The MQ-500 quantum meter is the tool of choice for scientists all over the world to accurately measure photosynthetically active radiation from all light sources. It 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.
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.
Full-spectrum Quantum Sensor
Measure photosynthetically active radiation, PAR, in µmol m-2 s-1.
Apogee Instruments‘ quantum sensors provide accurate and cost-effective measurement of photosynthetically active radiation (PAR) from all light sources used to grow plants and corals.
The full-spectrum quantum sensor has a spectral range of 389 to 692 ± 5 nm. The improved spectral response increases the accuracy of LED measurements.
Accurate, Stable Measurements
Sensors are cosine-corrected to maintain their accuracy when radiation comes from low zenith angles. The sensors measure PPFD with a cosine response accurate within ± 5 % at 75° zenith angle. Long-term non-stability determined from multiple replicate quantum sensors in accelerated aging test and field conditions is less than 2 % per year.
PPFD measurements 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 PPFD in aquatic environments, including salt water aquariums where corals are grown.
Rugged, Self-cleaning Housing
Patented domed shaped sensor head (diffuser and body) facilitate runoff of dew and rain to keep the sensor clean and minimize errors caused by dust blocking the radiation path. Sensors are housed in a rugged anodized aluminum body and electronics are fully potted.
Ideal for Measurements in Air and Underwater
Apogee quantum sensor are calibrated to make absolute PPFD measurements in air. The waterproof sensors can be used to make absolute PPFD measurements underwater by applying an immersion effect correction factor, the SQ-420, SQ-520, MQ-210, and MQ-510 already apply the correction factor. For details on making underwater measurements, please refer to Underwater PAR Measurements.
To ensure accuracy each sensor is carefully calibrated in controlled conditions and traceable to NIST reference standards. The full-spectrum sensors are pre-calibrated for all light sources.
The AL-120 Solar Mounting Bracket with Leveling Plate facilitates mounting the sensor to a mast or pipe. The AL-100 Solar Sensor Leveling Plate is designed to level the sensor while sitting an a flat surface or mounting to a surface.
Available in multiple analog output option including 0 to 40 mV, 0 to 2.5 V, and 0 to 5 V. Additionally, a digital “smart“ sensor that uses USB cummunication and custom Software to interface directly to a computer is available. Sensors are also available attached to a hand-held meter with digital readout.
High Quality Cable
Pigtail-lead sensors feature an IP68, marine-grade stainless steel cable connector approximately 30 cm from the head to simplify sensor removal for maintenance and recalibration. Cable is shielded-twisted pair wire with a TPR jacket for high water resistance, UV stability, and flexibility in cold conditions.
Where is the MQ-500 used?
The MQ-500 is used to measure incoming PPFD measurements in outdoor environments, greenhouses, growth chambers, and aquariums.
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. This improved spectral response of this new meter increases the accuracy of LED measurements when compared to our previous original models.
Apogee MQ series quantum meters are designed for spot-check measurements, and calculation of daily light integral (DLI; total number of photons incident on a planar surface over the course of a day) through the built-in logging feature. To accurately measure PFFD incident on a horizontal surface, the sensor must be level. For this purpose, each MQ model comes with a different option for mounting the sensor to a horizontal plane.
The AM-320 Saltwater Submersible Sensor Wand accessory incorporates a mounting fixture at the end of a 40 inch segmented fiberglass wand and is well-suited for saltwater use. The wand allows the user to place the sensor in hard reach areas such as aquariums.
Operation and Measurement
MQ series quantum meters are designed with a user-friendly interface allowing quick and easy measurements.
To power the meter, slide the included battery (CR2320) into the battery holder, after removing the battery door from the meter’s back panel. The positive side (designated by a “+” sign) should be facing out from the meter circuit board.
- Press the power button to activate the LCD display. After two minutes of non-activity the meter will revert to sleep mode and the display will shut off to conserve battery life.
- Press the mode button to access the main menu, where manual or automatic logging are selected, and where the meter can be reset.
- Press the sample button to log a reading while taking manual measurements.
- Press the up button to make selections in the main menu. This button is also used to view and scroll through the logged measurements on the LCD display.
- Press the down button to make selections in the main menu. This button is also used to view and scroll through the logged measurements on the LCD display.
The LCD display consists of the total number of logged measurements in the upper right hand corner, the real-time PPFD value in the center, and the selected menu options along the bottom.
Logging: To choose between manual or automatic logging, push the mode button once and use the up/down buttons to make the appropriate selection (SMPL or LOG). Once the desired mode is blinking, press the mode button two more times to exit the menu. When in SMPL mode press the sample button to record up to 99 manual measurements (a counter in the upper right hand corner of the LCD display indicates the total number of saved measurements). When in LOG mode the meter will power 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 and will start to overwrite the oldest measurement once there are 99 measurements. Every 48 averaged measurements (making a 24 hour period), the meter will also store an integrated daily total in moles per meter squared per day (mol m-2 d-1).
Reset: To reset the meter, in either SMPL or LOG mode, push the mode button three times (RUN should be blinking), then while pressing the down button, press the mode button once. This will erase all of the saved measurements in memory, but only for the selected mode. That is, performing a reset when in SMPL mode will only erase the manual measurements and performing a reset when in LOG mode will only erase the automatic measurements.
Review/Download Data: Each of the logged measurements in either SMPL or LOG mode can be reviewed on the LCD display by pressing the up/down buttons. To exit and return to the real-time readings, press the sample button. Note that the integrated daily total values are not accessible through the LCD and can only be viewed by downloading to a computer.
Downloading the stored measurements will require the AC-100 communication cable and software (sold separately). The meter outputs data using the UART protocol and requires the AC-100 to convert from UART to USB, so standard USB cables will not work.
Set up instructions and software can be downloaded from the Apogee website.
Immersion Effect Correction Factor
When a radiation sensor is submerged in water, more of the incident radiation is backscattered out of the diffuser than when the sensor is in air (Smith, 1969; Tyler and Smith, 1970). This phenomenon is caused by the difference in the refractive index for air (1.00) and water (1.33), and is called the immersion effect. Without correction for the immersion effect, radiation sensors calibrated in air can only provide relative values underwater (Smith, 1969; Tyler and Smith, 1970). Immersion effect correction factors can be derived by making measurements in air and at multiple water depths at a constant distance from a lamp in a controlled laboratory setting.
Apogee SQ-500 series quantum sensors have an immersion effect correction factor of 1.32. This correction factor should be multiplied by PPFD measurements made underwater to yield accurate PPFD.
Further information on underwater measurements and the immersion effect can be found on the Apogee webpage.
126 x 70 x 24 mm
0 to 4000 µmol m¯² s¯¹
389 to 692 nm ± 5 nm (wavelengths where response is greater than 50 % of maximum).
|Long-term Drift (Non-stability):||
Less than 2 % per year
Less than 1 ms
Less than 10 % from 412 to 682 nm ± 5 nm
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.
24 mm diameter
2 m of shielded, twisted-pair wire with santoprene rubber jacket (high water resistance, high UV stability, flexibility in cold conditions), additional cable available.