would we tell if it is rotating or not? And perhaps the next step is controversial, but if there is no way to tell, maybe there is no dependence? This is a similar argument to why the electric field of an infinite plane is constant with respect to distance from it.

not quite as they are missing the radial dependence

you are correct. The Schrödinger equation for the hydrogen atoms in spherical coordinates demonstrates separability which allows you to separate the radial and angular coordinates. The radial term, which is most interesting due to the 1/r potential is typically a Laguerre polynomial. The angular term is 'free' from any potential is typically a spherical harmonic.

The spherical harmonics in general are typically derived as part of the solution to the Laplace equation in spherical coordinates. A bit of a semantic point (though perhaps the distinction is important) though, since the Laplace equation's angular dependence is identical to that of the Schrödinger equation for the hydrogen atom.

I think he was replaced by a robot at some point and is now in Cuba with JFK and Tupac

the key difference is in the function of the reticle if we want to do it in bulk analogous to normal lithography

in normal 2D lithography, you're typically only concerned with exposing area on a relatively flat film. This allows you to essentially 'block' the areas you don't want to expose and flood the areas you do want to expose. So you make your reticle with your pattern on it and you just shine the active wavelength (lets say 400 nm) through it and you get an exposed pattern and the areas not exposed.

in this volume lithography, you still have a relative thin flat film, but the pattern is no longer confined to a 2D surface, but in general is a 3D volume. So the reticle now needs to project a 3D pattern (essentially a hologram) instead of a 2D pattern. This is in general going to be quite difficult, and in some cases physically impossible if we're illuminating with the active wavelength.

eg. imagine a pattern like this where we are exposing from the top

---------------------

++++++++++++

--++----++--------

where --- is unexposed and ++ is exposed. There is basically no way we can get the active light to the 2nd layer without at least partially exposing the first layer.

The way the nanoscribe and similar systems goes about this is to use nonlinear effects. If I shine very intense 800 nm light onto a medium with a special optical property called a third order nonlinearity, I can sometimes get the medium to accept 2 800 nm photons as a substitute for a 400 nm photon (energy conservation is obeyed here since an 800 nm photon has half the energy of a 400 nm photon).

The crux here is that it needs to be very intense 800 nm light, so it needs to be concentrated. It's much harder to get intense light to expose an entire 3d hologram than it is to focus it into a single spot and raster it around.

Of course I'm not saying it will never be possible, but it is a significant effort.

Here's the way I'm thinking about this:

the vertical cuts do not significantly the internal structure of the onion as each individual cut I make does not entirely sever the connection between the thin vertical slices I'm making. This means that I can do a lot of these, and not worry about harming the overall structural integrity. Then I make a single horizontal cut which does harm the overall structural integrity. This is not intrinsic to the horizontal cut itself, but the fact that I have both horizontal and vertical cuts.

If I start with the horizontal cut, again I do not signficantly harm the structural integrity of the onion. However, each subsequent vertical cut I make is now going to individually compromise the integrity of the onion.

With a sufficiently sharp knife, the single horizontal cut at the end does not really pose a significant danger overall.

This all being said I almost never do the horizontal cut out of pure laziness, and instead prefer to just do angled vertical cuts analogous to the video. They're never perfect but fine enough for me...

making the single horizontal cut first makes every vertical cut after more difficult to perform without harming the structure of the onion.

technique and a sharp knife enable the horizontal cut second to be vastly superior to doing it first.

angling the horizontal cut down is a good way to handle this. The horizontal cut is mostly only necessary for the lower sides of the onion anyways.

really isn't a right and wrong way to do it. Erring too far toward either extreme makes your food probably a bit boring versus poorly executed.

That being said, most of Ragusea's takes haven't aged all that well, some by his own admission.

the tool they used is basically a nanoscale version of a 3D printer that uses UV epoxy. Essentially using a laser focused through a high numerical aperture microscope to focus light and cure the epoxy (there's some nonlinear action here but it isn't that important).

The key point here being that it is a serial process where a single spot is rastered over the sample, unlike conventional optical lithography which is an area illuminating parallel process.