Model SL-3101 SP-Meter™ Scotopic / Photopic Meter

Solar Light’s Model SL-3101 SP-Meter™  is an innovative, portable meter which measures spectral response following the CIE scotopic and photopic action spectra,  providing an accurate measurement of brightness as perceived by the human eye. This unit provides on-board calculations for:

• S/P ratio

• Visually effective light level

• Perceived brightness

  
  

The human eye has three distinctive regions of response: The first region is the response of the eye under typical lighting conditions (photopic,) defined as intensities greater than approximately 0.1 Lux. The second region is a transitional region known as the Purkinje Region, defined as intensities between approximately 0.01 and 0.1 Lux. The third region is the dark adapted region of the human eye (scotopic,) defined as intensities between about 0.01 and 0.0001 Lux. Intensities less than 0.0001 Lux are undetectable to the human eye. These three regions are distinctive in that the human eye has a different spectral response for each region of intensity.

U.S. Pat. 5,946,641

U.S. Pat. 5,790,432