# Output power of pulse-lasers

1. May 18, 2006

### breezels

For pulse lasers, thers are two parameters describing its output power.
One is "the average power",which equals to the product of the energy of single pulse and the pulse repetition rate(per.second.);
the other is "the peak power", which is defined as the ratio of the energy of single puse to pulse duration.
My question: When we want to get the values of "power density(w/cm2)",
which power value( "the average power" value or "the peak power" value )should be used as the output power in the calculation?

2. May 22, 2006

### Integral

Staff Emeritus
I would think that the average power would be the more meaningful in this case. But there is a direct relationship, the area of the pulse is directly proportional to the average power so if you are careful it should not matter.

This is a quick off the top of my head response. I will see if I can learn any different when I get to my references at work.

3. May 23, 2006

### Gokul43201

Staff Emeritus
It depends on what you're using the power density (or intensity) for.

4. May 24, 2006

### breezels

For example: nanosecond pump pulse lasers are used in my experiments--stimulated Raman scattering Experiment.
As long as the pump intensity (W/cm^2) exceeds some threshold value( at least 1.0 MW/cm^2) , the stimulated Raman scattering would occur.
For this case, the peak power is chosen. Right?

5. May 24, 2006

### ZapperZ

Staff Emeritus
If all you care about is the output power of your laser, you could easily verify it by using a power meter. There are power meters that work under both pulse and cw operations.

Zz.

6. May 24, 2006

### Gokul43201

Staff Emeritus
Yes, that sounds right.

7. May 27, 2006

### armandowww

If you use a laser emitting an average power so loud, you'll surely find output mirror melted, after broken.

8. Jun 7, 2006

### breezels

Yeah! This situation may occur.But sometimes a fused-silicon glass
could withstand the intense power.

9. Jun 9, 2006

### Mindscrape

Class IV lasers

I have a question, are class IV lasers actually bad for your skin? I work with some class IV lasers, and if I want to temporarily block a beam I will usually just put my hand in the way. I suppose that exposing yourself to any sort of radiation is generally not good for you, but I don't suppose that it's really harmful at all.

10. Jun 9, 2006

### breezels

Do you have an black iron plate ?It can block the beam instead of your hands.

11. Jun 9, 2006

### Gokul43201

Staff Emeritus
From the OSHA Technical Manual, SECTION III, CHAPTER 6 : LASER HAZARDS

http://www.osha.gov/dts/osta/otm/otm_iii/otm_iii_6.html

12. Jun 10, 2006

### Mindscrape

Oh, I didn't realize that Class IV were 500mW, it must just be that we have the Class IV laser hazard on our door for some kind of safety reason (maybe we have one laying around), though all the ones we have must be Class III since they are around 100-200mW (which is still nothing to scoff at). Yeah, we do have iron plates around, but I'm using that to block off my split beams. Just sticking your hand in and out real quick to see how well a laser is coupled can't really be bad for you.