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488 results on '"Steinvall, Ove"'

37. Advanced short-wavelength infrared range-gated imaging for ground applications in monostatic and bistatic configurations

Author

Repasi, Endre, Lutzmann, Peter, Steinvall, Ove, Elmqvist, Magnus, Gohler, Benjamin, and Anstett, Gregor

Subjects
Optics -- Research, Gates (Electronics) -- Usage, Gates (Electronics) -- Methods, Astronomy, Physics
Abstract

Some advanced concepts for gated viewing are presented, including spectral diversity illumination techniques, non-line-of-sight imaging, indirect scene illumination, and in particular setups in bistatic configurations. By using a multiple-wavelength illumination source target speckles could be substantially reduced, leading to an improved image quality and enhanced range accuracy. In non-line-of-sight imaging experiments we observed the scenery through the reflections in a window plane. The scene was illuminated indirectly as well by a diffuse reflection of the laser beam at different nearby objects. In this setup several targets could be spotted, which, e.g., offers the capability to look around the corner in urban situations. In the presented measuring campaigns the advantages of bistatic setups in comparison with common monostatic configurations are discussed. The appearance of shadows or local contrast enhancements as well as the mitigation of retroreflections supports the human observer in interpreting the scene. Furthermore a bistatic configuration contributes to a reduced dazzling risk and to observer convertness. OCIS codes: 110.6150, 280.3420.

Published
2009

38. Laser system range calculations and the Lambert W function

Author

Steinvall, Ove

Subjects
Lasers -- Models, Lasers -- Properties, Electrooptics -- Research, Optical radar -- Models, Optical radar -- Properties, Dispersion measures (Statistics) -- Research, Signal processing -- Methods, Atmosphere -- Influence, Atmosphere -- Properties, Earth -- Atmosphere, Earth -- Influence, Earth -- Properties, Laser, Digital signal processor, Astronomy, Physics
Abstract

The knowledge of range performance versus atmospheric transmission, often given by the visibility, is critical for the design, use, and prediction of laser and passive electro-optic systems. I present a solution of the ladar-lidar equation based on Lambert's W function. This solution will reveal the dependence of the maximum range on the system and target parameters for different atmospheric attenuations and will also allow us to take the signal statistics into account by studying the influence on the threshold signal-to-noise ratio. The method is also applicable to many range calculations for passive systems where the atmospheric loss can be approximated by an exponential term. OCIS codes: 000.3860, 010.0280, 010.3640, 280.3400, 280.3420, 280.3640.

Published
2009

41. Simulation of sea surface wave influence on small target detection with airborne laser depth sounding

Author

Tulldahl, H. Michael and Steinvall, Ove K.

Subjects
Astronomy, Physics
Abstract

A theoretical model for simulation of airborne depth-sounding lidar is presented with the purpose of analyzing the influence from water surface waves on the ability to detect 1-[m.sup.3] targets placed on the sea bottom. Although water clarity is the main limitation, sea surface waves can significantly affect the detectability. The detection probability for a target at a 9-m depth can be above 90% at 1-m/s wind and below 80% at 6-m/s wind for the same water clarity. The simulation model contains both numerical and analytical components. Simulated data are compared with measured data and give realistic results for bottom depths between 3 and 10 m. OCIS codes: 010.3640, 010.4450, 010.3310, 120.0280, 290.7050.

Published
2004

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