Just getting Started - Need help please

[Jem]

Oh good! Another old-timer (I'm 51)
I bought one of Marconi's 660 (658)nm >200mw module, and I'm happy with it. They have a good reliability record which is worth ALOT.
Steve

'Old timer' - That's a nice way of putting it. I'd say 'knackered' myself :-)

It seems there are a few 'old timers' on the forum. Could it be something to do with having to save up our cash for most of our lives in order to have enough to spend on our 'Hobby' ? ;-)

Are Marconi's reds analogue, also how easy would it be to combine two in order to get 400mw out? I realise a cube beam splitter would be required in order to combine the beams. How much does polarisation matter in laser shows? In my holography hobby it's pretty crucial.

Cheeers

Jem

[JimBo]

You can check out Marconi's red's here

Jim
ps I'm an old timer too, 43.

[Jem]

Thanks Jim

I'd just PM'd Marconi before I saw your link. I like the idea of being able able to purchase a ready built unit with two lasers and the beamsplitter etc all built and ready to go :-)

I'll wait till marconi PM's me back and see what he has to say. All I need now is to win some money !!

Cheers

Jem

[steve-o]

Jem,
Yeah, I doubt if a kid of 16-18 could scare up enough cash for this hobby.
'knackered' hmm -British slang? If it means pre-dementia, I'm there!
Steve

[JimBo]

Steve, knackered normally meens either exhausted, broken beyond repair, worn out or just plain old.
I am all of them

Jim

[Jem]

Absolutely correct Jim, that just about sums me up !!!

Jem

[steve-o]

I hear ya! .

[buffo]

I'm an old fart myself.. (40) Now that my kids are grown I can start spending money on *MY* toys instead of theirs!

Jem - Marconi will sell you a pair of his modules already mounted on a flat plate with the bounce mirror and polarizing beam-splitting cube installed and aligned. Basically you stick the fully-assembled plate in your projector and you get 400 + mw of red out! I think it costs less than $200 to add that setup to your order. (plus the cost of the two diodes of course)

Might want to ask him how much it would cost for a "performance-tweaked" pair that might get you closer to 500 mw while you're at it... Be sure you understand the pitfalls though. (Back-reflection into the diodes will *kill* them instantly.) Oh yeah, and Marconi's units are analog, so no worries there - you'l get great color mixing.

Adam

[Jem]

Thanks Adam

I've PM'd Marconi and am awaiting info. I forgot to ask about power supplies though. I read Marconi's thread on these lasers and I guess the power needs of a diode laser are much simpler than those required for a DPSS. am I correct?

Is it really just a case of coupling up a simple 7v to 10v (ish) switched mode supply?

Quote: "Back-reflection into the diodes will *kill* them instantly" - Does this just apply to the 'tweaked' diodes or are all diodes at risk from this? If it is all diodes is there any way of preventing back reflections other than being careful during setting up?

Cheers

Jem

[buffo]

Hey Jem;

It's even simpler! Marconi's lasers each come with a driver module that regulates the current going to the diode. You feed it 7 to 10 volts DC at 500 ma and it does the rest. Basically, all you need is a wall wart that puts out anywhere from 7 to 10 volts DC at 500 ma, and the driver that comes with the Maxyz module will do the rest. (No need for a switching power supply.)

The driver for a DPSS laser is the same as for a direct injection diode. The 808 nm pump diode is still a laser diode, and it behaves the same as a 660 nm diode. However, some DPSS lasers also include a TEC to regulate temperatures inside the head assembly. The control circuits for the TEC (if present) would be the only difference between a DPSS power supply and a red diode power supply.

As for the back-reflection issue, it is a danger with all diodes, but the closer you are to the max output, the greater the risk. One of the most common failure modes for a laser diode is excessive light intensity at the emitter face. The intensity actually damages the face of the diode, much like a high power laser pulse will damage the face of a razor blade! The damage is irreversable, and happens much too fast to allow any sort of feedback circuit enough time to act.

The way you avoid the problem is to prevent back-reflection in the first place. This means being very careful when aligning your optics (not just during setup, but any time you are adjusting), and turning the power down when you're messing around with your alignment - particularly when adjusting the alignment of the polarizing beam splitting cube.

BTW - here's a link to one of Marconi's auctions on E-bay. It lists even more info on the Maxyz modules...

Adam