Advice in projector building

[Antonj91]

Hi everybody,

I'm Antonello from Italy, i'm a master student in physics and for my thesis i'm building a Pr3+ solid state laser. This fantastic doped-crystal has got many emission lines in the visible (6 or 7), from blue to dark red. Among all the applications of the visible laser, i think that the display/projector are very interesting and for this reason i want to build a projector to learn some stuff.

Firstly thanks to all for this fantastic forum. For the building of my first (and hope not the last) projector and i found much of the informations here, without this forum it would have been harder.

I ordered all the stuff, but i miss some other and i want to ask you some advice.

1. I will have 100mW Green 532nm, 500mW Red 635nm and up to 1.2W Blue 445nm. Since i have little green, maybe to lose less power is better to put the Green laser like the last laser (the closest to the scanners), just to have only one reflection through the dichros, and usually the reflectivity of the dichro is higher than the transmittivity (see this dichro for example http://www.ebay.it/itm/RGB-System-Op...item20dc8318f6). For this reason i need a dichro that reflect Green and pass Blue,Red. Where i can find this dichro? the least expensive possible
2. How to build the case? Which material? I think that the material should be a good heat conductor. So maybe aluminium? Can you suggest me hot to build a good but cheap case?
3. Where i can buy some cheap but good PSU? I don't know yet what kind i need but can you suggest where is possible to find this stuff?

This is all for the moment. Sorry for my english but i'm learning this language


Thanks
--
Antonello Matteo

[catalanjo]

Welcome to PL.
Please post some pics of your (presumably) Lilu setup when you get the opportunity.
Lots of different sources for green reflect dichros but when cheap the efficiency is reduced....try Lillyelectronics for Chinese cheap and cheerful.
Best use ally for case since it is easy to cut/drill/bend and generally muck about with as well as being light/strong and very heat conductive.
PSU is something else again ....some people are wary of cheap switch mode PSUs from China, but since you need a very fast Oscope to see spikes that can reduce the life of LDs there is no clear consensus on this one, so lots of people here just play safe and go for Meanwell but they are pricey,
I would recommend choosing an oversized scanner amp PSU first, then use DC-DC step down convertors to get the voltages and currents you need for all the other bits and bobs.

Use Lasorbs from Pango to protect your diodes.

Use BIG slow fans.... they are much quieter!

Cheers

PS. Your English is fine ...and most people here talk American anyway!

[kecked]

I would forget the 532nm laser and get a 120mw 520nm laser diode. You will get a bit more power and better modulation.
You can combine two for about 250mw of green using a polarized beam splitter cube.

Aluminum is a good material for the baseplate if you can drill and tap. Wood works with the low power you are using but will not be as stable over time.

Go for the best power supply you can. I don't mean a lab grade supply but mean well is worth while.

Dichroic filters are very variable. I do not use your rbg. But rgb instead as then I use all low pass filters that seems to be more efficient and easy to find.

You can make a very nice and bright projector using the Dtr diode pack. You get about 200mw and that is plenty.

I suggest pangolin 506 scanners. Can't be beat for the cost in terms of performance and they run cool. Thus you can use wood for the baseplate and even the box.

The case can be anything. What diode drivers are you looking at?

i suggest you stay away from the 500mw red unless you plan to do correction optics. Even then if all you need is 500mw use single mode diodes and build a quad. That is two diodes knife edged and the pbs cube combined with a waveplate polarization rotator.

[Antonj91]

This is the stuff i have already bought:
20k Scanner http://www.ebay.it/itm/201622731221?...%3AMEBIDX%3AIT
RedLaser 635nm 500mW, analog driver, 3mm beam diameter at the aperture, 2.5mrad full angle divergence http://www.ebay.it/itm/262442006998?...%3AMEBIDX%3AIT
GreenLaser 532nm 100mW, analog driver, 3mm beam diam., 1.5mrad full angle http://www.ebay.it/itm/Grun-Laser-Mo.../191919670542?
BlueLaser 450nm, 1.2W, analog driver, 1.5 beam diam., 1.5mrad full angle http://www.ebay.it/itm/141718405731?...%3AMEBIDX%3AIT
Laser ShowCard OLSD v4 by Chris Favreau http://www.fab-favreau.com/index.php/Main/OLSDRev4

@catalanjo:
what do you mean for Lilu setup?
All the purchased lasers and the scanner include the PSU but, if i understand, you suggest me to buy another Meanwell PSU and don't use the PSU supplied by the ebay sellers?
About the Lasorb i think that i will buy 3 of these, you convinced me.

@kecked:
unfortunately at the time I can not afford a 520 LD but in future i will replace the 532nm. The ebay sellers assured me that i can modulate the 532nm laser analogically at a maximum speed of 10k/sec without having 'tails' effect.
About the low pass filter, i couldn't find these. Can you link me some sellers? I found only this dichro that reflect green and pass red and blue http://lasershowparts.com/store/inde...&productId=316 but is too much expensive.

What dimension you suggest me for the case? And is better to divide the electric components from the optics components building a 2 floor case or not?

Thanks guys!

[catalanjo]

This is the stuff i have already bought:
20k Scanner http://www.ebay.it/itm/201622731221?...%3AMEBIDX%3AIT
RedLaser 635nm 500mW, analog driver, 3mm beam diameter at the aperture, 2.5mrad full angle divergence http://www.ebay.it/itm/262442006998?...%3AMEBIDX%3AIT
GreenLaser 532nm 100mW, analog driver, 3mm beam diam., 1.5mrad full angle http://www.ebay.it/itm/Grun-Laser-Mo.../191919670542?
BlueLaser 450nm, 1.2W, analog driver, 1.5 beam diam., 1.5mrad full angle http://www.ebay.it/itm/141718405731?...%3AMEBIDX%3AIT
Laser ShowCard OLSD v4 by Chris Favreau http://www.fab-favreau.com/index.php/Main/OLSDRev4

@catalanjo:
what do you mean for Lilu setup? .............. "for my thesis i'm building a Pr3+ solid state laser"= I was referring to this !

All the purchased lasers and the scanner include the PSU but, if i understand, you suggest me to buy another Meanwell PSU and don't use the PSU supplied by the ebay sellers?........NO,not at all ............ if you have already purchased them then use what you have .. I was merely answering your original question 3,... "Where i can buy some cheap but good PSU? I don't know yet what kind i need but can you suggest where is possible to find this stuff?"

About the Lasorb i think that i will buy 3 of these, you convinced me......... You will probably not need one for the 532 green since it is pumped by an infrared diode which usually will take a lot of beating with no complaint, also the other modules may well already have them inside.


What dimension you suggest me for the case? Depends entirely on the size of the stuff you have already purchased ... but bare in mind that you may well need more optics for the RED which has thicker beam AND more divergence although since you have more power then the green here you might be able to just increase it's size with a telescope lens set to reduce divergence and then just mask it to conform to other beam sizes. You will also have to attenuate the Blue drastically to get a decent colour balance.

It seems you may have purchased a green module with too little power so instead of spending extra cash on unusual dichros, it might be better to just get a higher power green (DPSS green laser modules are pretty cheap up to 300mw) or change over to a purdiode as kecked suggests (lasorb needed in this case)

And is better to divide the electric components from the optics components building a 2 floor case or not? ............It is only a question of not allowing the air cooling to dirty the optics ... so keep the airflow separate from them, however if any electronics card cooling is through an angle plate it can share the space with the optics and get cooled from under/behind the separation plate.

If your modules already have fans mounted it is often best to make the separation barrier just between optics/scanners and the rest (including laser modules) by inputing the beams thru tubes and creating a sealed optics box within the projector, obviously this must be sealed against the face plate since it includes the scanners and the output window. (Black ally sticky tape helps a lot to achieve this).

If you are going to use adjustable dichro mounts it is also nice to be able to access the adjustment (using allen keys) from outside the case (covering access holes in face plate with tape) so that they can be aligned without dismounting the projector.

Thanks guys!

.... [Your welcome. Cheers

[Bradfo69]

I don't think Lasorbs are going to help you with these since they are complete modules and not just the raw diode. Also, I agree that the red is a poor choice compared to the other two. It's going to be much larger in diameter than the beans from the other two. Granted this is a cheap build but, it's like mixing a beam the size of a pencil with beans the size of the lead itself.

[Antonj91]

@catalanjo:
About my master thesis work, i didn't understand how you know that the crystal is LiLuF, because is more frequently the use of YLF. Anyway, is a standing-wave cavity for the moment. In future we will understand if and how much we can tune the emission frequency and do some test of single frequency operation using another cavity design. It's a pure laboratory work, i think that is early to think about something marketable.

@Bradfo69 and catalanjo
I tought that maybe i have only to increase the diameter of the blue because the green and the red should be quite of the same dimension (even if the divergence of the red is bigger, the green is more bright, so should appear larger in diameter. This was only a tesi, i don't know if will be in this way).

[Bradfo69]

I didn't happen to pay attention to the diameter of the green. That seems pretty large for a 532 beam. Often that's the smallest of the three colors. Oh well... experiment away!

[kecked]

if 20.00 is too much for a dichro you my friend are in the wrong hobby. Those are very good filters/dichros/long pass filters.

If some day you can I would go with the DTR rgb diode pack and start over. I wish you the best. Your result will be substandard using that red.
Save up and switch out the red and green.

Here is an idea if you really cant. Use a spatial pinhole filter to sample the red down to the size that matches. You will loose a lot of power but I am sure you can find a couple lenses and some blacktape to make the filter. 100mm--->blacktape at focus--->100mm--->out Move the tape around to burn a larger hole. A guitar pick worked well for me.

[swamidog]

if 20.00 is too much for a dichro you my friend are in the wrong hobby. Those are very good filters/dichros/long pass filters.

If some day you can I would go with the DTR rgb diode pack and start over. I wish you the best. Your result will be substandard using that red.
Save up and switch out the red and green.

Here is an idea if you really cant. Use a spatial pinhole filter to sample the red down to the size that matches. You will loose a lot of power but I am sure you can find a couple lenses and some blacktape to make the filter. 100mm--->blacktape at focus--->100mm--->out Move the tape around to burn a larger hole. A guitar pick worked well for me.

kecked is right about those single mode diode kits from DTR. that's what i used in my projector and the results are very very nice.