Chemical imaging using infrared photothermal microspectroscopy

Furstenberg, Robert; Kendziora, Christopher A.; Papantonakis, Michael R.; Nguyen, Viet; McGill, R. Andrew

doi:10.1117/12.919574

Cited by 44 publications

(38 citation statements)

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“…We have been developing an eye-safe stand-off detection technique suitable for the detection of trace amounts of solid explosives (and other hazardous) particulates on solid surfaces [1][2][3][4][5][6][7][8][9][10][11][12][13] . In order to reach required detection sensitivity levels, we employ high-power (but below the eye-safe limit) tunable quantum cascade lasers (QCLs) as the active illumination source.…”

Section: Introductionmentioning

confidence: 99%

Characterization and control of tunable quantum cascade laser beam parameters for stand-off spectroscopy

et al. 2016

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Infrared active stand-off detection techniques often employ high power tunable quantum cascade lasers (QCLs) for target illumination. Due to the distances involved, any fluctuation of the laser beam direction and/or beam profile is amplified at the sample position. If not accounted for, this leads to diminished performance (both sensitivity and selectivity) of the detection technique as a direct result of uncertainties in laser irradiance at each imaged pixel of the sample. This is especially true for detection approaches which illuminate a relatively small footprint at the target since the laser beam profile spatial fluctuations are often comparable to the (focused) laser spot size. Also, there is often a necessary trade-off between high output QCL power and beam quality. Therefore, precise characterization of the laser beam profile and direction as a function of laser properties (tuning wavelength, current and operating mode: pulsed or CW) is imperative. We present detailed measurements of beam profiles, beam wander and power fluctuations and their reproducibility as function of laser wavelength and stand-off distance for a commercially available tunable quantum cascade laser. We present strategies for improving beam quality by compensating for fluctuations using a motorized mirror and a pair of motorized lenses. We also investigate QCL mode hops and how they affect laser beam properties at the sample. Detailed mode-hop stability maps were measured.

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Section: Introductionmentioning

confidence: 99%

Characterization and control of tunable quantum cascade laser beam parameters for stand-off spectroscopy

et al. 2016

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“…While progress in classical IR microscopy is hindered by fundamental physical limitations (e.g., diffraction limit), our results reveal the potential of IR-OH for superresolution IR imaging, largely improved coverage, and suppression of IR scattering that can be employed for unforeseen, transformative applications in histopathologic imaging. Further, the interferometric detection in IR-OH provides a sensitivity advantage over previous photothermal techniques that relied on beam deflection from IR absorption-induced refractive index change (41,42,44,45,48,53). While our method measures the physical response of expansion directly, deflection methods measure the refractive index change that occurs upon deflection and need higher probe intensity than we have employed.…”

Section: Significancementioning

confidence: 99%

“…The concept of dynamic photothermal changes in morphology (34,35), force (36,37), or near-field coupling (38)(39)(40), using an atomic force microscope cantilever as local probe, has been reported for point-by-point IR measurements. Noncontact optical photothermal microscopy is more recent (41)(42)(43)(44)(45)(46)(47)(48)(49)(50) and typically utilizes a local IR illumination coincident with a highly focused visible probe beam to measure local refractive index change by beam scattered out of the angular acceptance of the objective lens. This method has been applied to chemical imaging of tissue and live cells (44,46,47), bacteria (48), and pharmaceutical tablets (49).…”

Section: Significancementioning

confidence: 99%

All-digital histopathology by infrared-optical hybrid microscopy

Schnell

Mittal

Falahkheirkhah

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

102

118

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Optical microscopy for biomedical samples requires expertise in staining to visualize structure and composition. Midinfrared (mid-IR) spectroscopic imaging offers label-free molecular recording and virtual staining by probing fundamental vibrational modes of molecular components. This quantitative signal can be combined with machine learning to enable microscopy in diverse fields from cancer diagnoses to forensics. However, absorption of IR light by common optical imaging components makes mid-IR light incompatible with modern optical microscopy and almost all biomedical research and clinical workflows. Here we conceptualize an IR-optical hybrid (IR-OH) approach that sensitively measures molecular composition based on an optical microscope with wide-field interferometric detection of absorption-induced sample expansion. We demonstrate that IR-OH exceeds state-of-the-art IR microscopy in coverage (10-fold), spatial resolution (fourfold), and spectral consistency (by mitigating the effects of scattering). The combined impact of these advances allows full slide infrared absorption images of unstained breast tissue sections on a visible microscope platform. We further show that automated histopathologic segmentation and generation of computationally stained (stainless) images is possible, resolving morphological features in both color and spatial detail comparable to current pathology protocols but without stains or human interpretation. IR-OH is compatible with clinical and research pathology practice and could make for a cost-effective alternative to conventional stain-based protocols for stainless, all-digital pathology.

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“…In addiction such lasers, due to their high optical power, could be used for infrared imaging with tens of different approaches: Chemical Imaging, Photo-thermal imaging, holography, microscopy, etc. [62,63,64,65,66].…”

Section: Optical Monitoring Of Dioxins and Related Compounds A Scmentioning

confidence: 99%

Dioxin and Related Compound Detection: Perspectives for Optical Monitoring

Patrizi

Cumis

Viciani

et al. 2019

IJMS

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Dioxins and related compounds are environmental xenobiotics that are dangerous to human life, due to the accumulation and persistence in the environment and in the food chain. Cancer, reproductive and developmental issues, and damage to the immune system and endocrine system are only a few examples of the impact of such substances in everyday life. For these reasons, it is fundamental to detect and monitor these molecules in biological samples. The consolidated technique for analytical evaluation is gas chromatography combined with high-resolution mass spectrometry. Nowadays, the development of mid-infrared optical components like broadband laser sources, optical frequency combs, high performance Fourier-transform infrared spectroscopy, and plasmonic sensors open the way to new techniques for detection and real time monitoring of these organic pollutants in gaseous or liquid phase, with sufficient sensitivity and selectivity, and in short time periods. In this review, we report the latest techniques for the detection of dioxins, furans and related compounds based on optical and spectroscopic methods, looking at future perspectives.

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Chemical imaging using infrared photothermal microspectroscopy

Cited by 44 publications

References 0 publications

Characterization and control of tunable quantum cascade laser beam parameters for stand-off spectroscopy

Characterization and control of tunable quantum cascade laser beam parameters for stand-off spectroscopy

All-digital histopathology by infrared-optical hybrid microscopy

Dioxin and Related Compound Detection: Perspectives for Optical Monitoring

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