Blasts and detonations release large amount of energy in short time duration. Some of this energy is released through
radiation in the whole optical spectrum. Measurement of this radiation may serve as a base for investigation of the blast
phenomena. A fast multispectral radiometer that operates in proper chosen spectral bands provides extensive information
on the physical processes that govern the blast. This information includes the time dependence of the temperature, area
of the blast as-well-as of the aerosols and gases that are generated. Analysis of this data indicates the order of the
detonation and provides good estimation on the masses and types of the high-explosives (HE) materials and their casing.
This paper presents the methodology and instrumentation of fast multispectral radiometry in application to the blast
measurement and analysis in a Near-ground Explosion Test (NET). In NET, the flash radiation of the blast was measured
for two HE materials: TNT and composition B (CB). The investigation includes charges of different masses (0.25 - 20.0
kg) and of various casing materials (steel, Al, PVC), thickness (2 – 6 mm) and various casing type (open on both face
ends and hermetically closed). Analysis of the data demonstrates the power of fast radiometry methodology and reveals
the governing characteristics of atmospheric blasts.
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
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.
Dew and dust layers on the surface of an object may significantly affect its thermal state and IR signature. Dew formation
begins when the object surface temperature falls below atmospheric dew point temperature. Due to the latent heat
released by the water accumulated on the surface the temperature drop stagnates and the object appears warmer then it
would be without dew formation. An attempt was made to modify RadThermIR software to account for dew effects. A
simple plate model and the more elaborate CUBI thermal modeling benchmarking object were used to study the extent to
which dew may change thermal object signatures. A dust layer on an object surface may affect its optical properties and
may act as additional thermal insulation when it is thick enough. Both effects influence the temperature and IR signature
of the object. Parametric calculations by RadThermIR were performed for various dust thicknesses and optical properties.
This data was used in an object/background contrast analysis. The obtained dust/dew layer results will be used in the
planning of the next CUBI experiment in natural desert environments. In addition, CUBI data from another geographic
location was used for studying different wind models resulting in some interesting conclusions concerning the applicability
of the wind model used in RadThermIR.
Accurate thermal modeling requires verification and validation of the model and software being used. For basic evaluation of thermal prediction models and software tools, a generic model - CUBI was build. The model was designed to have simple geometry yet, consisted of similar characteristics as of a ground vehicle. The model was equipped with thermocouples for measuring its temperature variations and was placed in a typical desert environment for field testing. The experimental setup also included a meteorological station. The data collected was used for the thermal behavior analysis of the generic model and for comparison with the thermal calculations predictions. Comparison of the results shows sufficient compliance but yet reviles some issues in the modeling that should be addressed.