To calculate laser radiance or brightness:
Find the laser's power in watts.
Write down the laser's wavelength in nanometers and divide by 1,000,000,000. If you don't know the wavelength, use:
473 nm for blue lasers;
532 nm for green lasers; or
650 nm for red lasers.
Divide the power by the square of the wavelength. The result is the radiance or brightness of your laser.
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