Unusual 532nm-module from Aries-type host

I bought a few Aries-type lasers from Glenn's LG-group-buy last winter. One was very different from the others in design, it was designed to unscrew in the "middle" of the body to replace the battery, (instead of removing the tail-cap). Also, it was designed to take a 18650, instead of (2) C-cells, like the rest of the Aries-units.

With Gooey Gus's help, we were able to power-it up. It makes over 230mW of green-output in a very unusual-shaped beam, wide and blob-shaped. Shortly after power-up, the power quickly drops to under 10mW, (20 seconds or so). When Gooey, removed the module from the head, it appeared completly sealed-up, no way to get inside. He did note however that there were two-drivers below the module, leading him to believe there may be a TEC-inside, along with the C-mount. Really cool, if it is true

Yesterday, I mounted the myterious-module in my lathe and began surgery. Soon I was able to unscrew the cover of the module, I did not expect what I found inside. It does appear to have some sort-of thermal-device going to the mount of the final-crystal.
Judging from how quickly it heats up when powered-up, I am pretty-sure it is heating the crystal. Thier are 4-wires coming from the mount, 2 for power and likley 2 for a thermo-couple to measure and adjust the temp of the crystal-mount.

My first instinct is that maybe the power-wires are switched and it is heating when it should be cooling. Also, I wonder if this is a prototype that did not work-out for LG and the idea was abonded. I am not sure where the heat from the TEC would go, if it is supposed to be cooling. Maybe it is just a heater to make peak-output more quickly?

Anyone have any ideas?
Barry

This is neat thanks for sharing. I'd love to get my hands on this setup. Would be very easy to switch out crystals and turn it into a blue.

Kenom said:

This is neat thanks for sharing. I'd love to get my hands on this setup. Would be very easy to switch out crystals and turn it into a blue.

Click to expand...

I had similar thoughts. But I will have to understand it's intended opperation much more first. Right now it seams to be cooking the second-crystal.

now I can't imagine that being the case. Cooling it maybe. You should be able to feel the metal under said TEC and if it's cold, then it really is heating it, and if it's hot, then it's cooling it.

Wow. Impressed

That doesn't appear to be a TEC. I have two lasers of similar design, both rated over 600mW. Though I no longer do much work on portable systems as far as modification or dissasembly, the pump LD in one is dead, I'll take it apart and see if this device is in it aswell. If so, I'm suspecting it is there to heat to crystals to optimal efficency, but the probelm is the output is not long held as the crystals get to hot. I'll update once I've performed the operation.

I have taken the final-crystal mount off now. It does appear to have a tiny TEC mounted under the crystal. When powered up disassembled, the small-white pad (ceramic I think), does get warm, the other side likely is meant to cool the rest of the module, (brass).

This seams like a great idea, if it is practicle. Cool the module with a TEC and use the excess heat generated to warm the final-crystal to peak more quickly. Not sure if the math works out though. Seams like it will need more "cool" than warm. When assembled, the copper crystal-mount is uncomfortable to the touch within 20-30 seconds, while optical-output drops by more than an order of magnitude (230mW-10mW).

Barry

Dark_Horse said:

I have taken the final-crystal mount off now. It does appear to have a tiny TEC mounted under the crystal. When powered up disassembled, the small-white pad (ceramic I think), does get warm, the other side likely is meant to cool the rest of the module, (brass).

This seams like a great idea, if it is practicle. Cool the module with a TEC and use the excess heat generated to warm the final-crystal to peak more quickly. Not sure if the math works out though. Seams like it will need more "cool" than warm. When assembled, the copper crystal-mount is uncomfortable to the touch within 20-30 seconds, while optical-output drops by more than an order of magnitude (230mW-10mW).

Barry

Click to expand...

Yes indeed that is definitely a TEC.

Thanks for taking the plunge and opening this baby, man! As Kenom said, it could be easy to machine a crystal holder... the hard part would be getting the damned crystal!

Upon closer-inspection of the TEC-driver, I noticed a couple of things.

First, there are labels in the PCB screenprinting that are labeled "TEC -" and "TEC+", the leads soldered to these are grey and black.

Next: These wires are in-turn soldered to the leads coming from the red and black-wires that appear to be powering the TEC. However, what you cannot see in the picture is, the grey-wire, soldered to the "TEC-" pad, is connected directly to the "red" wire going to the TEC-module.

These would tend to support that there is in fact an ob-board TEC used here, and it is connected backwards from how I would guess it would be.

Does anyone know the ideal operating-temps for the 532-crystal-set. Not specific-temps, but which crsytal likes to be warmer?

Could it be that I only need switch the TEC-leads to fix this interesting-module. Why would someone before me not have noticed this?
Check out the pic.
Barry

The second crystal is the KTP. It's common practice to heat KTP since it's efficiency goes up when warmed to a specific temperature range.

That's actually a fairly nice little module. Discreet crystals are the best when it comes to generating good power with good stability but aligning the crystals can be very difficult and time consuming..

It could be a miswired tec, who knows...

Controlling teperature of the pump and doubler seems to be a very good approach if done properly. It does add a lot of complexity to the design though, perhaps more proper for a labby setup than for anything portable...

So, I switched the lead from the TEC to the correctly-labled-pads on the driver. Now it cools the crystal-side for sure.

While I was switching the leads, I used one of Laserbee's 1ohm resistors to check the amperage coming from each driver, here are the goodies:

TEC-driver, (using a 1-ohm test-resistor in series): 500mA
Diode-Driver (same test-resistor) 700mA

I will reassemble to see if the power-drop problem remains.

I have roughly realigned the KTP-crystal for now and check on the LPM. It's output is more stable now, about 100mW, dropping to 90mW after a minute or so. The brass-module now gets noticably "warm" in the hand after a minute now.

Seams like a lot of trouble to go through for a 100mW laser. More current would make more heat. I am pretty sure this was someones R&D-effort and may not be practicle in it's original intent.

I have the host all shined-up too. I still need to make a aperture-cap with shutter and do a custom anodize-job.

As Electrofreak said, the KTP crystal is actually more efficient when it's warmed, so I don't think having the TEC heat it was unintentional.

It was intentional, however it gets to hot to fast. Also the ND:YVO4 is in close proximity and is likely getting to hot. In larger mains powered systems the crystals are farther appart with a more complex optical train. The hope here is guess was to heat up hte KTP and somehow dispearse the heat quickly, perhaps the tec comes into contact with the housing, since the cold side is much to small or nonexistant from the images.

I found a TEC in a lyra host that I got, that was on the crystals. Still got it somewhere