Modeling the target acquisition performance of active imaging systems

Espinola, Richard L.; Jacobs, Eddie L.; Halford, Carl E.; Vollmerhausen, Richard H.; Tofsted, David H.

doi:10.1364/oe.15.003816

Cited by 60 publications

(20 citation statements)

References 20 publications

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“…20 Various system, target, and environment parameters are input to the model. Intermediate results are modulation transfer functions (MTF), noise variances, and contrast threshold functions.…”

Section: Analytical Range Performance Predictionmentioning

confidence: 99%

Review on short-wavelength infrared laser gated-viewing at Fraunhofer IOSB

Göhler

Lutzmann

2016

Opt. Eng

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Abstract. This paper reviews the work that has been done at Fraunhofer IOSB (and its predecessor institutes) in the past ten years in the area of laser gated-viewing (GV) in the short-wavelength infrared (SWIR) band. Experimental system demonstrators in various configurations have been built up to show the potential for different applications and to investigate specific topics. The wavelength of the pulsed illumination laser is 1.57 μm and lies in the invisible, retina-safe region allowing much higher pulse energies than for wavelengths in the visible or near-infrared band concerning eye safety. All systems built up, consist of gated Intevac LIVAR ® cameras based on EBCCD/EBCMOS detectors sensitive in the SWIR band. This review comprises military and civilian applications in maritime and land domain-in particular vision enhancement in bad visibility, long-range applications, silhouette imaging, 3-D imaging by sliding gates and slope method, bistatic GV imaging, and looking through windows. In addition, theoretical studies that were conducted-e.g., estimating 3-D accuracy or modeling range performance-are presented. Finally, an outlook for future work in the area of SWIR laser GV at Fraunhofer IOSB is given. 1 Introduction A gated-viewing (GV) system consists of a pulsed laser illuminator and a synchronizable GV camera. After the laser pulse is emitted, the GV camera waits a predefined delay time until the detector elements integrate all photons that arrive within a very short integration time. Only laser photons that arrive from the corresponding range gate are collected; the fore-and the background are suppressed. The camera delay time determines the gate position and the integration time determines the gate length. The result is a rangegated image with a high target/background contrast as it can be seen in the right image of Fig. 1 for a vehicle at a distance of 480 m and a laser wavelength of 1.57 μm. For comparison, also a nongated, passive image of the vehicle in the wavelength region between 950 and 1650 nm in the shortwavelength infrared (SWIR: 1 to 3 μm) is shown at the left.In Sec. 2, a brief historical overview of some conducted GV experiments in the past 40 years at Fraunhofer IOSB and its predecessor research institutes is given. The main Sec. 3 is divided into 11 sections giving a broad overview of the performed SWIR laser GV activities.

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Section: Analytical Range Performance Predictionmentioning

confidence: 99%

Review on short-wavelength infrared laser gated-viewing at Fraunhofer IOSB

Göhler

Lutzmann

2016

Opt. Eng

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“…The performance of range-gated systems is limited by the sensor parameters as well as the target and atmospheric induced speckles, beam wander and image dancing 76,77 . Close to the range limit, the shot noise restricts the image quality.…”

Section: Spatially Resolved Vibration Imagingmentioning

confidence: 99%

Laser radar: from early history to new trends

Molebny

Kamerman²,

Steinvall

2010

SPIE Proceedings

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The first steps of laser radar are discussed with the examples from range finding and designation. The followed successes in field tests and further fast development provided their wide use. Coherent laser radar, developed almost simultaneously, tried the ideas from microwaves including chirp technology for pulse compression, and Doppler mode of operation. This latter found a unique implementation in a cruise missile. In many applications, environmental studies very strongly rely upon the lidars sensing the wind, temperature, constituents, optical parameters. Lidars are used in the atmosphere and in the sea water measurements. Imaging and mapping is an important role prescribed to ladars. One of the prospective trends in laser radar development is incorporation of range and velocity data into the image information. Deep space program, even having not come to the finish, gave a lot for 3D imaging. Gated imaging, as one of the 3D techniques, demonstrated its prospects (seeing through scattering layers) for military and security usage. Synthetic aperture laser radar, which had a long incubation period, started to show first results, at least in modeling. Coherent laser radar baptized as the optical coherence tomography, along with the position sensitive laser radar, synthetic aperture laser radar, multispectral laser radar demonstrated very pragmatic results in the micro-scale applications.

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“…21 Moreover, the Rayleigh resolution was originally defined for incoherent illumination sources but more recent research has demonstrated that Rayleigh resolution increases with the degree of beam coherence. 21 Increasing beam coherence increases speckle noise 23 which, in turn, increases measurement uncertainty. The resolution of ToF scanners is further limited by the rise time of the laser pulse generated by the system, while both ToF and continuous-wave (AM and FM) scanners are limited by the resolution of the system clock.…”

Section: Spatial Resolutionmentioning

confidence: 99%

Evaluating laser range scanner lateral resolution in 3D metrology

MacKinnon

Beraldin

Cournoyer

et al. 2009

Three-Dimensional Imaging Metrology

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In this study, laser range scanner lateral resolution is investigated for laser range scanners. A standardized method is proposed and demonstrated for quantifying the lateral surface resolvability of a laser range scanner through the use of an appropriately-designed artefact. A new metric for lateral surface resolution, the limit of surface resolvability, is presented and is obtained using what is referred to as the wedge test. The results of applying this metrics using this test method to laser range scanners is also presented.

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Modeling the target acquisition performance of active imaging systems

Cited by 60 publications

References 20 publications

Review on short-wavelength infrared laser gated-viewing at Fraunhofer IOSB

Review on short-wavelength infrared laser gated-viewing at Fraunhofer IOSB

Laser radar: from early history to new trends

Evaluating laser range scanner lateral resolution in 3D metrology

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