DAMN nice setup ! I like the beam combiner - I may have to get a small optics stage for doing some of that !
DAMN nice setup ! I like the beam combiner - I may have to get a small optics stage for doing some of that !
What are the dimentions of that BS?
Jim
Some quick photos... Not good, but they show enough.
The module is a quickly built copy of the non-cooled non-modulated design I used to sell on eBay a few times with 80 mW diodes in.
That long lobe spreading away from the beam axis interests me, I don't know what it is, but it's definitely related to the diode structure, because it's in focus at the exact same depth of focus for the central spot, so is not a reflection of some part of lens or mount. The spot is slightly elliptical, clean, <5 mm long at 6 metres from source. 3mm at aperture, CAY046 acylic asphere, no AR coating. Drive current 266 mA, constant, not measured but calculated by 1.25/4R7 in LM317 constant current circuit. Temperature 25°C, almost constant, little change, module is efficiently carrying heat from the diode via thermpath goop between clamped aluminium surfaces. Module is placed flat on 12mm thick aluminium baseplate. Power >220 mW constant, duration about 2.5 days so far. No problems with retroreflection from the Lasercheck's ND filter.
One thing I want to watch, especially as I didn't include temperature compensation in the circuit of this one, is whether it can be turned off, left to cool, wait for a few hours maybe, then turn it on again. Even with the soft start circuit AND some temperature compensation, I saw a Rohm diode die this way even though it was only putting out 164 mW after the lens. It had only been running for 10 days.
Last edited by The_Doctor; 03-13-2007 at 23:34.
I have also seen that on all 4 I have tested so far, so it's fair to say it's a constant. I wasn't sure if it was my collimators at first.
It looks almost medical when the beams are combined as you end up with a dim crosshair type of thing around the axis. Reminds me of the opening scene of the Hulk back in the 70's, when David Banner took a shot of gamma radiation
Pit.
A little bit werrrr, a little bit weyyyyyy, a little bit arrrrgggghhh
Important update: Diode died spontaneously after three or four days. I've been working on the computer in the quiet hours of the night, and it died during this time, so it can't have been line noise or any ambient condition, it just upped and left.
220 mW is a lot after an uncoated optic though, the Rohm diodes will do the same if putting 160 mW after that lens. My guess is that a decent lifetime could be had if the power was reduced to just over 200 mW.
I was hoping that it might go further, and can't entirely rule out the possibility that something else killed both diodes recently, but as both were pushed well beyond spec, this is the most likely reason.
The one at 320mA died after about 24 hours, which I'm not totally surprised at, although it would've been nice had it stayed put
I did have one running at 275mA (around 238mW raw) for about 20 hours, but on the basis of the Doctors failure have knocked that back this morning to 264mA which measures 223mA before collimating optics and 198mW after with the LC at 660nm. This one is also not cooled by peltier the so temp is ambient, around 23-25 degrees.
Let's see how this one holds up, hopefully we're getting somewhere near a reliable output now, but time will tell.
I'll contact those who indicated an interest in the group buy on Friday, and so long as we still have 12 or more pieces required, I can still get that order in.
Pit.
A little bit werrrr, a little bit weyyyyyy, a little bit arrrrgggghhh
Count me in for 10 diodes
They wouldn't have HL6323MG at a discount price would they?
A little bit werrrr, a little bit weyyyyyy, a little bit arrrrgggghhh