Background Luminance Sensor LM21

Fully featured ambient light sensor for Runway Visual Range (RVR) applications.

Precise measurements

Vaisala Background Luminance Sensor LM21

The Background Luminance Sensor LM21 is a precision photometer with a verified photopic spectral response. It measures the total amount of light coming in from an angle of 6 degrees to assess the visibility range of runway lights or warning lights.

The LM21 features:

Verified accuracy and photopic response
Extensive self-diagnostics
Window contamination measurement and compensation
Optical path blockage detection
High power heaters to prevent snow accumulation
Calibration traceable to measurement standards
Easy-to-use field calibration device available

It integrates with the Vaisala Transmissometer LT31 and Vaisala Forward Scatter Sensor FD70 to create an expanded runway visual range (RVR) system.

LM21 can only be purchased with LT31 or FD70; or as a spare part to the same product platforms.

Comprehensive self diagnostics

To ensure reliable and uninterrupted operation, the LM21 has extensive self-monitoring functions and high-power heating features built into its design.

Optical path clearance monitoring circuitry verifies measurements are not affected by obstructions. Attenuation compensation for window contamination ensures measurement accuracy between window cleanings, and also extends the cleaning interval.

Easy calibration

The calibration of LM21 is traceable to international measurement standards for luminous intensity. The calibration coefficients for light intensity have been defined during factory calibration and stored in the LM21 memory.

Quick field calibration can be done using a unique field calibration device (LMA21) that provides a stabilized and diffused white light beam for LM21 calibration. Calibration starts automatically when the calibration unit is connected.

Precise measurements

The Background Luminance Sensor LM21 is a precision photometer with a verified photopic spectral response. It measures the total amount of light coming in from an angle of 6 degrees to assess the visibility range of runway lights or warning lights.

The LM21 features:

Verified accuracy and photopic response
Extensive self-diagnostics
Window contamination measurement and compensation
Optical path blockage detection
High power heaters to prevent snow accumulation
Calibration traceable to measurement standards
Easy-to-use field calibration device available

It integrates with the Vaisala Transmissometer LT31 and Vaisala Forward Scatter Sensor FD70 to create an expanded runway visual range (RVR) system.

LM21 can only be purchased with LT31 or FD70; or as a spare part to the same product platforms.

Comprehensive self diagnostics

To ensure reliable and uninterrupted operation, the LM21 has extensive self-monitoring functions and high-power heating features built into its design.

Optical path clearance monitoring circuitry verifies measurements are not affected by obstructions. Attenuation compensation for window contamination ensures measurement accuracy between window cleanings, and also extends the cleaning interval.

Easy calibration

The calibration of LM21 is traceable to international measurement standards for luminous intensity. The calibration coefficients for light intensity have been defined during factory calibration and stored in the LM21 memory.

Quick field calibration can be done using a unique field calibration device (LMA21) that provides a stabilized and diffused white light beam for LM21 calibration. Calibration starts automatically when the calibration unit is connected.

Industry Applications

Aviation

Ensure safe and efficient airport operations in any weather with our comprehensive selection of weather and runway management solutions.

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Meteorology

Protect people and communities from the impacts of day-to-day and extreme weather with the industry's most accurate and reliable weather observation solutions.

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Get Started with Background Luminance Sensor LM21 Today

Contact Vaisala to learn how this stand-alone ambient light sensor can deliver crucial data while helping simplify your Runway Visual Range (RVR) system.

Contact us

Product documentation

Datasheet

Docs.vaisala.com

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