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- Feb 5, 2008
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Hiya all, i would like to post some idea that i came up with during very booooring school class.
A laser power meter, based on a thermistor and a resistance meter (multimeter set to ohms)
By now you should already guessed what I 'm aiming at,
Wrap the thermistor with black tape, and connecting it as a probe to the multimeter set to ohms,
Problem is as follows: I need tomeone with some degree in themics to do some math.
Lets say that a laser dot shoots on a piece of tape covering the thermistor (black tape, goes without saying). Laser dot is 4 mm in diameter, and is heating up the tape.
Thermistor changes resistance from R1 to R2. (during 30 seconds period or something)
Now, we make the difference between those two R2-R1= R
Now let's say that the beggining resistance was (I'm guessing, never dealed with thermos before) 500 Ohms, now it is like, 20 k Ohms.
That is R = 19.5 K ohms.
Now i need some one to possibly come up with a relation to:
1) Restistance to temperature
2) Temperature to wattage of a laser power.
I know it ain't simple, however thermistor are fairly cheap, and i cannot afford a power meter. Simply cannot . Period.
I also want to know the wattage of my laser that i make so if someone would make this possible, i would be very gratefull.
I am also aware that it is not accurate, give or take 20 % or so.
A'ight, anybody?
A laser power meter, based on a thermistor and a resistance meter (multimeter set to ohms)
By now you should already guessed what I 'm aiming at,
Wrap the thermistor with black tape, and connecting it as a probe to the multimeter set to ohms,
Problem is as follows: I need tomeone with some degree in themics to do some math.
Lets say that a laser dot shoots on a piece of tape covering the thermistor (black tape, goes without saying). Laser dot is 4 mm in diameter, and is heating up the tape.
Thermistor changes resistance from R1 to R2. (during 30 seconds period or something)
Now, we make the difference between those two R2-R1= R
Now let's say that the beggining resistance was (I'm guessing, never dealed with thermos before) 500 Ohms, now it is like, 20 k Ohms.
That is R = 19.5 K ohms.
Now i need some one to possibly come up with a relation to:
1) Restistance to temperature
2) Temperature to wattage of a laser power.
I know it ain't simple, however thermistor are fairly cheap, and i cannot afford a power meter. Simply cannot . Period.
I also want to know the wattage of my laser that i make so if someone would make this possible, i would be very gratefull.
I am also aware that it is not accurate, give or take 20 % or so.
A'ight, anybody?
