Question about anamorphic prisms

[absolom7691]

I have seen a bunch of threads talking about how the anamorphic prisms can clean up the beam a little for 445's. What kind of "clean" are we talking here? I am using one of the aixiz collimators right now, and that has helped a little. Basically, will a pair of prisms get me an "adequate" beam profile for graphics? I understand that, at best, I will be getting a square beam, but how tight will the dot be? Right now, anything has got to be better than the "|" shape I am getting.

[steve-o]

The prisms, when correctly aligned, will "squeeze" the line " | " into a smaller line " | " and appear more dot-like at close range. There will be some losses incurred, of course.

[allthatwhichis]

If you want a "square"; the best way is to stack 4 "||||" and use a prism afterwards. Using one will only get you a | at longer distances.

[absolom7691]

I am mainly looking for a decent beam profile that will work for graphics.

[allthatwhichis]

Uh, Simon... Andy... I'd prefer someone with experience break his heart.

The 445 beam is not too bad for graphics but I don't think you can get its beam to what you are really wanting.

[Jem]

I guess it all depends on the distance at which you want to project your graphics. If this is a constant you can just focus the lens for a tight(ish) 'dot' at that particular distance. I have a 445 with anamorphics and to be honest it's not that bad at all for graphics. If you're being picky there are better blues for graphics work (473nm DPSS), however, there's nothing to beat the price of the 445's

Jem

[absolom7691]

Thanks everyone for your input. I am not talking long distances no more than 50 feet and even then, probably not that much. I am using a 445 right now for graphics and it isn't horribly bad, it just isn't good. I am just looking for something a little more adequate. I am not doing commercial shows or anything like that so, it is really coming down to personal preference rather than professional results. I own a 473nm but unfortunately, it is TTL and only 100mW. Besides that, I like the look of the purples I get from 445nm in combination with my 640nm. The perfect solution for me is a 457nm, but there is about a $3000 difference between that and 445nm at the power level I require .

I ordered a set of prisms to experiment. That is the good thing about these diodes, cheap enough to play around with. I am hoping a diode manufacturer will come up with a blue that has a beam profile close to the 640nm reds!

[edison]

If you set the angle between the prisms bigger then normal you get a very thight beam. Kvant and RGB do the same And their projectors have a tight beam. You have more losses but not to much so you can end up with a 800mw thight beam. That is when you use a 405g2 lens with a FL of 4.

allthatwhichis:

If you want a "square"; the best way is to stack 4 "||||" and use a prism afterwards. Using one will only get you a | at longer distances.

Sorry but that won,t work. When stacking 4 next to eachother like this IIII and shoot it throug a prism you will end up with this I I I I after the prisms

[andy_con]

edison is spot on about combining 4 beam using prisms, it just dont work

no prisms -




with prism pair -

[laser_freak]

edison is spot on about combining 4 beam using prisms, it just dont work

no prisms -
...
with prism pair -
...

Do you mind sharing how far away from the prisms that was measured, and with what collimating lens?

Thanks

[MechEng3]

A telescope will do wonders for a properly stacked array.....cylinder lenses get the best from a single diode...near DPSS in terms of spot size at a long distance and small diameter at apeture.

[andy_con]

18 metres and o-like lens

[edison]

I will try different telescopes with the 4 watt module that i have here. It would be nice to get a tight beam because it will increase visability. I have stacked them like this llll
But one thing is for sure it,s a damn nasty diode to get a good beam out of it

[andy_con]

I will try different telescopes with the 4 watt module that i have here. It would be nice to get a tight beam because it will increase visability. I have stacked them like this llll
But one thing is for sure it,s a damn nasty diode to get a good beam out of it

look forward to seeing the results

[edison]

I will fire up my quad red first. If the housings are ready from the metalshop i can finish that one and then play with the quad blue. I have doubts about the telescope but we will see. I don,t have a clue if this will work
When the quad red is ready i will can start with an 8 setup red.... Finally

[absolom7691]

I will mess around with the prisms I purchased to see what they will yield. I might also try a telescope as well. I am not too concerned with losses. My 640 red is only 350mW and my 532 is only 200mW so, if I only get 500mW after all is said and done, I will still be over the mark.

This is very good info. Thanks again everyone for pitching in with some ideas. It would be awesome if someone with all the right equipment could donate some time and put together configurations and measurements for all of us here that shows the best steup for a specific type of beam/power desired. I am going to mess around and post my findings when I get my prisms. My only problem is that I only have one 445 and very few optics in my drawer.

Thanks again all!

[allthatwhichis]

I will fire up my quad red first. If the housings are ready from the metalshop i can finish that one and then play with the quad blue. I have doubts about the telescope but we will see. I don,t have a clue if this will work
When the quad red is ready i will can start with an 8 setup red.... Finally

I have a feeling testing reds will not tell us anything in regards to the blue. Andy has pretty much shown us first hand how well telescopes work on a stack of reds...

http://www.laser-man.co.uk/projects/...ode-array.html

But hey, ride out, I am always down to look at more pictures of lasers.

Based what you said about the stack of blues using the prism it almost seems like adding a prism to each blue before it is stacked might do something favorable although that would be kinda expensive and take up some space; you'd have to use something besides your quad mounts to try it with.

Are there optics that correct only one axis or polarity? I am wondering if you could throw something on Andy's quad 445 though a prism (2nd picture above), after the prism, that could either fix the fast axis a bit more or fatten the slow axis a bit to match and then throw that quad beam through a telescope. I haven't been able to see the logical argument in the beam size/divergence issue anyway; I can't wrap my head around only being able to fix one, not both, or fixing one makes the other worse... even after talking with... buffo, DZ, Spec... even Marconi* among others, who have all made great attempts to explain, but I don't get it.

* Yes, take a second and wonder... WTF is Mr. Maxy up to now?

[Solarfire]

IMO I would say the following 2 options have proven to deliver very good results.

1.) O-Like lens (long FL) in combination with prisms. Beam @ Approx. 4.5mm dia. at the apperture @ < 1.5 mrad

2.) 405-G-2 lens (short FL) in combination with cylinders. Beam @ Approx. 3mm dia. at the apperture @ < 1.2 mrad

Option 2 is the one you are looking for.
These 2 have also proven to be most cost effectiv.

cheers!

[dnar]

With my 445 prism build, I cropped the beam at aperture to "round" it up. At 17M I have a round spot.

[LaNeK779]

With my 445 prism build, I cropped the beam at aperture to "round" it up. At 17M I have a round spot.

my thought exactly. collimate, use correction optics and then run the beam through an apperture.

with 1w of power available, i can't even be bothered to think about losses

[edison]

exactly. If you stack 4 blue diodes like this llll and then shoot it trough a small hole of 3mm then the beam will be round. You probably end up with 3.5 watt of blue but who cares

I have a customer and he told me how he looks at things. When the divergence is low and the beam is thight no one cares about losses.

[dnar]

Yep, with the 445nm diodes we have power "to burn". Be careful with reflections when using a pin-hole. I painted mine in stove black, as with the internals of the B&K housing.

[LaNeK779]

i was thinking to sand it a fair bit to make a rough surface and then paint it black

[kitatit]

With my 445 prism build, I cropped the beam at aperture to "round" it up. At 17M I have a round spot.

Hi Wayne,
I'm real keen to see your results. I was thinking the same thing a while ago but after reading this thread below, it sounded like it wouldn't work that well.
http://www.photonlexicon.com/forums/...Spatial+filter

Have you got any pics of the beam with and without your pinhole?

Graphics ability is quiet important to me and it would be great if this method helped tidy up the beam.

[dnar]

Hi Wayne,
I'm real keen to see your results. I was thinking the same thing a while ago but after reading this thread below, it sounded like it wouldn't work that well.
http://www.photonlexicon.com/forums/...Spatial+filter

Have you got any pics of the beam with and without your pinhole?

Graphics ability is quiet important to me and it would be great if this method helped tidy up the beam.

Hi Kit, here is a shot of the final beam after pinhole. Taken at 500mW, single diode with Simon's prisms. The daytime photo with the green shows the beam is tight, the 532nm is the CNI 1.5mrad.

DSCF4460.jpgDSCF4499.jpg