Hi FoLCs,
I don´t think anyone could see the rays... on the Premier Clark destroyed a machine "i dont know how you call that in english" that was supposed to put down the old theater. He did it in the middle of the crowd and he was supposed to be very careful those days... so, I guess the answer is no. no one could see that.
On the other hand, I can remember that in the episode lethal weapon, when Clark was heating the steak in the kitchen, Lois got down on her knees when she saw his heat vision was coming to both sides... (I´m contradicting myself here... but honestly the show didn´t gives much data to believe people could see it or not).. Maybe Lois just went on her knees because of the explosion of popcorn though i´m not so sure...
MDL.
