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

Apogee S2-141 PAR-Far Red

Apogee PAR-FAR sensors combine two photodetectors that measure photosynthetically active and far-red radiation. The PAR sensor is the same as the Apogee model SQ-500 full-spectrum quantum sensor and is designed to measure photosynthetic photon flux density (PPFD, 400-700 nm). The far-red sensor is a quantum sensor that measures photons in the 700-760 nm range.

Typical Applications

  • Monitoring plant light environments
  • Research plant morphogenic activity
  • Photobiology studies

Key Features

A domed diffuser promotes self-cleaning to minimize errors from dust and debris. 0-40mV output, SDI-12 version available (S2-441).

High Quality Cable

Pigtail-lead sensors feature on IP68, marine-grade stainless-steel cable connectors attached directly to the sensor head to simplify sensor removal for maintenance and recalibration.

Available Package

The S2-141 PAR-Far Red Sensor is also available as a package with a microCache Bluetooth micro-logger at a special introductory price.

Above: Spectral response of PAR detector (blue) and Far Red detector (red) compared to defined response of plants to radiation (dashed).

Power Supply: Self-Powered
Output (sensitivity): 0.01 mV per μmol m⁻² s⁻¹ (PAR)
0.02 mV per μmol m⁻² s⁻¹ (Far Red)
Calibration Factor (reciprocal of sensitivity): 100 μmol m⁻² s⁻¹ per mV (PAR)
50 μmol m⁻² s⁻¹ per mV (Far Red)
Calibration Uncertainty: ± 5%
Output Range: 0 to 40 mV (PAR)
0 to 20 mV (Far Red)
Measurement Repeatability: Less than 1%
Long-term Drift: Less than 2% per year
Non-Linearity: Less than 1% (up to 4000 μmol m⁻² s⁻¹) (PAR)
Less than 1% (up to 1000 μmol m⁻² s⁻¹) (Far Red)
Response Time: Less than 1 ms
Field of View: 180°
Spectral Ranges: 389 to 692 nm ± 5 nm (PAR)
700 to 760 nm ± 5 nm (Far Red)
Directional (Cosine) Response: ± 2% at 45°; ± 5% at 75° zenith angle
Temperature Response: Less than 0.1% per °C
Housing: Anodised aluminium body with acrylic diffuser
IP Rating: IP68
Operating Environment: -40°C to 70°C; 0 to 100% relative humidity
Dimensions: 30.5mm diameter, 36.6mm height
Mass: 51g