1. A unit of illumination equal to one lumen per square centimeter.
Usage: technical; physics; largely replaced by the lux in modern usage

Examples

• The phot was commonly used in older lighting calculations before the lux became standard.
• One phot equals 10,000 lux in the metric system.
• Early photometry textbooks often referenced measurements in phots.
• The laboratory equipment was calibrated using the phot scale.