Klv8r, via Twitter asked:
Can a laser be any spectrum of light?
We put this question to Dr Graeme Hirst, from the STFC's Central Laser Facility...
Graeme - These days they can, yes. The very first laser that was produced worked in the near infrared. It was really, really bright, so you could probably see it, but only just about. Gradually, as time went on, more and more lasers were developed with a wider range of available colours – a wider range of available wavelengths. And these days, the range is spectacular. Just last year, a group of scientists in America demonstrated a really high power laser that’s actually working in the x-ray region.
I thought the first laser was a ruby laser emitting 694.3nm which is visible red light. Bored chemist, Tue, 15th Jun 2010
I still think the first laser was a ruby laser emitting 694.3nm which is visible red light. Bored chemist, Wed, 16th Jun 2010
Hmm... using the quote button for the Doc doesn't seem to work, but anyway...
BC and Tommy
The eye can sense 695nm, but it is very insensitive to it - something like only 1% of the sensitivity that you would get at 620nm which is a bright slightly orangey red.
I checked before I posted and I can assure you that I can see light at 694nM.
I had a colleague who worked with ruby lasers, and the beam, while not bright to the eyes, really had high power, enough to burn though photo paper with every pulse.