Apogee Instruments SQ-646 User manual

APOGEE INSTRUMENTS, INC. | 721 WEST 1800 NORTH, LOGAN, UTAH 84321, USA
TEL: [phone] | FAX: [phone] | WEB: APOGEEINSTRUMENTS.COM
Copyright © 2021 Apogee Instrument, Inc.
OWNER’S MANUAL
QUANTUM LIGHT POLLUTION
SENSOR
Model SQ-646
Rev: 4-Oct-2021

TABLE OF CONTENTS
Owner’s Manual ............................................................................................................................................................................... 1
Certificate of Compliance............................................................................................................................................................. 3
Introduction.................................................................................................................................................................................. 4
Sensor Models.............................................................................................................................................................................. 5
Specifications................................................................................................................................................................................ 6
Deployment and Installation ........................................................................................................................................................ 8
Software Installation .................................................................................................................................................................... 9
Operation and Measurement..................................................................................................................................................... 10
Windows Software ..................................................................................................................................................................... 11
Mac Software ............................................................................................................................................................................. 16
Maintenance and Recalibration ................................................................................................................................................. 22
Troubleshooting and Customer Support .................................................................................................................................... 23
Return and Warranty Policy ....................................................................................................................................................... 24

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-646
Type: Quantum Light Pollution 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 we rely on the information provided to us by our material suppliers.
Signed for and on behalf of:
Apogee Instruments, October 2021
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) 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). However,
ultraviolet and far-red photons outside the defined PAR range of 400-700 nm can also contribute to
photosynthesis and influence plant responses (e.g., flowering).
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. Sensors that function like
traditional quantum sensors but measure a wider range of wavelengths can be thought of as an ‘extended range’
quantum sensor.
Typical applications of traditional 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. The Extended Range PFD Sensor detailed in this manual uses a detector
that is sensitive to radiation up to about 1100 nm, well beyond the range of wavelengths that influence
photosynthesis and plant responses. This means this particular sensor should only be used for photon flux
density measurements under LEDs.
Apogee Instruments SQ-600 series Quantum Light Pollution Sensors consist of a cast acrylic diffuser (filter),
photodiode, and signal processing circuitry mounted in an anodized aluminum housing, and a cable to connect the
sensor to a measurement device. SQ-600 series sensors are designed for continuous photon flux density
measurements in indoor environments under LEDs. The SQ-640 Quantum Light Pollution models output a voltage
that is directly proportional to photon flux density.

SENSOR MODELS
This manual covers the USB Quantum Light Pollution sensor, model SQ-646 (listed in bold below). Additional
models are covered in their respective manuals.
Model
Signal
SQ-640
Self-powered
SQ-642
0-2.5 V
SQ-644
4-20 mA
SQ-645
0-5 V
SQ-646
USB
SQ-647
SDI-12
SQ-648
Modbus
A sensor’s model number and serial number are
located on the bottom of the sensor. 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-600 series quantum light pollution sensors are calibrated through side-by-side comparison
to the mean of four transfer standard quantum light pollution sensors under a reference lamp. The transfer
standard quantum light pollution sensors are recalibrated with a quartz halogen lamp traceable to the National
Institute of Standards and Technology (NIST).
SQ-646
Resolution
0.1 µmol m-2 s-1
Calibration Factor
Custom for each sensor and stored in the firmware
Calibration Uncertainty
± 5 % (see calibration Traceability below)
Measurement Range
0 to 200 µmol m-2 s-1
Measurement Repeatability
Less than 0.5 %
Long-term Drift
(Non-stability)
Less than 2 % per year
Non-linearity
Less than 1 % (up to 200 µmol m-2 s-1)
Response Time
Software updates every second
Field of View
180°
Spectral Range
340 to 1040 nm ± 5 nm (wavelengths where response is greater than 50 %; see Spectral
Response below)
Directional (Cosine) Response
± 2 % at 45° zenith angle, ± 5 % at 75° zenith angle (see Cosine Response below)
Temperature Response
-0.11± 0.04 % per C
Azimuth Error
Less than 0.5 %
Tilt Error
Less than 0.5 %
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
30.5 mm diameter, 37 mm height
Mass (with 5 m of cable)
140 g
USB Cable
4.5 m (15 ft)
Current Draw (when Logging)
61 mA

Spectral Response
Cosine Response
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.
Mean spectral response measurements of
six replicate Apogee SQ-600 series Extended
Range PFD Sensors. Spectral response
measurements were made at 10 nm
increments across a wavelength range of
300 to 1100 nm in a monochromator with
an attached electric light source. Measured
spectral data from each PFD sensor were
normalized by the measured spectral
response of the monochromator/electric
light combination, which was measured with
a spectroradiometer
Directional, or cosine, response is defined as the
measurement error at a specific angle of radiation
incidence. Error for Apogee SQ-600 series Quantum Light
Pollution Sensor is approximately ± 2 % and ± 5 % at solar
zenith angles of 45° and 75°, respectively.
Mean spectral response measurements of
six replicate Apogee SQ-600 series Quantum
Light Pollution Sensors. Spectral response
measurements were made at 10 nm
increments across a wavelength range of
300 to 1100 nm in a monochromator with
an attached electric light source. Measured
spectral data from each quantum light
pollution sensor were normalized by the
measured spectral response of the
monochromator/electric light combination,
which was measured with a
spectroradiometer

DEPLOYMENT AND INSTALLATION
Mount the sensor to a solid surface with the nylon mounting screw provided. To accurately measure photon flux
density 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 AL-
120 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 blue cap should be removed from the sensor. The blue 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-100
Model: AL-120
Nylon Screw: 10-32 x 3/8

SOFTWARE INSTALLATION
The most recent version of ApogeeConnect software can be downloaded at
http://www.apogeeinstruments.com/downloads/.
Installing the software on a PC (Windows compatible, XP and later)
1. Double click on the installer package:
2. On the ‘Welcome’ screen, please click ‘Next’ to continue.
3. Select the radio button next to “I Agree” to the UELA… and click ‘Next’ to continue.
4. On the ‘Ready to Install the Program’ screen, click ‘Install’ to continue.
5. Click ‘Finish’ to complete the installation. There are shortcuts on your desktop and in your start bar.
Installing the software on a Mac (Mac compatible, 10.10 and later)
1. Double click on the installer package
2. On the ‘Introduction’ screen, please click ‘Continue’ to proceed.
3. Select ‘Continue’ on the ‘Read Me’ screen to continue, this screen contains a history of updates made to
the ApogeeConnect software versions.
4. Select ‘Continue’ on the ‘License’ screen to receive a prompt to agree to the terms of the software license
agreement. Click ‘Agree’ to continue once you receive the prompt.
5. On the ‘Installation Type’ screen, click ‘Install’ to install the software. You can change the location the
software installs to by clicking ‘Change Install Location…’. *Note: You may be prompted for an
administrator password at this time. If you are, proceed by entering your respective password and clicking
‘Install Software’.
6. Once you receive the message “The installation was successful.” on the ‘Summary’ screen click ‘Close’.
Your software is now ready to be used.

OPERATION AND MEASUREMENT
Low Light Measurements
Accurate low light measurements are required in flowering and light pollution studies. Research indicates
flowering can be triggered in some plants at photosynthetic and/or far-red photon flux densities less than 0.1 mol
m-2 s-1. The threshold photon flux density at which flowering is triggered is variable among species. Two of the
most light-sensitive species are Poinsettias and Cannabis. For reference, photon flux density of moonlight when
the moon is full and near the minimum zenith angle is 0.005 mol m-2 s-1.
The model SQ-620 Extended Range Quantum Sensor can measure a photon flux density range of 0-4000 mol m-2
s-1. The model SQ-640 Quantum Light Pollution Sensor is designed for low light measurements and can only
measure a photon flux density range of 0-200 mol m-2 s-1 (the sensor will output values beyond, 200 mol m-2 s-1,
but these are beyond the linear range of the sensor) and is referred to as the low light version. The sensitivity of
the SQ-640 is twenty times higher than the sensitivity of the SQ-620 (1 mV per mol m-2 s-1 versus 0.05 mV per
mol m-2 s-1) to provide greater measurement resolution under low light conditions. For example, if the photon
flux density were 0.1 mol m-2 s-1, the SQ-640 would output 0.1 mV, whereas the SQ-620 would output 0.005 mV.