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warm up time and working temperature

M

milantheone

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Dec 2, 2008
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339
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Hello guys, i am courious about warming up times and working temperatures of the lases..
I have had a few experience with my lasers and most of them reach peak power after couple of seconds.. cca 30sec..
When i was not patient i simply put it on a heater and then i got working temperature immediately...
My question is , what does it mean??? Why is there any warm up time??? What is getting warmer??? Diode, crystal???

I really dont like this warm up time and i just want to know what is the matter??
I have had 10mw laser which has warm up time cca 30seconds, but it of courese depended on batteries... then i pot moded this laser and i got unbelievable results in brightness and additonal bonus, there was no warm up time since i did it...  but when i took this laser outside where was cca 10 degrees celsius it was dimming till there was no lase...

My other experience with my other laser  50mw greenie was great.. there was no warm up, and even if i was outside in a winter with this laser there was no dimming...
After that i was thinking that warm up time depends on power of laser and if i will have more powerfull laser there will be no  warm up time and my laser will lase at full power immediately.. but as i am checking around the forum i can see that you guys posting about your lasers which are 200, or 300mw and have a warm up time on it...

I am comfused, i dont understand it....
Could anyone enlighten me please???

Cheers guys
 





maxkillz

maxkillz

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Jul 22, 2008
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heh good thing you don't have a lab laser, my warm up is just over 10 minutes if it's cold in my room :p


I think it needs to warm up the crystals inside or something because when my Alpha is cold then it runs in a different TEM. same when hot. but then it's between 70 and 90 degrees it runs TEM00. my labby always runs near TEM00 or TEM00 but it's just much weaker when it's very cold (my room stays around 55-60 degrees)
 
FrothyChimp

FrothyChimp

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Warm up is the time it takes for the laser output to stabilize. This is due to many factors such as crystal temperature, pump temperature, temperature feedback control etc. Peak power means nothing. It's used for marketing absolutely nothing. Because it is peak power it never reaches it again during operation so it does no useful work. Stabilized output is the key and is determined by the warm up period. The actual time is dependent on the complexity of the laser system and its electronics.
 
M

milantheone

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Dec 2, 2008
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339
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well i am curious why some lasers does have this warm up period and others doesnt...
 
E

ElektroFreak

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Nov 7, 2008
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The warm-up time required for stability varies from laser to laser. Cheap DPSS lasers generally require more of a warm-up than more expensive models, since the expensive ones usually include temperature and power control circuitry to aviod the need for a long warm-up period. With cheap DPSS lasers the warm-up is required to allow the diode and crystals to reach a stable operating temperature. As the laser warms up, the power will fluctuate and the laser will often mode-hop until this stable temperature is reached. Most manufacturers specify a warm-up time of 5-15 minutes. I just recently bought a green module from Sandstone11 here on the forum, and it requires every bit of 15 minutes before it is stable.

The crystals and the diode each have specific points along the temperature curve at which maximum operating efficiency is reached. Once the overall temperature is closest to these "sweet spots" the warm-up is complete and the laser should be emitting a nice TEM00 beam with limited power fluctuation.

The warm-up is unavoidable in cheap DPSS lasers and is most pronounced in higher powered ones. The only way to avoid a warm-up completely is to build circuitry that actively detects power output and beam quality, and adjusts current and temperature for maximum stability. These added design features can be expensive, and so are generally left out of cheaper systems.

Don't worry too much about having a warm-up. This is caused by the increased complexity of DPSS lasers and is a normal part of their use.
 
M

milantheone

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Dec 2, 2008
Messages
339
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18
ElektroFreak said:
The warm-up time required for stability varies from laser to laser. Cheap DPSS lasers generally require more of a warm-up than more expensive models, since the expensive ones usually include temperature and power control circuitry to aviod the need for a long warm-up period. With cheap DPSS lasers the warm-up is required to allow the diode and crystals to reach a stable operating temperature. As the laser warms up, the power will fluctuate and the laser will often mode-hop until this stable temperature is reached. Most manufacturers specify a warm-up time of 5-15 minutes. I just recently bought a green module from Sandstone11 here on the forum, and it requires every bit of 15 minutes before it is stable.

The crystals and the diode each have specific points along the temperature curve at which maximum operating efficiency is reached. Once the overall temperature is closest to these "sweet spots" the warm-up is complete and the laser should be emitting a nice TEM00 beam with limited power fluctuation.

The warm-up is unavoidable in cheap DPSS lasers and is most pronounced in higher powered ones. The only way to avoid a warm-up completely is to build circuitry that actively detects power output and beam quality, and adjusts current and temperature for maximum stability. These added design features can be expensive, and so are generally left out of cheaper systems.

Don't worry too much about having a warm-up. This is caused by the increased complexity of DPSS lasers and is a normal part of their use.
Click to expand...


your explanation is amazing... thank you very much.. you deserve +1 from me..
cheers
 
john_lawson

john_lawson

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:'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :':)'( :'( :'( :'( :'( :'( :':)'( :'( :'( :'( :'( :'( :'( :'( :'( :':'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'(( :'( :'( :'( :'( :'( :'( :'( :':)'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'(

yea what he said ;D ;D ;D
 
murrat

murrat

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Feb 25, 2008
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All lasers have different figures.
I had several lasers.
Some likes hot, some likes cold.
My old Fusion needs a warm up time than it reaches the average powers indicated. When the wheather is cold lower as 5 degrees celcius or less it dimmes.
But my nova likes cold. At room temperatures it cannot reach even 100mW but at cold it peaks 125mW and stabilizes at 115mW :) :cool:
I think this is all about the cyrstal in it. ::)
 
M

MrViper82

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Nov 26, 2008
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Yes it is all about the crystals. No two crystals will be exactly the same, their individual structure will dictate what temp produces highest efficiency.

Now, warm-up time depends on the individual crystal and current temp. If the crystal is most efficiant at current room temp than there is no warm-up time. if the room is cooler, than it needs to heat up a bit but most crystals reach max eff. at greater than room temp so there is generally at least some warm-up.
 
M

milantheone

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cheers guys, but now i am considering a fact that it could depend on a diode as well, because diode produce a heat which warm up a crystal...
i mean if i will drive diode at
100mA then it will take much longer than i drive a diode at
200mA or more....
if diode will run at higher current than it will produce more heat which warm up crystal more quickly...

am i right or not???
:-/
 
E

ElektroFreak

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You very well could be right for that laser only. Since each laser is different like fingerprints, so is the way they each respond to temperature and input current/power.
 
M

MrViper82

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Nov 26, 2008
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the more power a diode puts out, the faster the crystals heat up. Also, the efficiency of crystals comes into play. The less efficient crystals heat up quicker because they are absorbing more energy instead of letting it pass through.
 
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