532 for first projector?!?!?!

[ZeroPoint]

Ok, here's my dilemma, I've ventured into a hobby that is not exactly centered around students with school loans to be paid back but I can't help it. I must build a projector!! 445's are no problem as they are quite cheap, but green on the other hand has me thinking hard about what I should do. I will be using 1W of blue so I figured about 300mW of green should be sufficient. The problem is that I really can't afford $400 for one laser. So unless I can find somebody with an old one lying around that they are willing to let go for no more than $200 the only other solution I can think of is using 2 of the cheap 150mW modules you can get off eBay. I guess my question is would two of those modules perform well enough for a first projector, or am I risking more hastle than would be worth saving the $200? I would plan on replacing the drivers that come with the modules to something better that can handle analog modulation. Any advice? I will also have the same issue when it comes to red, except I know I will need just about as much red as I have blue Anyway, any thoughts, advice, or links to cheap/used 532/640 lasers would be greatly appreciated. I will be keeping a close eye on the buy/sell forum here also Thanks!! -Luke

[allthatwhichis]

The 2 x 150s should perform fine and you could try to knife edge them to match the beam profile of the 445. I have 300mW of green goign with a 1W 445 and it mxes well. There is a 300mW Laserwave in the FS section for just under twice what you want to spend...

[ZeroPoint]

Hey, thanks a lot! I'm not familiar with knife edging so I'll have to look into that but it will probably be the route I take. I have a feeling I will need to save as much as I can for red since I will need a few of them to get the power I need for somewhat of a balance. Thanks again! -Luke

[allthatwhichis]

Both my projectors have about 300mW of 640 red and 300mW or so of green with 1W 445 diodes and both look good. My DIY projector has the blue running low due to the power supply and driver set up; it also has a 350mW 640 red so it seems a bit red heavy. If you can get two 640nm red diodes you should be good with the 1W 445 and 300mW of green.

[ZeroPoint]

If you can get two 640nm red diodes you should be good with the 1W 445 and 300mW of green.

Do you mean two 150mW 640's? That would be good. But of course it doesn't have to be a perfect balance anyway as this is just a practice projector that I'm sure I'll be tweaking for a long time to come. Im just trying to get my feet wet with somewhat decent results

[ZeroPoint]

So it appears that 640nm is hard to come by at a reasonable price (reasonable to me anyway) but it seems that 650nm is readily available for a good price and in the right power range. How much difference is there in visibility between 640 and 650? I know I can't really complain if I'm not willing to spend the money but I've never compared the wavelengths before. Is there a huge difference or does it mostly just affect the high end equipment designed to be a precise as possible?

[Steve Milani]

Main differences between these reds are:
- 640nm red is more visible and brighter than 650nm. It has a smaller spot and better divergence also.
- 650nm has a larger spot (about 5x7 mm) than 640nm. It needs much more output power to match with green to obtain a good yellow (or white into a RGB projector) but it is cheaper.

[White-Light]

How much difference is there in visibility between 640 and 650?

350mw 640 is equivalent in brightness to 570mw 650nm! (61% brighter (- source for figures, Chroma utility)).

So its quite a lot brighter. Also, you have to factor in beam specs. 650nm is a fat beam so some will get lost inside the projector as it will miss the scanners. 640 is a tight beam so 100% should exit (less any dichro or mirror losses which apply to each colour anyway).

You can probably say overall therefore its approaching twice as bright.

So there are advantages to 640nm.

Other thing to factor in is when striking a balance, remember that you need more green to balance 640 than 650 because of the greater visibility. Alternatively you can just substitute a smaller red so have less 640 compared to what you'd use if using 650. That's what a lot of people on here do because it also makes the projector safer (using less power).

[ZeroPoint]

Wow, that does seem like a pretty big difference. So, if I were to have 1W of 445 and 300mW of 532 how much 640/650, respectively, would i need to get a decent (although doesn't need to be perfect) balance. I suppose if I'm going to need so much 650 that it would cancel out any savings in money then I should just go with 640. However, if it's still cheaper to get a sufficient amount of 650 as opposed to the 640 then I can live with the lesser beam specs for the time being. I'm going to track down one of those graphs I've seen floating around here but i cant guarantee I'll know how to read it so I may still need some assistance, lol. Thanks for your replies! I'm getting really excited about this

[White-Light]

With 642nm most people reckon around 1:1:1 is about right so 300mw of each should give a nice balance.

If your 445 doesn't modulate well at 300mw you turn it up to 500mw but the balance then shifts towards the blue spectrum.