They verified safety.
4 seconds sound clip from the TRON (1982) movie soundboard.
You can hear this line at 00:14:31 in the Blu-ray version of the movie.
Quote context
[...]
- I know. This will narrow your theory that the scanned U-V beam is superior to single pulse exposure.
- Laser activity will exist in 30 seconds. Put on your goggles.
- Let's see if we've got the green light.
- Is the target area shielded?
- This is what we've been waiting for.
[...]