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Enabling better global research outcomes in soil, plant & environmental monitoring.

Decagon IRT Sensors

The infrared thermometer monitors surface temperature by measuring the thermal energy radiated from any surface within its field of view.

Highly Accurate, Meticulously Calibrated

Has an accuracy of ± 0.2°C when the target temperature is within 20°C of the sensor body temperature. The IR Thermometer is calibrated from -30 to 65°C.

Non-Contact, Continuous Monitoring

Delivers a continuous stream of temperature data from the entire field of view, not just data from a single leaf.

Purpose Built for Plant Science Applications

Not a generic IR thermometer, but a scientific-grade sensor designed for making canopy measurements. It comes with a highly accurate factory calibration. A radiation shield and mounting bracket are included.

Four Field of View Options

Select the right field of view for your application. Choose a circular aperture with a half angles of 14, 18, or 22 degrees, or pick a horizontal aperture with 13 degree vertical half angle and 32 degree horizontal half angle.

Corrects for Sensor Temperature

Measures both the target temperature and the temperature of the sensor itself to correct for the temperature sensitivity of the detector.

Rugged, Lightweight, Weatherproof

Tough germanium window makes the sensor durable without decreasing its accuracy. A weatherproof aluminium body withstands harsh weather conditions.

Monitor Temperature from your Mobile Device

Compatible with Decagon’s simple, low-power Em50 series data loggers. Run the sensor and logger on 6 AA batteries. Download data in your office or anywhere with an internet connection. No programming required.

Signal Output/Data logging SDI-12 Version 1.3 (24-bit ADC)
Compatible with Em50 series loggers or other SDI-12 compatible loggers
Input Voltage Requirement 4.5 to 24V DC
Current Drain 1.1mA (quiescent), 6mA (transmitting)
Measurement range -30 to 65°C
Calibration Uncertainty (-20 to 65°C) 0.2°C (Models SI-411, SI-421 and SI-4H1), 0.3°C (Model SI-431), when target and detector temperature are within 20°C.
Calibration Uncertainty (-40 to 80°C) 0.5°C (Models SI-411, SI-421 and SI-4H1), 0.6°C (model SI-431), when target and temperature are different by more than 20°C
(See Calibration Traceability below)
Measurement Repeatability < 0.05°C
Stability (Long-term Drift) Less than 2% change in slope per year when germanium filter is maintained in a clean condition.
Response Time 0.6s, time for detector signal to reach 95% following a step change; fastest data transmission rate for SDI-12 circuitry is 1s.
Field of View SI-411 – 22° half angle
SI-421 – 18° half angle
SI-431 – 14° half angle
SI-4H1 – 32° horizontal half angle; 13° vertical half angle
Spectral Range 8 to 14um; atmospheric window
Operating Environment -45 to 80°C
0 to 100% relative humidity (Non-condensing)
Dimensions 2.3cm Diameter, 6.0cm Length.
Mass 190g (with 5m lead wire)
Cable 5m of four conductor, shielded, twisted-pair wire.
Additional cable available in multiples of 5m.
Santoprene rubber jacket (High water resistance, high UV stability, flexibility in cold conditions),
Pigtail lead wires
Calibration Traceability
Apogee SI series infrared radiometers are calibrated to the temperature of a custom blackbody cone held at multiple fixed temperatures over a range of radiometer (detector/sensor body) temperatures. The temperature of the blackbody cone is measured with replicate precision thermistors thermally bonded to the cone surface. The precision thermistors are calibrated for absolute temperature measurement against a platinum resistance thermometer (PRT) in a constant temperature bath. The PRT calibration is directly traceable to the NIST.
  • Most accurate infrared radiometer on the market
  • Measures surface temperature rapidly
  • Uncertainty of 0.2°C (95% confidence)
  • 8-14 μm germanium atmospheric window
  • Radiation shield included
  • Multiple field of view (FOV) options
  • Calibrated target temperature range from -30 to 65°C
  • Rugged and lightweight
  • Available in sensor-only version with pigtail leads (for dataloggers) or with handheld meter

Applications

  • Stomatal Conductance: Monitor water use in real time by using a biophysical model to back-calculate stomatal conductance
  • Plant Water Stress
  • Evapotranspiration: Use temperature to estimate stomatal conductance instead of using a crop coefficient
  • Calculate true Vapour Pressure Deficit (VPD): Reduce errors when modelling by using actual canopy temperature instead of air temperature
  • Most accurate infrared radiometer on the market
  • Measures surface temperature rapidly
  • Uncertainty of 0.2°C (95% confidence)
  • 8-14 μm germanium atmospheric window
  • Radiation shield included
  • Multiple field of view (FOV) options
  • Calibrated target temperature range from -30 to 65°C
  • Rugged and lightweight
  • Available in sensor-only version with pigtail leads (for dataloggers) or with handheld meter