| 1. |
- Barup, Kerstin, et al.
(författare)
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Multi-disciplinary lidar applications
- 2010
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Ingår i: Laser Applications to Chemical, Security and Environmental Analysis, LACSEA 2010. - 2162-2701. - 9781557528803
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Konferensbidrag (refereegranskat)abstract
- Lidar is a powerful technique normally associated with atmospheric monitoring. However, lidar techniques, also of the laser-induced fluorescence and laser-induced breakdown spectroscopy varieties, provide many new possibilities in unconventional fields including cultural heritage and ecological applications.
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| 2. |
- Brydegaard, Mikkel, et al.
(författare)
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Feasibility study: fluorescence lidar for remote bird classification
- 2010
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Ingår i: Applied Optics. - 2155-3165. ; 49:24, s. 4531-4544
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Tidskriftsartikel (refereegranskat)abstract
- We present a method for remote classification of birds based on eye-safe fluorescence lidar techniques. Mechanisms of quenching are discussed. Plumage reflectance is related to plumage fluorescence. Laboratory measurements on reflectance and fluorescence are presented, as well as test-range measurements. Also we present examples of birds' in-flight lidar returns. The methods are suitable for studies of night migrating species and high-altitude classification with implications for the detailed understanding of bird migration and global virus spread. (C) 2010 Optical Society of America
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| 3. |
- Guan, Zuguang, et al.
(författare)
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Insect monitoring with fluorescence lidar techniques: field experiments.
- 2010
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Ingår i: Applied Optics. - 2155-3165. ; 49:27, s. 5133-5142
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Tidskriftsartikel (refereegranskat)abstract
- Results from field experiments using a fluorescence lidar system to monitor movements of insects are reported. Measurements over a river surface were made at distances between 100 and 300 m, detecting, in particular, damselflies entering the 355 nm pulsed laser beam. The lidar system recorded the depolarized elastic backscattering and two broad bands of laser-induced fluorescence, with the separation wavelength at 500 nm. Captured species, dusted with characteristic fluorescent dye powders, could be followed spatially and temporally after release. Implications for ecological research are discussed.
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| 4. |
- Guan, Zuguang
(författare)
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Laser Remote Sensing for Environmental Monitoring
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis studies the techniques of laser remote sensing and their applications in environmental monitoring, as documented in several published papers. The environment where the human being live is degrading with an accelerating speed. Quantitative monitoring characterizes the quality of the environment and offers possibilities to solve environmental problems. Laser remote sensing actively probes physical quantities with advantages of, e.g., large spatial coverage and little environmental influence, and hence becomes a very suitable tool for environmental analysis. Light detection and ranging (LIDAR) measures the backscattered light from remote targets using a short-pulsed laser. Three varieties of LIDAR techniques, based on a vehicle-carried laboratory, have been developed in the work within the thesis. Elastic LIDAR measures the elastic backscattering from the atmospheric aerosols, and has been used to comparatively study their vertical distribution above a Swedish rural area and a Chinese Magacity. Differential absorption LIDAR (DIAL) is able to analyze the distribution of trace pollutants in the atmosphere. Vertical measurements of two serious pollutants, atomic mercury and nitrogen monoxide, have been performed in the same Chinese city. Further, DIAL is also proved to be valid for remote gas analysis in multiple-scattering media. Fluorescence LIDAR can recognize the molecules contained in a remote target, through analyzing the laser-induced fluorescence fingerprint. Such a technique is employed in this thesis mainly for ecological studies, particularly for insect and bird monitoring. Promising performances have been revealed through feasibility tests and field experiments. Tunable diode laser absorption spectroscopy (TDLAS) attracts research attention for its compactness, cost-effectiveness, and high sensitivity. The signal-to-noise ratio of a TDLAS can be conventionally improved by applying modulation; while in the thesis, a different idea is proposed and demonstrated by operating the absorption spectroscopy on a zero light background. Proof-of-principle experiments are performed and considerations regarding real-world applications are discussed. GAs in Scattering Media Absorption Spectroscopy (GASMAS) employs diode lasers for gas analysis as well, and wavelength modulation is frequently applied for sensitivity enhancement. Such an advanced TDLAS tool is applied in the thesis for food package monitoring. Finally, fiber-optic remote sensing realizes the environmental monitoring by employing fiber-optic devices, e.g., fiber Bragg gratings (FBGs). Applications of these sensors are usually limited to temperature and stain monitoring. By using a methane catalyst which transfers the ambient methane into heat, FBG sensors become sensitive to methane. The sensitivity can be improved if the sensing FBG is interrogated by another reference grating having a matched spectrum. The multiplexing of such twin-grating-structure sensors is realized, and thus a distributed sensor network is possible to construct.
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| 5. |
- Guan, Zuguang, et al.
(författare)
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Vertical lidar sounding of atomic mercury and nitric oxide in a major Chinese city
- 2010
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Ingår i: Applied Physics B. - : Springer Science and Business Media LLC. - 0946-2171 .- 1432-0649. ; 101:1-2, s. 465-470
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Tidskriftsartikel (refereegranskat)abstract
- Vertical range-resolved measurements of atmospheric pollutants were performed in a major city in southern China, employing a lidar system operating with an optical parametric oscillator transmitter. Recordings of atomic mercury (Hg) and nitric oxide (NO) absorbing in the deep-UV region were taken, yielding concentration profiles only attainable with lidar techniques. In particular, the potential influence of molecular oxygen in low-concentration mercury monitoring was elucidated. Diurnal observations are discussed and presented together with weather parameters.
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| 6. |
- Zhou, Bin, et al.
(författare)
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Low Coherent Optical Frequency Domain Reflectometry Interrogates Fiber Bragg Grating Sensors
- 2010
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 28:21, s. 3409-3414
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Tidskriftsartikel (refereegranskat)abstract
- A novel fiber optical reflectometry is proposed for long distance measurements and sensing applications. The reflectrometric information is included in the phase difference of two interfering light beams reflected at the same scattering point on the fiber under test (FUT). The reflection position and local information can be determined by modulating the frequency difference and analyzing the reflecting signal in frequency domain. Theoretical analysis and experimental demonstration are presented. Two adjacent reflection points 50 km away from the reflectometry with a gap of 11 meters between each other is distinguished. It is estimated that the operating range could be over 500 km theoretically by employing a light source with 0.3 nm bandwidth. This novel reflectometry is applied as a fiber Bragg grating interrogation solution as an example.
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