Dr. Johan Öhgren Profile

Dr. Johan Öhgren

at Swedish Defence Research Agency FOI

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Author

Publications (8)

Proceedings Article | 7 October 2019 Paper

NATO SET-249 joint measurement campaign on laser dazzle effects in airborne scenarios

Bernd Eberle, Wesley Kinerk, Michael Koerber, Johan Öhgren, Gunnar Ritt, Cristiane Santos, Bastian Schwarz, Ove Steinvall, Sean Tipper, Marijke Vandewal, Christopher Westgate

Proceedings Volume 11161, 111610C (2019) https://doi.org/10.1117/12.2533744

KEYWORDS: Cameras, Sensors, Laser safety, Laser scattering, Airborne laser technology, Laser sources, Light sources

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In October 2018, NATO SET-249 performed a common trial at WTD 52, Oberjettenberg, Germany, to study laser dazzle effects in an airborne scenario. The facility is equipped with a cable car and is ideal for slanted path experiments from the base station to the cable car where the sensors were mounted. NATO SET-249’s background is laser threat evaluation and the evaluation of the impact of laser eye dazzle on the visual performance of humans. This work gives an overview on the various measurements performed here: 1. Assessment of dazzle effects originating from light scattering at an aircraft canopy by comparing the images of two cameras: one outside and one inside the canopy. The general findings showed that the canopy, which had been used previously on an aircraft, substantially affected the dazzle pattern in the camera within the canopy as compared to the camera outside. 2. Sensor dazzling: Laser dazzling of complementary metal-oxide-semiconductor (CMOS) cameras in the visible domain and, in addition, laser dazzling of a camera equipped with a fisheye lens, which is commonly present in micro-unmanned aerial vehicles, is demonstrated. The dazzled area in the camera field of view (FoV) grows with increasing laser irradiance, and dazzling is effective at irradiance levels around a few μW/cm². 3. An overview on realistic handheld laser engagement scenarios to test the capabilities of a DSTL-developed Laser Event Recorder (LER) is provided. This technology is able to detect continuous wave (CW) and pulsed lasers, and extract their wavelengths, irradiances, Pulse Repetition Frequency (PRF) and directionality. Applications for this LER include collecting information on aircraft laser exposure events, giving information to assess if engagements are eye safe. 4. Measurements performed on various Fraunhofer IOSB developed sensor systems hardened against laser dazzle: The hardening measure of these systems is based either on the use of spatial light modulators or on the implementation of the principle of complementary wavelength bands. The field trial offered the possibility to generate data of the hardened systems under real life conditions.

Proceedings Article | 16 October 2015 Paper

Passive and active EO sensing of small surface vessels

Ove Steinvall, Folke Berglund, Lars Allard, Johan Öhgren, Håkan Larsson, Elias Amselem, Frank Gustafsson, Endre Repasi, Peter Lutzmann, Benjamin Göhler, Marcus Hammer, Kennedy McEwen, Ken McEwan

Proceedings Volume 9649, 96490I (2015) https://doi.org/10.1117/12.2195320

KEYWORDS: Sensors, Cameras, Mid-IR, Visibility, Short wave infrared radiation, Profiling, Infrared cameras, Target detection, Imaging systems, Clouds

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SPIE Journal Paper | 21 July 2015

Using an eye-safe laser rangefinder to assist active and passive electro-optical sensor performance prediction in low visibility conditions

Ove Steinvall, Rolf Persson, Folke Berglund, Ove Gustafsson, Johan Öhgren, Frank Gustafsson

OE, Vol. 54, Issue 07, 074103, (July 2015) https://doi.org/10.1117/12.10.1117/1.OE.54.7.074103

KEYWORDS: Visibility, LIDAR, Backscatter, Mass attenuation coefficient, Cameras, Aerosols, Visibility through fog, Sensors, Modulation transfer functions, Signal attenuation

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Proceedings Article | 13 October 2014 Paper

Passive and active EO sensing close to the sea surface

Ove Steinvall, Rolf Persson, Folke Berglund, Johan Öhgren, Frank Gustafsson

Proceedings Volume 9250, 92500A (2014) https://doi.org/10.1117/12.2067239

KEYWORDS: Visibility, LIDAR, Cameras, Turbulence, Aerosols, Sensors, Infrared imaging, Signal attenuation, Modulation transfer functions, Backscatter

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Proceedings Article | 15 October 2013 Paper

Laser dazzling impacts on car driver performance

Ove Steinvall, Stig Sandberg, Ulf Hörberg, Rolf Persson, Folke Berglund, Kjell Karslsson, Johan Öhgren, Zhaohua Yu, Per Söderberg

Proceedings Volume 8898, 88980H (2013) https://doi.org/10.1117/12.2028505

KEYWORDS: Visualization, Cones, Sensors, Eye, Roads, Headlamps, Laser countermeasures, Visual system, Laser development, Defense and security

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Proceedings Article | 5 October 2007 Paper

A high-speed modulated retro-reflector communication link with a transmissive modulator in a cat's eye optics arrangement

Johan Öhgren, Fredrik Kullander, Lars Sjöqvist, Kun Wang, Qin Wang, Stéphane Junique, Susanne Almqvist, Bertrand Noharet

Proceedings Volume 6736, 673619 (2007) https://doi.org/10.1117/12.737959

KEYWORDS: Modulation, Modulators, Eye, Sensors, Signal to noise ratio, Signal detection, Transceivers, Free space optics, Retroreflectors, Optical communications

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SPIE Journal Paper | 1 April 2005

Retrocommunication utilizing electroabsorption modulators and nonmechanical beam steering

Emil Hällstig, Johan Öhgren, Lars Allard, Lars Sjöqvist, David Engstroem, Sverker Hard, Daniel Ågren, Stéphane Junique, Qin Wang, Bertrand Noharet

OE, Vol. 44, Issue 04, 045001, (April 2005) https://doi.org/10.1117/12.10.1117/1.1883063

KEYWORDS: Modulators, Spatial light modulators, Beam steering, Reflectivity, Sensors, Liquid crystals, Transceivers, Video, Optical engineering, Quantum wells

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Proceedings Article | 8 December 2004 Paper

A novel free-space retrocommunication link

Lars Sjoqvist, Emil Hallstig, Johan Ohgren, Lars Allard, Daniel Agren, Stephane Junique, Qin Wang, Bertrand Noharet, David Engstrom, Sverker Hard

Proceedings Volume 5614, (2004) https://doi.org/10.1117/12.578267

KEYWORDS: Modulators, Spatial light modulators, Beam steering, Transceivers, Reflectivity, Quantum wells, Liquid crystals, Turbulence, Optical modulators, Sensors

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Showing 5 of 8 publications

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