Single Mode RGB Diode Balance

[planters]

I am laying out a pure diode RGB projector that might use the trio of diodes from DTR. I want to stay single mode and might use a PBS to double up any diodes that are weak to achieve good color balance. I do not intend to go beyond dual diode pairs to keep the smallest beam and use the fastest scanner. I do not know if the single modes are SO GOOD that spatial filtering is not worth it, but even with a filter I think I can keep the deck to 10 x 30 cm. including the scanner.

Any advise? Are the colors well balanced enough that 3 pairs of two diodes will work or is there an overwhelming color to compensate for? Are the beams so clean that a filter is pointless? Is there a better diode choice than the components of DTR's trio?

[kecked]

there is a 120mw green out there. If you can get that then you can go to the 170mw single mode optinext red diodes. The advantage of the 80mw blues is they are 450nm.

320mw red 120mw green 160mw blue should work but might need a bit more blue. 642nm/520nm/450nm
110mw red 50mw green 80mw blue is almost perfect. 638nm 520nm 450nm

There are wings on the reds. the green has some smuts as does the blue in a halo.

A trick I use on higher power is to use a 2x or 3x beam expander. It clips the diodes and cleans up the wings while decreasing divergence. Not needed on these tiny diodes but it would give near ion quality divergence. This makes a nice living room unit or programming projector.

The first company to make a cheap (500.00) all diode source will make a mint.

[polishedball]

The 120mw are multimode though iirc. A lot better multimode than we are used to but still multimode.

[planters]

I was worried that the 50mW greens may be just too feeble and the 120 mW multimode greens too dirty. A spatial filter does a nice job of cleaning up the beam without needing to enlarge it and loose power at the scanner, but the divergence still there. Maybe a PBSed pair of 50mW greens and a single 170mW Optinext red and a ?? blue would fit the bill.

I can see obtaining the bits and pieces including a 40K scanner (from Omar) for close to $500. My set up with Laserwave makes some of the optics more reasonable and Lasertack has some nice prisms. What are the optimal lenses for collimating these diodes? All of my builds to date have been weapons grade and the drivers I am familiar with are from Dr Lava, Wavelength Electronics and alas Badpip (defunct?). Any opinions on good, lower power (lower cost) drivers? Three will be needed even if I series drive any paired diodes. One nice feature is that I will avoid the need for a color correction board. A spatial filter will require a pair of achromatic lenses as opposed to simple lenses and this will add some cost and may be overkill for single modes. I will probably design it in no matter what and then compare and decide.

I was just thinking of putting this together for fun, but maybe I could assemble a parts list and show the build (with details) on a video?

[dnar]

The first company to make a cheap (500.00) all diode source will make a mint.

Are you throwing down the gauntlet? I have time, glorious time up my sleeves....

[planters]

No gauntlet, just that several members have PMed me about building such a projector for them and I agree it would be nice to have a super portable unit that you could set up with a comp to run shows in a small room or work out seeing a show as you write it. Kvant has an RGB module that I understand you could couple with a scanner and could do this , but with their company's ANNOYING 1/2 angle divergence spec, I think I could (many could) do better for substantially less.

You want to make these for people? That could be fun. I'd be happy to help. The design seems straightforward to me and depends somewhat on the diodes and the philosophy ie incredible performance at modest power or good performance at higher power or lowest possible cost and the necessary compromises.

[dnar]

Mmmm. Food for thought. Small beams with low divergence result in powerful looking beams....

[DTR]

there is a 120mw green out there. If you can get that then you can go to the 170mw single mode optinext red diodes. The advantage of the 80mw blues is they are 450nm.

Keep in mind the 120mW green is multimode so it will not match beam specs with the other diodes and from what I am being told when it does become available it sounds like it will be pretty expensive but still I can't wait to see them. The 170mW 635 from the prices I have seen is 2-3X more expensive than the 120mW version for a small gain of 50mW in "rated" power so not sure if the price is justified but I have stuck to selling the 120mW version. On the blue 450nm diode it is actually the 120mW version of the diode not the old 80mW diode.

[The_Doctor]

Mmmm. Food for thought. Small beams with low divergence result in powerful looking beams....

Indeed. So for future thinking, do the 405-G-2 lenses, and LFL or Dave's 2mm lens work equally well for single mode? The trouble with aspheres is that aspherical means not spherical. A lot of gotchas might lurk behind such a small point. I try to get stuff that has the greatest chance of accommodating changes of plan because I have the poet Burn's notions about those.

[planters]

So, two 50mW greens and the 120mW red and blue should be pretty good. Now what lenses? Doc, the aspheric is to compensate for the very short FL. The multimode give complex and asymmetrical beams and a radially symmetric lens of simple spherical or aspherical design is always going to be a compromise. My guess is the best lens for the multimodes will be the best for the single modes, but to avoid a lot of telescoping up or down to fit say the 3mm aperture scanners what lens will be the best match for diameter/ divergence and cost?