Aquameter
™
Series Instruction Manual
10401-00188 Rev M
22. Appendix 1. The Tech Behind Aquaread’s Optical DO Measurement System
22.1. Principle of Operation
The Aquaread™ AquaPlus™ Optical DO measurement system works on the principle of
Dynamic Luminescence Quenching. A gas-permeable chemical known as a luminophore is
excited with short bursts of blue light, which causes molecules in the luminophore to emit
red photons. The presence of oxygen in contact with the luminophore causes the emission
of the red photons to be quenched or delayed. By measuring the delay of the returned red
photons with respect to the blue excitation, it is possible to determine the level of dissolved
oxygen present.
Whilst this sounds very simple in principle, the optical system and the high-speed
electronics required to obtain good accuracy are extremely complex. Calling on many
years’ experience designing military Night Vision Goggle (NVG) compatible optics,
Aquaread engineers have produced an amazingly small and elegant solution.
Housed in a resin filled, marine grade aluminium body that measures just 8mm (0.3”)
diameter by 13mm (0.5”) long, the fully waterproof AquaPlus Sensor Module contains blue
excitation and red reference LEDs, optical filters, a photon detector, temperature sensor,
driver circuitry and high gain amplification circuitry.
The nano-engineered AquaPlus™ Sensor Module
The incredibly small size of the Sensor Module allows it to fit comfortably into the end of a
standard 12mm diameter DO electrode in place of a traditional Clark Cell. The addition of a
replaceable cap containing a lens coated with the luminophore material completes the DO
section of the electrode.
© 2011 Aquaread Ltd.
www.aquaread.co.uk
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