Apogee SQ-500 Series User manual

APOGEE INSTRUMENTS, INC. | 721 WEST 1800 NORTH, LOGAN, UTAH 84321, USA
TEL: [phone] | FAX: [phone] | WEB: APOGEEINSTRUMENTS.COM
Copyright © 2020 Apogee Instruments, Inc.
OWNER’S MANUAL
QUANTUM SENSOR
Model SQ-500
(including SS model, formerly gold)

TABLE OF CONTENTS
Owner’s Manual ............................................................................................................................................................................... 1
Certificate of Compliance......................................................................................................................................................... 3
Introduction ............................................................................................................................................................................. 4
Sensor Models ......................................................................................................................................................................... 5
Specifications ........................................................................................................................................................................... 6
Deployment and Installation.................................................................................................................................................... 9
Cable Connectors................................................................................................................................................................... 10
Operation and Measurement ................................................................................................................................................ 11
Maintenance and Recalibration............................................................................................................................................. 17
Troubleshooting and Customer Support................................................................................................................................ 19
Return and Warranty Policy................................................................................................................................................... 20

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: SQ-500
Type: Quantum Sensor
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 50581:2012 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 rely on the information provided to us by our material suppliers.
Signed for and on behalf of:
Apogee Instruments, June 2020
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 almost universally quantified as photosynthetic photon flux
density (PPFD), the sum of photons from 400 to 700 nm in units of micromoles per square meter per second (µmol
m-2 s-1, equal to microEinsteins m-2 s-1). While microEinsteins 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. Daily total PPFD is typically
reported in units of moles of photons per square meter per day (mol m-2 d-1) and is often called daily light integral
(DLI).
The acronym PPF is also used and refers to the photosynthetic photon flux. The acronyms PPF and PPFD refer to
the same variable. Both terms are used because there is not a universal definition of the term flux. Flux is
sometimes defined as per unit area per unit time and sometimes defined as per unit time only. PPFD is used in this
manual.
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 measurement of incident PPFD on 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 SQ-500 series quantum sensors consist of a cast acrylic diffuser (filter), interference filter,
photodiode, and signal processing circuitry mounted in an anodized aluminum housing, and a cable to connect the
sensor to a measurement device. SQ-500 series quantum sensors are designed for continuous PPFD measurement
in indoor or outdoor environments. The SQ-500 model quantum sensor outputs a voltage that is directly
proportional to PPFD. The voltage output by the sensor is directly proportional to radiation incident on a planar
surface (does not have to be horizontal), where the radiation emanates from all angles of a hemisphere.

SENSOR MODELS
This manual covers the unamplified analog output quantum sensor, model SQ-500 (listed in bold below).
Additional models are covered in their respective manuals.
Model
Signal
SQ-500
0-40 mV
SQ-512
0-2.5 V
SQ-515
0-5 V
SQ-520
USB
SQ-521
SDI-12
SQ-522
Modbus
Sensor model number and serial number are
located near the pigtail leads on the sensor cable.
If the manufacturing date of a specific sensor is
required, please contact Apogee Instruments
with the serial number of the sensor.

SPECIFICATIONS
Calibration Traceability
Apogee Instruments SQ-500 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 quartz halogen lamp traceable to the National Institute of Standards and Technology (NIST).
SQ-500-SS
Power Supply
Self-powered
Sensitivity
0.01 mV per µmol m-2 s-1
Calibration Factor
100 µmol m-2 s-1 per mV
Calibration Uncertainty
± 5 % (see Calibration Traceability below)
Measurement Range
0 to 4000 µmol m-2 s-1
Measurement
Repeatability
Less than 0.5 %
Calibrated Output Range
0 to 40 mV
Long-term Drift
(Non-stability)
Less than 2 % per year
Non-linearity
Less than 1 % (up to 4000 µmol m-2 s-1)
Response Time
Less than 1 ms
Field of View
180°
Spectral Range
389 to 692 nm ± 5 nm (wavelengths where response is greater than 50 %)
Spectral Selectivity
Less than 10 % from 412 to 682 ± 5 nm (see Spectral Response below)
Directional (Cosine)
Response
± 2 % at 45° zenith angle, ± 5 % at 75° zenith angle (see Directional Response below)
Azimuth Error
Less than 0.5 %
Tilt Error
Less than 0.5 %
Temperature Response
-0.11 ± 0.04 % per C (see Temperature Response below)
Uncertainty in Daily Total
Less than 5 %
Detector
Blue-enhanced silicon photodiode
Housing
Anodized aluminum body with acrylic diffuser
IP Rating
IP68
Operating Environment
-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
Mass (with 5 m of cable)
100 g
Cable
5 m of two conductor, shielded, twisted-pair wire; TPR jacket; pigtail lead wires; stainless steel
(316), M8 connector located 25 cm from sensor head

Spectral Response
Temperature Response
Mean temperature response of ten SQ-500
series quantum sensors (errors bars represent
two standard deviations above and below
mean). Temperature response measurements
were made at 10 C intervals across a
temperature range of approximately -10 to 40
C in a temperature controlled chamber under
a fixed, broad spectrum, electric lamp. At each
temperature set point, a spectroradiometer
was used to measure light intensity from the
lamp and all quantum sensors were compared
to the spectroradiometer. The
spectroradiometer was mounted external to
the temperature control chamber and
remained at room temperature during the
experiment.
Mean spectral response measurements of six
replicate Apogee SQ-100 (original) and SQ-500
(full-spectrum) series quantum sensors.
Spectral response measurements were made
at 10 nm increments across a wavelength
range of 300 to 800 nm with a
monochromator and 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
Mean directional (cosine) response
of seven apogee SQ-500 series
quantum sensors. Directional
response measurements were made
on the rooftop of the Apogee
building in Logan, Utah. Directional
response was calculated as the
relative difference of SQ-500
quantum sensors from the mean of
replicate reference quantum sensors
(LI-COR models LI-190 and LI-190R,
Kipp & Zonen model PQS 1). Data
were also collected in the laboratory
using a reference lamp and
positioning the sensor at varying
angles.
Directional (cosine) response is defined as the measurement
error at a specific angle of radiation incidence. Error for
Apogee SQ-500 series quantum sensors is approximately ± 2
% and ± 5 % at solar zenith angles of 45° and 75°,
respectively.

Important: Only use the nylon screw provided
when mounting to insulate the non-anodized
threads of the aluminum sensor head from the
base to help prevent galvanic corrosion. For
extended submersion applications, more insulation
may be necessary. Contact Apogee tech support for
details.
DEPLOYMENT AND INSTALLATION
Mount the sensor to a solid surface with the nylon mounting screw provided. To accurately measure PPFD incident
on a horizontal surface, the sensor must be level. An Apogee Instruments model AL-100 leveling plate is
recommended for this purpose. To facilitate mounting on a cross arm, an Apogee Instruments model AM-110
mounting bracket is recommended.
To minimize azimuth error, the sensor should be mounted with the cable pointing toward true north in the
northern hemisphere or true south in the southern hemisphere. Azimuth error is typically less than 0.5 %, but it is
easy to minimize by proper cable orientation.
In addition to orienting the cable to point toward the nearest pole, the sensor should also be mounted such that
obstructions (e.g., weather station tripod/tower or other instrumentation) do not shade the sensor. Once
mounted, the green cap should be removed from the sensor. The green cap can be used as a protective covering
for the sensor when it is not in use.
Nylon Screw: 10-32 x 3/8
Model: AL-110
Model: AL-120
Nylon Screw: 10-32 x 3/8

CABLE CONNECTORS
Apogee started offering in-line cable connectors on
some bare-lead wire sensors in March 2018 to simplify
the process of removing sensors from installations for
recalibration (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 30 cm from the
sensor 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 connection to a measurement
device, the unused pigtail lead wire colors are
removed.
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 an installation, 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 back for recalibration, only send the
section of cable that is hard-wired to the sensor. The
section of cable with the pigtail is not required.
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, one to two
threads may still be visible.
WARNING: Do not tighten the connector by twisting
the black cable, only twist the metal connector.
Finger-tighten firmly.