Microplastics (MP) have been found all over the planet and it is quite difficult to model the impact on the biosphere due to the low throughput of conventional measurement techniques. They actually restrict the number of measurable samples in appropriate time frames. Even the fastest conventional methods to quantify MP such as Fourier-Transform-IRmicroscopes (μFTIR) or Raman microscopes do not provide the required speed for measuring the desirable number of samples. By combining a wide field quantum cascade laser (QCL) based microscope with an automated vibrational spectroscopy data base (siMPle) identification and quantification of the particles fit into normal laboratory routine time slots. The MIDIR transmission spectra of environmental samples on standard and cost-effective Aluminum oxide filters were measured and evaluated using the adaptable data base design1 2 . The results turned out to be very similar to the common techniques, and particles assigned by FT-IR to one material, were connotated to the same using the laser-based method. Furthermore, the spatial resolution of the laser-based system is slightly superior to the one of μFTIR and the size distribution determined was found similar to results from even slower Raman-microscopy especially for small particle size smaller than 50 μm. Amongst others a treated waste water sample of 12*12 mm2 was measured in less than 36 minutes delivering 8,294,400 spectra with 2 cm-1 resolution, while the time to analyze the data remains the same order of magnitude, the pure measurement is more than ten times faster compared to using state of the art FT-IR-microscopes.
We report on a new class of turnkey liquid analyzers powered by tunable mid-IR quantum cascade lasers. These analyzers offer excellent chemical selectivity, speed and sensitivity in a variety of applications from water quality assessment to biopharmaceutical process monitoring. We will discuss the theory of operation of these new instruments and provide relevant application examples.
A non-tomographic analysis method is proposed to determine the 3D angles and the order parameter of molecular orientation using polarization-dependent infrared (IR) spectroscopy. Conventional polarization-based imaging approaches provide only 2D-projected orientational information of single chromophores or vibrational modes. The newly proposed method concurrently analyses polarization-dependent absorption profiles of two non-parallel transition dipole moments. The relative phase angle and the maximum-to-minimum ratios of the two polarization-dependent absorption profiles are used to calculate the 3D angles and the order parameter of molecular orientation. The relativity of those intermediate observables makes the analysis output values unaffected by variations in concentration, thickness, absorption peak, and absorption cross-section, which can occur in typical imaging conditions. This analysis is based on a single-step, non-iterative calculation that does not require any analytical model function of an orientational distribution function. This concurrent polarization analysis method is demonstrated using two simulation data examples and the error propagation analysis is discussed as well. Application of this robust spectral analysis method to polarization IR microscopy will provide a full molecular orientation image without tilting that tomographies require. In this talk, I describe this new approach that non-iteratively determines the 3D angles and the orientational order parameter without assuming a model function for an ODF. Then, I will demonstrate an application of this analysis using experimental image data acquired from a semicrystalline polymer film with polarization IR microscopy. The results clearly show how the 3D angles and the order parameter are determined for every pixel using straightforward formulas without iterative calculation.
The field of infrared spectral imaging and microscopy is advancing rapidly due in large measure to the recent commercialization of the first high-throughput, high-spatial-definition quantum cascade laser (QCL) microscope. Having speed, resolution and noise performance advantages while also eliminating the need for cryogenic cooling, its introduction has established a clear path to translating the well-established diagnostic capability of infrared spectroscopy into clinical and pre-clinical histology, cytology and hematology workflows.
Demand for even higher throughput while maintaining high-spectral fidelity and low-noise performance continues to drive innovation in QCL-based spectral imaging instrumentation. In this talk, we will present for the first time, recent technological advances in tunable QCL photonics which have led to an additional 10X enhancement in spectral image data collection speed while preserving the high spectral fidelity and SNR exhibited by the first generation of QCL microscopes. This new approach continues to leverage the benefits of uncooled microbolometer focal plane array cameras, which we find to be essential for ensuring both reproducibility of data across instruments and achieving the high-reliability needed in clinical applications. We will discuss the physics underlying these technological advancements as well as the new biomedical applications these advancements are enabling, including automated whole-slide infrared chemical imaging on clinically relevant timescales.
High-fidelity, broadly-tunable quantum cascade lasers (QCLs) are replacing thermal light sources in next-generation infrared chemical imaging and microscopy instrumentation. Their superior spectral brightness, beam quality, and reliability are enabling new applications in biomedical, pharmaceutical, and industrial markets which demand substantially better noise performance, higher throughput, and ease-of-use. In this talk we will discuss the state-of-the-art in QCL source technology and describe our systems approach to leveraging QCL sources in the next-generation of infrared chemical imaging microscopes.
The utilization of the broad gain bandwidth available from quantum cascade (QC) devices is considered. The performance of homogeneous and heterogeneous QC gain media is explored in an external-cavity configuration. Paradigms for realizing fixed wavelength or broad tuning performance of QC devices are considered.
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