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The radiant intensities of the muzzle flash of M1 rifle (left), compared to that of Jericho gun (right)
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Understanding of the temporal and spectral behavior of the radiation emitted from fast transients such as gun shots, explosions, missile launches and kinetic ammunition is very important for the development of IRST, MWS and IRCM systems. The spectral-temporal behavior of the signature of these events is an essential factor for their detection and f...
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... NEI (Noise Equivalent Intensity) was measured to be 9.0⋅10 -11 W/cm 2 for the two InSb channels and 4.5⋅10 -10 W/cm 2 for the InGaAs channel. We measured the muzzle flashes of M1 rifle and a Jericho pistol ( Figure 6). The charts in the figure give the radiant intensity in the three above mentioned spectral bands as function of time. ...
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... Work by Klingenberg et al. 3 confirmed that line, band, and continuum emissions result from excitation due to shock heating and exothermicity in the combusting plume. Study of muzzle flash has focused on its occurrence and suppression [4][5][6] , the characteristics and identification of flash signatures [7][8][9][10][11] . The measurement of temperature and species concentration is one of the main contents of the related research. ...
It is quite a challenge to obtain the temperature and species concentration fields of muzzle flash at high noise level. In this numerical study, radiation intensity of muzzle flash received by the high-speed Complementary Metal-Oxide-Semiconductor (CMOS) camera was simulated based on the line-of-sight method in the direct radiative transfer problem. The inverse radiative transfer problem of reconstructing distributions of temperature and soot volume fraction from the knowledge of flame radiation intensity was transformed into a minimization optimization problem and a meta-heuristic algorithm was used to solve the problem. The effects of the number of detection lines, optical thickness and measurement errors on the reconstruction results were discussed in details. A method to estimate the noise level of radiation intensity was developed, experimental results showed that the signal-to-noise ratio (SNR) of radiation intensity can be successfully inferred when the SNR is greater than 20 dB. Subsequently, prior knowledge of the noise level was introduced in the regularization to achieve a meaningful approximation of the exact value. The reconstruction of the soot volume fraction filed with SNR greater than 40 dB is considered successful with the inclusion of an appropriate regularization term in the objective function, and the reconstruction of the temperature field is feasible even with SNR as low as 15 dB. The high tolerance to the noise level of the radiation intensity gives the reconstruction algorithm the potential to be used in practical experiments of muzzle flash.
... Frame rates significantly higher than 1000 Hz can be reached with single element detectors. Multispectral measurements with high-speed single radiometers has been demonstrated [1, 2]. In this paper we present a low-cost setup with six single element detectors covering the UV-MWIR spectral range. ...
This paper presents the design and performance of a multispectral, high-speed, low-cost device. It is composed of six separate single element detectors covering the spectral range from UV to MWIR. Due to the wide spectral ranges of the detectors, these are used in conjunction with spectral filters. The device is a tool to spectrally and temporally resolve large field of view angularly integrated signatures from very fast events and get a total amplitude measure. One application has been to determine the maximal amplitude signal in muzzle flashes. Since the pulse width of a muzzle flash is on the order of 1 ms, a sensor with a bandwidth significantly higher than 1000 Hz is needed to resolve the flash. Examples from experimental trials are given.
... The application of proper Optics Chopper Spectrel besd filter procedures (see section 6 below) allows us to calculate the radiant intensities of the target events at the target plane. This fact allows us to apply the method of color thermometry [1] to two adjacent atmospheric windows through which we measure the radiant intensity of the "continuum" emission, and to calculate from it the equivalent temperature (T eq ) and effective area (A eff ) of its emission. Usually all target events of interest have, more-or-less, the same spectral shape for their CO 2 emission but with different intensities and different durations. ...
... An example for such a multi-spectral radiometer is the ColoRad Fast Multi-Spectral Radiometer. We have described in previous papers the ColoRad radiometer [2] and some measurements carried out with it of light weapon muzzle flashes [1]. The ColoRad radiometer was developed for carrying out signature measurements of flares and munitions flashes. ...
Transient multi-spectral signatures have become a basis for the development of IRST (IR Search and Track) and automatic target acquisition systems. Multi-spectral signatures must be measured in absolute physical system-independent units in order to be valid for use in system design. The required data comprise a temporal profile of the radiant intensity (or radiance) emitted by the target at the target plane in the required spectral bands. The methodology for converting electronic output signal from a multi spectral radiometer - volts - into the radiant intensity of the object is a complex procedure. In this procedure the following parameters have to be taken into account: the nature of the measured target (gray body or molecular emission spectra), the spectral filter, the detector responsivity, the frequency response and rise time and all ambient parameters such as atmospheric attenuation and solar radiance. Avoiding the correct analysis procedure, leads to erroneous data which may mislead users of multi-spectral signatures. This paper describes the appropriate methodology for multi-spectral signature measurement, analysis and factors that influence the accuracy of the resultant data.
It is quite a challenge to obtain the temperature and species concentration fields of muzzle flash at high noise level. In this numerical study, radiation intensity of muzzle flash received by the high-speed Complementary Metal-Oxide-Semiconductor (CMOS) camera was simulated based on the line-of-sight method in the direct radiative transfer problem. The inverse radiative transfer problem of reconstructing distributions of temperature and soot volume fraction from the knowledge of flame radiation intensity was transformed into a minimization optimization problem and a meta-heuristic algorithm was used to solve the problem. The effects of the number of detection lines, optical thickness and measurement errors on the reconstruction results were discussed in details. A method to estimate the noise level of radiation intensity was developed, experimental results showed that the signal-to-noise ratio (SNR) of radiation intensity can be successfully inferred when the SNR is greater than 20 dB. Subsequently, prior knowledge of the noise level was introduced in the regularization to achieve a meaningful approximation of the exact value. The reconstruction of the soot volume fraction filed with SNR greater than 40 dB is considered successful with the inclusion of an appropriate regularization term in the objective function, and the reconstruction of the temperature field is feasible even with SNR as low as 15 dB. The high tolerance to the noise level of the radiation intensity gives the reconstruction algorithm the potential to be used in practical experiments of muzzle flash.
This article describes the basic methodological aspects of designing multispectral optoelectronic devices for the remote inspection of overhead power lines. A method for selecting operating spectral areas for these devices was suggested on the basis of the proposed detection criteria. The proposed method considers physical phenomena that occur during the visual inspection and detection of objects. It allows the rational selection of operating areas of a multispectral device, including the number, width, and location of these areas in the optical spectrum. The author determines that effect of the spectral area width on object detection probability can be estimated by the correlation between spectral and integral contrasts. The optimal operating areas for multispectral devices with direct image visualization are selected according to the developed method.
Knowledge regarding the processes involved in blasts and detonations is required in various applications, e.g. missile interception, blasts of high-explosive materials, final ballistics and IED identification. Blasts release large amount of energy in short time duration. Some part of this energy is released as intense radiation in the optical spectral bands. This paper proposes to measure the blast radiation by a fast multispectral radiometer. The measurement is made, simultaneously, in appropriately chosen spectral bands. These spectral bands provide extensive information on the physical and chemical processes that govern the blast through the time-dependence of the molecular and aerosol contributions to the detonation products. Multi-spectral blast measurements are performed in the visible, SWIR and MWIR spectral bands. Analysis of the cross-correlation between the measured multi-spectral signals gives the time dependence of the temperature, aerosol and gas composition of the blast. Farther analysis of the development of these quantities in time may indicate on the order of the detonation and amount and type of explosive materials. Examples of analysis of measured explosions are presented to demonstrate the power of the suggested fast multispectral radiometric analysis approach.
Infrared Search and Track (IRST), Missile Warning Systems (MWS) and other optical target detection systems have established solutions in the MWIR, UV and LWIR bands. Imaging technology in the SWIR optical band which has small Size, Weight and Power (SWAP) has been recently added as detection means. We bring an update on recent field trials and demonstrations of Optigo's gun shot detection modules. We then provide some more insight into the advantages of using the SWIR band, and specifically InGaAs detectors for the typical HFI missions. We conclude by demonstrating that detection systems operating in the SWIR band can significantly improve their performance when the cutoff wavelength approaches longer edge of SWIR.
Blasts and detonations release large amount of energy in short time duration. Some of this energy is released in the form of intense radiation in the whole optical spectrum. In most cases, the study of blasts is mainly based on cameras that document the event in the visible range at very high frame rates. We propose to complement this mode of blast analysis with a fast measurement of the radiation emitted by the blast at different spectral bands simultaneously. A fast multispectral radiometer that operates in the proper spectral bands provides extensive information on the physical processes that govern the blast. This information includes the time dependence of the temperature, aerosol and gas composition of the blast, as well as minute changes in the expansion of the blast - changes that may indicate the order of the detonation. This paper presents the new methodology and instrumentation of fast multispectral blast radiometry and shows analysis of measured explosions that demonstrate the power of this methodology.
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