Improving underwater imaging in an amplitude modulated laser system with radio frequency control technique

Dominicis, L. De; Collibus, Mario Ferri De; Fornetti, G.; Guarneri, Massimiliano; Nuvoli, Marcello; Ricci, R.; Francucci, M.

doi:10.2971/jeos.2009.10004

Cited by 11 publications

(8 citation statements)

References 13 publications

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“…give clues to detect micro-Doppler signature, where vibrations and rotations have to be discriminated [16]. As the method can be used with virtually any Q-switched lasers, it could be applied with green lasers for underwater remote sensing where visible light is mandatory [4,17].…”

Section: Resultsmentioning

confidence: 99%

“…In 1980, Eberhard and Schotland demonstrated wind velocity measurement using Doppler-shifted backscattering of dual-frequency laser beams on aerosols [1]. More recently, RF-modulated optical beams were proposed for the detection of underwater objects [2,3], leading to the development of 3D imagers [4]. At the same time, architectures based on dual-frequency sources were shown to provide accurate range and velocity measurements of moving targets in air, at short and long distances [5,6].…”

Section: Introductionmentioning

confidence: 99%

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Lidar–radar velocimetry using a pulse-to-pulse coherent rf-modulated Q-switched laser

et al. 2013

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An rf-modulated pulse train from a passively Q-switched Nd:YAG laser has been generated using an extra-cavity acousto-optic modulator. The rf modulation reproduces the spectral quality of the local oscillator. It leads to a high pulse-to-pulse phase coherence, i.e., phase memory, over thousands of pulses. The potentialities of this transmitter for lidar-radar are demonstrated by performing Doppler velocimetry on indoor moving targets. The experimental results are in good agreement with a model based on elementary signal processing theory. In particular, we show experimentally and theoretically that lidar-radar is a promising technique that allows discrimination between translation and rotation movements. Being independent of the laser internal dynamics, this scheme can be applied to any Q-switched laser.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Lidar–radar velocimetry using a pulse-to-pulse coherent rf-modulated Q-switched laser

et al. 2013

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“…Underwater impulse response measurements can quantify the effects of optical absorption and scattering, [5][6][7] which are relevant to underwater lidar systems. [8][9][10][11][12][13][14][15][16][17][18] These impulse response measurements have been made in the blue-green wavelengths using pulsed bulk lasers 8,19,20 or frequencymodulated continuous-wave (FMCW) systems based on diodes or fiber optic transmitters. 21,22 Properties such as the extinction coefficient of the water and the power spectrum of the backscatter's modulation response can be extracted from these measurements.…”

Section: Introductionmentioning

confidence: 99%

Underwater optical impulse response measurement using a chaotic lidar sensor

Rumbaugh

Banavar

Jemison

2015

Ocean Sensing and Monitoring VII

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This paper explores the use of a recently developed chaotic lidar sensor to perform impulse response measurements underwater. The sensor's measured system impulse response, which approximates a thumbtack function with a 1 ns peak width, is used with an ocean impulse response simulator to predict the chaotic lidar's expected performance underwater. A calibration routine is developed to compensate for the finite resolution and sidelobes in the sensor's system impulse response, improving the accuracy of the simulated chaotic lidar results. In an example application of water turbidity measurement, the extinction coefficient of water, c, is extracted from simulated chaotic lidar impulse responses with an average error of 0.03/m over a range of turbidities from c=0.1/m to c=0.3/m. Simulations are also presented to demonstrate that the chaotic lidar sensor impulse response can simultaneously detect multiple reflective elements and the volumetric backscatter response with a 1 ns temporal resolution. Laboratory water tank measurements are performed to validate the simulation approach, and the experimental chaotic lidar measurements are in reasonable agreement with the simulated results.

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“…(Tardos et al, 2002) (Feder et al, 1999) (Campos et al, 2015) (Gorman and Sejnowski, 1988) (Laser Range Finder: LRF) (Englot and Hover, 2013) (Dominicis et al, 2010) (Gonzalez et al, 2007) (O'Connor et al, 2014 ( Grigg et al, 2007) (Albiez et al, 2015) (Wang and Tang, 2012) (Kulp et al, 1993) (Moore, 2001) ( , 2006) (complex refractive index)…”

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confidence: 99%

Correction methods for underwater scan data measured by general-purpose laser range finders

Fujiwara

Kamegawa

Hasegawa

et al. 2015

Transactions of the JSME (In Japanese)

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We propose a method that corrects effects of refractions and absorptions for underwater scan data obtained by generalpurpose laser range finders (LRFs) using HOKUYO UTM-30LX (Top-URG). For measurements by LRFs in water, it is known that refractions make measurement distances longer and absorptions make reflection intensities weaker. In order to confirm those characteristics of measurements in water, we first conduct two basic experiments that Top-URG measures a target in the environment with the assumed turbid deep-sea and evaluate an accuracy and a performance of Top-URG in water. The first basic experiment is that Top-URG measures surroundings in a sink filled with water by changing the turbidity of the water. The second basic experiment is conducted by changing a location and an angle of a target. Next, we develop a method that (1) corrects scan data of Top-URG by considering a refractive index of water and (2) eliminates scan data with low reliabilities based on reflection intensities obtained by Top-URG using automatically calculated thresholds. We evaluate those two methods by using two types of target objects and seven situations. Our developed methods can correct distorted scan points by refractions in water and can eliminate ghost scan points which are not existent. We confirm that their performances for underwater scan data are effective enough to use Top-URG in water.

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Improving underwater imaging in an amplitude modulated laser system with radio frequency control technique

Cited by 11 publications

References 13 publications

Lidar–radar velocimetry using a pulse-to-pulse coherent rf-modulated Q-switched laser

Lidar–radar velocimetry using a pulse-to-pulse coherent rf-modulated Q-switched laser

Underwater optical impulse response measurement using a chaotic lidar sensor

Correction methods for underwater scan data measured by general-purpose laser range finders

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