Light focusing tube

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ions?

ot an LED. Does the spot of light *have* to be green?

Yes, a Laser seems to be the way forward

And it has to be green

Cheers

Klaus

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not an LED. Does the spot of light *have* to be green?

Well you're in luck then, direct green laser diodes are now on the market. (hmm not much stock... and you have to drive them hard for ~40 mW of power. )

How many photons/ sec do you need?

George H.

That's a worryingly large amount of coherent radiation needing safety interlocks. A class 3A 5mW green laser pointer will comfortably put a spot onto high clouds and be easily visible in daylight at closer range. Class 2

Jeff Liebermann wrote in news: snipped-for-privacy@4ax.com:

When I worked at the IR thermometry place, we used an optically correct fiber pipe to segregate the bolometer from the front end optics. It had a half turn in it mid span so righted our single lens design making spot aiming easier. It also created a planar face for the IR 'image' to be cast upon, whereas the bolometer devices typically have the actual bolometer a couple mm below an IR window. Easier to focus on the 'face' of the end of the optical 'stick'.

It was comprised of a bundle of indexed fibers bonded together when the stick is made and that is also when they apply the half twist in the center. I still have one somewhere. It had a small chip at the edge of one end.

One could place it against one's fingertip at one end and look at the other and see the fingerprint ridges quite clearly. Optical clarity, in fact, as the faces were polished. They were about 3mm in diameter. Maybe 4mm.

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The other thing to watch with cheap green LED lasers is that they may have an unspeakable amount of near IR NdYAG 1064nm leakage. Makes them good for popping balloons and the like but not so good in a laser pointer unless you want the thing being pointed at to catch fire.

I recall some green 532nm leakage visible in our UV 266nm offering (although that was a slight benefit meaning you could see the beam).

The battle was always for using ever shorter wavelengths at decent power for laser ablation work - it saves all that messy wet corrosive chemistry stuff going directly from solid to plasma phase/fine dust.