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Scotopic Light
Detector |
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FEATURES
 | High sensitivity |
| Wide dynamic range |
| Excellent long term stability |
| Cosine corrected |
| NIST traceable calibration |
| Selectable units |
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| The PMA2131 is a portable
illumination detector (Lux detector) with spectral response following the CIE scotopic
action spectrum. This detector is designed to have a spectral response like that of the
human eye’s visual response in the photopic (dark adapted) region. |
APPLICATIONS
| Low light level testing |
| Night vision technology |
| Display and illuminator testing |
| Luminescence and fluorescence |
| Photography and film studios |
| Clinical studies |
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| The
spectral response of the human eye changes with light intensity. The eye
has two distinctive spectral responses, which are defined according to the
brightness of the light entering the eye. The first spectral response of
the eye occurs under typical daytime lighting conditions (photopic)
defined for light intensity greater than 0.1 Lux. The second spectral
response occurs under low light conditions (scotopic) defined for light
intensity between 0.01 and 0.0001 Lux. Light intensity less than 0.0001
Lux is undetectable by the human eye. The eye's shift from the photopic
response to the scotopic response is know as the Purkinje shift. 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. |
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SPECIFICATIONS |
| Spectral response |
Follows CIE scotopic
spectral luminous efficiency curve (400-600nm) Figure 1 |
| Angular response |
5% for angles <60° |
| Range |
200,000
scotopic mLux
20,000 mft-cd
120,000 µW/m2 |
| Display resolution |
1 mLux
0.1 mft-cd
1 µW/m2 |
| Operating environment |
32 to 120 °F (0 to
+50 °C) no precipitation |
| Cable |
1ft, retractable to
5ft (0.3m/1.5m) |
| Diameter |
1.6" (40.6 mm) |
| Height |
1.8" (45.8 mm) |
| Weight |
7.1 oz. (200 grams) |
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Analog versions of this detector are available See PMA1131 |
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Return to Detector Selection Guide
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