Cross Dichroic Prism Laser Project

Alaskan · Oct 8, 2014

Has anyone here combined RGB lasers to make a white beam through the use of a Cross Dichroic Prism? I'm considering it but don't know the difficulties involved. Right now there as a sale for some at SurplusShed.com for some 35mm x 35mm x 35mm cubes. I am also finding some defective ones for even lower prices on ebay, but don't know what the defect might affect, anyone buy any of those?

I've been looking for a video on youtube on this, but so far nothing really good except this on 3LCD: https://www.youtube.com/watch?v=MetjQ1Rmfe4

Tomorrows System · Oct 8, 2014

Laser Project said:
Has anyone here combined RGB lasers to make a white beam through the use of a Cross Dichroic Prism? I'm considering it but don't know the difficulties involved. Right now there as a sale for some at SurplusShed.com for some 35mm x 35mm x 35mm cubes. I am also finding some defective ones for even lower prices on ebay, but don't know what the defect might affect, anyone buy any of those?

I've been looking for a video on youtube on this, but so far nothing really good except this on 3LCD: https://www.youtube.com/watch?v=MetjQ1Rmfe4

You must use 35mm cubes? 10mm re much easier to get.
Actually cubes are pretty easy to use. Important is to have turn regulation for diodes to get maximum output power. One source of light you fix with glue, second one you can move and turn adjusting to the first one. You are moving the light source and the cube also.

But why use CUBE for RGB instead of dichros?

For the X cube I have somewhere old Cube similar to the one on the video. I unmounted it from the old projector but didn;t use. PM me for more detaild

Cyparagon · Oct 9, 2014

OP has me on ignore, but this is for anyone else wondering.

It'll work okay, but losses will typically be a bit higher than with dichros. The main difficulty is alignment. One color passes through the cube, and the other two are reflected, so you cannot align one color without altering the alignment of the other. If you can manage directional as well as positional adjustment of at least one of the side lasers, it would be easier. But with the money you're going to spend on such a positioner, you might as well use dichros.

Alaskan · Oct 9, 2014

Thanks, I took you off ignore, my reasons for putting you there were petty and you are too valuable of a resource to do that to also. The reason for the 35mm cubes is that I found some for 18 dollars each and thought that would be a way to combine some R, G and B laser diodes to produce a white output beam. I have lots of single mode diodes I want to combine into a huge laser pointer which I can use to produce an output I can control the color on, depending on how many of the R, G or B diodes are turned on and how hard they are each driven.

I'm not hoping to build something quick, this might take some time and a lot of money. Perhaps the cubes, due to alignment issues, isn't the way to go.

Tomorrows System · Oct 9, 2014

I can help you a little with project using dichros.
I was doing RGB systems already, I even have one small mounted on base plate.

Alaskan · Oct 9, 2014

Thanks, I have the X-cubes coming so the money is spent on a few of those already but if they are too difficult to work with and the losses too high I can save them for another project. I have 16 each of each color R, G, and B single mode diodes mounted in modules with G1 lenses to work with but no drivers yet. Was thinking of running strings of them in series to reduce the number of drivers.

Tomorrows System · Oct 9, 2014

As always with drivers I serve you well especially for higher voltages for diodes in series.

The x cube has really a lot of power loos. I also bought them to make rgb laser. I wanted to put three diodes around the X cube, but... but it had around 70% efficiency it is decitaded for projectors not lasers. But maybe yours are better. Anyway if you have cube you need to move lasers if you have dichros you move lasers only a little and you operate with mirror mounts.

Alaskan · Oct 9, 2014

OK, I will save the cubes for another project and just use dicros on that advice, I saw you are selling some on your web site too

Yes, with the higher supply voltage needed to run diodes in series and the ability to heat sink the driver well with plenty of current capability, your drivers are the best choice I have come across for something like this due to that.

Tomorrows System · Oct 9, 2014

Sure, just write me email or PM. I will make a discount.

Alaskan · Oct 10, 2014

Thanks, do you know of a simple way to combine the beams of 12 red, 12 green and 12 blue single mode diodes using these filters? I'm thinking I'd have to combine the white light from each set of three with a knife edge to do that. Anyone?

Tomorrows System · Oct 10, 2014

Probably knife edge would be the best, and additional telescope system at the output to change the diameter.
Google acrtos in the internet

Arctos Multi Diode Array

Alaskan · Oct 10, 2014

Thanks Mateusz,

I've seen is page before and happened to be looking for it earlier today, but couldn't find it. I might have to do something unconventional to get all of these diodes multiplexed together as one output. I'm still looking for solutions on how best to do that while at the same time reducing the physical size. I do believe I will have a mix of dicros, knife edges, a cube and telescopes will be in the works. I'm trying to think out of the box while at the same time learning.

Bionic-Badger · Oct 11, 2014

I've used those X-cubes, but you need to make sure the laser is properly oriented, as cube does polarized combining and probably want to position the lasers so that what leaks through the surface doesn't enter other diodes.

Alaskan · Oct 12, 2014

I cancelled the order for the cubes and ordered some dichro filters instead. I bought some inexpensive ones to play with and see what I can do, later will get some better ones.

I guess I can only use these filters in pairs for each set of R, G and B diodes but I have many RGB diodes I want to use to increase the total power. Maybe some kind of mirror arrangement and a knife edge will be needed. I can't quite wrap my head around how this can be done for three 12 diode groupings of each color.

Bionic-Badger · Oct 12, 2014

Just treat each knifed-edged monochromatic combination as a single beam to be combined. As long as the knife-edging pattern has the same geometry they'll combine just fine. That's all there is to it. The dichroic filters aren't polarized; it only matters that you get combining wavelengths correct.

Alaskan · Oct 12, 2014

Why didn't I think of that. Thank you. I have some nice stair stepped knife edges I bought from Jeremy that have some lenses in them too.

Edit: I found something which might work to mount my 12mm Aixiz modules in to line the beams up accurately on the knife edge assembly with fixed 45 degree mirrors. Will this work well? Maybe I could adjust the height with all-thread and some nuts on them to tighten each one down, once set. Maybe I would need something more sophisticated than this? I don't need a lot of heat sinking as the individual diodes are all low power single modes.

Cross Dichroic Prism Laser Project

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