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Long shot: operating high power laser modules in vacuum

Guest
Dudes of all flavours;

I have an itch: I wish to run a 10W laser module in a vacuum chamber (UHV: 10^-6mbar or so).

Anyone got any direct experience of the 'fun' in keeping the diode cool?
And any tips on doing so?
<heat pipes, lots of copper, lowered duty cycles etc.>

Cheers;

-James G.
 
J

Jon Elson

Guest
On Thu, 28 Mar 2019 16:06:09 -0700, jrcgarry wrote:

Dudes of all flavours;

I have an itch: I wish to run a 10W laser module in a vacuum chamber
(UHV: 10^-6mbar or so).

Anyone got any direct experience of the 'fun' in keeping the diode cool?
And any tips on doing so?
heat pipes, lots of copper, lowered duty cycles etc.
Water cooling loops will work, but that is pretty complicated. In
vacuum, metal surfaces that are pressed together conduct heat very poorly.
You need some sort of thermal conductor (either loaded silicone grease or
gap-pads) to carry the heat across. If your laser can be attached to the
chamber by some structure, that can conduct the heat out.

Jon
 
J

James Garry

Guest
Jon,

Aye, I've cooled lamps (tiddly 10Watt deuterium lamps, of all things) inside vacuum chambers with fluid lines on KF flanges in the past.

But the suggestion of mating that to the chamber wall's a good one - I suspect I'll have to remake the mount that the laser diode sits in.

<mind, I've yet to acquire the laser module so I suspect that there'll be some entertainment ahead to remove the diode, fabricate a new mount, and reassemble>

Thanks!
 
P

Phil Hobbs

Guest
On 3/29/19 2:36 PM, Jon Elson wrote:
On Thu, 28 Mar 2019 16:06:09 -0700, jrcgarry wrote:

Dudes of all flavours;

I have an itch: I wish to run a 10W laser module in a vacuum chamber
(UHV: 10^-6mbar or so).

Anyone got any direct experience of the 'fun' in keeping the diode cool?
And any tips on doing so?
heat pipes, lots of copper, lowered duty cycles etc.
Water cooling loops will work, but that is pretty complicated. In
vacuum, metal surfaces that are pressed together conduct heat very poorly.
You need some sort of thermal conductor (either loaded silicone grease or
gap-pads) to carry the heat across. If your laser can be attached to the
chamber by some structure, that can conduct the heat out.

Jon
Heat sinking to the wall is the way to go, for sure. However, grease
and polymers are verboten in UHV on account of outgassing. You can't
even use soft solder because it outgasses during bakeout.

I'd recommend using indium foil as a thermal interface between the
module and the chamber wall. If you compress it enough, it'll seal in
the incidental gas it accumulates at ambient pressure pretty reliably.
Otherwise it'll probably outgas like a screw with no vent hole.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
J

James Garry

Guest
Thanks Phil.

A solid recommendation - Indium foil is known to me - as is Grafoil.

Still prevaricating over the laser module choice.

Cheers.

-JG
 
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