diode mounts and sockets

[darren]

Hello folks,
I'm embarking on my first RGB build for home - I'm building the modules and was after some recommendations for mounts.
I'm using paired diodes - 2 pairs of 5.6mm and a pair of 3.8mm.

Being that it's my first build, and I'm combining combining the beams through PBS cubes, I'd like to opt for a mount that

1. Allows for easy rotational adjustment of the diode
2. lets me to use a connection socket for the diode

Does that rule out the Lasershow Parts type brass mount type, which I'd quite like to go for?
laser-diode-mount-38mm.jpg
I guess with a bit of practice, I could learn to orientate the diode (by trial and error if it's not a tight fit, or before I fit it if it is): once it's done, it's done
I'm less confident I'd be able to fit a socket though, because of the depth of the backplate and because unlike a directly soldered and heatshrunk connection, it's going to leave bare pins passing through that backplate (!)

Or there's the SK12 rail type which fits the bill for both:
s-l300.jpg
But doesn't look as effective from a heatsinking perspective. My diodes are only in the 80 to 200 mW range, but I wouldn't want to risk under-cooling them.

Any thoughts? I appreciate I could suck it up and ditch the connectors but given I've got 6 diodes to work with and I'm not at my happiest soldering, I'd prefer the additional confidence and safety they'll provide.

[kecked]

I rather like them. They are fine

[laserist]

Solder a real connector to the diode rather than pretending whatever you can find that fits will handle the current, voltage, and vibration without killing your diodes

[darren]

I rather like them. They are fine

which of the two do you like?

- - - Updated - - -

Solder a real connector to the diode rather than pretending whatever you can find that fits will handle the current, voltage, and vibration without killing your diodes

Would you mind posting a link or pic to the sort of connector you're referring to?

[kecked]

I like Dave’s. For the power you are using it’s irrelavent for heat sinking but for larger high power brass isn’t the best but can and does work. Dtr makes nice copper 20mm hosts. I like those. It depends on your beam height too. Dave’s like the one you show are much easier to change a diode and mount align. If it was copper it would always be the choice. Make sure you you solder up the diode add heat shrink tube. For 9mm diodes you have to drill the back. Add tube on the wires for strain relief and shorting. You can just slide the diode around to align and then lock in place. It will slide a little when you lock it down so be slow and adjust the screws.

Add lasorb just cuz. They are worth the cost and effort. Most glue it to the top of the brass mount. In fact use as terminals now there is no flex issue with the leads.

And remember everything you hear here is an opinion. The level of real knowledge is highly variable. I’d rate myself low to mid low. Just saying cuz I hate spreading bull. This is just how I should do it. In reality my stuff looks like steampunk.

[dkumpula]

Well, I'd say that the shaft mounts are easier to build for a newbie, but in my experience Dave's mounts are easier to align and take up less space in a build. Dave's look better in my opinion too.

Although I have built several using both approaches, I prefer Dave's because the beam comes out perpendicular to the plate instead of at a slight angle like the shaft rail mounts do. This makes alignment much easier as all the diodes are hitting your dichros as the same height, where as the rail mounts require you to either elevate them or shim them to get the beam to hit your dichros at the right height. The downside of Dave's is rotating the diodes is more challenging of course. Rotation is necessary for getting polarization right for your PBS cubes for combining and even in non-PBS'd builds you generally want your beams to have the same fast and slow axis alignment for better beam overlap.

Now there's a couple tricks for rotating a diode in Dave's mounts. You can either loosen the screws on the back-plate a bit and then rotate as necessary. Do this with the power off so you don't burn out the diode or short it out if you don't have heat-shrink tubing all the way down to the base of the diode. (Getting heat-shrink tubing all the way down on 3.8mm diodes takes practice. Hint: slightly preshrink and use a super-small screwdriver to jam them in there.) With either method, you can tell the diode orientation easily if the diode is slightly unfocused. You'll get a nice line that you can orient horizontally or vertically.

But after many builds with Dave's mount, I eventually found a better way to orient diodes. . .

In my experience, laser diodes are made so that you get polarization parallel to the pins. For example, if you mount the diode so that the anode and cathode pins are vertically oriented, you'll get one polarization, and if you rotate it 90 degrees so those pins are horizontally oriented, you get the other polarization. In addition, looking at the front of the diode in the mount (without a colimating lens) you'll see that there is a straight piece of metal behind the lens cap. Kind of like this picture, but not quite as obvious. If you have a good eye, you can orient one diode so that this metal is perpendicular to the base of the diode mount and the other one is horizontal to the base. I'm sure there are exceptions where this trick doesn't work, but it works consistently on all the single mode diodes I have used over the past decade.

Now, Swamidog swears that PBS cubes aren't always consistent so that sending the fast axis in horizontally or vertically doesn't always result in the best combination without loss due to the cube not having the polarization material carefully laid out to work with this input, but I have yet to find a cube that wasn't consistently built to work this way. With my approach, I consistently get very efficient output through the cube without having to go back and fiddle with the diode rotation.

Have fun whatever approach you decide on!

-David

[darren]

Thanks both - that's a wealth of information and just what I needed. I must admit I was leaning towards Daves, so it's good to have some additional justification from those who have gone through it

I'll play around with some socket connectors to see if I can get some hybrid solution that uses Dave's mounts and allows for use of sockets, otherwise I'll bite the bullet, practice more soldering on thin wire to act as leg-substitutes, then go the direct-solder route.

Lasorbs I reckoned, definitely justified the small additional cost. I appreciate they can't prevent killing a diode in every situation but they're definitely better than nothing. I'm hoping Evil's Laserbugs are still available - they were a really neat solution.

Thanks to kekced for reminding me that opinions are just that - it's all to easy to take a comment in isolation as gospel, when you're new to this like I am! The steampunk reference made me smile

[dkumpula]

Sure thing, Darren.

I forgot to mention that I agree with Laserist in regards to soldering your diode connections. Yes, you should practice first, but when you think you've got it, try presoldering the wire (heat the wire that you are connecting, add a bit of solder to it). Then heat that wire so the solder is melted and then touch it to the diode pin making sure the diode pin and the wire overlap for at least a couple millimeters. Then immediately remove the soldering iron from the wire and wait for a second or two for the solder to cool. This should result in a good solid solder joint, but give it a bit of a tug just to make sure its attached tightly. As Laserist said, poor diode connections will kill your diode. I have learned this the hard way several times!

-David

[darren]

Thanks David!

Point taken. Ironic though it may be, I have an interest in large scale electric RC: I have a 6ft Airwolf heli and a 1:5 scale offroad car (the motor in this is about the size of a soda can and pulls around 250A peak)
In these applications, connections have always been key (bad connections=increased resistance=higher current draw=disaster)

[kecked]

I wish there was a solder connector you slip over the wire and pin and just heat to make the connection. I tried crimps but they take up too much room. I eventually found using the mount to hold the diode and then solder to work best. My problem is shaky hands and bad eyesight. That’s why I went to 20mm copper. DTR does it for me when I order like that. I just rotate the whole assembly.

I also have found cubes where the best transmitting was not always square to the beam. I measured it too. Another trip I use is a single drop of tool grip on the back of the diode after I solder. It pots the heat shrink and prevents shorts. Just use as little you can so it doesn’t get in the way. Toothpick works. Wonder if a drop of candle wax would do the same. Probably too soft.