Optical Level Switch

Optical level sensors consist of two main parts: an infrared LED coupled with a light transistor, and a transparent prism tip in the front. The LED projects an infrared light outward; when the sensor tip is surrounded by air the light reacts by bouncing back within the tip before returning to the transistor. When the sensor is immersed in liquid, the light disperses throughout and less is returned to the transistor. The amount of returned light to the transistor affects output levels, making point level sensing possible.

Advantages and Disadvantages of Optical Level Sensors

The main advantages of optical level sensors are their compact size, their lack of moving parts, and their low cost. However, while extremely accurate for point level detection in high-stress environments, they’re less useful for continuous level measurement. In addition, optical level sensors are unsuited for applications where top mounting is necessary; when top-mounted, the accuracy optical level sensors may be adversely affected by moisture condensation.