Application of lidar in ultraviolet, visible and infrared ranges for early forest fire detection (original) (raw)
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Application of lidar at 1.54 um for forest fire detection
1999
A mathematical model for computation of parameters of eyesafe lidar for detection of forest fire smoke has been developed. It is assumed that the lidar uses a wavelength of 1.54 micrometer. This wavelength can be obtained from Er:glass lasers, from Nd:YAG lasers with an optical parametric oscillator, or from Nd:YAG lasers with a Raman cell. It is assumed that receiver optics of 20 cm diameter and an avalanche photodiode are used. Particle size distributions in the smoke from experiments in the literature are utilized for calculation of backscattering efficiency. The backscattering cross section is calculated on the basis of Mie formulae. Diffusion of the smoke plume is estimated on the basis of an analytical solution of the relevant hydrodynamics equations. Results of the calculations show that for detection of forest fires with fuel mass burned in unit time 2 kg/s at a distance of 10 km it is necessary to have a laser pulse energy of 120 mJ.
Feasibility of forest-fire smoke detection using lidar
International Journal of Wildland Fire, 2003
The feasibility and fundamentals of forest fire detection by smoke sensing with single-wavelength lidar are discussed with reference to results of 532-nm lidar measurements of smoke plumes from experimental forest fires in Portugal within the scope of the Gestosa 2001 project. The investigations included tracing smoke-plume evolution, estimating forest-fire alarm promptness, and smoke-plume location by azimuth rastering of the lidar optical axis. The possibility of locating a smoke plume whose source is out of line of sight and detection under extremely unfavourable visibility conditions was also demonstrated. The eye hazard problem is addressed and three possibilities of providing eye-safety conditions without loss of lidar sensitivity (namely, using a low energy-per-pulse and high repetition-rate laser, an expanded laser beam, or eye-safe radiation) are discussed.
Application of lidar at 1.54 μm for forest fire detection
Remote Sensing for Earth Science, Ocean, and Sea Ice Applications, 1999
A mathematical model for computation of parameters of eyesafe lidar for detection of forest fire smoke has been developed. It is assumed that the lidar uses a wavelength of 1.54 m. This wavelength can be obtained from Er:glass lasers, from Nd:YAG lasers with an optical parametric oscillator, or from Nd:YAG lasers with a Raman cell. It is assumed that receiver optics of 20cm diameter and an avalanche photodiode are used. Particle size distributions in the smoke from experiments in the literature are utilised for calculation of backscattering efficiency. The backscattering cross section is calculated on the basis of Mie formulae. Diffusion of the smoke plume is estimated on the basis of an analytical solution of the relevant hydrodynamics equations. Results of the calculations show that for detection of forest fires with fuel mass burned in unit time 2 kg/s at a distance of 10 km it is necessary to have a laser pulse energy of 120 mJ.
Detection of small forest fires by lidar
Applied Physics B-lasers and Optics, 2002
The possibility of detecting small forest fires with the help of a simple and cheap lidar operating at 0.532-μm wavelength up to distances of about 6.5 km is demonstrated. The values of the signal-to-noise ratio (SNR) achieved in the experiments are consistent with theoretical estimations obtained by computational modeling of the lidar detection process, including simulation of the smoke-plume shape and of the laser beam–plume interaction. This model was used to assess the potential of the lidar technique for fire surveillance in large forest areas. In particular, the upper limiting range for effective detection (SNR>5) of small localized fires in dry- and clear-weather conditions is estimated at 7–15 km depending on operation mode, burning rate, and observation geometry.
Estimation of required parameters for detection of small smoke plumes by lidar at 1.54��m
Appl Phys B Lasers Opt, 2000
Parameters of eyesafe lidar at 1.54 µm for detection of small plumes of smoke from burning wood or oil have been evaluated. It was assumed that a diode-pumped solid-state Er:glass laser at 1.54 µm or a Nd:YAG laser with a Raman cell or optical-parametric oscillator is used as a light source and that detection of backscattered light is performed with an avalanche photodiode. Ash and soot particle size distributions were taken from experiments. A backscattering coefficient at 1.54 µm for various source of smoke was estimated. In computing the laser energy, range between lidar and smoke, receiver optics diameter, fuel mass burned in unit time, fire source radius, laser pulse duration and visibility were varied. Results of the computations enabled estimation of the required laser energy, which ranges from 0.05 to 1400 mJ depending on the parameters. PACS: 42.68.Wt; 92.60.Mt Detection of smoke from sources such as power plants, factories, forest fires, etc., was one of the first practical applications of lidar . Smoke contains a large number of small particles of ash or soot, leading to a large backscattering efficiency and consequently favourable conditions for lidar application. The use of lidar increased considerably during the following years, and this technology is now widely used . In general the first lidars used ruby or Nd:YAG lasers (wavelength 694 and 1064 nm, respectively), which are dangerous to the eye. They were applied to the investigation of plumes, which have a great output of smoke. However the modern tendency in lidar is to use lasers with eyesafe wavelengths (at 1.54 or ≈ 2.1 µm [5, 6]) and to increase its sensitivity, allowing increasingly small sources of smoke to be detected . It is obvious that detection of the early stages of a fire, when smoke plumes are tenuous, allows the means required to extinguish the fire and fire damage to be minimized. For eyesafety, lidars with a wavelength within the range ≈ 1.54 µm are increasingly being used. It is possible in this lidar to use solid-state Er:glass lasers at 1.54 µm, Nd:YAG lasers with a Raman cell at 1.54 µm [9], and Nd:YAG lasers with opticalparametric oscillators (OPO) . Detection of smoke is pos-sible by direct or heterodyne detection mode . But it is known [5] that OPO leads to frequency instability, so in this case it is preferable to use lidar with direct-detection mode.
Estimation of required parameters for detection of small smoke plumes by lidar at 1.54 μm
Applied Physics B, 2000
Parameters of eyesafe lidar at 1.54 µm for detection of small plumes of smoke from burning wood or oil have been evaluated. It was assumed that a diode-pumped solid-state Er:glass laser at 1.54 µm or a Nd:YAG laser with a Raman cell or optical-parametric oscillator is used as a light source and that detection of backscattered light is performed with an avalanche photodiode. Ash and soot particle size distributions were taken from experiments. A backscattering coefficient at 1.54 µm for various source of smoke was estimated. In computing the laser energy, range between lidar and smoke, receiver optics diameter, fuel mass burned in unit time, fire source radius, laser pulse duration and visibility were varied. Results of the computations enabled estimation of the required laser energy, which ranges from 0.05 to 1400 mJ depending on the parameters. PACS: 42.68.Wt; 92.60.Mt Detection of smoke from sources such as power plants, factories, forest fires, etc., was one of the first practical applications of lidar . Smoke contains a large number of small particles of ash or soot, leading to a large backscattering efficiency and consequently favourable conditions for lidar application. The use of lidar increased considerably during the following years, and this technology is now widely used . In general the first lidars used ruby or Nd:YAG lasers (wavelength 694 and 1064 nm, respectively), which are dangerous to the eye. They were applied to the investigation of plumes, which have a great output of smoke. However the modern tendency in lidar is to use lasers with eyesafe wavelengths (at 1.54 or ≈ 2.1 µm [5, 6]) and to increase its sensitivity, allowing increasingly small sources of smoke to be detected . It is obvious that detection of the early stages of a fire, when smoke plumes are tenuous, allows the means required to extinguish the fire and fire damage to be minimized. For eyesafety, lidars with a wavelength within the range ≈ 1.54 µm are increasingly being used. It is possible in this lidar to use solid-state Er:glass lasers at 1.54 µm, Nd:YAG lasers with a Raman cell at 1.54 µm [9], and Nd:YAG lasers with opticalparametric oscillators (OPO) . Detection of smoke is pos-sible by direct or heterodyne detection mode . But it is known [5] that OPO leads to frequency instability, so in this case it is preferable to use lidar with direct-detection mode.
Lidar Technique for Early Forest Fire Detection : Design and Development Aspects
AIP Conference Proceedings, 2008
Many countries suffer from forest fires every summer, a phenomenon which wreaks havoc on both local and global environment. As well, it causes enormous damage to public health especially for people living in surrounding areas. For fighting against forest fires, ocular surveillance, in spite of its wide use, is not efficient owing to the costly mobilization of a great number of forest agents and to the fact that most of forest regions are not accessible. Other passive techniques such as infrared camera remote sensing are neither efficient under unfavorable weather conditions. An efficient way to early detect forest fires even under worse environmental conditions and in inaccessible mountainous regions uses the backscattering Lidar technique. This consists of the emission of monowavelength laser pulses spanning azimuthally the entire region subject to surveillance and the detection of the backscattered signal. The detection parameter is the signal to noise ration SNR. In this contribution, we will deal with approach and design aspects inherent to the development task of such a Lidar.
XVII International Symposium on Gas Flow, Chemical Lasers, and High-Power Lasers, 2008
The possibility of early forest fire detection within a range up to ~2 km using a portable eye-safe 1540 nm lidar is demonstrated in this paper, both on experimental and theoretical ground. An estimation of the detection efficiency using a mathematical model based on the 3D system of Navier-Stokes equations describing the smoke plume evolution in the presence of wind, agrees reasonably well with experimental results. Calculations made using the model show that a detection range up to ~5.5 km can be achieved by accumulating lidar return signals.
Fire Surveillance and Evaluation by Means of Lidar Technique
Lidar (light detection and ranging) is an active remote detection technique that uses a pulsed laser beam to probe the atmosphere. When the laser radiation illuminates a target, such as a smoke plume originating from a forest fire, part of the incident radiation is backscattered, the intensity of this radiation is measured as a function of time by a suitable detector, and the resulting signal is analyzed by artificial intelligence methods. If the signature of a smoke plume is identified, an alarm is emitted. Precise position of the smoke plume is derived from the current azimuth/elevation angles of the laser beam (provided by the scanning system) and the distance to the target (calculated from the detection time).
Eye-safe lidar measurements for detection and investigation of forest-fire smoke
International Journal of Wildland Fire, 2004
The problem of eye safety in lidar-assisted wildland fire detection and investigation is considered as a problem of reduction of the hazard range within which the laser beam is dangerous for direct eye exposure. The dependence of this hazard range on the lidar characteristics is examined and possible eye-safety measures discussed. The potential of one of the cheapest ways of providing eye safety, which is based on placing the lidar in an elevated position and using a 1064-nm laser beam with increased divergence, is also investigated experimentally. It is demonstrated that a lidar system operating with wider beams maintains its ability to detect smoke plumes efficiently. Providing eye-safe conditions allows scanning of the internal 3D structure of smoke plumes in the vicinity of fire plots. Examples are given as layer-by-layer smoke concentration plots on the topographic map.