OK-Here we go again ..

[Stoney3K]

Have you ever done text or complex grapics projection for a customer? (I dont think so because you prefer 635nm flashlight which are useless for grapics anyway)

not us laserist who see every wrong color pallete but your customer will imiadiate see the difference between a flickering logo (scanned @ 20k) or a smooth logo (scanned @ 60K).

However, 60K scanners are pretty useless when you're doing an outdoor beam show with a huge KTP/CuBr/445/Dye rig.

Graphics are less demanding on beam power so it's easier to build pin-point beam projectors for them, whereas beam shows can get away with slower scanning (if you're not into crowd-blasting) and higher powers. Most audiences won't mind a flickering beam pattern or fat beams overhead if it's not too dramatic.

[flecom]

Have you ever done text or complex grapics projection for a customer? (I dont think so because you prefer 635nm flashlight which are useless for grapics anyway)

not us laserist who see every wrong color pallete but your customer will imiadiate see the difference between a flickering logo (scanned @ 20k) or a smooth logo (scanned @ 60K).

don't tell that to laser net

the projector they sold our planetarium uses 635's and ya, its terrible for graphics... we actually had people telling us "I think the projector is out of focus" when we first got it (people were used to the Lexel Ar/KR)

but ya, for beams they are not that great either because of the power density... 635 diverges so quickly that at great distances a lower power better red will still be perceived as brighter

[steve-o]

I woke up this morning thinking oh sh*t, what did I post last nite? Thank you all for responding with level-headed commentaries and good information.

laserdj [quote:
I somewhat agree.. but hey, that's just me...

Thank you.

dnar [quote:
Correct me if I am wrong, but isn't the point of faster scanners (40-60K) really translate to scanning wider and larger at a decent frame rate, which is the real point?

BTW, if your mirrors really are 2x3mm then you got VERY SMALL MIRRORS!!!!

Probably, i dont know.

allthatwhichis [quote:
It'a be aaight Steve. I'll pour myself another so we can chill together. . Can't you throw some fatty mirrors on those G124s you got and run em at 12 or 20k for some good beam shows?

That woulda been fun! I am gonna put bigger mirrors on those. Yep!

taggalucci [quote:
Originally Posted by steve-o
Get Big galvo mirrors and ENJOY 635-636 1-2-3-5 WATTS Red ecstasy!!!
I'm in... seriously. I think some 9mm ping pong bats should do it! What do you recommend to achieve 4W of 635-636?

I was thinking of six or eight of those 500mw diodes bouncing around in group-buys some months ago. I think a 1-watt red diode is out there somewhere.. 4 of those should do it.

norty303 [quote:
Uuummm...... :unsure: Yes, the reason why everyone goes on about smaller beams is due to the higher power density in the smaller beam.

No BS, tried and tested

I'm sure that it is, but I think cramming more power into the same size beam diameter would effectively brighten it, even if it is a "flashlight" sized beam.

Stoney3K [quote:
And the reason that appears brighter is partly because the incident power on (dust or smoke) particles in the air will be higher (just as it would be on your retina!) and therefore the scatter from those particles will be brighter as well.

Admittedly, the amount of particles that will scatter any light will be less -- the brightness will be concentrated in a smaller volume, but audiences won't be able to distinguish an 1/2" beam from a pencil-sized beam at the distance they're viewing it. Therefore, from an audience POV, a narrower beam appears brighter even though the same power is captured in that beam.

Thought experiment: Take a 1W CCFL tube and a 1W EL sheet. Even though they are just as bright on paper, which one would be brighter to your eyes?

OK

mccarrot [quote:
Have you ever done text or complex grapics projection for a customer? (I dont think so because you prefer 635nm flashlight which are useless for grapics anyway)

not us laserist who see every wrong color pallete but your customer will imiadiate see the difference between a flickering logo (scanned @ 20k) or a smooth logo (scanned @ 60K).
You really dont get it, do you?

the biggest problem of 635nm is the divergence not the beam diameter. we want lasers, not flashlights.

Let me try to explain, a 3W 635nm got 5mm beam with 4 mRad!

at 50 meters distance you beam will be more than 20cm wide! and you know what it will be even MPE safe because the power is so weak at this distance as it is spread out over a 20cm diameter.

at 50 meters distance a 250mW red with 3mm 1mRad will look brighter than a a 3W 635nm 4mRad flashlight! .

I guess I don't get it because I'm very much against a divergent beam and very for a tight beam with less than 1 mrad divergence, no matter what the beam size. A divergent beam kind of defeats the purpose it being a laser beam imho.
And no, I don't do graphics; beam-shows only. (except for when a liquid sky effect is bouncing off of a distant tree and everyone says "cool, looks like the alien in the tree from that movie"

flecom [quote:
the projector they sold our planetarium uses 635's and ya, its terrible for graphics... we actually had people telling us "I think the projector is out of focus" when we first got it (people were used to the Lexel Ar/KR)

but ya, for beams they are not that great either because of the power density... 635 diverges so quickly that at great distances a lower power better red will still be perceived as brighter

My 636 projector using two 150mw ML520G51 diodes has a beam of about 6x8mm at the aperature and has no more divergence than a DPSS 473 blue . Here is a pic of the 2 beams at 100ft on a tree in my front yard. It's not very divergent.

The left beam is mine, the right beam is from a Laserwave 473. So I know that it is possible to have a high frequency red even if it's 9x40 divergent out of the LD and multimode. I just lucked into some very good optics to acheive this. They are triple element lens assemblies with a very large clear aperture.

[taggalucci]

OK, so to confirm... Is this just an idea and you do not yet know the specific diodes, combining method and optics to achieve a 5W beam that would fit say 9mm scanners and have good divergence then?

[steve-o]

Yeah.. well ...mmm. . no. I'd be rich if i did , right? Although I do think that there might be somebody here who may indeed have that info (who's name shall remain anonymous , but initials are SR) but I think he wants to see a big fat checkbook 1st

--I do believe that it is possible though-- Ball lenses, somebody mentioned fiber optics .. There are definitely alternatives out there that no one has thought of as of yet, I'm sure of it. It's just a challenge with no easy quick answer or fix. ..

[taggalucci]

Righto, I'll revert to my previous plans for big red then...

[steve-o]

Righto, I'll revert to my previous plans for big red then...

That being?? ..

Ok , Ill draw a picture.. I think we need:


The problem with laser diodes is that they're too damn small.. the output comes out all funky and weird. I do applaud the folks who did put a resonator cavity in the size of a pinhead (almost) but .. If someone could develop a 5-6" resonator cavity using the same principles as the LDs (that are only a few mm's long) the output surely would be a lot more stabilized and Gaussian profile...

[flecom]

My 636 projector using two 150mw ML520G51 diodes has a beam of about 6x8mm at the aperature and has no more divergence than a DPSS 473 blue . Here is a pic of the 2 beams at 100ft on a tree in my front yard. It's not very divergent.

ya but I figure we were talking about high power 635's? their divergence is significantly worse

[taggalucci]

Now if we could find some of these high power diodes directly fibre coupled into a decent diameter fibre...

[steve-o]

ya but I figure we were talking about high power 635's? their divergence is significantly worse

The ML520G51 diodes that I'm using have a divergence of 9x39. That's just as bad as the higher power ones as far as I know. Maybe the 40um emitter helps, I dont know..

Now if we could find some of these high power diodes directly fibre coupled into a decent diameter fibre...

Fiber sounds fun. Are you thinking single mode diodes , large diameter glass single mode fiber and ball lenses for coupling or something like that?