As I recall, the laser goes through a frequency multiplier stage to make it visible to the human eye. It's visible coming out of the optical bed mounted on the telescope, but at certain stages inside the bed it's invisible and capable of burning you, so if work is being performed inside the cabinet, you have to be VERY conscious of where the optical path is and what you're doing! Once it's out of the telescope, the laser is 3.5 meters wide (the telescope diameter), it's too diffuse to damage skin. Theoretically you should still be using eye protection, but when we were standing on the catwalk looking for aircraft while the laser was shining, you couldn't afford the light loss while trying to spot aircraft against the night sky. Now, that job is automated with an IR camera to detect engine heat and a directional radio detector to detect the transponder.
no subject
As I recall, the laser goes through a frequency multiplier stage to make it visible to the human eye. It's visible coming out of the optical bed mounted on the telescope, but at certain stages inside the bed it's invisible and capable of burning you, so if work is being performed inside the cabinet, you have to be VERY conscious of where the optical path is and what you're doing! Once it's out of the telescope, the laser is 3.5 meters wide (the telescope diameter), it's too diffuse to damage skin. Theoretically you should still be using eye protection, but when we were standing on the catwalk looking for aircraft while the laser was shining, you couldn't afford the light loss while trying to spot aircraft against the night sky. Now, that job is automated with an IR camera to detect engine heat and a directional radio detector to detect the transponder.