For starters let me clear two things.
You cannot measure power of a laser, or brightness output of a flashlight, or similar things, by just "looking" at a beam, or seeing how fast something burns etc., etc.,
Accurate measurements require specialized equipment.
What if you don't have specialized equipment?
Here is a way to approximate laser power without an LPM to a degree of accuracy of 10% with ease.
All you need to do is follow the footsteps of Mr. Joule.
So what we would need is joules apparatus and a copper vessel(black painted inside) with about 100g of water, and a thermometer.
We use the forula
W*s = T*4.18*100
W = watts
S = time of exposure
T = Change in temperature of water
100 is the mass in grams.
So if you have a laser which you shine for 50 seconds, and this causes the temperature of 100g of water to rise by 1 degrees, you would get approx power as
W = 1*4.18*100/50 = 9W
If you have a 100-200mw Laser its best to use around 10g of water in a vial or tube with base painted black.
If tiny amount of ink is added to water to make it black, I guess it will absorb the energy instead of copper doing the job and fudging up readings.
couple of 100 years back, Joule used this to measure mechanical power equivalent of heat. Today you can do it to measure Optical power equivalent of heat using his apparatus.
You cannot measure power of a laser, or brightness output of a flashlight, or similar things, by just "looking" at a beam, or seeing how fast something burns etc., etc.,
Accurate measurements require specialized equipment.
What if you don't have specialized equipment?
Here is a way to approximate laser power without an LPM to a degree of accuracy of 10% with ease.
All you need to do is follow the footsteps of Mr. Joule.
So what we would need is joules apparatus and a copper vessel(black painted inside) with about 100g of water, and a thermometer.
We use the forula
W*s = T*4.18*100
W = watts
S = time of exposure
T = Change in temperature of water
100 is the mass in grams.
So if you have a laser which you shine for 50 seconds, and this causes the temperature of 100g of water to rise by 1 degrees, you would get approx power as
W = 1*4.18*100/50 = 9W
If you have a 100-200mw Laser its best to use around 10g of water in a vial or tube with base painted black.
If tiny amount of ink is added to water to make it black, I guess it will absorb the energy instead of copper doing the job and fudging up readings.
couple of 100 years back, Joule used this to measure mechanical power equivalent of heat. Today you can do it to measure Optical power equivalent of heat using his apparatus.
