Apogee Instruments SE-100 Посібник користувача - Сторінка 5
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Друкувати сторінкуINTRODUCTION
The human eye is sensitive to radiation from about 380 to 780 nm but is most sensitive in the middle of this range
near 555 nm. The photopic luminosity function (there are different versions, but the CIE 1931 standard is widely
accepted and commonly used) describes the average sensitivity of the human eye, or the average human
perception of brightness, in well-lit conditions. The scotopic luminosity function describes the average sensitivity of
the human eye in dimly-lit conditions.
Illuminance is a measurement of radiant energy on a surface, weighted by the human eye response. Illuminance is
quantified in units of lux or footcandles. Lux is luminous flux (radiant intensity weighted by the photopic luminosity
-2
function) incident on a surface in units of lumens per square meter [lm m
] and footcandles is luminous flux
-2
incident on a surface in units of lumens per square foot [lm ft
]. There are 10.7639 square feet in a square meter,
so lux can be converted to footcandles by dividing by 10.7639. Sensors that measure illuminance are referred to by
many names, including light sensors, photometric radiometers, photopic sensors, and lux sensors.
Typical applications of illuminance sensors include determination of optimum light levels in indoor environments
and quantification of material/substance exposure to light.
Apogee Instruments SE series photometric sensors consist of a cast acrylic diffuser, optical filter, photodiode, and
signal processing circuitry mounted in an anodized aluminum housing, and a cable to connect the sensor to a
measurement device. Sensors are designed for continuous illuminance measurement in indoor and outdoor
environments. SE-100 and SE-200 series sensors output an analog voltage that is directly proportional to
illuminance incident on a planar surface (does not have to be horizontal), where the radiation emanates from all
angles of a hemisphere.