Now its dead :( 800mw Lasever module

[numquamretro]

Wich of the parts are most effected by the heat? Maybe i can improve the cooling with adding some copper? Anyway, i wonder why the module housing is made of brass instead out of copper!? Brass conducts heat only half as good as aluminum and only quarter as good as copper Maybe i drill a new housing... what do you think?

 

[ultimatekaiser]

Because beyond a certain point, it won't help... and copper is VERY expensive. Heat only transfers so fast, so ultimately indium foil and a TEC is better. Plus, some of these parts we actually want somewhat warm, not too cold or too hot.

Lab modules actually do something similar but with optical, electrical, and thermal feedback added, allowing it to adjust the output to keep it constant and steady for a long time. (indefinitely in theory) Certain Gas lasers do this as well, though they inherently have an easier time doing it, as many of these properties naturally occur more easily.

The diode and KTP like to be warm, but not hot, the vanadate doesn't care as much but prefers to be cool.

 

[numquamretro]

Don´t you think the runtime (even if not controlled) will extend by adding some extra copper elements (or maybe craft the module host out of copper). It probatly takes more time to reach the perfect temperature and get stable, but then it should stay there longer.

Can you explain me what the vanadate is (on the pics) an what it does?
Sorry to bother you with these questions.

 

[shokkunlasers]

Brass is easier to maschine and doesn't tarnish as fast the heat capacity per volume is also much better than aluminium

Leave it so :beer:

 

[numquamretro]

Brass is easier to maschine and doesn't tarnish as fast the heat capacity per volume is also much better than aluminium

Leave it so :beer:

the tarnishing effect doesn´t matter since it´s inside the host

Since the heat capacity of Aluminium is ~896J/(kg*k) and that of copper is 382J/(kg*k), copper does a better job compared to volume of the material. Copper weighs 8,97g/cm3 and Aluminum 2,7g/cm3, means copper is 3,3x heavier. -> 3.3x385=1155J at the same size as 1kg Aluminum. Brass has little less heat capacity then copper and it conducts heat only 1/4th as good.

So my conclusion is: copper is the material to go with, if something needs to be cooled and heat is needed to be transfered very fast.

 

[DashApple]

Don´t you think the runtime (even if not controlled) will extend by adding some extra copper elements (or maybe craft the module host out of copper). It probatly takes more time to reach the perfect temperature and get stable, but then it should stay there longer.

Can you explain me what the vanadate is (on the pics) an what it does?
Sorry to bother you with these questions.

The Vandate is Neodymium-doped yttrium orthovanadate ( ND:YVO4 ) , its a crystal that is doped with neodymium . when it is pumped by 808nm light it will fluoresces and lase producing the 1064nm light that then undergoes SHG inside the KTP to give the green @ 532nm

Its the first crystal after the diode followed by the KTP .

Looking at the pictures I would guess the YVO4 is under the rectangle brass piece along with the KTP .

Just as a example in my 1W CNI Lab head the YVO4 is in the brass block with the single screw in the top of it , followed by the KTP and then the OC mirror


IMG_0184 by TwirlyWhirly555, on Flickr

 

[ultimatekaiser]

indeed he's correct. the vanadate (or yag possibly, but not likely) is probably in the copper disk, and the three center screws are the aligning screws (one for each axis usually) and then the aluminum support with the KTP mounted in the copper block, and then whatever filters and lenses after.

In the CNI module's case, I can be more specific....it would be the diode at the far left, then likely a BK7 (concave side inward) coupling lens in the silver block, then the vanadate in the copper block then the KTP cradled in its own copper U-mount, and then the OC mirror, and IR filter and corrections in the end, and then the collimator and aperture.

 

[numquamretro]

Thanks for the explanation guys, i´m sorry i can´t give you any more rep. Need to give some to others first

I think i got it now (also did a little research).

Is it hard to control a TEC cooling? Because Lasever also sells these
and i think it could be possible to drive the TEC with a certain voltage (maybe adjustable from the outside to find out whats the best setting). What do you think about that?

Edit: sadly my host is not designed for this module. Too much rework to make it fit/work. But maybe i´ll build another one sometimes with that TEC module.