The modified Goldman perimeter is used for various visibility experiments. The Goldman perimeter is a hemisphere (diameter 60 cm) to the surface of which a light spot can be reflected as a visual target. The hemisphere surface luminance and the target (light spot) luminance can be independently adjusted. The control of the visual and lighting conditions are provided by a lighting control system consisting of optical fibres.
The perimeter can be used for visual field measurements, contrast threshold measurements at different eccentricities etc. As the spectral characteristics of the background (hemisphere surface) and the target can be altered, the perimeter can be used in versatile experiments on e.g. mesopic vision.