Apogee Instruments Quantum sensors are a trusted standard for measuring photosynthetically active radiation by researchers and agricultural professionals all over the world. Apogee offers two types of quantum sensors; the Full Spectrum (gold head) and Original (black head). Our newer Full-spectrum Quantum Sensors feature an advanced optical detector that provides accurate PAR measurements under all light sources, including all modern colored LEDs. Our Original Quantum Sensors feature a less expensive optical detector that is highly accurate at measuring broadband light sources, but is less accurate when measuring certain isolated LED colors. Consult our spectral response graphs to decide which model is the most cost-effective for your application.
Light Source
Provides accurate measurements under all light sources, including all LEDs.
Spectral Range
389 to 692 nm ± 5 nm (wavelengths where response is greater than 50 % of maximum)
Output Options
Available in multiple analog options, attached to a hand-held reader with a digital output, and as a "smart" sensor that uses USB communication and custom software.
Waterproof
Light Source
Excellent for all light sources except certain colored LEDs, although post-measurement correction factors can be applied to improve accuracy. Click here for correction factors >
Spectral Range
410 to 655 nm (wavelengths where response is greater than 50 %)
Output Options
Available in multiple analog options, attached to a hand-held reader with a digital output, and as a "smart" sensor that uses USB communication and custom software.
Waterproof
Line Quantum Option
| SQ-500 | SQ-512 | SQ-514 | SQ-515 | SQ-520 | SQ-521 | SQ-110/120 | SQ-212/222 | SQ-214/224 | SQ-215/225 | SQ-300 Series | SQ-420 | SQ-421 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Power Supply | Self-powered | 3.3 to 24 V DC, current draw at 12 V is 57 µA | 12 to 24 V DC | 5.5 to 24 V DC, current draw at 12 V is 57 µA | Uses a 5 V USB power source and has a 2.1 mA current draw when logging | 4.5 to 24 V DC | Self-powered |
3.3 to 24 V DC; current draw 10 µA |
7 to 24 V DC, maximum current draw of 22 mA (2mA quiescent current draw) | 5.5 to 24 V DC; current draw 10 µA | Self-powered | Uses a 5 V USB power source and has a 2.1 mA current draw when logging | 5.5 to 24 V DC |
| Output (Sensitivity) | 0.01 mV per µmol m-2 s-1 | 0.625 mV per µmol m-2 s-1 | 0.004 µmol m-2 s-1 per mA | 1.25 mV per µmol m-2 s-1 | - | - | 0.2 mV per µmol m-2 s-1 | 1 mV per µmol m-2 s-1 | 0.004 mA per µmol m-2 s-1 | 2 mV per µmol m-2 s-1 | 0.2 mV per µmol m-2 s-1 | - | - |
| Output Type | 0 to 40 mV | 0 to 2.5 V | 4 to 20 mA | 0 to 5 V | USB | SDI-12 | 0 to 800 mV | 0 to 2.5 V | 4 to 20 mA | 0 to 5 V | 0 to 800 mV | USB | SDI-12 |
| Resolution | - | - | - | - | 0.1 µmol m-2 s-1 | - | - | - | - | - | - | 0.1 µmol m-2 s-1 | - |
| Calibration Factor (reciprocal of sensitivity) | 100 µmol m-2 s-1 per mV | 1.6 µmol m-2 s-1 per mV | 250 µmol m-2 s-1 per mA | 0.8 µmol m-2 s-1 per mV | Custom for each sensor and stored in the firmware | Custom for each sensor and stored in the firmware | 5 µmol m-2 s-1 per mV | 1 µmol m-2 s-1 per mV | 250 µmol m-2 s-1 per mV | 0.5 µmol m-2 s-1 per mV | 5 µmol m-2 s-1 per mV | Custom for each sensor and stored in the firmware | Custom for each sensor and stored in the firmware |
| Calibration Uncertainty | ± 5 % | ± 5 % | ± 5 % | ± 5 % | ± 5 % | ± 5 % | ± 5 % | ± 5 % | ± 5 % | ± 5 % | ± 5 % | ± 5 % | ± 5 % |
| Measurement Repeatability | Less than 0.5 % | Less than 1 % (up to 4000 µmol m-2 s-1) | Less than 0.5 % | Less than 1 % (up to 4000 µmol m-2 s-1) | Less than 0.5 % | Less than 1 % (up to 4000 µmol m-2 s-1) | Less than 0.5 % | Less than 0.5 % | Less than 0.5 % | Less than 0.5 % | Less than 0.5 % | Less than 0.5 % | Less than 1 % |
| Long-term Drift | Less than 2 % per year | Less than 2 % per year | Less than 2 % per year | Less than 2 % per year | Less than 2 % per year | Less than 2 % per year | Less than 2 % per year | Less than 2 % per year | Less than 2 % per year | Less than 2 % per year | Less than 2 % per year | Less than 2 % per year | Less than 2 % per year |
| Non-linearity | Less than 1 % (up to 4000 µmol m-2 s-1) | Less than 1 % (up to 4000 µmol m-2 s-1) | Less than 1 % (up to 4000 µmol m-2 s-1) | Less than 1 % (up to 4000 µmol m-2 s-1) | Less than 1 % (up to 4000 µmol m-2 s-1) | Less than 1 % (up to 4000 µmol m-2 s-1) | Less than 1 % (up to 4000 µmol m-2 s-1) | Less than 1 % (up to 2500 µmol m-2 s-1, maximum PPFD measurement is 2500 µmol m-2 s-1) | Less than 1 % (up to 4000 µmol m-2 s-1, maximum PPFD measurement is 4000 µmol m-2 s-1) | Less than 1 % (up to 2500 µmol m-2 s-1, maximum PPFD measurement is 2500 µmol m-2 s-1) | Less than 1 % (up to 4000 µmol m-2 s-1) | Less than 1 % (up to 4000 µmol m-2 s-1) | Less than 1 % (up to 4000 µmol m-2 s-1) |
| Response Time | Less than 1 ms | Less than 1 ms | Less than 1 ms | Less than 1 ms | Software updates every second | Less than 0.6 s | Less than 1 ms | Less than 1 ms | Less than 1 ms | Less than 1 ms | Less than 1 ms | Software updates every second | Less than 0.6 s |
| Field of View | 180° | 180° | 180° | 180° | 180° | 180° | 180° | 180° | 180° | 180° | 180° | 180° | 180° |
| Spectral Range | 389 to 692 nm ± 5 nm (wavelengths where response is greater than 50 % of maximum) | 389 to 692 nm ± 5 nm (wavelengths where response is greater than 50 %) | 391 to 695 nm (wavelengths where response is greater than 50 % of maximum) | 389 to 692 nm ± 5 nm (wavelengths where response is greater than 50 %) | 389 to 692 nm ± 5 nm (wavelengths where response is greater than 50 % of maximum) | 389 to 692 nm ± 5 nm (wavelengths where response is greater than 50 %) | 410 to 655 nm (wavelengths where response is greater than 50 % of maximum) | 410 to 655 nm (wavelengths where response is greater than 50 % of maximum) | 410 to 655 nm (wavelengths where response is greater than 50 % of maximum) | 410 to 655 nm (wavelengths where response is greater than 50 % of maximum) | 410 to 655 nm (wavelengths where response is greater than 50 % of maximum) | 410 to 655 nm (wavelengths where response is greater than 50 % of maximum) | 410 to 655 nm (wavelengths where response is greater than 50 % of maximum) |
| Spectral Selectivity | Less than 10 % from 412 to 682 ± 5 nm | Less than 10 % from 412 to 682 ± 5 nm | Less than 10 % from 412 to 682 ± 5 nm | Less than 10 % from 412 to 682 ± 5 nm | Less than 10 % from 412 to 682 ± 5 nm | Less than 10 % from 412 to 682 ± 5 nm | Less than 10 % from 469 to 655 nm | Less than 10 % from 469 to 655 nm | Less than 10 % from 469 to 655 nm | Less than 10 % from 469 to 655 nm | Less than 10 % from 469 to 655 nm | Less than 10 % from 469 to 655 nm | Less than 10 % from 469 to 655 nm |
| Directional (Cosine) Response | ± 5 % at 75° zenith angle | ± 2 % at 45°, ± 5 % at 75° | ± 2 % at 45°, ± 5 % at 75° | ± 2 % at 45°, ± 5 % at 75° | ± 5 % at 75° zenith angle | ± 2 % at 45°, ± 5 % at 75° | ± 5 % at 75° zenith angle | ± 5 % at 75° zenith angle | ± 5 % at 75° zenith angle | ± 5 % at 75° zenith angle | ± 5 % at 75° zenith angle | ± 5 % at 75° zenith angle | ± 5 % at 75° zenith angle |
| Temperature Response | -0.11 ± 0.04 % per C | -0.11 ± 0.04 % per C | -0.1 % per C | -0.11 ± 0.04 % per C | -0.11 ± 0.04 % per C | -0.11 ± 0.04 % per C | 0.06 ± 0.06 % per C | 0.06 ± 0.06 % per C | 0.06 ± 0.06 % per C | 0.06 ± 0.06 % per C | 0.06 ± 0.06 % per C | 0.06 ± 0.06 % per C | 0.06 ± 0.06 % per C |
| Operating Environment | -40 to 70 C; 0 to 100 % relative humidity; can be submerged in water up to depths of 30 m | -40 to 70 C; 0 to 100 % relative humidity; can be submerged in water up to depths of 30 m | -40 to 70 C; 0 to 100 % relative humidity; can be submerged in water up to depths of 30 m | -40 to 70 C; 0 to 100 % relative humidity; can be submerged in water up to depths of 30 m | -40 to 70 C; 0 to 100 % relative humidity; can be submerged in water up to depths of 30 m | -40 to 70 C; 0 to 100 % relative humidity; can be submerged in water up to depths of 30 m | -40 to 70 C; 0 to 100 % relative humidity; can be submerged in water up to depths of 30 m | -40 to 70 C; 0 to 100 % relative humidity; can be submerged in water up to depths of 30 m | -40 to 70 C; 0 to 100 % relative humidity; can be submerged in water up to depths of 30 m | -40 to 70 C; 0 to 100 % relative humidity; can be submerged in water up to depths of 30 m | -40 to 70 C; 0 to 100 % relative humidity; can be submerged in water up to depths of 30 m | -40 to 70 C; 0 to 100 % relative humidity; can be submerged in water up to depths of 30 m | -40 to 70 C; 0 to 100 % relative humidity; can be submerged in water up to depths of 30 m |
| Dimensions | 24 mm diameter, 37 mm height | 24 mm diameter, 37 mm height | 24 mm diameter, 37 mm height | 24 mm diameter, 37 mm height | 24 mm diameter, 37 mm height | 23.5 mm diameter, 45 mm height | 24 mm diameter, 33 mm height | 24 mm diameter, 33 mm height | 24 mm diameter, 33 mm height | 24 mm diameter, 33 mm height | SQ-313/316/323/326: 500 mm x 15 mm x 15 mm, SQ-311/321: 700 mm x 15 mm x 15 mm | 24 mm diameter, 33 mm height | 23.5 mm diameter, 44 mm height |
| Mass (with 5 m of cable) | 100 g | 100 g | 100 g | 100 g | 100 g | 117 g | 90 g | 100 g | 100 g | 100 g | SQ-313/316/323/326: 275 g, SQ-311/321: 375g | 90 g | 117 g |
How to Choose a Quantum Sensor
Why do I need a PAR-Quantum Meter?
In-depth Look at PAR-Quantum Meters
Lecture 4-PAR
Apogee Instruments Meter User Guide
Making a Durable Wire Splice
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