Ocean Optics OOISensors - Manual (Page 11)

Chapter 1
Sensors System Overview
Overview
The following sections provide a general overview of the Oxygen Sensors System and the pH Sensors
System.
Oxygen Sensors System Overview
Fiber Optic Oxygen Sensors are spectrometer and/or phase fluorometer-coupled chemical sensors for
monitoring oxygen partial pressure in gases and liquids. A fluorescence method measures the partial
pressure of dissolved or gaseous oxygen. Optical fiber carries excitation light produced by the blue LED
to the thin-film coating at the probe tip. The probe collects fluorescence generated at the tip and carries it
via the optical fiber to the high-sensitivity spectrometer. When oxygen in the gas or liquid sample diffuses
into the thin film coating, it quenches the fluorescence. The degree of quenching correlates to the level of
oxygen pressure.
Fiber Optic Oxygen Sensors are low-power, portable devices that offer high sensitivity, reversibility, and
stability. Their small size is useful for remote monitoring. What's more, the thin film used in the probe
tips consumes no oxygen, allowing for continuous contact with the sample. FOXY Sensors offer other
key advantages: They're ideal for viscous samples and are immune to interference caused by pH change
or from changes in ionic strength, salinity, and biofouling.
pH Sensors System Overview
Fiber optic probes for pH monitoring couple to Ocean Optics spectrometers to measure pH by monitoring
color changes in indicator dyes. These dyes are immobilized in polymer films. You then place the films in
the optical path of a transflection dip probe and exposed to the sample solution. These pH probe sensors
are especially useful for monitoring low conductivity samples such as boiler water, where potentiometric
devices fail; or for turbid, fouling environments, where particulate matter, slurries, and other media can
coat or destroy electrodes.
Ocean Optics' fully integrated pH systems provide full spectral analysis to help eliminate errors from dye
leaching or from changes in turbidity, temperature, and ionic strength. Inherent calibration based on the
physical properties of the immobilized indicator dye eliminates the need for frequent calibration.
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