Automatically guiding a telescope to a laser beam on a biaxial antarctic light detection and ranging system

Innis, J. L.; Cunningham, A.P.; Graham, A. D.; Klekociuk, Andrew

doi:10.1117/1.2801411

Cited by 1 publication

(4 citation statements)

References 10 publications

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“…Kaifler et al (2015b) report 74 observations with a daylight-capable iron lidar in 2011 (20 %). Li et al (2018) state 154 nights with sodium lidar observations in 2012-2016 (8 %), Jalali et al (2018) 519 Rayleigh lidar observations in 1994-2013 (7 %), and Llamedo et al (2019) 302 Rayleigh lidar observations in 2005-2015 (8 %). The comparison of latter numbers (7 %-20 %) with CORAL observations (66 %) shows the extraordinariness of the CORAL data set.…”

Section: Discussionmentioning

confidence: 99%

“…The search is repeated at regular intervals, e.g., hourly. Innis et al (2007) describe an automatic autoguiding system which uses a camera looking through the receiving telescope to image the spot of the laser beam in the atmosphere at a certain altitude. A piece of software analyzes the images and computes the beam position.…”

Section: Automatic Tracking Of the Laser Beammentioning

confidence: 99%

“…While the latter method is suitable for an automatic lidar like CORAL, we opted to implement the conscan method that is widely used for tracking spacecraft (see e.g., Gawronski and Craparo, 2002). Its main advantages over the autoguiding method (Innis et al, 2007) are the possibility to evaluate the lidar signal for tracking purposes in the stratosphere and thus well above any potential cloud layer and that there is no requirement for a predetermined target position. In particular, the resilience to clouds is attractive as CORAL is designed to operate in marginal weather conditions.…”

Section: Automatic Tracking Of the Laser Beammentioning

confidence: 99%

“…It is important to note that conscan always evaluates the lidar signal within a constant altitude range in the stratosphere. This is in particular beneficial for bistatic lidars in which in an autoguiding setup (Innis et al, 2007), the camera images the laser beam at an angle in the lower troposphere as scattering in the stratosphere is too weak for imaging. Due to the finite exposure time, the camera integrates the beam profile along a certain height range.…”

Section: Automatic Tracking Of the Laser Beammentioning

confidence: 99%

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A Compact Rayleigh Autonomous Lidar (CORAL) for the middle atmosphere

Kaifler

2021

Atmos. Meas. Tech.

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Abstract. The Compact Rayleigh Autonomous Lidar (CORAL) is the first fully autonomous middle atmosphere lidar system to provide density and temperature profiles from 15 to approximately 90 km altitude. From October 2019 to October 2020, CORAL acquired temperature profiles on 243 out of the 365 nights (66 %) above Río Grande, southern Argentina, a cadence which is 3–8 times larger as compared to conventional human-operated lidars. The result is an unprecedented data set with measurements on 2 out of 3 nights on average and high temporal (20 min) and vertical (900 m) resolution. The first studies using CORAL data have shown, for example, the evolution of a strong atmospheric gravity wave event and its impact on the stratospheric circulation. We describe the instrument and its novel software which enables automatic and unattended observations over periods of more than a year. A frequency-doubled diode-pumped pulsed Nd:YAG laser is used as the light source, and backscattered photons are detected using three elastic channels (532 nm wavelength) and one Raman channel (608 nm wavelength). Automatic tracking of the laser beam is realized by the implementation of the conical scan (conscan) method. The CORAL software detects blue sky conditions and makes the decision to start the instrument based on local meteorological measurements, detection of stars in all-sky images, and analysis of European Center for Medium-range Weather Forecasts Integrated Forecasting System data. After the instrument is up and running, the strength of the lidar return signal is used as additional information to assess sky conditions. Safety features in the software allow for the operation of the lidar even in marginal weather, which is a prerequisite to achieving the very high observation cadence.

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