Skip to main content
No longer sold

O₂ – Subsea oxygen sensor

The CONTROS HydroFlash® O₂ optode is a versatile subsea, shallow and deep-water oxygen sensor which can be used for autonomous deployments as well as integrated into sensor systems. The CONTROS HydroFlash® O₂ is designed for a wide variety of deployment schemes and platforms including but not limited to AUVs, gliders, floats, water sampling rosettes, buoys, and moorings.

Individual 'in-situ' calibration

The optode head has a unique design featuring an anti-fouling head, a fast response temperature probe and a curved glass substrate coated with the sensing membrane. All sensors are individually calibrated in a water tank over a wide range of temperatures and oxygen concentrations. An established laboratory method ('Winkler test') is used to ensure the quality of the calibration.

Operating principle

The advanced, optical sensor is based on the principle of fluorescence quenching. Dissolved oxygen (O₂) molecules diffuse into a membrane in which a fluorescent dye is embedded. Oxygen is capable of quenching this fluorescence by transferring the excitation energy from the dye to the O₂ molecule. The sensor repeatedly excites the dye in the membrane and measures the intensity and phase shift of the fluorescence light. The more O₂ is present in the water, the smaller is the measured fluorescence signal and the higher is the phase shift.


  • Highly efficient fluorescent dye embedded on a curved, solid substrate to enhance light yield
  • Very fast response time (t63 < 3 s) combined with high stability and accuracy
  • Versatile - easy integration into almost every oceanographic measurement system and platform
  • Robust - can be used in water depths up to 6000 meters
  • Titanium housing with small dimensions
  • Very low power consumption
  • Programmable sleep mode extends battery lifetime during autonomous deployment
  • Comprehensive software for programming, data download and visualization included
  • Non-consumptive O₂ measurement


  • Flow head
  • Autonomous deployment with CONTROS HydroB® Flash (attachable battery) possible
  • Easy deployments together with CO₂ and CH₄ sensors
  • ROV and AUV installation packages
  • Profiling and mooring frames


KONGSBERG provides a dedicated power solution for the CONTROS HydroFlash® O₂ optode, the CONTROS HydroB® Flash. Its simple yet efficient "plug-and-play" design allows for autonomous deployments of up to three months.

Services and support

  • 24/7 Technical support

    Our 24/7 technical support team is there to help at any time, day or night, wherever your vessel is.

    Contact us:

  • Spares

    We understand the importance of having the right parts, available in the right place, at the right time.

  • Training

    Ensure that your crew is properly and thoroughly trained. This will reduce operational risk, downtime and maximise return on asset investment.