uv to pink

[kaz]

For some reason the 405nm chips do put out a bit of unwanted light around the main beam but in saying that the optics i am using are not the best, only cheap acrylic types but with a lense designed for that lower wavelength it could make quite a bit of differnce,also the beam diameter is also coverned by the focal point of the lense that you are using in most cases the larger the beam at the optic apature the longer the coherence length will be, theres a few ways to combine to make white light i think buffo had one set up had a picture of it to it think it was a X-cube apparently it was a real bitch to align ( i can imagin)

[kaz]

Hi Doc, i think that idea is very good and i cant see any reason why that would not work,espeacialy as green lasers are cheap in comparison to other lasers in the higher output band, but i think it might interfear with a white light setup because as you start to run the colours through the dicro's you would lose the green somewhere down the line, unless you used some other method to combine the beams

[The_Doctor]

If it worked at all as I hoped (which I doubt) it would work in a whitelight system, all you'd need to do is set the green to keep the red and blue looking slightly closer to green than they do on their own. Mixing a small amount of the R and B intensity signals into the G channel would do it. But I'm not at all sure there's a point to this. I'm sure it's been tried, too.

[stanwax]

I bet if anyone has tried this sort of thing it will be Bill Benner.

Rob

[The_Doctor]

Actually I was thinking of Steve Roberts. I bet he's done it. Or knows there's no point.

[kaz]

i think that idea of the axicon would be good Doc,for combining lots of reds and maybe for a colour set up, obviously the smaller the axicon the smaller the beam would have to be to hit one of the facets unless the beam was focused to a small point then refocused at a later stage to get the desired beam diameter, thats just given me an idea

[The_Doctor]

The idea wouldn't be to throw several beams through a common focus and group-collimate the entire output, would it? That would be extremely hard to align, I think. That's also why the axicon thing won't work well. It won't improve on the standard thing like Arctos do, and it definitely won't be as easy to build or align. Anyway, if people with far more resources than I have are hoping I can do it, then it's not going to happen. Several people have asked, some in private messages. It won't happen though, for exactly the same reasons it never did.

[allthatwhichis]

I'd like to see what a very near infrared, 690+ and a 405 would look like combined... Probably not much different.

That is a nice pink there. How do the two beams compare? Spec wise.

[kaz]

Hi, both beams work out fairly well, The 405nm i used for this is slightly damaged and throws out a bit of extra light scatter probably due to damge to the front face of the chip, but even then far field divergence is still very good at around 60 feet ( the length of my garden) the blue will focus down to around 6 mm the red at about 10mm and that is with cheap acrylic optics, i think that is why they use shorter wavelength lasers to read the blu ray disk as they can be focused down to a smaller point. but even on the best 405nm diode i have there still seems to be a fair amount of near field scatter probably coming fron the fast axis from the chip, i dont know if some of this can be solved by using the optics that come with diode ( never used them) i would imagin that if you used a 690nm you would have to introduce more of the red to get the same affect i was using around 22mw at 658-660 to get that colour you would probably need around 100+ to get the same affect with a 690nm

[mliptack]

i think that is why they use shorter wavelength lasers to read the blu ray disk as they can be focused down to a smaller point.

That thought is absolutely correct, the fact that you can bring the 405nm wavelength down to a much smaller point than say 660nm allows you to fit more data on the same disk.

Ahhh physics... why is the sky blue!?