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Troy, NY -  7/1/2002

LRC Develops Retinal Flux Density Meter

New device could lead to improved safety and energy efficiency standards

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 You may also view a poster about the device at Note: This is a pdf file, which requires Adobe Acrobat Reader to view.

About the Lighting Research Center
The Lighting Research Center (LRC) at Rensselaer Polytechnic Institute is the world's leading center for lighting research and education. Established in 1988 by the New York State Energy Research and Development Authority (NYSERDA), the LRC conducts research in light and human health, transportation lighting and safety, solid-state lighting, energy efficiency, and plant health. LRC lighting scientists with multidisciplinary expertise in research, technology, design, and human factors, collaborate with a global network of leading manufacturers and government agencies, developing innovative lighting solutions for projects that range from the Boeing 787 Dreamliner to U.S. Navy submarines to hospital neonatal intensive-care units. In 1990, the LRC became the first university research center to offer graduate degrees in lighting and today, offers a M.S. in lighting and a Ph.D. to educate future leaders in lighting. Learn more at

About Rensselaer Polytechnic Institute
Founded in 1824, Rensselaer Polytechnic Institute is America's first technological research university. Rensselaer encompasses five schools, 32 research centers, more than 145 academic programs, and a dynamic community made up of more than 7,900 students and more than 100,000 living alumni. Rensselaer faculty and alumni include more than 145 National Academy members, six members of the National Inventors Hall of Fame, six National Medal of Technology winners, five National Medal of Science winners, and a Nobel Prize winner in Physics. With nearly 200 years of experience advancing scientific and technological knowledge, Rensselaer remains focused on addressing global challenges with a spirit of ingenuity and collaboration.