Hacker News new | past | comments | ask | show | jobs | submit | more PaulHoule's comments login

Go into a lab in the first floor of the physics building at my Uni and you are likely to find a femtosecond laser inside which sprawls over an optical bench which takes up most of the room. At the heart of it is a fiber laser that costs about $250,000 but they usually have added a lot of stuff to it.

A femtosecond laser for medical use is about $400,000

https://crstoday.com/articles/2014-sep/pricing-the-laser-cat...

which is one reason you might not see this become widespread.


Ironically that seems promising. This could just be an engineering problem where the only people making the required laser equipment are only making lab/medical grade gear with enormous markups. It's possible someone comes up with a practical to manufacture solid state version that unlocks these displays for the masses.

There is one consideration however where one failure mode for this device includes a situation where the processing locks up and leaves the laser pointed at a single spot continuously, burning a hole and possibly starting a fire.


Lasers used for laser light shows already have interlocks that will stop the laser if the mirror stops moving.

My understanding is that femtosecond lasers have some parts that are physically large because they use prisms, diffraction gratings, and such, to spread out a pulse so the laser can effectively amplify it and then recompress the pulse to use it.

See

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

note a workable laser "gun" could plausibly be "set to stun" because if the energy of a pulse sparks the air near your skin or clothing, the plasma absorbs almost all the energy causing a plasma explosion which can knock you down plus cause severe pain from an electromagnetic pulse.


The pulses are not entrained to software. They are inherent to the laser's design, such as with Q-switching.


I think ops point still holds - actively modulated q switches could still have a failure that pushes the laser outside the safety parameters, no? I don’t think OP was necessarily suggesting a software failure.


Q-switching does not operate like a transistor's base. It is more like the charge pump on a camera flash. It will not produce a high-power pulse if operated outside of parameters. There are other ways with different physics but comparable principles.


> where the processing locks up and leaves the laser pointed at a single spot continuously, burning a hole and possibly starting a fire.

Already solved for 3d-printers locking up and starting a fire.


I'm incredibly curious as to what that even looks like. Where do you study? Can you give us a photo?



Archive link: https://archive.ph/5FfDu

Note Google’s been working on a very strong Android TV offering for a long time that not only includes YouTube but also numerous FAST services

https://en.wikipedia.org/wiki/Free_ad-supported_streaming_te...

some of which are run by Google and others by companies like Pluto and Tubi.



Funny, I've been having a correspondence with my health insurance company that seems like they're using ChatGPT to write bogus letters.


A weak post that keeps getting reposted.

Overall that blogger has a unique point of view and worthwhile perspectives but also a lot of superficially offputting noise. This article leans in the latter direction.

I find self-diagnosed “autism” to be flocking at its worst, it mocks the seriousness of autism as a disability while spreading ignorance when it comes to underdiagnosed neurodivergences. When we hear some billionaire was diagnosed as “autistic” I’ll note that people like that frequently get worse medical care than we do, see:

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


The authors are all academics…


There are processes for “chemical recycling of plastics” that either convert polymers back to the monomer (pretty easy for styrene) or to mixed petrochemicals (such as pyrolysis). There are other problems, but the economics are always going to be tough for them because bulk plastic monomers and other petrochemicals (even fuels) usually cost about 50 cents a pound which is a hard price to beat even when you don’t consider the cost of gathering and transporting all that plastic.


Also almost all cotton clothing today is "permanent press" which means the fibers are coated in plastic.


> fibers are coated in plastic

No: Cotton is chemically treated.

https://en.wikipedia.org/wiki/Wrinkle-resistant_fabric

Perhaps you are thinking of "However, almost all the wrinkle resistant garments are made with poly/cotton blends fabrics."


They could be thinking of the stain resistant treatments which are a ureathane (plastic) coating.


Are you claiming that "100% cotton" clothing labels can be inaccurate? Do you have a source for this?


You can see they are inaccurate because cotton doesn't grow in many different colors. The bulk fabric may be 100% cotton, but the dyes implanted into the substrate are not counted.


Wouldn't surprise me.

The premium "not from concentrate" orange juices contain additives not required to be listed on the packaging.

Great value "natural flavor" chocolate syrup contains vanilin (artificial vanilla). So I guess the natural part only applies to the chocolate and not other flavors used.

Many "100% alpaca" socks contain other fibers too (elastics, etc).

The list goes on...

Edit: why disagree? You can even see stuff like "100% cotton with Scotchgard" or the sublimation process used on clothes. Want to share any evidence to the contrary or tell me why it's wrong?


I don't think that is true, but am open to learning otherwise.

A quick review of Wikipedia indicates dimethylol ethylene urea (DMEU) is used to crosslink the cellulose polymers itself.

Cotton is already a polymer (albeit a bio-degradable one). DMEU is not a polymer/plastic in its own right.

As far as I was able to see, permanent press is biodegradable.

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


The sublimation process on cotton clothes uses synthetics as the bonding base. It could be a polyester resin or a vinyl. The shirt itself will still be listed as 100% cotton.


DMEU is a synthectic bonding resin. but im not sure that by itself is in any way a problem. Are you talking about pattens that are sublimated onto cotton shirts?


Yes


Here's an idea, maybe we stop doing that.


Yeah, "frustration free packaging" could save the Earth. Often it is such a terrible experience cutting into plastic clamshells.


I've felt like I haven't seen a proper plastic clamshell in years


Shaving blades, which millions are sold of per year, Ive never seen without what amounts to a plastic clamshell.


I only see the paper backed ones with the small plastic panel never the full monty with the two plastic sides anymore. Maybe its taxed more or something in this part of the world.


I do live in one of the (if not the biggest) excessive packaging capitals of the world, so it might be that. Happy to hear they've moved away from it elsewhere.


Plenty of them in the grocery stores around here.


Wow!


Guidelines | FAQ | Lists | API | Security | Legal | Apply to YC | Contact

Search: