| 1. |
- Lundin, Patrik, et al.
(författare)
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Gas Monitoring in Human Body Cavities Using Non-Intrusive Diode Laser Absorption Spectroscopy
- 2012
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Ingår i: 2012 Asia Communications and Photonics Conference. - : IEEE. - 2162-108X. ; , s. 4-7
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Konferensbidrag (refereegranskat)abstract
- Diode laser absorption spectroscopy was utilized for non-intrusive assessment of gas content in human body cavities, including intestines and lungs of a new-born, the mastoid bone, and sinus cavities for monitoring sinusitis recovery in adults.
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| 2. |
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| 3. |
- Bengtsson, Magnus, et al.
(författare)
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Fluorescence lidar imaging of fungal growth on high-voltage outdoor composite insulators
- 2005
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Ingår i: Optics and Lasers in Engineering. - : Elsevier BV. - 0143-8166 .- 1873-0302. ; 43:6, s. 624-632
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Tidskriftsartikel (refereegranskat)abstract
- Remote fluorescence imaging of fungal growth on polymeric high-voltage insulators was performed using a mobile lidar system with a laser wavelength of 355 nm. Insulator areas contaminated by fungal growth could be distinguished from clean surfaces and readily be imaged. The experiments were supported by detailed spectral studies performed in laboratory using a fibre-optic fluorosensor incorporating an optical multi-channel analyser system (OMA) and a nitrogen laser emitting radiation at 33 7 nm.
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| 4. |
- Bengtsson, Magnus, et al.
(författare)
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Fungus covered insulator materials studied with laser-induced fluorescence and principal component analysis
- 2005
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Ingår i: Applied Spectroscopy. - : SAGE Publications. - 0003-7028 .- 1943-3530. ; 59:8, s. 1037-1041
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Tidskriftsartikel (refereegranskat)abstract
- A method combining laser-induced fluorescence and principal component analysis to detect and discriminate between algal and fungal growth on insulator materials has been studied. Eight fungal cultures and four insulator materials have been analyzed. Multivariate classifications were utilized to characterize the insulator material, and fungal growth could readily be distinguished from a clean surface. The results of the principal component analyses make it possible to distinguish between algae infected, fungi infected, and clean silicone rubber materials. The experiments were performed in the laboratory using a fiber-optic fluorosensor that consisted of a nitrogen laser and an optical multi-channel analyzer system.
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| 5. |
- Brydegaard, Mikkel, et al.
(författare)
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Short-Wave infrared atmospheric scheimpflug lidar
- 2018
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Ingår i: EPJ Web of Conferences. - : EDP Sciences. ; 176
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Konferensbidrag (refereegranskat)abstract
- Atmospheric dual-band Scheimpflug lidar is demonstrated at 980 and 1550 nm. Signals are compared during three weather conditions, and the spatio-temporal resolution of the atmospheric structure is considered. The potential for aerosol classification is evaluated, and future directions are discussed.
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| 6. |
- Lou, Xiutao, et al.
(författare)
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Detection of elemental mercury by multimode diode laser correlation spectroscopy
- 2012
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Ingår i: Optics Express. - 1094-4087. ; 20:5, s. 4927-4938
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a method for elemental mercury detection based on correlation spectroscopy employing UV laser radiation generated by sum-frequency mixing of two visible multimode diode lasers. Resonance matching of the multimode UV laser is achieved in a wide wavelength range and with good tolerance for various operating conditions. Large mode-hops provide an off-resonance baseline, eliminating interferences from other gas species with broadband absorption. A sensitivity of 1 mu g/m(3) is obtained for a 1-m path length and 30-s integration time. The performance of the system shows promise for mercury monitoring in industrial applications.
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| 7. |
- Mei, L., et al.
(författare)
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Agricultural pest monitoring using fluorescence lidar techniques Feasibility study
- 2012
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Ingår i: Applied physics. B, Lasers and optics (Print). - : Springer Science and Business Media LLC. - 0946-2171 .- 1432-0649. ; 106:3, s. 733-740
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Tidskriftsartikel (refereegranskat)abstract
- The fluorescence of different types of planthopper (Hemiptera) and moth (Lepidoptera), which constitute important Chinese agricultural pests, was investigated both in situ in a laboratory setting and remotely using a fluorescence light detection and ranging (lidar) system operating at a range of about 50 m. The natural autofluorescence of different species, as well as the fluorescence from insects that had been dusted with fluorescent dye powder for identification were studied. Autofluorescence spectra of both moths and planthoppers show a maximum intensity peak around 450 nm. Bleaching upon long-time laser illumination was modest and did not affect the shape of the spectrum. A single dyed rice planthopper, a few mm in size, could be detected at 50 m distance by using the fluorescence lidar system. By employing various marking dyes, different types of agricultural pest could be determined. We suggest that lidar may be used in studies of migration and movement of pest insects, including studies of their behavior in the vicinity of pheromone traps and in pheromone-treated fields.
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| 8. |
- Mei, Liang, et al.
(författare)
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Characterization and validation of the frequency-modulated continuous-wave technique for assessment of photon migration in solid scattering media
- 2012
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Ingår i: Applied physics. B, Lasers and optics (Print). - : Springer Nature. - 0946-2171 .- 1432-0649. ; 109:3, s. 467-475
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Tidskriftsartikel (refereegranskat)abstract
- The frequency-modulated continuous-wave (FM-CW) technique, based on the beat signal of a Mach-Zehnder interferometer employing a frequency-ramped light source, is studied for solid scattering media applications. The method is used to evaluate the mean time-of-flight (MTOF) of light traveling in scattering media, specifically polystyrene foams. We assume that each the time-of-flight (TOF) time corresponds to different light scattering paths resulting in a different phase shift. The phase shift variations produce a speckle pattern, which together with the frequency leakage induced by the discrete Fourier transform (DFT) cause "spikes" in the power spectrum of the beat signal, thus decreasing the accuracy of the measured MTOF values in solid scattering media. For comparison, time-of-flight spectroscopy (TOFS) is also employed to evaluate the MTOF for the same samples, while the geometrical difference between these two techniques is compensated for by using diffusion theory. The MTOFs measured by the FMCW and TOFS techniques agree well, which demonstrates a great potential to develop a robust FMCW setup for simplified MTOF assessment.
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| 9. |
- Mei, Liang, et al.
(författare)
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Combined optical porosimetry and gas absorption spectroscopy in gas-filled porous media using diode-laser-based frequency domain photon migration
- 2012
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Ingår i: Optics Express. - 1094-4087. ; 20:15, s. 16942-16954
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Tidskriftsartikel (refereegranskat)abstract
- A combination method of frequency domain photon migration (FDPM) and gas in scattering media absorption spectroscopy (GASMAS) is used for assessment of the mean optical path length (MOPL) and the gas absorption in gas-filled porous media, respectively. Polystyrene (PS) foams, with extremely high physical porosity, are utilized as sample materials for proof-of-principle demonstration. The optical porosity, defined as the ratio between the path length through the pores and the path length through the medium, is evaluated in PS foam and found consistent with the measured physical porosity. The method was also utilized for the study of balsa and spruce wood samples.
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| 10. |
- Mei, Liang, et al.
(författare)
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Frequency-modulated light scattering in colloidal suspensions
- 2013
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 102:6, s. 061104-
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Tidskriftsartikel (refereegranskat)abstract
- Frequency-modulated light field fluctuations due to moving particles in colloidal suspensions are examined using heterodyne interferometry. The power spectrum is the combined result of a time-of-flight-related frequency distribution due to light scattering and frequency shifts due to the Doppler effect. An approximation model is developed based on diffusion theory and verified experimentally. The potential for application towards comprehensive diagnosis of both particle dynamics and optical properties of the examined media is discussed.
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