Audiophile hardware in vision science; the soundcard as a digital to analog converter.

The design objective was to develop an inexpensive digital to analog (D/A) converter for use in vision science. Soundcards are hardware units that can be integral or can be added to a computer to add sound capability. A soundcard contains D/A converters designed to work in the audio frequency range, typically 20-20,000 Hz.

Photostimulator allowing independent control of rods and the three cone types.

This report describes a second-generation photostimulator with four primary lights that allows independent control of the stimulation of the four receptor types in the human eye. The new design uses LEDs (with light levels controlled by eight drivers that include voltage-to-frequency converters that provide 1-micros pulses at frequencies up to 250 kHz), with four center channels being combined by use of a fiber optic assembly, and likewise for four surround channels. Four fiber optic bundles are merged into a single bundle whose output is fed into a spatial homogenizer terminated by a diffuser.