- Joined
- Jan 12, 2011
- Messages
- 35
- Points
- 8
Here i want to share my experiment to estimate the average power of any laser.
You can measure weight, length, time and temperature but not the power of an optical device..
Then i have a solution for you.
All you need is a specified small piece of aluminium glued on the small sensor of a thermometer and a stopwatch.
Very important is to know the exact weight of the small piece of aluminium. You can use a scale or measure the dimensions to calculate the volume. With the density of 2,7 g/cm^3 you can get the weight.
In my case i use a little plate with exactly 1,000g
I used a black eding to blacken the surface but you can also use carbon black from a lighter. I estimate the absorption at about 90-95%.
All you have do do now is to shine your Laser for a specified time (about 10sec) on the black surface and watch the maximum temperature raise.
for example:
My Laser gives 8,0°C temperature raise in 10 seconds. (from 23,1°C to 31,1°C)
With that data and the specific heat capacity of aluminum (0,897 J/(g · K)) you can calculate your laserpower.
Formula:
[Mass in Gramm] * [Heat Capacity] * [Temperature Raise] / [Time in Seconds] / [Absobtion]= Laserpower in Watts
example:
1,00g * 0,897 J/g*K * 8°C / 10sec / 0,9 = 0,797W
The big advantage: You can calibrate the LPM yourself. I dont like to guess the power by using a plack piece of aluminum foil with nearly no heat capacity and a lot of unpredictable heat emission...
Have fun and (don't) watch out for the reflexion when measuring high power lasers
//EDIT: maybe its more an experiment than a tutorial...
You can measure weight, length, time and temperature but not the power of an optical device..
Then i have a solution for you.
All you need is a specified small piece of aluminium glued on the small sensor of a thermometer and a stopwatch.
Very important is to know the exact weight of the small piece of aluminium. You can use a scale or measure the dimensions to calculate the volume. With the density of 2,7 g/cm^3 you can get the weight.
In my case i use a little plate with exactly 1,000g
I used a black eding to blacken the surface but you can also use carbon black from a lighter. I estimate the absorption at about 90-95%.
All you have do do now is to shine your Laser for a specified time (about 10sec) on the black surface and watch the maximum temperature raise.
for example:
My Laser gives 8,0°C temperature raise in 10 seconds. (from 23,1°C to 31,1°C)
With that data and the specific heat capacity of aluminum (0,897 J/(g · K)) you can calculate your laserpower.
Formula:
[Mass in Gramm] * [Heat Capacity] * [Temperature Raise] / [Time in Seconds] / [Absobtion]= Laserpower in Watts
example:
1,00g * 0,897 J/g*K * 8°C / 10sec / 0,9 = 0,797W
The big advantage: You can calibrate the LPM yourself. I dont like to guess the power by using a plack piece of aluminum foil with nearly no heat capacity and a lot of unpredictable heat emission...
Have fun and (don't) watch out for the reflexion when measuring high power lasers
//EDIT: maybe its more an experiment than a tutorial...
Last edited: