Comparative evaluation of Light Emitting Diode cap lamps with an emphasis on visual performance in mesopic lighting conditions

Conducted at the Office of Mine Safety and Health Research laboratory of the National Institute for Occupational Safety and Health (NIOSH), this experiment is part of ongoing mine illumination research designed to explore the benefits of solid state lighting technologies when applied to the underground mining industry. This experiment involves the comparative evaluation of cap lamps with similar spectral power distributions, focusing on the electrical and battery discharge characteristics, with a secondary objective being exploring the benefits gained through alternative light beam distributions. NIOSH researchers conducted the investigation by comparing three commercially available LED cap lamps and a NIOSH prototype cap lamp at varying power settings. Visual performance for the detection of hazards was quantified by recording times of detection for finding rotating targets in the peripheral field of view and objects representing trip and fall hazards on the ground. Results show that the NIOSH prototype improved the ability to perceive objects in the visual field by improving peripheral motion detection times by as much as 79.5%, and ground hazard detection times by as much as 194.1%.