# In a laser, how many nm = a mw?

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6 years ago
These are two different quantities.

nm refers to the wavelength of the emitted light in nanometers
http://en.wikipedia.org/wiki/Wavelength

mw refers to emitted power in milliwatts
http://en.wikipedia.org/wiki/Power_%28physics%29
lemonie6 years ago

nm is a wavelength term, it's the distance between wave peaks in fractions of metres. mw is an energy term, but it links towards nm via ~Planck.
However, what you get out is proportional to what you put in, and lasers for sale generally have the mwattage given.

L

6 years ago
What you say is true, but isn't relevant for how lasers are rated. The milliwatts refers to the power consuption (or power output), which can be the same for any wavelength. Planck's constant just tells you how many photons per second you get.
6 years ago

That was the best connection between wavelength & energy I could think of at the time. I agree with you.

L
transuranic (author) 6 years ago
So is 500 nm a powerful laser?
6 years ago
500nm specifies the color. It says nothing about power.
kelseymh6 years ago
As Jack Lopez said, those are completely different parameters. Nanometers (wavelength) tells you what color the light is. Milliwatts (power) tells you how bright the light is.