When I was a kid, and saw photographs of these glass panels around a lectern, I just thought they were bullet-proof glass to protect the speaker. Like, someone Secret Service dude knew exactly where an enemy would fire from:) I’ve also had people ask if they were microphones—like those parabolic dish mics seen at football games.
The truth is simpler. In fact the technology is derived from the Pepper’s Ghost displays made famous in the 1800’s. Disneyland uses this in its famous Haunted Mansion, where phantoms “sit” in the cab with you.
In the case of a presidential teleprompter, there’s an LCD monitor flat on the ground, pointed at the ceiling. The words to your speech are large, typically 56 pt to 72 pt.
The speed of the speech is controlled by an operator, who listens to the speaker and follows along. If the speaker pauses, or ad libs, the operator waits before moving on.
Special teleprompter software reverses the words on the LCD monitors, so that when the speaker looks through the one-way mirror, it appears normal again.
However, the audience sees nothing of this. They just see through the glass to the curtain or the speaker. They think the speaker is just glancing around the audience. This effect is amplified if a video camera is zoomed in, omitting the glass. Often in live presentations, large screens have this projected video signal, called IMAG (for “image magnification”), so people rarely look at the actual speaker and thus don’t notice the presidential teleprompter equipment at all.
If someone does notice the teleprompter mirror, they quickly forget about it, since the speaker is usually more dynamic than some glass on a stick.
Good question, since multiple speakers typically means a variety of heights. The presidential mirrors are carefully aligned for an individual speaker. And that means that anyone more than a 3″ height difference from the original speaker, would either have to stoop or stand on their toes to see their words. Or a stagehand would come up mid-show to bring a box for a shorter speaker to stand on. Who wants that kind of attention? On the other hand, we’ve worked shows where they had a second lectern and presidential teleprompter setup for taller basketball players.
Neil saw the need and worked with his robotics engineer brother, Thom to create the robotic, rise and fall TeleStepper to solve this problem. Now both Apple and the White House own them!
I created a post about how the camera teleprompter works here.