KEYWORDS: Target detection, Detection and tracking algorithms, Sensors, Machine learning, Infrared search and track, Radar, Missiles, Video, Target acquisition, Signal to noise ratio
Infrared sensor technology, high performance computing hardware and advanced detection and tracking algorithms have enabled a new generation of infrared warning systems for navy surface vessels. In this paper we describe Sea Spotter - a new third-generation naval IRST system, which is unique in offering a fully staring electro-optical imaging unit. Starting from naval IRST operational requirements, we describe the considerations and constraints that led us to the configuration of the sensor head and the supporting hardware. The second part of the paper is dedicated to the target acquisition methodology, including the use of originally developed machine learning technology for target acquisition and tracking.
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.
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.
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.
As more and more spectral ranges are used by different threat detecting sensors, the effectiveness of a countermeasure is becoming more and more dependent on how similar its emitted spectrum is to the object that it is supposed to simulate. As a result, the need to model and test the countermeasure radiometric output (in radiance units) and contrast (in radiant intensity units) or effective temperature at different wavelengths simultaneously increases in importance during both R&D and production for both the producer of countermeasures (to confuse the seekers) and the producer of missile seekers (to prevent seeker confusion). We have developed a family of multi-spectral radiometers (ColoRad) specifically designed to quantitatively measure countermeasure spectral signatures dynamically for precise characterization. In this paper we describe the design of such instrumentation, including the various modes of operation and highlighting the important instrument features for the present application. In addition an example of measurement is given here to demonstrate its usefulness. The ColoRad performance parameter values are also given in this paper.
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 for the filtering of false alarms. Munitions flashes are fast transient phenomena with time duration that range from the sub-millisecond to a fraction of a second. A full characterization of the infrared signature of these events involves measurement of the evolution of its spectral distribution in time where the temporal resolution required is of the order of microseconds. We describe here a method for utilizing a four-channel radiometer to extract the above-mentioned data from these events. We show that we can derive the temporal evolution of the temperature of an explosion on time scale of 20&mgr;sec and separate energy releasing processes. Several practical examples will be given.
Cleaning applications in the semiconductor manufacturing industry are tougher to meet as the device dimensions decrease. The uniqueness of Oramir-Laser-Chemical process relies on the mutual combination and effectiveness of laser particle removal mechanisms and laser induced photon- thermal-chemical reaction in the mixture of O2/O3/NF3 gases. The process involves ozone blast wave, photodecomposition of O3 into O radicals, photo-thermal decomposition of NF3 into fluorine radicals, thermal effects and thin liquid-chemical ablation enhanced particle removal. Recent results on Bare Si wafers, photomasks, EUV masks and scalpel masks show substantial removal efficiency, up to 100 percent for certain applications.
Remote sensing is based on the ability to measure accurately the spectral radiance of remote objects in the object plane. This ability is limited by the measuring system (resolution and sensitivity) and by the atmospheric transmittance, especially when long distances are involved. As a result, the need to enhance S/N led us to develop new measurements techniques and analysis methods. This presentation deals with two different techniques of modern radiometry -- point spectroradiometry with moderate spectral resolution and spatial radiometry (imaging systems) with low spectral resolution. This presentation will address three issues related to advanced analysis methods of radiometric measurements: (1) The effect of the exact shape of the slit- function of the point radiometer on the results of the spectral analysis, (2) the optimal calculation of a signature from radiometric imager, and (3) the correcting factor that must be introduced into the analysis of a spatial picture of point target which is much smaller than the IFOV of the imaging system (star detection). The experience and knowledge gained by IMOD and EORD in the area of radiometric analysis was implemented in a user friendly software (TIRAS) that is used for the radiometric (and not temperature) analysis of various spatial radiometers. The radiometric data was measured for various applications of IMOD such as data bases of targets and backgrounds, and study of radiometric behavior of IR scene elements.
Passive MMW sensing is getting more and more attention as sensors in this spectral region get better. This development requires understanding of the passive MMW target detection scenario. This scenario consists of natural background elements and targets. Understanding of the behavior of backgrounds and targets as function of environmental conditions is vital for the analysis of any future sensor performance for this spectral region. During the past year, EORD has measured the radiometric properties of natural backgrounds and several man made objects using its dual frequency 140/220 GHz radiometer. This work will describe the measurement setup and give some of the results of background and target measurements. The measurement results will be correlated to the thermal IR radiometric data and the actual contact temperatures of the objects.
The development process of new FPA imaging systems should be accompanied by an operational research study. The tool for such a study should be a model that predicts the performance of the overall system (detector, optics, signal processing, human observer), together with the target signature characteristics and the background properties. This model should yield a figure of merit that will be used for the performance study during the design and development process of the system. The influence of various parameters that will be used in the design process of the system can be studied using this tool. This work presents an approach where an image based sensor model was used to study the ability to detect and recognize different targets at various scenarios. The sensor model was used to simulate images of bar patterns for the evaluation of the modeled sensor MRTD. The results were compared to FLIR 92 predictions and the real sensor MRTD measurements. The model was then used to simulate targets embedded at various types of backgrounds. The images were presented to human observers that determined whether they detect or recognize the targets. This paper will bring a short description of the FPA sensor model and will present the methodology of using the simulation for sensor performance study. An analysis of some of the obtained results will be included as well.
'Does it look like a real sensor image?' This is the question that is often asked by users of the TTIM model. A common way to examine the resemblance of simulated and measured images is to compare the MRTD curves obtained from simulation and measurements. But a good agreement between the MRTD curves does not necessarily ensure that the simulated images look like the actual sensor images of real scenarios. In this work, the approach taken to validate the sensor model was to compare images. Thermal images from various scenes and ranges were recorded in the field with known sensors. At the same time, high resolution radiometric maps of the same scenes were measured as well, and later on used as input for the TTIM sensor model. The simulated images were compared to the digitized images obtained from the sensors. This paper describes the field test procedure and presents the results of this comparison. Some of the sensor effects that are not taken into account in the model are identified.
This work presents quantitative evaluation of errors in measurement
that arise in using a thermal imager as a radiometer. The analysis will
mainly deal with the 7 13 micron spectral region . The main sources
contributing to errors in spatial radiometric measurements can be
divided into three categories: 1) inaccuracies in determining
atmospheric transmittance and path radiance, 2) calibration errors and
dynamic range problems due to nonlinearities of instrument response,
3) errors due to spatial response arising from the finite point spread
function and non uniformities of the field of view.
The contribution of each of these factors to the final cumulative error
in the measured radiometric quantity will be analysed and the
sensitivity to the individual factors shown. This analysis is done with
respect to an existing measurement system in use, namely the AGEMA 780
Dual Band Thermovision Imager.
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