An Automatic Sine-Wave Grating Controller to be Used for Contrast Sensitivity Testing.

This report documents the additional design, construction, and testing of the brightness and contrast controller system which includes an embedded microcomputer. It is planned that researchers will use this controller to maintain prescribed video output of laboratory video monitors during vision research. The controller requires a video signal consisting of a sine-wave grating. A 512-element photodiode array directly measures the monitors screen to produce an analog signal which is then digitized and stored in the computer. These data are used to compute the actual brightness and contrast of the monitor. In an attempt to complete the controllers system requirements, the controller prototype hardware was completed and partially packaged. Closed-loop system testing was performed for both the brightness and contrast control circuitry. Brightness and contrast control circuitry, a vertical synch pulse generator, a user-interface console, and power supply with additional voltage-regulator circuitry were designed and added to the existing prototype.