Physics of OWL^TM

Indtroduction

The OWL (Oil in Water Locator) is a complex and highly sensitive measurement device that is able to quantify organic molecules in water. These include different oils and Dissolved Organic Material - DOM. An overview of the measurement process and the physics principles responsible for device operation are given in layman terms.

Fluorescence

Fluorescence is the property of some molecules to emit light in effect of light of higher frequency. The light spectrum that the molecule produces when fluorescing is highly dependent on molecule structure and components. This in turn allows us to discriminate between different molecules in water. Also, the fluorescent light strength that emits from the water is proportional to the amount of fluorescing molecules in the water.

For more detailed information please see the Wikipedia page on fluorescence. ​https://en.wikipedia.org/wiki/Fluorescence

Laser

The laser in the Measurement device is used to excite the oil and other organic molecules in the water. The laser is an EXIMER type XeCl gas laser. The laser emits a very well focused pulse of ultraviolet light that excite the molecules. The laser type was selected so it would produce the most useful fluorescent light spectrum from the molecules of interest.

Detection

As the light emits from the molecules of interest it travels in all directions. This means that only a very small percentage of the light makes it back to the Measurement device. For detecting that light the Measurement device has a built in telescope for collecting the light. After the telescope the light is divided into different spectral components, amplified and then detected with a camera.

Data processing

When the light spectrum is collected and stored as digital data analyzis of the sample begins.

In the firs step the spectrum is divided into spectrum's of different molecules. This is done by specialized artificial intelligent. After that the shape of spectrum's and their magnitude is used to calculate the ammount of giver substance in the water. This is done in real time and posted on the OWL MAP^TM.