How does an optical dissolved oxygen (ODO) sensor work?

Optical dissolved oxygen (ODO) sensors measure the concentration of dissolved oxygen in a liquid sample by using a light source and a light detector. The principle behind these sensors is based on the fact that dissolved oxygen absorbs light at certain wavelengths.

1. There are several types of optical ODO sensors, but one common design consists of a light emitting diode (LED) as the light source and a photodetector as the light detector. The LED emits light at a specific wavelength that is absorbed by dissolved oxygen in the liquid sample. The photodetector is located on the other side of the sample and measures the intensity of the light that passes through the sample.

2. The intensity of the light that passes through the sample is directly related to the concentration of dissolved oxygen in the sample. When the concentration of dissolved oxygen is high, more light is absorbed, resulting in a lower intensity of light reaching the photodetector. When the concentration of dissolved oxygen is low, less light is absorbed, resulting in a higher intensity of light reaching the photodetector.

3. The photodetector sends an electrical signal to a microprocessor, which calculates the concentration of dissolved oxygen in the sample based on the intensity of the light received. The microprocessor then displays the DO concentration on a display screen or sends it to a computer for further analysis.

4. Optical ODO sensors have several advantages over other types of DO sensors, including high accuracy, fast response time, and the ability to measure DO over a wide range of concentrations. They are commonly used in a variety of applications, including water treatment plants, aquaculture, and environmental monitoring.

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