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 about 0.1 Lux. The second region is a transitional region known as the Purkinje region defined as intensities between about 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 with the human eye. These three regions are distinctive in that the human eye has different spectral response for each region of intensity. The scotopic spectral luminous efficiency curve peaks at 507 nm and it is normalized to 1 at that wavelength.

The power-like unit of brightness-sensation-producing ability of light is lumen [lm]. The relationship between effective Watts and scotopic lumen is now assumed to be 1754 lm/W. For example, 507-nm monochromatic radiation flux of 0.0001W would carry the scotopicluminous flux of 0.1754 lm. Please note, that photopic spectral luminous efficiency as well as the conversion factor between Watts and photopic lumens differ from their scotopic counterparts.

FEATURES

• High sensitivity
• Wide dynamic range
• Excellent long term stability
• Cosine corrected
• NIST traceable calibration
• Selectable units

APPLICATIONS

• Low light level testing
• Night vision technology
• Display and illuminator testing
• Luminescence and fluorescence
• Photography and film studios
• Clinical studies,