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). 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.
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. Monocromatic versions are available on request. Contact the factory for details.
The following matrix provides an overview of the most commonly available combinations of features, and the associated model numbers. Models are identified by a three‐letter code followed by a four‐digit number. The different options are explained in detail below the matrix. Click on the model numbers for more information.
| 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 Binary Output | QSP-2100 | QSL-2100, QSL-2101, QSPL-2100, QSPL-2101 | QSR-2100 | QCP-2100 | QCR-2100 |
| Digital ASCII Output | QSP-2150 | QSL-2150, QSL-2151, QSPL-2150, QSPL-2151 | QSR-2150 | QCP-2150 | QCR-2150 |
| Linear Analog Output | QSP-2200, QSP-2250 | QSL-2200, QSL-2201 | QSR-2200 | QCP-2200, QCP-2250 | QCR-2200 |
| Logarithmic Analog Output (Log) | QSP-2300, QSP-2350 | QCP-2300, QCP-2350 |
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 binary output (2100 series): a 24 bit analog-to-digital converter provides a binary output at a fixed sampling rate of approximately 4 Hz. Sensors are designed for use with “Logger 2100” software, which provides real-time display and data logging on a PC.
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 (2300 and 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 (2100 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. Data rates depend on the number of sensors; for example a system with four sensors has a maximum data rate of approximately 3 Hz.
Connectors
Digital binary output (2100 series) underwater models (QSP-2100, QCP-2100) use a SubConn MCBH5F bulkhead connector, which we rate to a maximum depth of 2,000 m.
Digital ASCII output (2150 series) underwater models (QSP-2150, QCP-2150) use a SubConn MCBH4M bulkhead connector, which we rate to a maximum depth of 2,000 m.
Legacy Analog and Log output (2200 and 2300 series) underwater models (QSP/QCP) use a LSG-4-BCL bulkhead connector, which is rated to a depth of 2,000 m.
Modern Analog and Log output (2250 and 2350 series) underwater models (QSP/QCP) use a SubConn MCBH4M bulkhead connector, which we rate to a maximum depth of 2,000 m.
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
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. Custom‐housed versions are available for gliders and other undersea or monitoring applications such as CTD profilers.
The QSP series comprises multiple models with digital binary (QSP-2100), digital ASCII (QSP-2150), linear analog (QSP-2200, QSP-2250), and compressed analog (QSP-2300, QSP-2350) output. The QSP-2100 model uses a SubConn MCBH5F connecor and QSP-2150, QSP-2250, and QSP-2350 models use SubConn MCBH4M connectors which we rate to 2000m. Legacy versions QSP-2200 and QSP-2300 use a LSG-4-BCL bulkhead connector, which is rated to a depth of 2,000 m.
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. Choosing a BH4M connector does not extend the instrument's depth rating. For greater depths, use a QCP-2350-HP sensor.
QSL Series
QSL sensors measure scalar irradiance with a PAR response and are optimized for use in the laboratory. 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 comprises 10 different versions, including four models with digital binary output (QSL-2100, QSL-2101, QSPL-2100, and QSPL-2101), four models with digital ASCII output (QSL-2150, QSL-2151, QSPL-2150, and QSPL-2151), and two models with analog output (QSL-2200 and QSL-2201).
Model numbers ending in "1" (QSL-2101, QSPL-2101, QSL-2151, QSPL-2151) use a small 1.25 cm (1/2”) diameter scalar irradiance collector while all other models use a collector with a diameter of 1.9 cm (3/4”). The smaller 1.25cm diameter collector is specifically designed for insertion in vials of the type commonly used in photosynthetrons. Models with the larger collector offer a more uniform directional response.
Two connector and housing options are available:
QSL models (QSL-2100, QSL-2101, QSL-2150, QSL-2151, QSL-2200 and QSL-2201) 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.
QSPL models (QSPL-2100, QSPL-2101, QSPL-2150, and QSPL-2151) use an O‐ring sealed, hard‐anodized aluminum housing and a SubConn MCBH5F (2100/2101) or MCBH4M (2150/2151) series marine grade bulkhead connector. These sensors are rated for depth up to 2,000 m.
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 QSR series comprises models with digital binary output (QSR-2100), digital ASCII output (QSR-2150), and analog output (QSR-2200). All models are equipped with a Switchcraft EN3P5M connector. Versions with 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 comprises models with digital binary output (QCP-2100), digital ASCII output (QCP-2150), linear analog output (QCP-2200 and QCP-2250), and compressed analog output (QCP-2300 and QCP-2350).
The QCP-2100 model uses a SubConn MCBH5F connecor and QCP-2150, QCP-2250, and QCP-2350 models use SubConn MCBH4M connectors which we rate to 2000m. Legacy versions QCP-2200 and QCP-2300 use a LSG-4-BCL bulkhead connector, which is rated to a depth of 2,000 m.
High-pressure (-HP) versions of the QCP series (QCP-2350-HP, QCP-2250-HP) use a SubConn BH4M connector and are rated to 10,000 m.
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. QSR 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.
The QCR series comprises models with digital binary output (QCR-2100), digital ASCII output (QCR-2150), and analog output (QCR-2200). All models are equipped with a Switchcraft EN3P5M connector. Versions with a marine-grade bulkhead connector for applications requiring a more rugged connector are available. Contact factory for details.
Most specifications of QCR models are identical to those of the QCP series. The largest difference is the collector of the sensor: QCR models are optimized for use above water while QCP models are designed for under-water use. A QCP sensor can be used above water, but the "cosine error" of the collector would be relatively large.
Brochures for QCR sensors are currently not available, but specifications are identical with those of QCP sensors with the exception of connectorization and cosine response optimization.
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
Binary Digital (2100 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 2100” software for Windows included
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 (2200 and 2250 series):
Positive output polarity
Maximum output voltage: 5V, other levels upon request
Output impedance: 100 Ω
Logarithmic Analog (2300 and 2350 series):
Positive output polarity
Minimum voltage to 5 V, proportional to logarithm of irradiance
Output impedance: 100 Ω
Input Power Requirements
Digital output models (2100 and 2150 series): Power is supplied by the PC comport which must meet these specs:
- 2100 series: 6-12.5 VDC, 2mA.
- 2150 series: 6-15 VDC, <5mA.
Biospherical offers customized USB-RS232 adaptors that insure proper voltage is supplied to these sensors.
Linear-analog output (2200 and 2250 series): 6–15 VDC at 2 mA
Logarithmic-analog output (2300 and 2350 series): 6–15 VDC at 5 mA
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)