A Versatile, Inexpensive Generator of Periodic Visual Stimuli.
ARMY MEDICAL RESEARCH LAB FORT KNOX KY
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The report describes a light modulator which consists of two parts 1 an aperture and rotating disc of varying radius and 2 an optical integrating bar with opal diffusers at each end. With the aperture typically a slit uniformly illuminated, the amount of light transmitted is determined by the area of the aperture which is unoccluded by the rotating opaque disc. The radius of the disc varies as the desired modulating function of time or angular position. Light from the aperture then passes through the optical integrating bar with its two opal diffusers. Together, these elements convert the fluctuations in size and location of the incident beam into periodic variations in luminous intensity over the whole area of the output opal diffusing surface. This report also describes the implementation of several waveforms, including sinusoidal modulation of intensity and brightness, square, triangular, cogwheel, and spike waves, as well as a form of dynamic color mixing. Author
- Biomedical Instrumentation and Bioengineering