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FrozenGate by Avery

Do I need a TEC?

laker

laker

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Hello all!

I joined this forum as I've decided to build my first laser! so far I've read a lot of pages in this forum and its been extremely helpful! but there is one question that I couldn't find an answer to.

I'll be building a 100mw red laser for holography. This laser will be run for 45-60 minutes at a time. My plan was to just install the diode and optics into a home made aluminium heat sink, but i'm wondering if this will be enough to dissipate all the heat.

Will a medium sized aluminium heat sink be enough or will I need to add a TEC to my circuit?
 





well seeing as your not running a crazy red laser i would say the heatsink should be fine maybe a fan but at that power i doubt it.
 
A 100mw diode laser is unsuitable for holography. The frequency drifts too much. You want a frequency stabilized laser, which is really hard to build. Also, 100mw is more than enough to do transmission holography.

Your best bet would be to just buy a whole bunch of cheap 5mw lasers, and pick the most stable one.
 
stabilize the temperature of a diode, and you stabilize the size of the lasing cavity, which sets a stable output wavelength. :)
 
I still think after you get a diode, a TEC, driver and thermocouple for TEC, make/buy diode mount for the TEC, etc, etc... You could just buy a decent powered HeNe and be done with it. Building lasers is fun.. if that's your goal, but if your goal is holography and not just making the laser, why spend hours on a project you never intended?
 
Thanks for your suggestions everyone!

I have a lovely 5mw HeNe which i already use for my holography. the reason I'm making this laser is because I bought two diodes very cheap from a company going into liquidation, they were sold as having a very long coherence length, and thats why i'd like to build this laser. Hene's tend to be limited to a coherence of about 30cm.

I know laser diode holography can be very hit or miss, but i'm feeling positive! I'll concentrate on keeping everything as stable as possible (thermally, mechanically and electrically) and hopefully get something that works.... with out any pops and bangs!
 
laker said:
Thanks for your suggestions everyone!

I have a lovely 5mw HeNe which i already use for my holography. the reason I'm making this laser is because I bought two diodes very cheap from a company going into liquidation, they were sold as having a very long coherence length, and thats why i'd like to build this laser. Hene's tend to be limited to a coherence of about 30cm.

I know laser diode holography can be very hit or miss, but i'm feeling positive! I'll concentrate on keeping everything as stable as possible (thermally, mechanically and electrically) and hopefully get something that works.... with out any pops and bangs!
Click to expand...

these 445nm candy bar outputting diodes would be fun for you as well id imagine :)
 
Um. Multimode diodes definitely won't work for holography. That rules out high powered 445's right off the bat. 445 would still work, providing you were using a stabilized single mode diode that had a decent coherence length.
 
Whoa. I guess they run single mode at really low powers then? I've never tried running either of mine just over threshold.
 
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Yeah most diodes are multimode but there are a few which are single mode (they normally cost a lot more).

I'll keep you posted on how I get on, I've got a few more questions and grey areas that need figuring through before I start work. But watch this space..!

Cheers guys!
 
Kewl effort! I have also made a nice but not very bright holo with a Meredith 14mw red 650 way back in2001. I am interested in stable diodes if we find good ones for HOLO work.
Best of luck and let us know how you go!!! =P
-Jeff
 
If you want to keep the same wavelength for such a long time, you require precisely controlled temperature and current for the laser diode.

Most LPF users want to keep a TEM00 beam, but for proper holographic application you need to get a single longitudinal mode as well, which is only possible if you can keep the diode temperature and current at a very constant level.

For applications like pointers or show projectors longitudinal mode is of litle or no concern, as it doesnt really affect the visible beam performace. Holography is anoter story though, since you must maintain coherence over a considerable amount of time.
 
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