from what i know the nm designation doesn't make light coherent or not. and if you could filter a source of light to 1nm (this is a question now), wouldn't it be cancerous, like an x-ray or gamma ray. I couldn't find a table to show.
No, like pseudo and pullbang said, I meant a BANDWIDTH of 1nm. So not filtering out everything except 1nm but filtering out everything except light in a 1nm range (ex. 495.25nm-496.25nm is all that passes through). And now I realize that the light would be monochromatic, but not coherent, thus not a functional laser.
Yea I know, but chipdouglas was refering to the wavelength since he compared 1nm with gamma-rays and x-rays.I know he didn't get what you wanted to say, I just wanted to answer his question , even though it was a completely different thing than what you originally wanted to say.
But anyway, like it was already said, you can filter out light to make it close to monochromatic, but you can't make incoherent light coherent.