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

Apogee SI-1H1 Horizontal View

Apogee infrared radiometers are the most accurate non-contact temperature sensors available anywhere. The unique geometry of the SI-1H1 gives a wide 32 degree half angle field of view in the horizontal direction with a 13 degree half angle field of view in the vertical direction. This enables the user to mount the sensor at shallower angles without seeing above the horizon while maximising the area measured. The sensor has tinned leads for connecting to a datalogger. Applications include measuring the temperatures of road surfaces, plant canopies, and soil, snow and water surfaces. Measurement of surface temperature is a crucial component of energy transfer. Accurate measurement of the leaf-to-air temperature gradient is essential to the determination of transpiration rate and stomatal conductance in both single leaves and plant canopies.

If you are using any SI-100 series sensor with Campbell Scientific Dataloggers, please view the three notices from Campbell Scientific and Apogee to the right.

Model SI-1H1 FOV = Horizontal 32.0°
Vertical 13.0°

Approximate Sensitivity: 40 µV per C
Output from Thermistor: 0 to 2500 mV (typical, depends on input voltage)
Input Voltage Requirement: 2500 mV excitation (typical, other voltages can be used)
Calibration Uncertainty (-20 to 65°C): 0.2°C, when target and detector temperature are within 20°C
Calibration Uncertainty (-40 to 80°C): 0.5°C, when target and detector temperature are different by more than 20°C
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: 0.2s
Field of View: 32° horizontal half angle; 13° vertical half angle
Spectral Range: 8 to 14 µm; atmospheric window
Operating Environment: -55 to 80°C, 0 to 100% relative humidity (non-condensing)
Dimensions: 2.3 cm diameter and 6.0 cm length
Mass: 190g (with 5m of 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.
Warranty: 4 years

The SI-100 series sensors measure the temperatures of road surfaces, plant canopies, and soil, snow and water surfaces.
• Measures surface temperature rapidly
• Calibrated target temperature range from -30 to 65°C
• Uncertainty of 0.2°C (95% confidence)
• 8-14 µm germanium atmospheric window
• Radiation shield included
• Multiple field of view (FOV) options
• Rugged and lightweight
Field of View (FOV) is reported as the half-angle of the apex of the cone formed by the target (cone base) and the detector (cone apex). The target is a circle from which 98% of the radiation being viewed by the detector is being emitted.


  • AA-100: Protective Carrying Case
    Protective carrying case designed to transport and store Apogee meters, sensors, and accessories.
  • Infrared Radiometer/Frost Detector Mounting Bracket
    The AM-210 mounting bracket is designed to orient sensors at varying angles to satisfy all applications. The bracket can be mounted to a mast or pipe with an outer diameter of 1.3 to 2.1 inches, while the sensor bracket will accommodate sensors with an outer diameter of 1.0 to 1.5 inches (e.g. SI-100 series and SF-110).