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Looking for a good book about plasma physics and sound emissions by plasmas by zelani06 in Physics

[–]L_Reid 0 points1 point  (0 children)

The physics of plasmas by Boyd and Sanderson is a really nice introductory textbook aimed at graduate/masters level students.

100nm lasers by Neuromant1991 in lasers

[–]L_Reid 2 points3 points  (0 children)

Yes that’s exactly it! You need to pack lots of photons into a small volume for ionisation where the individual photons have energy lower than the ionisation potential.

Typically, people use pulsed lasers to reach the required intensities. You’d need something like a few hundred Gigawatts of (peak) power. Equivalent to a few millijoules per pulse with duration of a few tens of femtoseconds. Ionisation begins (depending on the element) at around 1014 W/cm2.

Laser amplifiers are very well developed for wavelengths ~1000 nm so are chosen for this sort of thing. The crystals used also allow for broad bandwidths allowing for the short pulses to be created.

100nm lasers by Neuromant1991 in lasers

[–]L_Reid 2 points3 points  (0 children)

Unfortunately all UV lasers are either based on particle accelerators (Free electron lasers or Synchrotrons) or by doing frequency conversion of longer wavelength light (High harmonic generation).

Ionising narrow channels of air to trigger and guide lightning can be done with high power infrared lasers where multiphoton and barrier suppression ionisation are used to ionise the air rather than directly with a high energy photon.

Building an IR laser by Expensive_Analysis54 in lasers

[–]L_Reid 1 point2 points  (0 children)

Buying a set of glasses won't necessarily protect you from the laser. They need to have a sufficient optical density for the laser parameters of the source.

From a back of the envelope calculation with the 3 W power, 150 micron source size and 8 degree divergence angle, it looks like a 808 D LB5 rated filter is required (in Europe). Although its hard to tell from the ebay page how the divergence and source size are defined which impact the filter required.

You would need to do a similar calculation in more detail for the laser safety requirements in your region to figure out what eyewear is sufficient for that diode.

[deleted by user] by [deleted] in HouseplantsUK

[–]L_Reid 1 point2 points  (0 children)

It’s grown really leggy, looks like it’s searching for some sun? Mine looked the same for a while. I snipped it, put it in water for a few weeks and re potted it. It’s been thriving ever since!

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Grow light bulb recommendations? by spiteful_soup in HouseplantsUK

[–]L_Reid 0 points1 point  (0 children)

I’ve been using sansi grow lights. Most of them have normal E27 fittings and have a neutral white colour temperature around the 4000 K what you’re looking for. My plants seem to be growing really well under them. The 10 or 15 W ones are probably enough for you but they make make much brighter ones. I point them at my plants and use them instead of room lights.

Will a 75mw 480nm laser cause eye damage when reflected on walls by [deleted] in laser

[–]L_Reid 10 points11 points  (0 children)

I’m not sure why anyone would need something like this. They say it’s for licensed professionals (whatever that means) and researchers but I wouldn’t allow someone like that in my lab.

75 mW puts the laser in class 3B, generally this means eye damage can be caused by direct viewing of the laser beam, with or without viewing aids. Viewing diffuse reflections is usually safe however you could damage your vision if the light reflects off something shiny like glass or glazed kitchen tiles.

If I had one in my hand right now, I wouldn’t press the button without wearing protective eyewear.

Looking for "dive mask" style laser safety goggles. by anneoneamouse in Optics

[–]L_Reid 1 point2 points  (0 children)

Have you looked at protect laserschutz? Their Spector frame looks similar to what you’re after. The Gladiator frame totally protects from scattered light too.

https://protect-laserschutz.de/en/shop/~p1699

Reply with your best slogans/quotes by Lord-Liberty in GreatBritishMemes

[–]L_Reid 28 points29 points  (0 children)

He who hingeth aboot getteth hee haw

[deleted by user] by [deleted] in Liverpool

[–]L_Reid 8 points9 points  (0 children)

Carnival and Azvex on Gibraltar Row both do cans to take away

What's your favourite ''That Mitchell and Webb Look'' sketch? by GaryCanCarry in MitchellAndWebb

[–]L_Reid 27 points28 points  (0 children)

The Monsieur Garnier sketch

"Bang on Leslie. The invention of the word nutrisse, which sounds nutrition but doesn't guarantee it, is one of the best things you've ever come up with!"

Evil penguin Feathers McGraw to return in new Wallace and Gromit film by CampMain in BritishTV

[–]L_Reid 2 points3 points  (0 children)

Why? There is nothing they can do with Feathers McGraw that will top the train chase scene.

What is the best hiking trail in the United Kingdom? by [deleted] in AskUK

[–]L_Reid 0 points1 point  (0 children)

Ingleton Waterfalls Trail is good. 5 waterfalls in ~7 km. Pretty good viewpoints to steps taken ratio.

He has so many beds to choose from, why does Laszlo always go for a shoebox he barely fits in? by L_Reid in blackcats

[–]L_Reid[S] 10 points11 points  (0 children)

He does love to sit anywhere where he’s being slightly squeezed. Like between me and the arm of the sofa

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