Press Releases

Scientists at the Lighting Research Center (LRC) have designed and constructed a retinal flux density (RFD) meter. One reason lighting designers and practitioners most commonly use illuminance as a performance metric is that illuminance meters are easy to use and relatively inexpensive. Unfortunately, under certain conditions (such as under mesopic light levels) these meters don't accurately represent the human response to lighting. The LRC developed the RFD meter to address this issue. It can serve as a standard illuminance meter, or it can measure flux density on the retina using both photopic and scotopic spectral responses. This dual measurement ability allows the instrument to determine standard illuminances and RFDs at mesopic levels.

Although the prototype device is not yet commercially available, a commercial instrument that provides accurate measurements at photopic, scotopic, and mesopic light levels could be manufactured for less than $1000. Researchers and practitioners could use such device to assess the utility of moving beyond static photopic illuminance levels. Widespread use of these devices might lead to new standards that would improve both energy efficiency and safety.

For more information about the RFD meter, visit the LRC's Web site at www.lrc.rpi.edu. You may also view a poster about the device at www.lrc.rpi.edu/programs/partners/partnersonly/pdfs/RetinalFluxDensity.pdf. Note: This is a pdf file, which requires Adobe Acrobat Reader to view.