Figure 1. Schematic of the voltage-sensitive dye imaging apparatus.

Affordable optical components can be assembled with standard mountings to build a macroscope with high numerical aperture. The use of large numerical aperture optics and high-quality filters allows recording with high signal-to-noise ratio in single trials. Since the photodiode array itself has insufficient spatial resolution for micrography and focusing, an equifocal web camera is also incorporated in the setup.