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Environmental measurement & analysis
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MS-321LR Sky Scanner

MS-321LR Sky Scanner


  • Daylight analysis measurement system
  • Sky Irradiance and Illuminance 
  • 145 sequential measurements
  • Auto measurement schedule
  • Integrated values over full hemisphere

The automatic Sky Scanner MS-321LR is designed only to measure Luminance and Radiance of the sky hemisphere. The sensor has 2 highly sensitive detectors which respond to the low light levels of the diffuse sky and will automatically block direct radiation by the active shutter function.

The sensor with a viewing angle of 11 degrees will capture the hemisphere in 145 discrete steps. The sensor is attached to a tracker positioner having two-axis control. The MS-321LR has a precise tracking mechanism that achieves high durability and repeatability. Measurements are based on the CIE108-1994 recommendation (CIE - International Lighting Commission, IDMP - International Daylight Measurement Programme). Luminance value are measured per kcd/m2 and radiance value per W/m2/sr.

The sky scanner is used to study the radiation contribution of the diffuse sky which is an important parameter for building automation, building design, day light software modeling and light polution research. The advanced software control functions give full flexibility to export date for extensive research analysis and purposes.


Model MS-321 (Sensor)
Luminance: Measurement Range
50 kcd/m2 (full scale)
Irradiance: Measurement Range
300 W/m2·sr (full scale)
Entire sky scanning time
< 4.5 min/145 points


MS-321 (Tracker)
Stepping motor
Motor driving mode
Half step
Driving technology
Harmonic Drive
Pointing accuracy
< 0.01°
Angle resolution
12 Nm
7kg balanced
Temperature range
From -40 to +50°C
RS422/RS232C, 9600bps, 8N1
Power requirement
AC100 to 240V, 50/60Hz, 20W
DC18 to 30V, 15W for DC optional Sky Scanner
430(W) x 380(D) x 440(H) mm
12.5 kg



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