Development of a helicopter-mounted eye-safe laser radar system for distance measurement between power transmission lines and nearby trees

An on-board eye-safe laser radar system capable of measuring the distance between high voltage power transmission lines and nearby trees has been developed. An eye-safe laser operating at 1.572 m wavelength was used for the safety of the human cornea. The system can be mounted on the helicopter for general-patrol surveys as it is compact, lightweight, and consumes low power. Clearance on the opposite side of the flight position can also be measured. This system can be applied to all voltage level transmission lines from 66 kV to 500 kV. Clearance accuracy below 93 cm was obtained in our practical power transmission lines. Software running on personal computers was also developed to simulate the expected minimum clearance at field offices.