Stand-off identification and mapping of liquid surface contaminations by passive hyperspectral imaging

Braun, René; Harig, Roland

doi:10.1117/12.1518449

Cited by 3 publications

(8 citation statements)

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“…Harig and Braun have pursued similar research but used an imaging FT instrument, together with a radiative transfer model to show agreement between measured and calculated spectra on sundry surfaces. 11,14 During the course of those studies the authors also demonstrated that in a less thorough fashion it is possible to simultaneously derive the n/k optical constants, and indeed have measured n/k values for some of the same organophosphorous species as reported here. From the Braun paper, 14 we were able to digitize the n/k(n) optical constants data to compare the results for the three liquids DMMP, triethyl phosphate (TEP), and triethanolamine (TEA).…”

Section: Comparison To Previous Literature Valuesmentioning

confidence: 67%

“…From the Braun paper, 14 we were able to digitize the n/k (ν) optical constants data to compare the results for the three liquids DMMP, triethyl phosphate (TEP), and triethanolamine (TEA). In that paper, 14 a simple transmission spectrum was used to calculate n (ν) /k (ν) for their DMMP spectrum, but reflectance spectra were used to obtain the n/k for TEP and TEA. The DMMP transmission measurements were used to calculate the absorption coefficients and the refractive index value are derived via the Kramers–Kronig transform.…”

Section: Resultsmentioning

confidence: 99%

“…More recently Harig et al used an imaging Fourier transform (FT) spectrometer and applied a radiative transfer model to show agreement between measured and calculated spectra of various hazardous liquids on different surfaces. 11,14 Active IR multispectral imaging has also been used by Goyal et al 12 for detection of droplets and thin films of diethyl phthalate (DEP) on a diffusely reflecting gold surface; they modeled the first surface reflection for the droplets and the absorption for the thin film using the complex refractive index of DEP, which was derived from the absorption data using the Kramers-Kronig relation. [15][16][17] Such studies all demonstrate the validity of using optical constants to model the reflectance spectra of liquids under various environmental conditions, as one seldom encounters a neat liquid in bulk form, other than open bodies of water.…”

Section: Introductionmentioning

confidence: 99%

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Accurate Measurement of the Optical Constants n and k for a Series of 57 Inorganic and Organic Liquids for Optical Modeling and Detection

et al. 2017

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For optical modeling and other purposes, we have created a library of 57 liquids for which we have measured the complex optical constants n and k. These liquids vary in their nature, ranging in properties that include chemical structure, optical band strength, volatility, and viscosity. By obtaining the optical constants, one can model most optical phenomena in media and at interfaces including reflection, refraction, and dispersion. Based on the works of others, we have developed improved protocols using multiple path lengths to determine the optical constants n/k for dozens of liquids, including inorganic, organic, and organophosphorus compounds. Detailed descriptions of the measurement and data reduction protocols are discussed; agreement of the derived optical constant n and k values with literature values are presented. We also present results using the n/k values as applied to an optical modeling scenario whereby the derived data are presented and tested for models of 1 µm and 100 µm layers for dimethyl methylphosphonate (DMMP) on both metal (aluminum) and dielectric (soda lime glass) substrates to show substantial differences between the reflected signal from highly reflective substrates and less-reflective substrates.

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Section: Comparison To Previous Literature Valuesmentioning

confidence: 67%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Accurate Measurement of the Optical Constants n and k for a Series of 57 Inorganic and Organic Liquids for Optical Modeling and Detection

et al. 2017

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“…The results of this method include other components such as reflection components on the adhesive surface in addition to the absorption spectrum of the adhesive 3 . Furthermore, in this experimental system, since the light was obliquely irradiated only from one direction, there was a large unevenness in the amount of light on the sample.…”

Section: Discussionmentioning

confidence: 99%

“…However, with conventional microscopic mid-infrared hyperspectral imaging apparatus, we cannot measure the macroscopic-sized samples that are treated in forensic science and cultural properties science 1 , 2 . Wide-field mid-infrared hyperspectral imaging apparatus employing mercury cadmium telluride (MCT) detectors could be used 3 – 6 , but they are very expensive and difficult to handle legally because MCT detectors are a type of military equipment, thus making this approach difficult to use for daily work in forensic science and cultural properties science.…”

Section: Introductionmentioning

confidence: 99%

Wide-field mid-infrared hyperspectral imaging of adhesives using a bolometer camera

Sugawara

Nakayama²,

Taniguchi³

et al. 2017

Sci Rep

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By combining a bolometer detector with an imaging-type interferometer, an inexpensive, easy-to-handle wide-field mid-infrared hyperspectral imaging apparatus was produced. We measured the distributions of four types of thin adhesive layers on an aluminium plate and analysed the results using correlation coefficients to visualise the distribution of various adhesives that cannot be discerned by the naked eye or conventional methods such as visible/near-infrared spectroscopic/fluorescent photography. The measurement wavelength range, obtained spectrum’s wavenumber resolution, and measurement time was 8–14 μm, about 9 cm−1, and about 30 s, respectively. Using conventional methods, adhesives could not be distinguished from the others. By using this method, we found that adhesives could be precisely distinguished by setting an appropriate threshold value for the correlation coefficient. Thus, our approach can accurately measure the spatial distribution of different types of adhesive that cannot be discriminated by conventional methods.

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Reflectance Spectra Analysis Algorithms for the Characterization of Deposits and Condensed Traces on Surfaces

Aharoni¹,

Zuck²,

Peri³

et al. 2022

Colorimetry

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Identification of particulate matter and liquid spills contaminations is essential for many applications, such as forensics, agriculture, security, and environmental protection. For example, toxic industrial compounds deposition in the form of aerosols, or other residual contaminations, pose a secondary, long-lasting health concern due to resuspension and secondary evaporation. This chapter explores several approaches for employing diffuse reflectance spectroscopy in the mid-IR and SWIR to identify particles and films of materials in field conditions. Since the behavior of thin films and particles is more complex compared to absorption spectroscopy of pure compounds, due to the interactions with background materials, the use of physical models combined with statistically-based algorithms for material classification, provides a reliable and practical solution and will be presented.

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Stand-off identification and mapping of liquid surface contaminations by passive hyperspectral imaging

Cited by 3 publications

References 0 publications

Accurate Measurement of the Optical Constants n and k for a Series of 57 Inorganic and Organic Liquids for Optical Modeling and Detection

Accurate Measurement of the Optical Constants n and k for a Series of 57 Inorganic and Organic Liquids for Optical Modeling and Detection

Wide-field mid-infrared hyperspectral imaging of adhesives using a bolometer camera

Reflectance Spectra Analysis Algorithms for the Characterization of Deposits and Condensed Traces on Surfaces

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