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#04 [Detail] Showing 50Hz refresh rate modulation
| TITLE: | Death Star |
| DATE: | 2006 |
| SIZE: | 7 x 5 inches |
| MATERIALS: | Luminogram on Ilford RC |
A solid white disc on a black background was stored in the computer's memory. A programmer was forced to write a program to scan the disc in horizontal slices, from top to bottom. At each moment in time, the current pixel colour was either black (background) or white (foreground). This colour was used to fill the entire computer screen. Thus the screen alternately switched between black and white.
One end of a fibre optic cable was pointed at the screen. The other end was positioned in contact with a sheet of photographic paper, which was wrapped around a cylindrical rotating drum. The drum was attached to a threaded screw, so as it rotated, it slowly moved laterally. Like this, every point on the paper would be brought into position under the fibre optic beam.
The drum was rotated by hand at an approximately uniform angular velocity. Each rotation of the drum enabled the binary data from one scanline to be recorded onto the photographic paper, via the fibre optic link.
The computer monitor used was an older-style CRT (cathode ray tube), running at a 50Hz refresh rate. The linear velocity of the light beam across the photographic paper was approximately 1.25 inches per second. At this speed, the flicker from the screen is visible as a regular modulation in the density of the scanlines.
The total time for each exposure was approximately 20 minutes.