Apogee Instruments APOGEE LINE QUANTUM User manual

APOGEE INSTRUMENTS, INC. | 721 WEST 1800 NORTH, LOGAN, UTAH 84321, USA
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Copyright © 2022 Apogee Instruments, Inc.
OWNER’S MANUAL
APOGEE LINE QUANTUM
Models MQ-301X and SQ-301X
Rev: 30-Aug-2022

TABLE OF CONTENTS

CERTIFICATE OF COMPLIANCE
EU Declaration of Conformity
This declaration of conformity is issued under the sole responsibility of the manufacturer:
Apogee Instruments, Inc.
721 W 1800 N
Logan, Utah 84321
USA
for the following product(s):
Models: MQ-301X, SQ-301X
Type: Line Quantum
The object of the declaration described above is in conformity with the relevant Union harmonization legislation:
2014/30/EU Electromagnetic Compatibility (EMC) Directive
2011/65/EU Restriction of Hazardous Substances (RoHS 2) Directive
2015/863/EU Amending Annex II to Directive 2011/65/EU (RoHS 3)
Standards referenced during compliance assessment:
EN 61326-1:2013 Electrical equipment for measurement, control, and laboratory use –EMC requirements
EN 63000:2018 Technical documentation for the assessment of electrical and electronic products with
respect to the restriction of hazardous substances
Please be advised that based on the information available to us from our raw material suppliers, the products
manufactured by us do not contain, as intentional additives, any of the restricted materials including lead (see
note below), mercury, cadmium, hexavalent chromium, polybrominated biphenyls (PBB), polybrominated
diphenyls (PBDE), bis (2-ethylhexyl) phthalate (DEHP), butyl benzyl phthalate (BBP), dibutyl phthalate (DBP), and
diisobutyl phthalate (DIBP). However, please note that articles containing greater than 0.1 % lead concentration
are RoHS 3 compliant using exemption 6c.
Further note that Apogee Instruments does not specifically run any analysis on our raw materials or end products
for the presence of these substances, but we rely on the information provided to us by our material suppliers.
Signed for and on behalf of:
Apogee Instruments, August 2022
Bruce Bugbee
President
Apogee Instruments, Inc.

CERTIFICATE OF COMPLIANCE
UK Declaration of Conformity
This declaration of conformity is issued under the sole responsibility of the manufacturer:
Apogee Instruments, Inc.
721 W 1800 N
Logan, Utah 84321
USA
for the following product(s):
Models: MQ-301X, SQ-301X
Type: Line Quantum
The object of the declaration described above is in conformity with the relevant UK Statutory Instruments and
their amendments:
2016 No. 1091 The Electromagnetic Compatibility Regulations 2016
2012 No. 3032 The Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic
Equipment Regulations 2012
Standards referenced during compliance assessment:
BS EN 61326-1:2013 Electrical equipment for measurement, control, and laboratory use –EMC requirements
BS EN 63000:2018 Technical documentation for the assessment of electrical and electronic products with
respect to the restriction of hazardous substances
Please be advised that based on the information available to us from our raw material suppliers, the products
manufactured by us do not contain, as intentional additives, any of the restricted materials including lead (see
note below), mercury, cadmium, hexavalent chromium, polybrominated biphenyls (PBB), polybrominated
diphenyls (PBDE), bis (2-ethylhexyl) phthalate (DEHP), butyl benzyl phthalate (BBP), dibutyl phthalate (DBP), and
diisobutyl phthalate (DIBP). However, please note that articles containing greater than 0.1 % lead concentration
are RoHS 3 compliant using exemption 6c.
Further note that Apogee Instruments does not specifically run any analysis on our raw materials or end products
for the presence of these substances, but we rely on the information provided to us by our material suppliers.
Signed for and on behalf of:
Apogee Instruments, August 2022
Bruce Bugbee
President
Apogee Instruments, Inc.

INTRODUCTION
Radiation that drives photosynthesis is called photosynthetically active radiation (PAR) and is typically defined as
total radiation across a range of 400 to 700 nm. PAR is often expressed as photosynthetic photon flux density
(PPFD): photon flux in units of micromoles per square meter per second (µmol m-2 s-1, equal to microEinsteins per
square meter per second) summed from 400 to 700 nm (total number of photons from 400 to 700 nm). While
Einsteins and micromoles are equal (one Einstein = one mole of photons), the Einstein is not an SI unit, so
expressing PPFD as µmol m-2 s-1 is preferred.
The acronym PPF is also widely used and refers to the photosynthetic photon flux. The acronyms PPF and PPFD
refer to the same parameter. The two terms have co-evolved because there is not a universal definition of the
term “flux”. Some physicists define flux as per unit area per unit time. Others define flux only as per unit time.
We have used PPFD in this manual because we feel that it is better to be more complete and possibly redundant.
Sensors that measure PPFD are often called quantum sensors due to the quantized nature of radiation. A quantum
refers to the minimum quantity of radiation, one photon, involved in physical interactions (e.g., absorption by
photosynthetic pigments). In other words, one photon is a single quantum of radiation.
Typical applications of quantum sensors include incoming PPFD measurement over plant canopies in outdoor
environments or in greenhouses and growth chambers and reflected or under-canopy (transmitted) PPFD
measurement in the same environments.
Apogee Instruments MQ-301X line quantum consists of a separated sensor bar with 10 sensors connected to a
hand-held meter via cable. The SQ-301X line quantum consists of the sensor bar with 10 sensors and pre-tinned
pigtail leads. The sensor housing design features an integrated bubble level to ensure level deployment. The
sensors consist of a cast acrylic diffuser (filter) and photodiode, and the sensors are potted solid with no internal
air space. The meter provides a real-time PPFD reading on the LCD display and offers measurements for both
sunlight and electric light calibrations (menu selectable) that determine the radiation incident on a planar surface
(does not have to be horizontal), where the radiation emanates from all angles of a hemisphere. MQ X series line
quantum meters include manual and automatic data logging features for making spot-check measurements or
calculating daily light integral (DLI).

SENSOR MODELS
The Apogee MQ-310X line quantum meter covered in this manual is self-contained and comes complete with a
handheld meter and line of 10 sensors. The SQ-301X line quantum sensor comes with a line of 10 sensors and pre-
tinned pigtail leads.
Line quantum sensors provide spatially averaged PPFD measurements. All sensors along the length of the line are
connected in parallel, and as a result, Apogee line quantum meters display PPFD values that are averaged from the
location of the individual sensors.
A meter’s model number and serial number are
located on a label on the backside of the handheld
meter.
SQ-310X: Line quantum with 10 sensors and
cable with pre-tinned pigtail leads
MQ-310X: Line quantum with 10 sensors and
handheld meter
A sensor’s model number and serial number are
located near the pigtail leads on the sensor cable. If
you need the manufacturing date of your sensor,
please contact Apogee Instruments with the serial
number of your sensor.

SPECIFICATIONS
Calibration Traceability
Apogee SQX series quantum sensors are calibrated through side-by-side comparison to the mean of four transfer
standard quantum sensors under a reference lamp. The reference quantum sensors are recalibrated with a 200 W
quartz halogen lamp traceable to the National Institute of Standards and Technology (NIST).
MQ-301X
SQ-301X
Sensitivity
-
0.1 mV per µmol m-2 s-1
Calibrated Output
Range
-
0 to 250 mV
Calibration
Uncertainty
± 5 % (see calibration Traceability below)
Measurement
Repeatability
Less than 0.5 %
Long-term Drift
(Non-stability)
Less than 2 % per year
Non-linearity
Less than 1 % (up to 2500 µmol m-2 s-1)
Response Time
Less than 1 ms
Field of View
180°
Spectral Range
370 to 650 nm (wavelengths where response is greater than 50 % of maximum;
see Spectral Response graph)
Directional (Cosine)
Response
± 5 % at 75° zenith angle (see Cosine Response graph)
Temperature
Response
-0.04 % per C
Operating
Environment
-10 to 60 C; 0 to 100 % relative humidity; sensor can be submerged in water up to
depths of 30 m
Meter Dimensions
113.9 mm height; 59.9 mm width
-
Sensor Dimensions
616.4 mm length, 13.6 mm height, 16.5 mm width
Mass
460 g
310 g
Cable
2 m of shielded, twisted-pair wire; TPR
jacket (high water resistance, high UV
stability, flexibility in cold conditions)
5 m of two conductor, shielded, twisted-
pair wire; TPR jacket; pigtail lead wires;
stainless steel, M8 connector located 25
cm from sensor head

Spectral Response
Mean spectral response of four SQ-100X
series quantum sensors compared to PPFD
weighting function. Spectral response
measurements were made at 10 nm
increments across a wavelength range of
350 to 800 nm in a monochromator with
an attached electric light source. Measured
spectral data from each quantum sensor
were normalized by the measured spectral
response of the monochromator/electric
light combination, which was measured
with a spectroradiometer.

Cosine Response
Directional (cosine) response is defined as
the measurement error at a specific angle of
radiation incidence. Error for Apogee SQ-
100X series quantum sensors is
approximately ± 2 % and ± 5 % at solar zenith
angles of 45° and 75°, respectively.
Mean cosine response of five SQ-
100X series quantum sensors.
Cosine response measurements
were made by direct side-by-side
comparison to the mean of seven
reference SQ-500 quantum
sensors.

DEPLOYMENT AND INSTALLATION
Apogee MQ X series line quantums 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 bar must be level.
Line quantum sensors are leveled using the built-in bubble level located in the handle of the sensor. In addition to
leveling, all sensors should also be mounted such that obstructions (e.g., weather station tripod/tower or other
instrumentation) do not shade the sensor.
NOTE: The handheld meter portion of the instrument is not waterproof. Do not get the meter wet or leave the
meter in high humidity environments for prolonged periods of time. Doing so can lead to corrosion that could void
the warranty.

BATTERY INSTALLATION AND REPLACEMENT
Use a Phillips head screwdriver to remove the screw from the battery cover on the meter. Remove the battery
cover by slightly lifting and sliding the outer edge of the cover away from the meter.
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.
NOTE: The battery cradle can be damaged by using an incorrectly sized battery. If the battery cradle is damaged,
the circuit board will need to be replaced and the warranty will be void. To avoid this costly problem, use only a
CR2320 battery.
Battery Removal
Press down on the battery with a screwdriver or similar object. Slide battery out.
If the battery is difficult to move, turn the meter on its side so that the opening for the battery is facing downward
and tap the meter downward against an open palm to dislodge the battery enough so that it can be removed with
your thumb to slide the battery out of the battery holder.

CABLE CONNECTORS
Apogee sensors offer cable connectors to simplify the
process of removing sensors from weather stations
for calibration (the entire cable does not have to be
removed from the station and shipped with the
sensor).
The ruggedized M8 connectors are rated IP68, made
of corrosion-resistant marine-grade stainless-steel,
and designed for extended use in harsh
environmental conditions.
Inline cable connectors are installed 25 cm from the
head
Instructions
Pins and Wiring Colors: All Apogee connectors have
six pins, but not all pins are used for every sensor.
There may also be unused wire colors inside the
cable. To simplify datalogger connection, we remove
the unused pigtail lead colors at the datalogger end
of the cable.
If a replacement cable is required, please contact
Apogee directly to ensure ordering the proper pigtail
configuration.
Alignment: When reconnecting a sensor, arrows on
the connector jacket and an aligning notch ensure
proper orientation.
Disconnection for extended periods: When
disconnecting the sensor for an extended period of
time from a station, protect the remaining half of the
connector still on the station from water and dirt
with electrical tape or other method.
A reference notch inside the connector ensures
proper alignment before tightening.
When sending sensors in for calibration, only send the
short end of the cable and half the connector.
Tightening: Connectors are designed to be firmly
finger-tightened only. There is an o-ring inside the
connector that can be overly compressed if a wrench
is used. Pay attention to thread alignment to avoid
cross-threading. When fully tightened, 1-2 threads
may still be visible.
Finger-tighten firmly

OPERATION AND MEASUREMENT
Connect the sensor to a measurement device (meter, datalogger, controller) capable of measuring and displaying
or recording a millivolt signal (an input measurement range of approximately 0-500 mV is required to cover the
entire range of PPFD from the sun). In order to maximize measurement resolution and signal-to-noise ratio, the
input range of the measurement device should closely match the output range of the quantum sensor. DO NOT
connect the sensor to a power source. The sensor is self-powered and applying voltage will damage the sensor.
Wiring for SQ-301X:
White: Positive (signal from sensor)
Black: Negative (signal from sensor)
Clear: Shield/Ground

MQ X series line quantum meters are designed with a user-friendly interface allowing quick and easy
measurements.
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 the appropriate calibration (sunlight or electric
light) and 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.
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 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.
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.

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 (http://www.apogeeinstruments.com/ac-100-communcation-cable/).

Sensor Calibration
The MQ-301X quantum X line sensors have a standard PPFD calibration factor of exactly:
10.0 µmol m-2 s-1 per mV
Multiply this calibration factor by the measured mV signal to convert sensor output to PPFD in units of µmol m-2 s-1:
Calibration Factor (10.0 µmol m-2 s-1 per mV) * Sensor Output Signal (mV) = PPFD (µmol m-2 s-1)
10.0 * 200 = 2000
Example of PPFD measurement with an Apogee
quantum sensor. Full sunlight yields a PPFD on
a horizontal plane at the Earth’s surface of
approximately 2000 µmol m-2 s-1. This yields an
output signal of 200 mV. The signal is
converted to PPFD by multiplying by the
calibration factor of 10.00 µmol m-2 s-1 per mV.
Sensor Output
200 mV
Full Sunlight
(2000 µmol m-2 s-1)

Spectral Error
Apogee SQ-301X sensors can measure PPFD for sunlight and electric light with a single calibration factor. However,
errors occur in various light sources due to changes in spectral output. If the light source spectrum is known, then
errors can be estimated and used to adjust the measurements. The weighting function for PPFD is shown in the
graph below, along with the spectral response of Apogee MQ-301X series quantum sensors. The closer the spectral
response matches the defined PPFD spectral weighting functions, the smaller spectral errors will be. The table
below provides spectral error estimates for PPFD measurements from light sources different than the calibration
source. The method of Federer and Tanner (1966) was used to determine spectral errors based on the PPFD
spectral weighting functions, measured sensor spectral response, and radiation source spectral outputs (measured
with a spectroradiometer). This method calculates spectral error and does not consider calibration, cosine, and
temperature errors.
Federer, C. A., and C. B. Tanner, 1966. Sensors for measuring light available for photosynthesis. Ecology 47:654-
657.
McCree, K. J., 1972. The action spectrum, absorptance and quantum yield of photosynthesis in crop plants.
Agricultural Meteorology 9:191-216.
Spectral Errors for PPFD Measurements with Apogee SQ-100X Series Quantum Sensors
Radiation Source (Error Calculated Relative to Sun, Clear Sky)
PPFD Error [%]
Sun (Clear Sky)
0.0
Sun (Cloudy Sky)
0.2
Reflected from Grass Canopy
5.0
Reflected from Deciduous Canopy
7.0
Reflected from Conifer Canopy
7.3
Transmitted below Grass Canopy
8.3
Transmitted below Deciduous Canopy
8.4
Transmitted below Conifer Canopy
10.1
Cool White Fluorescent (T5)
7.2
Cool White Fluorescent (T12)
8.3
Metal Halide
6.9
Ceramic Metal Halide
-0.9
High Pressure Sodium
3.2
Blue LED (448 nm peak, 20 nm full-width half-maximum)
14.5
Green LED (524 nm peak, 30 nm full-width half-maximum)
29.6
Red LED (635 nm peak, 20 nm full-width half-maximum)
-30.9
Red, Blue LED Mixture (80 % Red, 20 % Blue)
-21.2
Red, Green, Blue LED Mixture (70 % Red, 15 % Green, 15 % Blue)
-16.4
Cool White Fluorescent LED
7.3
Neutral White Fluorescent LED
1.1
Warm White Fluorescent LED
-7.8
Quantum sensors can be a very practical means of measuring PPFD and YPFD from multiple radiation sources, but
spectral errors must be considered. The spectral errors in the table above can be used as correction factors for
individual radiation sources.

Underwater Measurements and Immersion Effect
When a quantum sensor that was calibrated in air is used to make underwater measurements, the sensor reads
low. This phenomenon is called the immersion effect and happens because the refractive index of water (1.33) is
greater than air (1.00). The higher refractive index of water causes more light to be backscattered (or reflected)
out of the sensor in water than in air (Smith,1969; Tyler and Smith,1970). As more light is reflected, less light is
transmitted through the diffuser to the detector, which causes the sensor to read low. Without correcting for this
effect, underwater measurements are only relative, which makes it difficult to compare light in different
environments.
The Apogee line quantum has an immersion effect correction factor of 1.15. This correction factor should be
multiplied to measurements made underwater.
NOTE: The handheld meter portion of the instrument is not waterproof. Do not get the meter wet or leave the
meter in high humidity environments for prolonged periods of time. Doing so can lead to corrosion that could void
the warranty.
Further information on underwater measurements and the immersion effect can be found at
http://www.apogeeinstruments.com/underwater-par-measurements/.
Smith, R.C., 1969. An underwater spectral irradiance collector. Journal of Marine Research 27:341-351.
Tyler, J.E., and R.C. Smith, 1970. Measurements of Spectral Irradiance Underwater. Gordon and Breach, New York,
New York. 103 pages

APOGEE AMS SOFTWARE
Downloading data to a computer requires the AC-100 communication cable and the free ApogeeAMS software.
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.
The most recent version of ApogeeAMS software can be downloaded at
http://www.apogeeinstruments.com/downloads/.
When the ApogeeAMS software is first opened, it will
show a blank screen until communication with the meter
is established. If you click “Open Port” it will say
“connection failed.”
To establish communication, make sure the meter is
plugged into your computer using the AC-100
communication cable. To connect click the dropdown
menu button and “COM#” options will appear. For more
details on how to figure out which COM is the right one,
watch our video.
When you have connected to the correct COM#, the
software will say “Connected”.
Click “Sample Data” to view saved sample readings.

“Daily Totals” shows all the saved Daily Light Integral
(DLI) totals per day.
Click “30 Min Avg” to see the meter’s 99, 30-minute
averages.
To analyze the data, click on “File” and “Save As” to save
the data as a .csv file.
Or you can highlight the numbers, copy, and paste them
into a blank Excel spreadsheet. Data will need to be
comma delimited.