DPSS Heads and Drivers Question

[Bradfo69]

Maybe "Advanced Technical Discussion" isn't the right category for this question but, my thinking is the smart people that can answer this probably hang out here more and it stands a better chance of being seen.

What exactly is it that ties a head to a particular driver and they can't be switched? I've heard that discussed before and, it seems to me that if you have two of the same lasers from a particular manufacturer that you ought to be able to take the head of one and still have it work hooked up to another driver. The basis for the question is I have a Viasho 1 watt 532 built into a projector where the head is easy to remove for a needed repair but the driver is VERY buried inside the projector and will require major dissasembly to remove. What is it that prevents me from removing the head and shipping it out for repair without the driver - assuming the individual doing the repair (an alignment) to the head has the same driver?

If someone bought 2 brand new (as an example) DHOM 500mW 532's from the manufacturer at the same time... why would the heads and drivers not be interchangable? Or... would they be?

Thanks!

[chad]

They should be, but.... They will need adjustment to tune pid temp stuff and diode current to get the max out of the system. Most of the stuff from china varies a lot from unit to unit. They take care of this in the driver.
The 808 diodes are static sensitive and disconnecting and reconnecting involves risk. They want the driver and laser together so they can make sure that the pair work together. Less stuff to ship...

chad

[Things]

Chances are it would work just fine, however like galvo's, the heads are matched to the drivers because every one is slightly different, for example the TEC in one of your heads might be slightly less efficient than one in the other, so using a different driver tuned for the lower efficiency means the other laser might not stabilize or operate properly.

All lasers have a "sweet" spot, and it's different on every one of them, so the drivers are tuned to match

[astatic]

Ones i've tried to switch the driver in a kvant and i agree it will work, but for how long.
Peter from kvant told me nearly the same as chad, and warned me never do this again!

[Bradfo69]

Thanks... I guess it makes sense they would "tune" the driver to the head. I just wouldn't have expected a lot of difference with two identical units.

[mixedgas]

Really good DPSS gets around this by placing the adjustment potentiometers in the laser head, or by just storing the data in a EEPROM chip. Odds are the first solution is not used in China so they can limit manufacturing costs. It also forces customers to buy expensive replacements. The second does not bode well for fast, cheap analog modulation in a laser designed to be assembled by "former peasant farmers."

Its all a matter of keeping costs down to maximize what they can do for themselves with YOUR Dollar.

Steve

[planters]

As I am learning more about these things I think you will probably be fine as far as risk is concerned. The drive diode current is not going to be critical and will probably be set to match the spec of the IR diode. It is unlikely this will be "tuned" in a low cost typical projector green. Where there is probably going to be some meaningful mismatch is if the KTP is temperature tuned in order to max output. But the risk here is less than optimal preformance and not catastrophic. If the crystal is being run warm it will probably be close to baseline. Are you sure the repair is limited to the head?

[Bradfo69]

Pretty certain. This was formerly smogthemogs projector with a 1 watt Viasho green. Shortly before buying it, the head went bad and Rob Stanley replaced the pump diode (and replaced it with a 5 watt rather than 4 watt pump. He worked on getting the internals aligned but was really pressed for time and only got it to 400mW before smog got it shipped it to me. This was a couple years ago. It's basically not been high on my priority list because, whether it's the low green or something else, it has had fabulous colors. Rob agreed to having me pull it from the projector and ship it to him to look at. It's quite a chore since smog did an excellent job of packing everything into this case with surgical precision. Recently I pulled it out to use and the green is now suddenly considerably dimmer so I HAVE to get off my arse and get it fixed - or just replace the green all together - which may end up being my preference since the 1 watt Viashos have less than a stellar reputation. I have several thousand tied up in it and have used it maybe 8 to 10 hours in the two years I've owned it.

I'm kind of on a kick right now of getting some things fixed that have been piling up.

[planters]

I'll be blunt. I would replace it as it sounds like there are too many unknowns here. Did the original 4W fail due to problems with the driver? Maybe. Buying a head without a driver may save some money, but will surly void a warranty. There is uncertainty about the comparability and it is likely that there will be less than optimal power output if there is any advantage to head/driver adjustment. If 1-1.5W of green is the target you can get this for a lot less than $1,000.

[buffo]

Hey Brad;

A CNI 1 watt analog green should fit in the same slot, and they're $525 from Goldenstarlaser right now. (I just picked up two of them, see this thread for testing details.)

Adam