Scanning pixels

The concept

Scanning pixels

Imagine entering a movie theater. At one end of the theater, there is a projector high up in the wall. At the opposite end, the wall is covered by a movie screen. The projector projects light onto this movie screen. We see this light when we watch the movie.

But now, the unthinkable happens: a nasty thief steals the movie screen. Nothing remains, not even the wall. The light from the projector escapes to the outside.

But now, you take an old fashioned light meter, the kind professional photographers used to use, along with a piece of checkered paper and a pencil. You walk up the stage where the movie screen used to be. What do you see?

Looking at the projector, not much. You won't be seeing the projected picture, that is for certain. Rather, you'd be seeing a bright spot of light: the lens of the projector. But you quickly realize that as you move from left to right, right to left, or if you squat and then stand on tiptoes, the brightness of the projector lens changes.

So now you take your light meter and checkered piece of paper and begin to methodically move left-to-right or right-to-left, standing, squatting, on tiptoes, all the time measuring the intensity of light using your light meter and marking the squares on your checkered piece of paper.

Pretty soon, the projected image will emerge on your checkered sheet. Its resolution may not be great and its quality will depend on how good your light meter is and how precisely you positioned it, but the image will be there.

This, basically, is how an SGL spacecraft can "scan" an image area that is measured in miles or kilometers in width and height.











Image reconstruction »