Oolite Bulletins

@Stargazer - the world is full of muppets!

We had a CO2 laser supplied a few years ago with one of its prisms fitted 90deg out - we turned it on - we wondered why the detector wasn't lit up by the beam - by the time we'd worked it out it had burned a whole in the side of the case and was blistering the paint off the breeze block wall...

We had a technical assistant who used to wave his hand in front of a different CO2 laser to check if it was on - he did it one day and fortunately was out by a few degrees and only scorched the sleeve of his lab coat - not knowing it had been upgraded the week before while he was on holiday...

DaddyHoggy wrote:

@Simon B- can't tell you what the crystals were (I don't remember their chemical composition anyway and I didn't have a high enough security classification to know how they were grown - just in case any Chinese spies are reading this - no point in kidnapping/grooming me I've been out of that area of work for several years now - sedate life of a University lecturer now)

I didn't need to know how it's grown, just the name of the crystal. That's usually not a secret... after all, the chemistry of the crystal is available to anyone with a spectrometer. Probably nobody thought to tell you, and you didn't need to know.

Well - for the record, I do have a very high security clearance indeed - and a blackberry. So any Chinese agents wanting to lay a honey-trap will find me a wonderful target of opportunity. I do hope none of them try, because I am notorious for talking in my sleep - spilling all kinds of state and international secrets. Especially after a few glasses of fine wine and a good dinner followed by several hours of inventive and acrobatic sex.

But, being "perfect" as Ahruman re-iterates meant no surface absorbtion, so no heat transfer

Now I really wan to see an example. AFAIK, this is not possible.

- our laser would punch a hole in 3-5mm of steel before it was run at full power (lab wasn't cleared to run at any higher powers from a H&S pov)

Well allright - I'll concede on the crystal coating. I'll still cling tenuously to the idea that mere polished metal won't be as effective.

I note: You do need high-energy reflectors to plate the laser cavity.... or it becomes difficult to effectively pump the thing. For very low power lasers - like diodes - we just polish the ends of the crystal.

CO2 lasers, I understand, need to cool their reflectors - and the cavity.
I did find this page - cute. But nothing "perfect".

Mind you - we are talking about a ooniverse where physics is quite different...

Like most Governments/Military doing damage with and protecting from damage with battlefield lasers is an on-going game of leap-frog and highly specialised

That's why it' called an "arms race" even when arms are not involved. ;)

@Simon B - sounds like you have an interesting job too!

When I started with the MOD 14 years ago they warned me about seductive Russian agents, willing to do anything to get to the contents of my brain - well I waited 13 years (I left last year) - nothing, nada, nowt, zip, zilch, zero - to my eternal disappointment.

Like you said, nobody thought to tell me the crystal type (I just modelled the sensor it was trying to protect) - I do know that the US came and took a sample away as they'd failed to grow their own, much to their annoyance. I know "perfect" is impossible but near-as-damn-it-as-makes-no-difference-for-the-ten-seconds-it-needs-to-reflect-the-beam is what we were going for and achieved.

As for "impossible" well, five years ago, negative refractive index materials were "impossible" and the stuff of Science-Fiction were they not?

lets see

Number of polygons to Armour to Lasers to blind muppets...

Amazing

As for "impossible" well, five years ago, negative refractive index materials were "impossible" and the stuff of Science-Fiction were they not?

SF is the fiction of the possible.

Five years ago lots of things were considered "impossible" which remain impossible. And over the years a great many things have been considered possible which have turned out otherwise.

The whole argument is meaningless.

Refractive-index, as it is conventionally defined - as the ratio of speeds - cannot be negative. (You can make it negative when you model light with wave-mechanics... so the EM-wave-speed can have complex components.)

So - it was impossible and still is. What the -ri people are doing is using the maths of classical optics to describe new phenominon.

A previous hypothetical negative need only have the refraction angle on the same side of the normal as the incident angle. There has never been anything actually ruling that out - no fundamental rules are violated and we can demonstrate that photons do not follow Snells law except on average. So, all refractors exhibit negative ri some of the time.

Bottom line is that "refractive index" never existed except as a kind of average.

In a perfect reflector, the reflecting material must completely give up the energy of the incoming photon to the outgoing one. Including any recoil energy.

There are circumstances where this can be done, involving very few particals. In a solid, lattice interactions mean that there are so many other things that can happen to dissipate the energy. With many particles you end up with thermodynamic effects - in other words, there are better reasons to doubt the possibility of perfect reflectors being built any time in the future than we had about doubting negative refractive index.

I suspect the material you witnessed would also have had vulnerable frequencies... soy (guessing) where recoil excitations come close to phonon frequencies - you could get more absorbtion if the laser was tuned to the material. But that would be an arms-race effect. Does show that adjusting the frequencies to match resonance may not be such silly technobabble after all.

Quite a fascinating discussion you two have here!

Simon B wrote:

... Does show that adjusting the frequencies to match resonance may not be such silly technobabble after all.

Do you mean to actually oscillate a material (with soundwaves?) to tune the material to a specific laser frequency (or even diverse lasers f.'s) in such a way that thermodynamic lattice interactions do dissipate as little as possible of the laser's energy, the absorption can be as high as possible and a maximum of energy is stopped at (actually, on third read, in) the armoring material?

Thrilled,

L

That sounds very similar to the 'energised plating' talked about in the 'Enterprise' version of 'Star Trek'...

It certainly wouldn't be soundwaves, more likely a variation on the experiments allegedly performed by the USN with gauss coils. Tuning magnetic resonance...?? ...atomic resonance...??

What an interesting discussion, first time I've thought about this area for many a year!

Hi Star Gazer!

Star Gazer wrote:

What an interesting discussion, first time I've thought about this area for many a year!

Me too ... quite some time ago I studied physics ... partially - meaning I stopped before it was finished, and did something completely different.

Don`t know about soundwaves, but some sort of kinetic vibration it would have to be, exactly tuned to remove dissipation of energy (and thereby local "peaks" that destroy or weaken the armor's material locally) and so enable as good as possible absorption, as smooth as possible over the armor surface ...

Not sure if my interpretation is correct, though.

Star Gazer wrote:

That sounds very similar to the 'energised plating' talked about in the 'Enterprise' version of 'Star Trek'...

To me, too. Well, a few things Star Trek envisioned might become a reality in the far future - like the concepts of beaming, warping or 3D-printing stuff (the replicators) - perhaps this one too?

Quite fascinating if some people who work/worked in this area once have a go at it

everytime the had a cup of coffee in star trek from the replicator machine it always came in a brand new china cup, what did they do with all the old ones? they must have had loads of them stashed away in the cupboards in the kitchen.

Griff wrote:

everytime the had a cup of coffee in star trek from the replicator machine it always came in a brand new china cup, what did they do with all the old ones? they must have had loads of them stashed away in the cupboards in the kitchen.

They prolly stuffed them into the Torpedo hulls, and everywhere else where they could get away with it..

And btw congrats on your new title Griff... if you have not noticed yet

You deserve it

Cheers Frame...

@DaddyHoggy, thanks I'm glad you liked it, thinking of developing something to attach to it when I have time and shouldn't REALLY be doing something else I ended up doodling some emblem ideas for the five trade/gypsy families, so I may end up adding some left over signs/further history's of/chance of some vessels to bump into...haven't done any OXPing other than skin repaints but I have three very seperate ideas on the boil, would much rather be working on this right now

Congrats at you by the way Griff, are you approving? Might need to be getting some tips off you at some point...

@Lestradae - certainly is fascinating discussion - and I'm completely outgunned by Simon B on this one - although my original Bachelors degree is in Physics - my Masters is in Defence Simulation and Modelling - I've always used my Physics knowledge to get me into trouble - as I've clearly demonstrated here.

I've enjoyed myself though - Simon B has got me digging out my old physics books and looking up Snell's law on the Internet.

Tunable crystals and tunable lasers - all good fun and good for the arms race t' boot!

later,

DH

Ha! no i hadn't noticed that! oo, I'll have to swap my computer chair for one of those foldable ones with 'director' written on the back of it, and shout all my posts out onto the forum through a megaphone!

* applaudes @Griff *

Wait a moment? Oolite 2?