Q-Series sensors
Biospherical Instruments offers a variety of small, single-channel radiometers for use in the laboratory; deployment with profilers, CTDs, gliders, floats, research vessels, and meteorological stations; use in aquaculture and biofuel plants; and for many other marine or terrestrial applications. The instruments are available in a large number of configurations with respect to directional response, depth rating, signal output, packaging, cabling, and accessories.
Our Q-Series sensors measure Photosynthetically Active Radiation (PAR) to identify the amount of usable light for photosynthesis. Quantifying this input gives our customers better awareness of the health and productivity potential within their environment.
A variety of our sensors have been interfaced with Sea-Bird CTD and data logging systems including the QSP, QCP, QSR, and QCR. For customers wishing to integrate a Q-Series sensor to a Sea-Bird CTD, please consult Sea-Bird for the proper sensor selection, as there are specific requirements for compatibility.
Selection Guide for Single-Channel Sensors
Overview
Q-Series single-channel sensors are available in a large number of configurations. Measurement geometries include cosine irradiance and scalar irradiance, and can be optimized for in-water or terrestrial observations. Depending on the model, measurements are outputted as either a digital data stream, or as "linear analog" or "logarithmic analog" signals.
| QSP | QSL | QSR | QCP | QCR | |
|---|---|---|---|---|---|
| Spectral Response | PAR | PAR | PAR | PAR | PAR |
| Collector | Scalar | Scalar | Scalar | Cosine | Cosine |
| Environment/ Depth | 2,000 m | Laboratory (QSL), 2000 m (QSPL) | Terrestrial | 2,000 m, 10,000 m. (Model dependent) | Terrestrial |
| Digital ASCII Output | QSP-2150 | QSL-2150, QSL-2151, QSPL-2150, QSPL-2151 | QSR-2150 | QCP-2150 | QCR-2150 |
| Linear Analog Output | QSP-2250 | QSL-2200, QSL-2201 | QSR-2200 | QCP-2250 | QCR-2200 |
| Logarithmic Analog Output (Log) | QSP-2350 | QCP-2350 |
QSP Series
QSP sensors are designed to measure scalar irradiance with a PAR response in natural waters to depths of up to 2,000 m.
The QSP series can be configured to output data in one of three options. Choose between digital ASCII (-2150), linear analog (-2250), and compressed analog (-2350) output.
These sensors use marine grade connector SubConn MCBH4M, which we rate to 2000m.
Note that the depth rating of all QSP sensors is 2,000 m, because the scalar collector can only withstand pressures of less than 3000 psi. For greater depths, use a QCP-2350-HP sensor.
QSL Series
QSL sensors measure scalar irradiance with a PAR response. These Sensors are optimized for laboratory use due to their lightweight hard resin housing and splash-proof integrated USB cable. The small size and convenient hand wand enable QSL scalar sensors to provide accurate light measurements from virtually all directions in the field or in the laboratory. The 25cm long light pipe is particularly convenient when used in growth chambers or aquaria for organisms such as photosynthetic bacteria, plankton, kelp, and higher plants.
The QSL series can be configured to output data in one of three options. Choose between digital ASCII (-2150) and linear analog (-2200)
For narrow spaces, the QSL is available with a smaller 1/2" scalar sphere for increased reach in test tubes and small crevices. Standard QSL's come with a 3/4" scalar sphere that has slightly increased uniformity in its directional response.
For a ruggedized design, the QSL can be upgraded to a QSPL. This marine grade version allows for 2,000m depth with an anodized aluminum housing.
QSL vs. QSPL:
QSL models are splash resistant and equipped with an O‐Ring sealed black plastic body with an integral strain relieved, 1.6 m long cable. The connector is not designed to be submerged. Available in digital or linear analog outputs
QSPL models use an O‐ring sealed, hard‐anodized aluminum housing and a SubConnMCBH4M series marine grade bulkhead connector. These sensors are rated for depth up to 2,000 m. Only available in digital output.
QSR Series
QSR sensors are surface reference radiometers to measure scalar irradiance from sunlight and have a PAR spectral response. These sensors are often used on ships during on-deck incubations, or while a QSP sensor is vertically profiling, for example, when mounted on a CTD.
QSR sensors are equipped with a detachable field-of-view cutoff shield to limit its response to light from the upper hemisphere (2 π steradians). The photo shows two QSR versions with and without the shield installed.
The QSP series can be configured to output data in one of two options. Choose between digital ASCII (-2150) and linear analog (-2200). All models are equipped with a Switchcraft EN3P5M connector. Upgrades to a marine-grade bulkhead connector for applications requiring a more rugged connector are available. Contact factory for details.
QCP Series
QCP sensors are designed to measure cosine irradiance in natural waters and have a PAR spectral response. Depending on model, maximum depths are 2,000 m or 10,000 m. Custom‐housed versions are available for gliders and other undersea or monitoring applications such as CTD profilers.
The QCP series can be configured to output data in one of three options. Choose between digital ASCII (-2150), linear analog (-2250), and compressed analog (-2350) output.
Standard QCP models use SubConn MCBH4M connectors which we rate to 2000m. High-pressure (-HP) versions of the QCP series use a SubConn BH4M connector and are rated to 10,000 m. Not available with digital output models.
QCR Series
QCR sensors are surface reference radiometers to measure cosine irradiance from sunlight with a PAR response. These sensors are weather resistant but not designed for immersion in water. QCR sensors are typically used on ships during on-deck incubations, or while a QCP sensor is vertically profiling, for example, when mounted on a CTD. These sensors are optically matched with the QCR being optimized for use above water to validate profiling cosine sensors that are calibrated for in-water use.
The QSR series can be configured to output data in one of two options. Choose between digital ASCII (-2150) and linear analog (-2200). All models are equipped with a Switchcraft EN3P5M connector. Upgrades to a marine-grade bulkhead connector for applications requiring a more rugged connector are available. Contact factory for details.
Spectral Response, Collector, and Depth Options
Spectral response: All sensors are calibrated using standards of spectral irradiance that are traceable to the National Institute of Standards and Technology (NIST).
PAR sensors measure Photosynthetically Available (or Active) Radiation. Sensors are equipped with a proprietary combination of multilayer interference filters and absorbing glasses to achieve a near-constant quantum response between 400 and 700 nm.
The PAR spectral response is encoded in the first letter of the model designator, which is “Q” for quantum response.
Collector: Sensors can be equipped with different collector types to measure either scalar irradiance or cosine irradiance.
Scalar irradiance collectors are insensitive to the direction of the incident radiation. The solid angle of acceptance is close to 4π (pi) steradians.
The sensitivity of cosine irradiance sensors varies with the cosine of the angle between the incident radiation and the normal vector of the collector.
The collector geometry is encoded in the second letter of the model designator, which is “S” or “C for scalar irradiance or cosine irradiance, respectively.
Environment / Depth: The third letter of the model designator is either “P”, “L”, or “R” and indicates the environment of operation. “P” specifies profiling underwater sensors used for continuous immersion. Maximum depths are 2,000 m or 10,000 m, depending on model. The letter “L” is specified for laboratory sensors, and “R” indicates reference above-water radiometers.
Output Options
Most sensors are available as analog and digital output models. The four‐digit number following the three-letter model designator indicates the electrical interface of the sensor:
Digital ASCII output (2150 series): the sensor uses a 24 bit analog-to-digital converter with low noise and excellent stability. Sampling rates range from 250 Hz to 1 sample average per hour. Output is provided as a calibrated ASCII text data stream with optional inclusion of sensor temperature. Sensor is designed for use with “Logger 2150” software but the data format is also ideally suited for integration with third-party software, for example, in multi-parameter monitoring systems.
Linear-analog output (2200 series): the sensor features a high-quality, low-drift, electrometer-grade amplifier. Output is voltage (0‐5 V). A 16 bit or higher analog-to-digital converter is recommended for optimum performance in a compatible data acquisition system. Normally, SeaWiFS guidelines are used to set the saturating irradiance or radiance values for a sensor, although a wide range of levels is available upon request.
Logarithmic (Log) analog voltage output (2350 series): these sensors use a 24‐bit analog-to-digital converter to sample the signal, the logarithm is computed and the result is converted into an analog voltage (0‐5 V) that can be satisfactorily digitized by most data acquisition systems. This output configuration is particularly useful for users that acquire their sensor readings through a CTD or other data acquisition system equipped with a less than 16 bit analog-to-digital conversion architecture.
Multiple Instruments. Multiple digital output (2150 series) sensors can be connected together with a Biospherical Instruments DSM Digital Signal Manifold. Data from all sensors are logged via a single PC serial or USB port. Multiple sensors may be powered via the same USB port. Note Logger2150 does not support multiple sensor configuration, user must generate their own code using the supplied command set.
Connectors
Marine Grade Sensors underwater models (QSP, QCP, QSPL) use a SubConn MCBH4M bulkhead connector, which we rate to a maximum depth of 2,000 m. *Surface reference sensors (QSR, QCR) that been upgraded to a marine grade sensors will also be equipped with this sensor.
Surface reference sensors (QSR and QCR series) use a splash-proof Switchcraft EN3P5M connector.
High-pressure (-HP) versions of the QCP series (QCP-2350-HP, QCP-2250-HP) use a SubConn BH4M connector.
Additional Options
Additional features and options are available, including specialized spectral sensitivity (e.g., photopic and “blue light hazard” responses), specialized connectors, direct photodiode current output (option “-PD”), and housings tailored for specific platforms (gliders. Please contact us if you cannot find the configuration most suitable for your application.
Detailed Sensor Descriptions
Specifications
The following list is a subset of specifications. For complete specifications see brochures for each model.
Optical Specifications of PAR Sensors (Q-Series)
Bandpass: 400–700 nm (PAR) quantum response; flatness: ±10% in core wavelength range
Out-of-band Rejection: >10E4
Calibration: calibrated following NIST procedures using Standards of Spectral Irradiance traceable to NIST.
Typical units
PAR scalar irradiance: quanta/(cm2 s)
PAR cosine irradiance: quanta/(cm2 s)
Directional Response
Scalar irradiance error: < ±3% for incidence angles < 90°; < ±10% for incidence angles < 130°.
Hemispherical scalar irradiance error: < ±6% for incidence angles <85°; cutoff to 0 at 95°.
Cosine collector: <±3% for incidence angles < 65°; < ±10% for incidence angles < 80°.
Output Characteristics
ASCII Digital (2150 series):
RS-232 compatible; RS-232 to USB converter included
Cable lengths up to 200 m from PC (longer may be possible if needed; contact factory)
9600 baud, 8 data bits, 1 stop bit, no parity (9600,N81)
“Logger 2150” software for Windows included
Linear Analog (2250 series):
Positive output polarity
Maximum output voltage: 5V, other levels upon request
Output impedance: 100 Ω
Logarithmic Analog (2350 series):
Positive output polarity
Minimum voltage to 5 V, proportional to logarithm of irradiance
Output impedance: 100 Ω
Input Power Requirements
2150 series: 6-15 VDC, <5mA.
When appropriate Biospherical offers customized USB-RS232 adaptors that insure proper voltage is supplied to these sensors.
Optical Collector Materials
Scalar collector: solid Teflon® sphere
Cosine collector: machined acrylic
Housing Materials
QSP, QSPL, QSR, QCP, and QCR series: hard black anodized T6061-T6 aluminum
QSL series: black acetal homopolymer resin (Delrin)