Single Channel Sensors

Biospherical Instruments manufacturers a variety of single-channel sensors for use in the laboratory,  deployment with CTDs, gliders, floats, and meteorological stations, and for many other marine or terrestrial applications. The instruments are available in a large number of configurations with respect to spectral response, directional response, depth rating, signal output, packaging, cabling, and accessories. 


Instruments are offered in PAR (Q-Series) and monochromatic (M-Series) versions. Wavelengths for monochromatic instruments are available over the visible to near-infrared spectrum. Measurement geometries include cosine irradiance, scalar irradiance, and radiance. Depending on the model, measurements are outputted as either a digital data stream, "linear analog," or "logarithmic analog" signals. 

Click here to view a comparison chart of single-channel sensor characteristics.
Please contact us if you cannot find the configuration most suitable for your application.

A variety of our sensors have been interfaced with Sea-Bird CTD and data logging systems including the QSP-2300L, MCP-2300, QCP-2300L, QSP-2200 (PD), QCP-2200 (PD), QSR-2200, and QCR-2200. Please consult Sea-Bird for the proper sensor selection.

Key Characteristics  

Entrance Optics (geometrical method of light collection)Left: Cosine Collector, Right: Scalar CollectorLeft: Cosine Collector, Right: Scalar Collector
Spectral Response (options from 250–1800 nm)
  • PAR — 400–700 nm
  • 10 nm wide bandwidth "monochromatic"
  • wideband
  • custom response
Signal Output
  • Linear analog voltage
  • Log transformed output voltage
  • Unamplified current output
  • RS-232 serial data in ASCII
  • USB

Packaging:Package options for field instrumentsPackage options for field instruments
  • Weatherproof
  • Waterproof to 2,000 m
  • Waterproof to 10,000 m
  • Custom housings

Featured Sensors

AMOUR: A new product for laboratory, field, and industrial use. A small probe that connects to your PC's USB port and supports a variety of light collectors including cosine, scalar, radiance and fiber optic ports.

QCP - MCP: Cosine irradiance sensors that are used on CTD/STD profilers to add measurements of downwelling irradiance to the data stream. For PAR spectral response, see the QCP series. For 10 nm wide monochromatic sensors, see the MCP series. Both are available with either a linear or logarithmic analog (voltage) output, or with digital data output.

Download QCP Brochure 
Download MCP Brochure

MRP:  Radiance sensors that are used on CTD/STD profilers to add measurements of upwelling radiance to the data stream. Available with either a linear or logarithmic analog (voltage) output, or with digital data output. 

QSP - MSP: Scalar irradiance sensors that are used on CTD/STD profilers to add measurements of light independent of the angle of incidence. The QSP sensor has the PAR spectral response while the MSP measures narrowband irradiance at a particular wavelength band. They are both available with either a linear or logarithmic analog (voltage) output, or with digital data output.

Download QSP Brochure

QSR: Scalar irradiance sensors with PAR spectral response designed to be used to monitor sunlight. The sensor features a hemispherical directional response, integrating the irradiance from the sky with equal weighting, as opposed to weighting the incident flux with the cosine of the angle of incidence. These sensors are often used shipboard during on-deck incubations, or while a QSP sensor is vertically profiling (typically while mounted on a CTD). 

Download QSR Brochure

QSL Laboratory scalar irradiance sensors that provide general purpose measurements of light in applications such as growth chambers, aquaria, or photosynthetrons. Read more here.

Download QSL Brochure

Common Features of QSP-, QCP-, MCP-, and MRP-series of instruments

QSP-, QCP-, MCP-, and MRP-series of instruments are designed to meet the need for small, rugged, low power light sensors useful for integration on CTDs or other profiling packages. The redesigned QSL-series laboratory light sensor is now entirely integrated into the handle. We manufacture over 20 varieties of single-channel sensors. This chart lists all available configurations.
  • Depth Capability:  The standard deployment depth for QSP, QCP, MCP, and MRP series sensors is 2,000 m. When equipped with a high pressure connector, QCP-series sensors may be deployed to 10,000 m. QSR and QCR-series surface reference sensors are designed for terrestrial use and are sealed for weather-resistance. QSL sensors are splash resistant and are not submersible. QSPL laboratory sensors are fully submersible.
  • Spectral Response:  PAR sensors are equipped with a proprietary combination of multilayer interference filters and absorbing glasses to achieve a near-constant quantum response. Monochromatic models employ proprietary filtered-photodetectors in which a multicavity interference filter is mounted with the photodetector in a hermetically sealed package. Additional absorbing glass filters are used to further reduce out-of-band response, which can cause unwanted measurement and calibration artifacts. All sensors come calibrated to standards of spectral irradiance, traceable to the National Institute of Standards and Technology (NIST).

Output Options 

  • Digital output (2100 series) sensors provides a direct serial data connection to a PC for both real-time display and logging.
  • Linear-analog output (2200 series) models feature high-quality, low-drift, electrometer-grade amplifiers (positive polarity is standard). 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. Direct-from-photodiode current output is also available for all 2200 sensor types.
  • Logarithmic-analog output (2300 series) sensors are particularly useful for users that acquire their sensor readings through a CTD or other data acquisition system equipped with a limited dynamic range. These sensors rely on a high-quality, industry-standard, log amplifier to produce an output that varies over three to four orders of magnitude range.
  • Multiple Instruments. Multiple digital output (2100) sensors can be connected together with a Biospherical Instruments DSM sensor multiplexer. Data from all sensors are logged via a single communications port of nearly any personal computer running Windows (versions 98 through XP are supported). All sensors are powered via the same communications port. Data rates depend on the number of sensors; for example a system with four sensors has a maximum data rate of a bit over 3 Hz. Statistics such as the minimum, maximum, average, and sum of squares are recorded for each sensor.


Left: LSG-4-BCL, Right: MCBH-5-F-SSLeft: LSG-4-BCL, Right: MCBH-5-F-SSThe LSG-4-BCL connector is used on all analog-output, single-channel sensors. This bulkhead connector is rated to a depth of 2,000 m. Manufacturered by Teledyne-Impulse and Seacon-Brantner.

The QSP-2200-HP, QCP-2200PD-HP and QCP-2300-HP sensors are equipped with the IMPULSE XSG-4-BCL-HP connector. The XSG-4-BCL-HP connector are rated to 10,000 m. NOTE: Although similar in appearance, the XSG and LSG bulkhead connectors are not interchangeable.

The MCBH-5-F-SS bulkhead connector is used on the digital-output, Qxx-2100 sensor models. This connector is rated to a maximum depth of 2,000 m.

The MCBH-4-M connector (not shown) is used on the ASCII-output, Qxx-2150 sensors. This bulkhead connector is rated to 2,000 m. Available from Subconn or Teledyne-Impulse. 


Optical Specifications of Monochromatic Sensors
Center wavelength range: filter-photodetector combinations are available between 320 to 875 nm
Bandpass: 10 nm FWHM ± <2 nm, approximately 20 nm for Natural Fluorescence (LuChl)
Center wavelength accuracy: ±<2 nm
Out-of-band Rejection: (10 nm sensors): >104, 20 nm from center wavelength

Optical Specifications of Quantum PAR Sensors
Bandpass: 400–700 nm (PAR) quantum response; flatness:  ±10% 
Out-of-band Rejection: >104
Calibrations: All instruments are calibrated following NIST procedures using Standards of Spectral Irradiance traceable to NIST.

Typical units
Monochromatic radiance:
  µW/(cm2 sr nm)
Monochromatic scalar or cosine irradiance:  µW/(cm2 nm)
PAR scalar irradiance:  µE/(cm2 s)
PAR cosine irradiance:  quanta/(cm2 s)

Directional Response
Radiance field of view (FOV) in water: 10° half-angle
Scalar irradiance error: ±7% over a range of ±135° zenith angle
Hemispherical scalar error: ±6%, over a range of ±85° zenith angle, cutoff to 0 at 95°.
Cosine collector: ±0 to 65°, ±3%, ±65 to 86°, ±10%

Output Characteristics

Digital (2100) Models:
RS-232 compliant
Cable lengths up to 350 m from PC
9600 baud, 8 data bits, 1 stop bit, no parity (9600,N81)
Software included (Windows 95, 98, 2000, NT, XP, and ME)

Linear Analog (2200) Models:
Positive output polarity
Maximum output voltage: 5V, other levels upon request
Saturating irradiance linear models: per SeaWiFS recommendations, other levels upon request
Maximum noise sensor dark: <100 µv rms
Dark offset: <1 mV
Output impedance: 100 Ω

Logarithmic Analog (2300) Models:
minimum voltage to 5 V, proportional to log of irradiance

Input Power Requirements
2100 digital output models:
supplied by PC serial port
Linear-analog output (2200 models):  6–15 VDC at 2 mA
Logarithmic-analog output (2300 models):  6–15 VDC at 100 mA
Photodiode current output:  none required

Light Collector Materials
Scalar collector:  solid Teflon sphere
Cosine collector:  Machined acrylic
Radiance window:  Clear acrylic

Housing Materials
Surface Scalar Reference: (QSR-2000 Series): Hard black anodized T6061 Aluminum
Surface Cosine Reference: (QCR-2000 Series): polyethylene terephthalate (PET) plastic
All standard marine series: Hard black anodized T6061 Aluminum and PET plastic 

Last Updated on Friday, 11 November 2011 14:41
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