Thick laser beams?

qumefox said:

That's cool looking. I'll have to try that with some of the plethora of tv lenses I have.

Click to expand...

I dont think I took pics, but I have a monster lens from
a surplus shop thats 8in dia the assembly approx 10in long...

I tried this once, the beam was huge, just didnt grab the pics.

Almost any lens will work, you just have to find the position
that gives a parallel beam.

'Fat' beams are awesome

Generally 'tube type' projection big screens have roughly 5" lenses, though I have some 6" lenses too. They're usually 3 element too, similar to the configuration aixiz uses.

qumefox said:

Generally 'tube type' projection big screens have roughly 5" lenses, though I have some 6" lenses too. They're usually 3 element too, similar to the configuration aixiz uses.

Click to expand...

The large one I have sounds similar. It has what looks to be a 'bubble' of
a lens within the larger lens.

I have not tried to take it apart though.

qumefox said:

It's a common practice really when building projectors using diode lasers.

search 'knife-edge'

Though you'll probably be disappointed, since I imagine your after 'burning' and most people who build knife edge rigs... aren't..

Click to expand...

the beam on my 24 diode build at aperture after optics is 5mm by 5mm @ 1mR.

as for burning it burns like fook, it can/has burn a big black mark in my shed door 2 metres away

I've done something similar, but it was with a TOSLINK fiber.

Nice :beer:

Beam out of that labby is a little cooked though :undecided: :na:

not to get off topic but have you ever seen where they do a red and green laser to make a yellow laser ....idk but to me it makes no sense ....just thought i would randomly put that out there:wave:

red and green mixing is a cheap way for obtain yellow ..... pure yellow DPSS units exists, too, but they cost you an arm and a leg, for decent powers

Staying on red+green ..... Cyparagon, have you tried to use your TosLink fiber as light mixer ? ..... shooting a red and a green in, i mean ..... :eg: :eg: :eg:

wannaburn said:

Ahh, got it.. new I had them somewhere....

Heres the pics, though the beam is more like 2in dia.. I had forgot
which lens I had used...

This is a LCC LD running @ 360mA. Didnt test the actual output
as no meter I have can fit the beam.. :thinking:
Should be around 190-200mW if memory serves..

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Neat, LPF is very educational (not to mention fun ) .......wide beam lasers !, it seems you can learn something new here often if you keep reading enough.

Someone had referred to building projectors, are there other practical applications for wide laser beams ?

(not that there has to be in order for it to be fun )

(+ Rep for you for those neat wide beam pics !)

Not directly wide beams .. but wide aperture (thus beam wide at the start) makes it possible to focus for burning at larger distances.

AstroLaser said:

Neat, LPF is very educational (not to mention fun ) .......wide beam lasers !, it seems you can learn something new here often if you keep reading enough.

Someone had referred to building projectors, are there other practical applications for wide laser beams ?

(not that there has to be in order for it to be fun )

(+ Rep for you for those neat wide beam pics !)

Click to expand...

Actually wide beams are bad in projectors. The reason they are has to do with the scanning galvos. Larger beam means needing larger mirrors on the XY galvos. Larger mirrors = more mass, which means your effective scanning speed will decrease... Stupid inertia.

Not only that, but the power density is lower and the beam appears dimmer.

HIMNL9 said:

have you tried to use your TosLink fiber as light mixer ? ..... shooting a red and a green in, i mean .....

Click to expand...

That's a good idea! I'll try that tomorrow if I remember.

Another idea (crazy as usual ) for those that want to try a pointer with a beam expander, without buy a very expensive one ..... i have one of these toys at home

DealExtreme: $12.06 8x20 3-IN-1 Monocular Microscope

And yesterday night i tried to shoot a green beam through the eyepiece lens (in reverse of the normal use, i mean ..... after all, these monoculars have basically the same internal structure of a beam expander ..... the main difference is the Porro prism for revert the image), and it works decently well ..... a bit tricky to focus, for long distances, but enough for see the reflection of my 65mW pen on a white wall at almost 2Km far away, at night, so must not be so bad, after all .....

Must need an adapter for keep the beam well centered, anyway, as any other beam expander ..... and, ofcourse, being not specifically planned for this use, there is a bit of loss, also if the lenses are AR coated, but can worth the effort to try, if no other for the fun and the fact that is relatively cheap (maybe also the others models, more cheap, can work good, i don't know, i only have this one)

Yeah, I use one of those sometimes, too. The biggest problem is power loss. The one I have drops about 40%.

You may try removing the inversion prisms from the inside, this must reduce the power loss (remember that in all these things there is always an inversion prism assembly, made using 2 prisms assembled together, usually ..... removing them, means 2 less optical elements in the beam path, also if it constrain you to keep it longer for get it focused)

Also, if the eyepiece is a doublet, can help taking away one of the lenses from it too ..... but this depend from the structure of your unit, not all them are identicals.