Light Meter

The LI-250A is a portable meter that displays the output from any LI-COR light sensor that has a cable terminated with a BNC connector. It shows instantaneous values or 15-second averages of values from a sensor.

The LI-250A automatically selects a sensitivity range to optimize accuracy and resolution for a given sensor. It provides a wide dynamic range for high-resolution measurements, even in low-light conditions.

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LI-250A Features

  • 15-second averaging is turned on or off by pressing a single button
  • Over 150 hours of operation from a single 9-volt battery
  • Automatic shut-off after 20 minutes of inactivity
  • O-ring sealed case for weather protection
  • Easy-to-enter calibration multipliers make it simple to change between sensors
  • Compatible with the LI-190R, LI-191R, LI-192, LI-193, LI-200R, or LI-210R
LI-250A Light Meter


  • Accuracy:
    • 25 °C: Typically ± 0.4% of reading ± 3 counts on the least significant digit displayed (all ranges).
    • 0 - 55 °C: Typically ± 0.6% of reading ± 3 counts on the least significant digit displayed (all ranges).
  • Range Selection: Autoranging (3 ranges).
  • Linearity: ± 0.05%.
  • Sensors: Designed for type "SA" sensors; type "SB" and "SL" sensors with BNC connectors are also compatible when calconnector or millivolt adapter are removed.
  • Sensor Calibration: Each sensor is supplied with a calibration multiplier. Calibration multipliers for two sensors can be stored in memory. Calibration multipliers are entered from the keypad.
  • Signal Averaging: Sensor output can be collected and displayed as a 15-second average (approximately 60 readings). Averages are retained on the display in HOLD mode.
  • Display: LCD display. Updated every 0.5 seconds in Instantaneous mode.
  • Battery Life: 150 hours typical with continuous operation.
  • Power Requirement: One 9V Alkaline battery.
  • Operating Conditions: 0 to 55 °C, 0 to 95% RH (non-condensing).
  • Storage Conditions: -55 to 60 °C, 0 to 95% RH (non-condensing).
  • Size: 14 cm × 7.7 cm × 3.8 cm (5.5" × 3" x1.5").
  • Weight: 0.26 kg (0.57 lbs).
  • Warranty: 1 year parts and labor.
  • LI-250A Range and Resolution:
    Sensor Range Resolution
    Quantum 0-199 µmol s-1 m-2
    0.01 µmol s-1 m-2
    Pyranometer 0-19 W m-2
    0.001 W m-2
    Photometric 0-1999 lux
    0-19999 lux
    0-199 klux
    0.1 lux
    0.01 klux

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