# how power of voltage is measured??

Discussion in 'General Electronics Chat' started by Engr Tech, Sep 1, 2017.

1. ### Engr Tech Thread Starter Member

Jun 24, 2017
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How can the power voltage and current of a DVD laser be measured?

2. ### Alec_t AAC Fanatic!

Sep 17, 2013
9,196
2,170
Measure the voltage V supplied to the laser, the current I through the laser. Power = V x I.

3. ### WBahn Moderator

Mar 31, 2012
23,576
7,214
Per the title, voltage doesn't have a power, so measuring the "power of voltage" is a fool's errand.

What Alec_t suggested will give you the power supplied to the laser, which may be the information you need, depending on why you need the power of a DVD laser.

If you need the power of the laser beam itself, then you need to put something in the path that converts the power in the beam to something that can be measured. There are a number of ways that can be done. There are optoelectronic detectors that convert it into an electrical signal. There are devices that absorb the light and convert it to heat, which you can then measure as a change in temperature. There are films that change color/shade in response to the amount of laser light that falls on them over a defined amount of time.

4. ### BobTPH Senior Member

Jun 5, 2013
1,368
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This may be apochryphal, but, when I worked in a physics lab back in about '72, the prof told me that the power of lasers was originally measured in Gillettes. That is, how many Gillette razor blade the beam could puncture.

Bob