Changing the unserviceable blue laser module in an RGB Laser Systems LP2000 Projector

Please could I ask for some advice before I start repairing my new ‘old’ laser. It’s an early LP2000 made by RGB Laser Systems, rated at 1800mW.

It had a strange double blue laser module with 2 output beams, which are combined with the green using a dichro for one blue & a PBS Cube for the 2nd. It is very low on power, so I have bought a replacement 445nm 2000mW analogue modulation module & PSU, which I’d like to fit into the system. I realise the balance of the RGB to White(ish) will be different, as the G & R are only 700mW & 1400mW respectively. I will just manually reduce the B using the appropriate potentiometer on the back panel or in software.

I have the owner manual for 2 different types of LP2000, but I cannot obtain any circuit or schematic diagrams, even from the manufacturer.

Physical Installation/Alignment:

I need to physically fit the new module where the older much larger one was, so I hope it’s beam is the same height as the old. But if it isn’t, could an adapter plate or shims be used raise the module? I will have to ensure heat is conducted away into the base. I just hope these things are a standard height & that my new module’s beam isn’t higher than the old. Not sure what to do in that case; can you buy ‘periscopes’ to lower laser beams? Extra loss & increased divergence.

Once I have sorted this do I introduce the new blue beam into the PBS cube or the blue dichro? If I can go into the dichro, do I still need the PBS cube, so could I remove it? (I can look up the wavelengths of the old dual blue module if that helps answer this question?).

Do I need to physically be able to slightly alter the position of the new blue module for alignment reasons? I’m fairly sure all alignment is by adjusting X & Y screws of the dichro & mirror mounts rather than the laser modules, which appear to be securely bolted in place.

Connections:

I would need to connect the new module’s analogue modulation input to the ILDA connector via the existing blue level pot.
But the colour channels in the ILDA interface are differential?, so there must be some opamps somewhere to convert that back to single ended. I think I will need to find this, or might be best to just connect to the wiper of the blue level pot possibly, if that is where the current blue laser module modulation wire is connected to.

All this would be SO much easier with circuit diagrams! Even schematic diagrams would be helpful.

Most of the internal wiring is strapped together, meaning I will have to release it to accertain where things are connected. That’s ok though, because I’m going to tidy-up the wiring into a proper wiring loom (I’m an ex-Avionics/Aerospace engineer, so am used to making looms using lacing cord etc.)


Removal of old PSU/driver(s):-

Do you think the removal of the old blue laser module’s PSU/driver could affect any other modules or the operation of the projector as a whole? e.g. there may be TEC cooled employed for a very old Blue laser module etc.

If anyone has any suggestions, observations, or ideas about these issues or if there are any other considerations I need to look into, then please let me know. I can send or post photos of the General Arrangement or specific areas.

Many thanks,

Si Bond,
Ilchester, Somerset, UK.

One picture would literally mean a thousand words. Also we generally stop reading after two paragraphs.

post a picture or ten. Annotate those. We will then ask questions or and suggest. Happy to help.

Ask Sandor Wensky at https://prolaser.hu/contact.html

Yes, of course. Sorry for the tardy response too. I’ve just started a new job as a Calibration/Metrology Engineer at our local Helicopter factory & get to play with a very nice 3D laser scanner!

But I will try to insert a few photos of the Blue laser module I’m trying to replace. As stated it has twin output beams from the same module. One goes into a dichro where it’s mixed with green & the second joins that Green/Blue using a PBS Cube.

hope the photos show this general arrangement. Not sure of the blue wavelengths; maybe I can borrow an Optical Spectrum Analyser from work.

Many thanks,

Si Bond.Attachment 55903

Regarding beam height. I heard Mixgas mention “use 2 fold mirrors per laser to adjust the height”.
I guess that’s in effect like a periscope to alter beam height. I hope I don’t need to do that as it must cause loss of power & increase divergence. But if I did need to, how would you go about implementing this, in a manner that would provide the precise adjustment needed whilst remaining stable & not prone to movement?

Thanks, Si B.

The pictures helped a lot. That is an odd beam path. I assume the two blues are different wavelengths, but its hard to tell from the photos. Assuming you want to replace both blues with one module, you can remove the cube and just choose the dichro that works best with the wavelengths you are combining. If you want to salvage the working blue due to a different wavelength (like 473nm), then you'll need to match the polarization of the old module to get it to work as it did before. This may mean mounting the new module on its side.

If instead you just want to replace the two blues with the new module, then just match the heights using aluminum plates of the appropriate height. Stack as necessary. The periscope thingy is more complicated and you have enough optics in there as it is.

The total powers of your new module with the existing greens and reds (assuming they are doing what they originally stated) should make for a nice white, IMO.

-David