Sequoia LISST-Tau Transmissometer
Features
- Measures optical transmission and beam attenuation
- RS-232 and analog real-time outputs
- Integrated temperature compensation & ambient light rejection
- Expedited repair and warranty service
- Lifetime technical support
- More
Overview
LISST-Tau is a high-precision transmissometer for underwater vehicles, profiling packages, CTDs, and other systems. With high-quality optics and a carefully selected LED source, it transmits a collimated beam through the water, and precisely measures the light transmitted through its 15 cm path. Light modulation with synchronous detection rejects ambient light, while oversampling and averaging yield better than 16-bit resolution. LISST-Tau’s digital controller applies calibration coefficients, corrects for temperature effects, and transmits data from both digital and analog outputs. Included software provides real-time display of data, and functions for checking and updating pure-water calibrations. An optional flow-through chamber simplifies calibrations and experiments. LISST-Tau advances the state of the art for in-situ transmissometers.
Remote Monitoring
The LISST-Tau transmissometer offers a plug-and-play interface to the NexSens X3 data loggers and telemetry systems. The X3 is available for pole-mount deployments with solar charging or connected to the SBP500 submersible alkaline battery pack for subsurface deployments.
Parameters Measured
- Optical transmission
- Beam attenuation
Operating Ranges and Stability
- Operational temperature range: -3 °C to 40 °C
- Storage temperature range: -20 °C to 60 °C
- Beam attenuation range: ~0 m-1 to 30 m-1
- Linearity (concentration): >99 %
- Short-term stability (typical standard deviation over 1 minute)
- Transmission: 0.003 %FS (Green) / 0.005% (Red)
- Beam attenuation: 0.0002 m-1 (Green) / 0.0004 m-1 (Red)
- Long-term stability (6 hr test)
- Transmission: ~0.003 %FS/hr
- Beam attenuation: ~0.0002 m-1∙hr-1
Technology
- Optical path length: 15 cm
- Source wavelength: ~532 nm (Green) or ~650 nm (Red) LED
- Source spectral bandwidth: <10 nm FWHM
- Acceptance angle (half angle, in water): 1.0 °
- Optical transmission @ 16-bit resolution
Mechanical and Electrical
- Dimensions [Ø x L]: 5.1 cm x 40.6 cm (2.00″ x 16″)
- Weight [air / seawater]: 1.140 kg / 0.585 kg (2.5 lbs / 1.3 lbs)
- Depth rating: 2,000 m
- Sampling rate: 1 Hz
- External power input: 7 VDC to 25 VDC
- Current drain @ 12V: 42 mA average during sampling
- Connector: SubConn MCBH6M
- LISST-Tau transmissometer
- LISST-Tau 2-meter integrated communication and external power USB cable
- Windows software for real-time display of data, and functions for checking and updating pure-water calibrations
- Shipping case
Select Options
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