Table of Contents
Applications and Principles of LIDAR Technology
LIDAR is a method of surveillance that measures the distance to a target by illuminating that target with a pulsed laser light and measuring the reflected pulses with a sensor. The received laser light is used to construct a 3D representation of the target. The main applications of LIDAR are the construction of high-resolution maps, laser guidance, airborne laser swath mapping, laser altimetry, etc.
Eye-Safe 1550 nm Fiber Lasers for Military and Mapping Uses
LIDAR systems that are used for scientific applications need to be eye safe; therefore, 600–1000 nm lasers cannot be used for LIDAR, as these lasers can be focused and easily absorbed by the eye, which causes limitations in the possible powers used. A common alternative is 1550 nm lasers, like 1550 nm fiber lasers. The latter type is eye-safe at much higher power levels since this wavelength is not focused by the eye. 1550 nm fiber lasers are typically used for military operations and provide accurate images over long distances. Another advantage of 1550 nm fiber lasers is their invisibility to night vision goggles, unlike 1000 nm infrared lasers.
LIDAR in Wind Measurement and Atmospheric Studies
LIDAR technology can be used not only in military or mapping but for air- and space-based wind measurements. Measurements of the wind intensity are essential for airport safety and pollution monitoring. When LIDAR is used for its regular applications, it works by the time between the firing of a laser pulse and the sensing of its reflection from the landscape or target. In wind speed measurement, the laser interacts with molecules such as aerosols in the atmosphere. The Doppler shift in the signal, which is caused by the molecule’s movement, is then converted to wind velocity. After performing multiple measurements, a full 3D vector field is constructed, which is then used to assess wind velocity, shear, and turbulence.
Challenges and Fiber Optic Solutions for Enhanced LIDAR Performance
Despite LIDAR being a precise measuring technique, the system, in most cases, can not be effectively used in harsh conditions such as strong winds. Another problem is the use of conventional avalanche photodiodes for the detection of the signal; the downfall of these is low resolution and high noise that undermines their use in sensitive data streams.
In order to improve the LIDAR system for wind velocity measurement, fiber optic elements may be used to simplify the system, which reduces its vulnerability to many variables, such as angle of incidence, instrument alignment, temperature gradients, and pressure fluctuations.