Page 23 Share Cite. Since the power levels are low and the radiation only penetrates to skin depth, no adverse health effects occur. An object is placed at the focus of the terahertz beam, and then the amplitude and delay of the wave that has traversed through the object is measured. Passive imaging systems require that there be an apparent temperature difference, either positive or negative, between the body and its surroundings. By translating the object and measuring the transmitted terahertz waveform for each position of the object, one can build an image pixel by pixel. Figurecompiled by Ohio State University, shows some of the spectral features of energetic materials as a function of frequency. Cook, Brian K.
[PDF] Quantitative THz Spectroscopy of Explosive Materials Semantic Scholar
Quantitative terahertz absorption spectra of the commonly encountered high explosives pentaerythritoltetranitrate and cyclotrimethy lenetrinitramine are. Quantitative terahertz absorption spectra of the commonly encountered high explosives pentaerythritoltetranitrate and cyclotrimethylenetrinitramine are.
Abstract: Nowadays terahertz spectroscopy is a well-established technique and recent progresses in technology large number of materials and consequently new data can potentially detection of explosives to fight against terrorism. The first context of quantitative analysis of combustion products of a.
According to the report data, These devices are at present in the development stage, and none has been deployed or tested in actual use.
One final concern that must be addressed is to distinguish the spectra of the materials when examined at a distance from which the spectra of the atmosphere itself will act to change the spectral intensity.
If an imaging or spectroscopic system were to be employed in an air-conditioned facility such as an air terminal, the curve for the clear air would be appropriate.
Text Resize Print icon. Recent advances in both electro-optic and radio-frequency RF techniques have enabled the undertaking of new investigations. To a first order, it can be stated that as the atmospheric attenuation increases, the range at which good image quality can be maintained will decrease.
Impact of Pellet Thickness on Quantitative Terahertz Spectroscopy of Solid Samples in Solar Energy Materials and Solar Cells, Recent Developments in Spectroscopic Techniques for the Detection of Explosives.
Terahertz Studies of a Nonlinear Optical Material l-Glutamine Picrate: A Quantitative Measurements of Amino Acids by Terahertz.
Bandwidths extending from GHz to 2 or 3 THz are routine, although the power generated is concentrated more in the lower frequencies of the emission band. An imaging system in which the terahertz beam is reflected from the sample rather than being transmitted through it can be used for tomographic imaging.
This imaging technique, similar to that used in medical computerized axial tomography scans, involves illuminating the subject with millimeter-wave radiation. An additional point is that there are few data available on materials such as cheese or thick liquids that might be confused, using other techniques such as x-ray, with explosives.
Although the average intensity of the radiation is quite low, the high spatial coherence produces a brightness that exceeds that of conventional thermal sources. For example, these technologies are being used to detect guns concealed underneath clothing by the detection of the contrast between the warmer human body and the apparently cooler metal weapon.
Terahertz Spectroscopy Analytical Chemistry
Due to its low energy characteristics, terahertz radiation is non-hazardous for humans and animals.
|New techniques for wave generation and detection that are unique to the terahertz spectrum are being developed in research laboratories worldwide.
The difference in these devices is in the implementation of the detection hardware. These transients consist of only one or two cycles of the electromagnetic field, and they consequently span a very broad bandwidth.
Page 22 Share Cite. No thanks. Since the power levels are low and the radiation only penetrates to skin depth, no adverse health effects occur.
Since resolution is inversely proportional to the frequency of the radiation, an imaging system would be desirable at as high a frequency as possible, given limitations in components and atmospheric propagation.