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cw vs pulsed...  

Ace82

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Because of the heavy flow of topics in this section, (and we lack a "Science of Lasers" forum ;) ) I thought I would start one based on a thought that occurred to me. (I don't doubt that there are multiple threads about this topic, so I apologize if this is "peat and repeat".)
I was thinking that Continuous Wave lasers are better then pulsed because 2 things mainly. 1. The crystals are of better quality and can handle continuous photon energy and emit semi-powerful laser beam for a constant, continuous flow with the aid of heat dissipation (for the more powerful lasers). 2. The diode is of better quality and of higher power rating since it is expected to undergo more stress although typically run ~95% to extend life. Most pulsed diodes emit rapid burst of photon energy equal or greater then the diodes max rating to get maximum power utilization. The crystals do not need to be as efficient since the chance of over saturating and load is lighter. I would imagine the only positive things about pulsed lasers would be less time/power consumption and heat.
 

Switch

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Re: cw vs pulsed...  

I think the crystal needs to be just as efficient as with CW.Oversaturation can happen within the pulse width. :p
For me , just seing a dotted line when swinging it around is a turnoff, so yeah, CW. :D
 

GooeyGus

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Re: cw vs pulsed...  

But, Pulsed lasers do have their uses, especially when talking about high power lasers. For example, most cutting lasers have to be pulsed. This has nothing to do with low or high quality, but of heat dissipation. If you are trying to cut aluminum with a laser, you need to hit it with enough energy such that the aluminum will be penetrated before it has a chance to dissipate the heat. This can generally only be done with very short powerful bursts since aluminum can dissipate heat so rapidly that its just not cost effective to use an ultra strong CW laser.
 

VW

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Re: cw vs pulsed...  

Also pulsed lasers allow you to get different effects with optics, such as stipes. I guess it's just personal preference on what you want the laser for. Personally I don't mind pulsed lasers as the striping effect with a time tunnel for example is pretty cool. When pointing it doesn't make much difference to me. But I would love to be able to Compare the Spartan BP 40mW to the RPL Blue 35mW, to see exactly where the differences lie...
 

Ace82

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Re: cw vs pulsed...  

GooeyGus said:
But, Pulsed lasers do have their uses, especially when talking about high power lasers. For example, most cutting lasers have to be pulsed. This has nothing to do with low or high quality, but of heat dissipation. If you are trying to cut aluminum with a laser, you need to hit it with enough energy such that the aluminum will be penetrated before it has a chance to dissipate the heat. This can generally only be done with very short powerful bursts since aluminum can dissipate heat so rapidly that its just not cost effective to use an ultra strong CW laser.
This is a really good point. Don't they use pulsed for tattoo removal as well?
 

Cyparagon

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I'm afraid you're mistaken. The KTP is more efficient at higher powers, and the diode can operate at higher average powers when pulsed.
 

VW

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Re: cw vs pulsed...  

So would there be any major differences between the Aurora BP (Pulsed 700Hz) and the Spartan BP (pulsed 2000Hz)? If so, what would those differences be and what effect would it have for the observer?
 

GooeyGus

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Re: cw vs pulsed...  

700hz would look a lot more 'choppy' when you wave it around. At 2000hz you will notice some chop, but far less than at 700.
 
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For the enthusiast, CW is the king but in the greater world of lasers pulsed is the bomb. I know some of you have already done this but most hobbyists have no clue and I guess don't really care about the greater circle of laser uses and systems. Watching a SHG 532nm YAG pulsed system bang away to the moon and back is really cool and watching the data come in about the distance more accurate than any other method is cool to me. Knowing that my safety equipment is assisting researchers at the Caltech gravity wave interferometer detect gravity waves is cool. Having a 60W q-switched 532nm pumping a femto or pico second pulse Ti:Sapphire system is cool. This is why I don't comment on a DX 150mW greenie for example. It's mainly because they really don't do anything. What I see these little laser pointers as is a stepping stone. It's the demarcation point that separates the wheat from the chaff. If it's just the cool factor then be safe and move on when the fun meter pegs. But for some of you, laser pointers will start a journey into an awesome world of high power, and/or short pulsed laser systems where the big boys play. Those who have that bug have the potential to end up knee deep in some of the wildest systems people can imagine. That's where the cool is. If that's for you then keep moving forward.

Sorry I guess this turned into a rah rah speech about the industry. </soapbox off>
 

GooeyGus

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Re: cw vs pulsed...  

FrothyChimp said:
For the enthusiast, CW is the king but in the greater world of lasers pulsed is the bomb. I know some of you have already done this but most hobbyists have no clue and I guess don't really care about the greater circle of laser uses and systems. Watching a SHG 532nm YAG pulsed system bang away to the moon and back is really cool and watching the data come in about the distance more accurate than any other method is cool to me. Knowing that my safety equipment is assisting researchers at the Caltech gravity wave interferometer detect gravity waves is cool. Having a 60W q-switched 532nm pumping a femto or pico second pulse Ti:Sapphire system is cool. This is why I don't comment on a DX 150mW greenie for example. It's mainly because they really don't do anything. What I see these little laser pointers as is a stepping stone. It's the demarcation point that separates the wheat from the chaff. If it's just the cool factor then be safe and move on when the fun meter pegs. But for some of you, laser pointers will start a journey into an awesome world of high power, and/or short pulsed laser systems where the big boys play. Those who have that bug have the potential to end up knee deep in some of the wildest systems people can imagine. That's where the cool is. If that's for you then keep moving forward.

Sorry I guess this turned into a rah rah speech about the industry. </soapbox off>

Amen brother :cool:

I'm trying to get a foot in the door into the laser industry, but I really don't even know where to start. :-[
 

GooeyGus

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Re: cw vs pulsed...  

FrothyChimp said:
Physics degree (graduate level)
Well... I'm about half way to my bachelors in engineering. I really have been contemplating switching to physics now before I finish the 'more important' last two years.

BUT my main reason for going into engineering is because I want to try to get into med school (I'll specialize in laser procedures ;D ) and my counselor told me that they are leaning away from the classic chem. or bio. majors and wanting people with more diverse degrees. He said engineering would be great, and I love engineering so here I am :D
 

paper183

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I really think CW and pulsed have their places... even for hobbyists, wouldn't we be able to get higher power from our lasers with pulsed operations ? I'm thinking about those dvd diodes we use in reds... they are rated for a lot more power when pulsed. And i love pics where we see pulsed lasers drawing dot lines on walls :p I'd like to have some hand held pulsed lasers :) they could make nice effects.
 

Xylicon

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Re: cw vs pulsed...  

Is anyone here running a pulsed laser setup? I havn't found any good ways to pulse mine. I was thinking of a 555 timer transistor setup.
 

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