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Laser warmup in reviews

LEDbeam

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I noticed something that is common in all the videos I've seen where burning things, lighting matches, popping balloons, etc. is done to show the power of the laser. At the beginning, we see the laser being turned on, then a match or whatever is placed in front of the beam. One thing that seems to never be addressed is the laser's warmup period. When these videos are done, is the laser "prewarmed" in order to be at full power when it's first turned on for the video? Otherwise, the first 30 seconds or so of the video is showing what the laser can do during it's warmup period rather than at full power.

I tried to test my idea by watching the very beginning of a video and then skipping to close to the end to see if the beam appears any brighter at the end, but it always looks the same to me.
 



Razako

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Direct diode lasers typically don't need much of a warmup period. Usually it's only 589nm/593.5nm, 532nm and 473nm where you need a warmup period.
 

GSS

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There really isn't much of a warm up period on at least the lasers they are videoing as they are most likely all of the time over 1W and not a DPSS. The 2 or 3 seconds they need to pic up the match after they click the switch is plenty with all that output and remember they are also following a duty cycle.

By the way did you get your laser yet from SciFi?
 
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LEDbeam

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Direct diode lasers typically don't need much of a warmup period. Usually it's only 589nm/593.5nm, 532nm and 473nm where you need a warmup period.

Well, I ordered a 1.5--1.8W 445nm laser from SciFi Lasers and I remember seeing an LPM chart somewhere (can't seem to find it now) that showed that it takes about 10 seconds to reach about 1W, and about 30 seconds to reach full power. That's just from what I remember. I might be a bit off on the exact numbers.
 

InfinitusEquitas

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Well, I ordered a 1.5--1.8W 445nm laser from SciFi Lasers and I remember seeing an LPM chart somewhere (can't seem to find it now) that showed that it takes about 10 seconds to reach about 1W, and about 30 seconds to reach full power. That's just from what I remember. I might be a bit off on the exact numbers.

Diode lasers are at full power pretty much immediately, and actually lose power after being turned due to heat, and voltage sag.

What you're seeing is not the laser warming up to reach full power, but the slow response of the LPM in question.
 

LEDbeam

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Diode lasers are at full power pretty much immediately, and actually lose power after being turned due to heat, and voltage sag.

What you're seeing is not the laser warming up to reach full power, but the slow response of the LPM in question.

Interesting! I did not know this. I thought the laser would start out rather dim and gradually brighten. Since I don't have my laser just 2 days short of a month after ordering (hint, hint) I don't have the hands-on experience yet.
 

InfinitusEquitas

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If you find videos by members with ophir based LPMs, you'll see the response time is cut to ~5-10 seconds before the lasers peak, and slowly start to drop. Sometimes after a good long while depending on the batteries and heatsinking.

DPSS lasers on the other hand, can sometimes need a bit of time to warm up, and do fluctuate. My best green laser for example, tends to peak only after about a minute or so of being on.
 

Pman

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My Ophir response is a couple seconds at the most and I can catch the output peak just as DTR shows in his vid before there's sometimes a drop from what I believe is voltage sag and heat as Infin mentioned. If I'm testing on my power supply there isn't a voltage sag so it's more of a slower heat drop but depending upon the diode this can take some time to happen. Personally can't stand a slow response LPM but I do have one as a backup.
 

Alien Laser

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My 303 laser was warming up for 2Hours :whistle:
 
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Benm

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In some cases a 'warm up period' on direct diode lasers can be intentionally built in to the driver circuitry. This as nothing to do with anything getting physically warm - the driver just ramps up the current a bit more slowly. Some believe this can help to reduce current spikes, and in some driver topologies it can.

Such a 'soft start' feature usually is not -very- slow though, the laser would be likely to produce >90% of power well within a second, though it can be as slow as you design it to be.

Laser power meters that work on a thermal principle will always have some delay in response, and often average the reading over some period of time to get a more stable readout. This can be a couple of seconds, but should not be something in the order of a minute that you sometimes find in DPSS lasers to actually reach optimum temperature.
 

LEDbeam

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By the way did you get your laser yet from SciFi?

Sorry I didn't see this from you right away. No, I haven't gotten it yet, but I checked my tracking number today (finally got THAT!) and today it shows it has arrived in New York City as of yesterday! If it takes 3 days from there as first class packages usually would, then I should have it in the middle of next week. That is, unless it sits in ISC for awhile first. I looked up what ISC means, as in "ISC NEW YORK NY(USPS)", which is how it reads on the tracking data, and it means International Sorting Center. I've been reading that it could stay there for as little as no time at all, to possibly 2 more weeks, based on what I've been reading of other peoples' experiences with it. https://answers.yahoo.com/question/index?qid=20120508115929AApm01f
 




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