Pulsed vs Constant Wave

[VW]

I was wondering if anyone can give me some information on the actual differences between the two. I've heard some people say that pulsed lasers are in some way better than constant wave, and vice versa. It gets really confusing trying to find some solid information. Things I was wondering was, which gives better beam quality, power, performance, and why?

 

[bobobob121]

well basically, the pulsed wave lasers can reach higher powers as they have time to cool between the picosecond pulses of light or w/e. In many applications one may aim to deposit as much energy as possible at a given place in as short time as possible. Constant wave is just as it sounds, a constant output of light being emitted. The population inversion required for lasing is continually maintained by a steady pump source. A good example of a strong single pulse laser is on these forums i believe...

http://www.laserpointerforums.com/forums/YaBB.pl?num=1211023863

 

[Razako]

I found this info on optotronics.

"The RPL-Blue laser provides true continuous output of it's rated power, not the cheaper and less powerful
Q-switched type that is rated at the peak power of a beam that is switched on & off with a duty cycle of typically 50% or less."

Basically a 100mw pulsed will always be less visible and worse for burning than 100mw CW.

 

[bobobob121]

Thats exactly right, if you have a laser that has a 50/50 cycle "like most pulsed lasers"; and it has a rated output power of 100mW. You would divide that power by half to get its "true" milliwattage. I other words, it would take a 200mW pulsed laser to reach the same brightness and burning power as a 100mW constant laser.

 

[VW]

Wouldn't a pulsed laser then read a lower output power? Or is it so minute it's only effected to the eye?

 

[bobobob121]

it depends on the meter. With a meter designed for constant output, it would read lower. But on one designed for pulsed beams, it would read what it was rated. That is, unless the laser itself is under spec ;D

 

[VW]

Thanks for the responses. So what if we tipped the balance and put both a 100mW constant wave laser and a 200mW pulsed laser side by side, what difference would there be? Other than the pulsed effect when shining it on walls etc...

 

[nikokapo]

Wouldn't a pulsed laser then read a lower output power?  Or is it so minute it's only effected to the eye?

you can see in any video where somebody's measuring the laser's power that power meters dont have a high refresh rate. i'm sure the calculations dont take too much time on the processor, but if it is a pulsed wave it would affect the reading but it will not be a huge deal, it'll measure the power output as it were a CW laser.

but between a CW and a PW you can see the difference when burning something or when taking a pic of them.

 

[Schrecken_Licht]

I'm going to be getting a pulsed laser soon - less powerful than my CO2 but still a class 4. Both are IR lasers, so you won't see the beam of course, but when I get my YAG I'm going to attempt to compare the damage each laser does to a given target.

Of course, this is a very poor comparison, like "apples and oranges" as they say. But I'll see what happens.....

 

[VW]

Cool. So, I have another question about pulsed lasers. As a good example, DL's Aurora BP is pulsed at 700Hz, then their Spartan BP is pulsed at 2000Hz. What's the defining difference between the two lasers, where power isn't concerned? As I guess, I noticed that spinning mirrors are very good at exposing pulsed lasers. Would the 700Hz laser have a wider beam fan than the 2000Hz laser? Meaning it pulses at a slower rate?