ALS-2 Ambient Light Sensor



Accurate and reliable determination of background light during all weather conditions.

The ALS-2 Ambient Light Sensor is designed to measure background luminance as part of a Runway Visual Range (RVR) system. Mounted alongside the runway the ambient light sensor is often deployed with a visibility meter to provide the data necessary for calculation of RVR.

Designed to comply with specifications and guidelines produced by the International Civil Aviation Organisation (ICAO), World Meteorological Organisation (WMO) and the Federal Aviation Administration in the USA (FAA), the ALS-2 meets all the requirements for use in typical RVR systems. The ability to connect the sensor directly to a Biral visibility or present weather sensor and have the background luminance data incorporated into the visibility sensors data string simplifies system design and construction.

  • Designed to FAA and ICAO requirements
  • 2 to 40,000 Cdm-2 measurement range
  • Choice of serial digital or analogue outputs
  • Simple and quick in field calibration
  • Direct connection to Biral visibility and present weather sensors
  • Extensive self-test capabilities
  • -60°C to 70°C operating range
Measurement Background luminance 2-40,000 Cdm-2 (0.5-11,700 fL)
Serial Output RS232, RS422
Analogue Output Optional – 2 x Analogue outputs
Low Output 2-4,000 Cdm-2 High Output 20-40,000 Cdm-2
Spectral Response Wavelength sensitivity range 420-675 nm, peak 565 nm. Analogous to CIE luminous spectral efficiency
Measurement Error <10%
Field of View
Averaging Period 60s
Sensor Power 9-36 V DC (2W)
Hood Heating Power 12W (24V AC or DC)
Window heating and contamination monitoring Fitted
Operating Temperature -40°C to 70°C, -60°C to 70°C (With extended heating Option)
Operating Humidity 0 – 100% RH
Protection rating IP66
Weight (Sensor Head) 1.5kg