Apogee MQ-500 Full Spectrum Quantum Meter

The MQ-500 has a hand-held meter, attached via cable, that displays and stores measurements. The sensor incorporates a blue-enhanced silicon photodiode and custom optical filters with a rugged, self-cleaning sensor housing design, anodized aluminum body with acrylic diffuser. Typical applications include PPFD measurement over plant canopies in outdoor environments, greenhouses, and growth chambers, and reflected or under-canopy (transmitted) PPFD measurements in the same environments. Quantum sensors are also used to measure PAR/PPFD in aquatic environments, including salt water aquariums where corals are grown.

The meter has a sample and log mode, and will record an integrated daily total in mol m-2 d-1. Sample mode will record up to 99 manual measurements. Log mode will power the meter on/off to make a measurement every 30 seconds. Every 30 minutes the meter will average the sixty 30 second measurements and record the averaged value to memory. The meter can store up to 99 averages, once full it will start to overwrite the oldest measurement with new ones. An integrated daily total will be recorded from the 48 averaged measurements (making a 24 hr period). Sample and log measurements can be reviewed on the LCD display or by downloading the data to a computer, however, the integrated daily total can only be viewed by downloading the data to a computer. Downloading data to a computer requires the AC-100 communication cable (a standard USB cable will not work) and ApogeeAMS software.

How is the MQ-500 different from previous Apogee quantum sensors?

The MQ-500 is a full spectrum quantum sensor with a spectral range of 389 to 692 nm ± 5 nm, which can be seen in the graph below. This improved spectral respose increases the acuracy of LED measurements.

Where is the MQ-500 used?

The MQ-500 is used to measure incoming PPFD measurements in outdoor environments, greenhouses, growth chambers, and aquariums.


Calibration Uncertainty
± 5 %
Measurement Range
0 to 4000 µmol m-2 s-1
Measurement Repeatability
less than 0.5 %
Long-term Drift (Non-stability)
less than 2 % per year
less than 1 % (up to 4000 µmol m-2 s-1)
Response Time
less than 1 ms
Field of View
Spectral Range
389 to 692 nm ± 5 nm (wavelengths where response is greater than 50 % of maximum)
Spectral Selectivity
less than 10 % from 412 to 682 nm ± 5 nm
Directional (Cosine) Response
± 5 % at 75 ° zenith angle
Azimuth Error
less than 0.5 %
Tilt Error
less than 0.5 %
Temperature Response
-0.11 ± 0.03 % C -1
Uncertainty in Daily Total
less than 5 %
blue-enhance silicon photodiode
anodized aluminum body with acrylic diffuser
IP Rating
Operating Environment
0 to 50 C; less than 90 % non-condensing relative humidity up to 30 C; less than 70 % non-condensing relative humidity from 30 to 50 C; separate sensors can be submerged in water up to depth of 30 m
Meter Dimensions
126 mm length; 70 mm width; 24 mm height
Sensor Dimensions
24 mm diameter; 37 mm height
100 g (with 5 m of lead wire)
2 m of shielded, twisted-pair wire; additional cable available; santoprene rubber jacket
4 years against defects in materials and workmanship