Effect of Liquid on Garmin LIDAR-Lite Products Signal

There are a few considerations to take into account if your application requires measuring distances to, or within, liquid:

• Reflectivity and other characteristics of the liquid itself
• Reflectivity characteristics of particles suspended in the liquid
• Turbidity
• Refractive characteristics of the liquid

Reflectivity of the liquid is important when measuring distance to the surface of a liquid or if measuring through liquid to the bottom of a container (see Related Content).

It is important to note that measuring distance with the device depends on reflected energy from the transmitted signal being detected by the receiver in the sensor. For that reason, the surface condition of the liquid may play an important role in the overall reflectivity and detectability of the liquid. In the case of a flat, highly reflective liquid surface, the laser's reflected energy may not disperse adequately to allow detection unless viewed from the normal. By contrast, small surface ripples may create enough dispersion of the reflected energy to allow detection of the liquid without the need to position the sensor so that the transmitted beam strikes the liquid's surface from the normal.

Reflectivity of suspended particles is a characteristic that may help or hinder depending on the application.

Turbidity, or the clarity of a liquid created by the presence or absence of suspended particles, can similarly help or hinder measurement efforts. If the application requires detecting the surface of the liquid, then suspended particles may help by reflecting more of the transmitted beam back to the receiver, increasing detectability and permitting measurements to be taken.

It is important to note that, attempting to measure through suspended particles in a liquid will only be successful if the transmitted beam is allowed to reflect off of the desired target without first being absorbed or reflected by the suspended particles.

When the near infrared energy transmitted by the device transitions from the atmosphere to a liquid, the energy may be bent, or refracted, and absorbed in addition to being dispersed. The degree to which the transmitted beam is refracted and absorbed is defined by its refraction index. That being said, the most important criteria impacting successful measurement through a liquid is the amount of dispersion of the transmitted beam and whether any of the dispersed beam makes its way back to the receiver on the device.

Remember that electromagnetic energy travels slower through a liquid and may affect accuracy of the final measurement output.