ALOMAR Ozone DIAL 1984
The stratospheric ozone DIAL (Differential Absorption Lidar) at the arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR, Andøya, 69.28oN, 16.01oE) started operation in December 1994. Due to the Arctic location of the site, measurements at ALOMAR are well suited for validation of satellites with polar orbits. In the first years the lidar had no operational daylight capability, and due to the Arctic location no measurements were possible from about May 10th to July 30th. In this period the solar elevation angle exceeds -2o C 24 hours a day. To extend the use of the system, in July 1998 a new daylight receiver module was installed.
Visible in the picture are the red container enclosing the XeCl laser, the gray-blue container enclosing the hydrogen gas Raman shifters, the telescope cylinder containing an F/??, 40 cm (?) Newtonian telescope and the detection module, seen attached to the side of the telescope. The operator PC interface is seen at the desk.
Close-ip of the operator station, ALOMAR Ozone DIAL. The Optech photon counting boards are used with this system. |
British Gas Raman Lidar for Methane Detection 1983
The British Gas Raman Lidar was designed and built in order to remotely detect gas leaks. It comprised a XeCl laser transmitter, emitting at 308 nm, with 5 W average optical output at a 100 Hz repetition frequency. The laser is seen towards the right just in front of the telescoping base in the lift platform. The light was outcoupled parallel to the 50 cm diameter +110 cassegrain receiver telescope, mounted on a steerable yoke. The telescope and yoke are shown raised through the roof of the van for operation. The equipment rack and operator control interfaces are visible towards the left and front of the vehicle. The operator station is air-conditioned.
Close-up of the British Gas Raman Lidar 50 cm diameter Cassegrain telescope. The XeCl laser transmitter is outcoupled through beam steering prisms mounted in the right hand side of the telescope yoke as shown (Fig.4). The small telescope attached to frame of the Cassegrain telescope is a sighting camera to monitor the system pointing direction. The yoke has a slew/pitch rate of XX degrees(radians?) per second and a pointing knowledge of ± radians. The aft optics, including relay optics, filters and detectors, are contained within the white cylinder attached to the back of the telescope. The output is electronically connected to the photon counting electronics mounted on the equipment rack.
The fully deployed telescope if seen. It is about 4 meters above ground-level, which is conveniently above many visual obstacles, such as embankments, fences and walls. The vehicle is parked by the side of the road and performs its measurements. (Fig.5) |
AES Aerosol Detection Lidar 1976
AES Aerosol Detection Lidar was built for the Canadian Atmospheric Environment Service (AES, now Meteorological Sercices Canada), Center for Atmospheric Research Experiments (CARE). The lidar is a single channel system, detecting and profiling scatter from aerosols, smoke and particulate plumes by means of elastic backscatter. The transmitter is a pulsed ruby laser, emitting at 694 nm, with a pulse energy of 1.0 J and pulse repetition frequency of 1 Hz. The transmitter output is seen to the right of the receiver lens (Fig6). The receiver aperture is a F/1?, 30 cm diameter Fresnel lens. The transceiver is mounted on a yoke, with full hemispheric scan coverage. the transceiver is weather-proofed and is always exposed to the elements.
The system was designed to be able to detect typical aerosol background at 3 km altitude.
The AES Aerosol Detection Lidar transceiver is visible on top of the van, about three meters from the ground (Fig.7). The van has been lifted from the ground by jacks to level the platform and reduce rocking due to wind. |
Ontario Hydro Plume-Detecting Lidar
The Ontario Hydro Plume-Detecting Lidar was a single channel lidar built for detecting and profiling aerosol and smoke plumes (Fig.8). It comprises a ruby laser transmitter, emitting 1.5 J at 694 nm and a pulse repetition frequency of 1 Hz. the receiver is a f/1(?) 30 cm diameter Fresnel lens. The integrated transceiver is mounted on a yoke capable of scanning in a vertical plane at 4 degrees per second. The instrument is field-deployed by truck.
The Ontario Hydro Plume-Detecting Lidar is shown here in deployment mode, appearing in the hatch area towards the rear of the vehicle (Fig.9). |
Defense Research Establisment Valcartier, Multi-Field of View Lidar 1989
The Defense Research Establisment Valcartier (DREV), Multi-Field of View (MFOV) Lidar was a single wavelength lidar used to detect and assess aerosols through elastic backscatter and the use of four simultaneous fields of views (5 to 75 mrad), corresponding to particle size distribution of the aerosol clouds and plumes being probed. The system was completed in 1989 for DREV, and uses a Nd:Glass laser transmitter emitting a 1.5 J output at 1.054 nm and a pulse repettion frequency of 1 Hz. The receiver is a f/1.33, 15 cm diameter refractive four ens construction. The system is mounted as a steerable transceiver. The yoke can point within ± 45o in azimuth and from -5 to +90o in elevation (Fig.10). It has a pointing knowledge of 0.01 degrees. A microwave radar was incorporated into the system which would automatically shut off the laser upon detection of any objects in the transmitter field of view. |
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