What the HECK!

[Artix]

Bad ass, cant do that with any hobby materials

But that would be awesome!

[Artix]

real optical trapping:

http://ca.youtube.com/watch?v=jCdnBmQZ6_s


I'm impressed.

Steve

So what exactly would my video be? I'm confused.

[mixedgas]

wrong choice of words late at night,. You may have something there,

Steve

[The_Doctor]

Thats a very neat effect! Just tried it with my 405nm pointer and it worked!

On the strength of that I had a go with a 100 mW 405 nm beam. I have a small optic from a scrapped photocopier or scanner, focal length around 2 cm. I'm going to retry soon as I barely got anything. It lasted only a fraction of a second. But I think it was the right stuff because it seemed to gravitate to the beam focus like something caught in a balance of strong magnetism, and stayed locked in the instant before it vanished. The pen was a black permanent ink Staedtler Lumocolour, the closest I have to the pens people described. I didn't try for long because I need that pen intact.

I tried several things, no others worked. Tried green light but the beam was too thin, the focal point too long. I'm guessing that the fine particles from burning diesel or paraffin might do it, and that longer wavelengths will make it easier to catch one.


EDIT. And before actually posting, for once. It works. I got a few in succession, several seconds each, from the 405 nm/black permanent Staedtler Lumocolour combination I tried before. It;s interesting, I'm sure it's the smallest point of light I've ever seen. Never seen anything that bright and small at so close a range. Whatever applications this might have, one is a neat way to accurately gauge the focal length of a lens... it was easier to spot it this way than any other I know.


MORE EDIT:
Maybe it's not so accurate a gauge of focal length, I just got a string of them! Two close, plus a smaller third one forward of the two (away from source). They sat like a string of beads on a taut line, and persisted for about 40 seconds. While I have a camera with a limited movie capability, it's not that long. I might try to capture this tomorrow. It hasn't got much magnification though, so I don't know yet if it can cope. Probably not though. Anyway, I found it was really easy to trigger with tiny movements in and out of the beam once I found the focus. Just one mm off and it's more than twice as hard to trigger them. But there is some leeway, the string of points seemed to be a mm long. Probably wasn't though, I think the extremely fine detail made it all look bigger than it was.

[mixedgas]

Upcollimate the beam, circularize it, run the beam through a spatial filter , then refocus it, and this would last much longer.

Steve

[Artix]

Upcollimate the beam, circularize it, run the beam through a spatial filter , then refocus it, and this would last much longer.

Steve

How exactly would I do that?

All I have is a couple convex lenses... nothing special.

[mixedgas]

How exactly would I do that?

All I have is a couple convex lenses... nothing special.

see:

http://www.edmundoptics.com/techSupp...?articleid=272

Steve

[allthatwhichis]

No one seems to see the really important part of the post...

"I have a 635nm laser from a 16x DVD burner. "

Anyone know the power of this diode, or if this diode is worth putting in a projector?

[The_Doctor]

Upcollimate the beam, circularize it, run the beam through a spatial filter , then refocus it, and this would last much longer.

Steve

Which is exactly what I had in mind for the green. (At least, the expansion and refocussing). Although, that one has some strong IR in it too. Would that help or hinder this? Until I try with a better shaped beam from that one I have no way to know if presence of two wavelengths is a problem due to interference or a help due to extra energy.

Another question which I have wondered about is the use of optical tweezers for tiny biological samples. Hard to see how they could be held intact, wouldn't the energy destroy them efficiently?


Edit: Allthat.. I noticed it but I don't think it's 635. Weird though, they'd store a bit more so there is a reason to try them, unless violet takes over all. I hope that strong single mode shortwave reds do get to optical drives. If someone makes one that isn't vulnerable to retroreflection they might, but I doubt it will happen. They only have to live as long as the rest of the mechanics..

[Things]

They are not 635nm, more like 650nm, but people use them in lower powered projectors all the time.

EDIT: The typical closed can DVD diodes can range from about 80-200mw of so, usually around 120mw though.