Originally Posted by
The_Doctor
Ok, was just a thought. Like I said in answer to Ben, I'd always thought it was just a longer cavity before this new wheeze occurred to me. I'm not sure if all microlensing will get a circular beam anyway. To do that you need very precise positioning. Maybe all we want to do is tame the fast axis a bit so it is no more eliptical than an unlensed single mode diode. (Most DVD diodes actually ARE microlensed, I was told recently, I think by Steve Roberts or Sam Goldwasser). In this case it might be a lot more efficient. The idea is not to circularise the beam perfectly, it's just to make sure we lose less light by optics loss, than we otherwise would by blatant spill, while at same time getting a shape that makes a narrow beam with little divergence possible with a single asphere. A single cylindrical plano convex lens might do it, if it is tiny, placed right up close to the diode chip inside a can.
Yep, the bottom line is that one, that's a deeply technical issue I really want to understand.
These just have a longer cavity and larger die. They do sport that quantum well window..no microlensing required.
Still, I have to respect the manu's wishes but I believe they are already being
made ready for the public.. I suspect they are already being used in equipment now. we'll see.
I can say that over 400 of these modules made by us are in use and only a couple of dozen or so have returned, either due to backreflection or overvoltaged from accidents or just plain died. or for an upgraded driver..Only one was my fault due to lack of sleep forgetting an insulator shim.
Still, I dont know how many hours are placed on them, I do know some are being used constantly, I still have my original unit outputting 240mW and it has been abused a lot when I ran it at over 300mW.
We may have to resort to using microlensing to get the newest 635-645nm diodes or any diode that has a fast divergence of greater of 20 degrees to be ready for use if we want to use them for our projectors..heck just getting them to use for beam shows will be fun in any event.
Also, the use of near field focal lenses helps, its not enough, plus we sacrifice beamwidth quality due to spherical anomalies with the quality of the lens becoming an issue because we then use more surface area of the lens.
It seems that all high powered diodes I have come across at this wavelength area have a very large divergence due to its cavity and die construction which is required to work at this wavelength.
Its laws of physics here that makes it tuff right now..otherwise
we are left with stacking or combining...
Last edited by marconi; 10-30-2007 at 10:27.
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, otherwise, with a poor cube you will have a lot more back-reflection and poor output .
