Background Luminance Sensor LM21 Fully featured ambient light sensor for Runway Visual Range (RVR) applications. PRECISE MEASUREMENTS PRECISE MEASUREMENTS Image 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 FD70, FS11, or FS11P to create an expanded runway visual range (RVR) system. COMPREHENSIVE SELF DIAGNOSTICS 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 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. LEARN MORE 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. LEARN MORE 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 DATASHEET Background Luminance Sensor LM21 Discover the power of stand-alone ambient light sensors to improve runway illumination monitoring. DOWNLOAD PDF PRODUCT SPOTLIGHT Background Luminance Sensor LM21 The industry's most accurate runway visibility data. DOWNLOAD PDF TRAINING Transmissometer LT31 & LM21 Operation and Maintenance Training A comprehensive, hands-on training course for the Vaisala LT31 and LM21 operation and maintenance. This in-depth four-day course gives you practical training on how to operate, maintain, and troubleshoot LT31 and LM21. FIND OUT MORE
