3 ms·

I had to re-read that part. They are talking about an ordinary red or green laser pointer. The beam itself is hardly visible compared to the spot on the wall-

I had to re-read that part. They are talking about an ordinary red or green laser pointer. The beam itself is hardly visible compared to the spot on the wall--unless your air contains a lot of dust or smoke or fog.

kazinator 11y ago
To anyone with a grade 5 science education, "visible light" means a frequency between IR and UV. No beam of any type of light is visible in vacuum; it is superfluous to call it invisible in that sense because there is no contrasting opposite. Patent office staff should have a decent background in science.