All-fiber multifunction continuous-wave coherent laser radar at 155 µm for range, speed, vibration, and wind measurements

Abstract

The design and performance of a simple, multifunction 1.55-mum continuous-wave (cw) and frequency-modulated cw coherent laser radar system with an output power of 1 W is presented. The system is based on a semiconductor laser source plus an erbium-doped fiber amplifier, a polarization-independent fiber-optic circulator used as the transmit-receive switch, and digital signal processing. The system is shown to be able to perform wind-speed measurements even in clear atmospheric conditions when the visibility exceeds 40 km. The aerosol measurements indicate the potential to use single-particle detection for wind measurements with enhanced sensitivity. The system can perform range and line-of-sight velocity measurements of hard targets at ranges of the order of several kilometers with a range accuracy of a few meters and a velocity accuracy of 0.1 m/s by use of triangular-wave frequency modulation with compensation of the frequency-modulation response of the semiconductor laser. The system also demonstrates a capability for vibration sensing.

Direct measurement of the spectral transfer function of a laser based anemometer

“…Its design concept follows the fundamental principles of a monostatic, fiber-based, coherent detection cw laser anemometer. 3 The theoretical spatial and temporal resolution of this system have been thoroughly studied 4,5 and its ability to accurately measure the wind speed has been verified through inter-comparison with data acquired by calibrated cup anemometers. 6 The design of the system offers the possibility of operating in two different modes; a staring mode (laser beam is emitted in a straight line parallel with the orientation of the system) and a conical scanning mode (the laser beam is deflected by a rotating optical wedge prism).…”

Variations of the Wake Height over the Bolund Escarpment Measured by a Scanning Lidar

“…The lidar is a continuous-wave, coherent Doppler lidar first described in Karlsson et al (2000). Its two main components are a modified directional sensing version of a commercial ZephIR Z150 wind lidar (Kindler et al 2007;Smith et al 2006) and a fast-scanning scanner head (Mikkelsen et al 2011).…”

100-mW linear polarization single-frequency all-fiber seed laser for coherent Doppler lidar application

“…The coherent Doppler lidars (CDLs) [1,2] are quite suitable for atmospheric measurement such as wind speed and aerosols' concentration, thus they have been investigated widely by many researchers since the 1970s. Due to the usage of the heterodyne detection by mixing the laser light scattering from a remote target with a reference local coherent laser oscillator, the CDLs offer very high sensitivity to obtain the detailed phase and velocity information of the measurand [2].…”