Diffraction limited mid-infrared reflectance microspectroscopy with a supercontinuum laser

Kilgus, Jakob; Langer, Gregor; Duswald, Kristina; Zimmerleiter, Robert; Zorin, Ivan; Berer, Thomas; Brandstetter, Markus

doi:10.1364/oe.26.030644

Cited by 54 publications

(35 citation statements)

References 33 publications

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“…Given its unique analytical capabilities, it is perhaps surprising that MIR-based imaging is not a more widely adopted technology for chemical mapping. The relatively scarce implementation of MIR imaging has been due in part to the lack of bright and affordable light sources in this range, although recent developments in MIR light source technology have largely overcome this problem 9 – 11 . Nonetheless, a remaining limitation is the performance and high cost of the MIR cameras.…”

Section: Introductionmentioning

confidence: 99%

Infrared chemical imaging through non-degenerate two-photon absorption in silicon-based cameras

et al. 2020

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Chemical imaging based on mid-infrared (MIR) spectroscopic contrast is an important technique with a myriad of applications, including biomedical imaging and environmental monitoring. Current MIR cameras, however, lack performance and are much less affordable than mature Si-based devices, which operate in the visible and nearinfrared regions. Here, we demonstrate fast MIR chemical imaging through non-degenerate two-photon absorption (NTA) in a standard Si-based charge-coupled device (CCD). We show that wide-field MIR images can be obtained at 100 ms exposure times using picosecond pulse energies of only a few femtojoules per pixel through NTA directly on the CCD chip. Because this on-chip approach does not rely on phase matching, it is alignment-free and does not necessitate complex postprocessing of the images. We emphasize the utility of this technique through chemically selective MIR imaging of polymers and biological samples, including MIR videos of moving targets, physical processes and live nematodes.

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Section: Introductionmentioning

confidence: 99%

Infrared chemical imaging through non-degenerate two-photon absorption in silicon-based cameras

et al. 2020

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“…6,7 The noise characteristics of supercontinuum generation, which had been a deterrent in their early days, were significantly improved since then. 8,9,5 Successful demonstrations of mid-IR supercontinuum based setups in a wide variety of noise sensitive applications [10][11][12][13][14][15] prove their practical suitability. Furthermore, it is expected that the trend of noise reduction will continue, e.g., by implementing the supercontinuum generation in an all-normal-dispersion regime, which is insensitive to the input pump noise delivering the enhanced shot-to-shot spectral coherence.…”

Section: Introductionmentioning

confidence: 99%

Sensitivity-Enhanced Fourier Transform Mid-Infrared Spectroscopy Using a Supercontinuum Laser Source

et al. 2020

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Fourier transform infrared (FT-IR) spectrometers have been the dominant technology in the field of mid-infrared (mid-IR) spectroscopy for decades. Supercontinuum laser sources operating in the mid-IR spectral region now offer the potential to enrich the field of FT-IR spectroscopy due to their distinctive properties, such as high-brightness, broadband spectral coverage and enhanced stability. In our contribution, we introduce this advanced light source as a replacement for conventional thermal emitters. Furthermore, an approach to efficient coupling of pulsed mid-IR supercontinuum sources to FT-IR spectrometers is proposed and considered in detail. The experimental part is devoted to pulse-to-pulse energy fluctuations of the applied supercontinuum laser, performance of the system, as well as the noise and long-term stability. Comparative measurements performed with a conventional FT-IR instrument equipped with a thermal emitter illustrate that similar noise levels can be achieved with the supercontinuum-based system. The analytical performance of the supercontinuum-based FT-IR spectrometer was tested for a concentration series of aqueous formaldehyde solutions in a liquid flow cell (500 µm path length) and compared with the conventional FT-IR (130 µm path length). The results show a four-times-enhanced detection limit due to the extended path length enabled by the high brightness of the laser. In conclusion, FT-IR spectrometers equipped with novel broadband mid-IR supercontinuum lasers could outperform traditional systems providing superior performance, e.g., interaction path lengths formerly unattainable, while maintaining low noise levels known from highly stable thermal emitters.

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“…Different instrument technologies are available, with the most widespread being Fourier transform, Fabry-Pérot (FP), and dispersive spectrometers [16]. In recent years, the potential of microspectrometer technology has already been demonstrated in spectroscopy [17,18], hyperspectral imaging [19], and compressive sensing [20] applications.…”

Section: Introductionmentioning

confidence: 99%

Probeless non-invasive near-infrared spectroscopic bioprocess monitoring using microspectrometer technology

et al. 2019

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Real-time measurements and adjustments of critical process parameters are essential for the precise control of fermentation processes and thus for increasing both quality and yield of the desired product. However, the measurement of some crucial process parameters such as biomass, product, and product precursor concentrations usually requires time-consuming offline laboratory analysis. In this work, we demonstrate the in-line monitoring of biomass, penicillin (PEN), and phenoxyacetic acid (POX) in a Penicillium chrysogenum fed-batch fermentation process using low-cost microspectrometer technology operating in the near-infrared (NIR). In particular, NIR reflection spectra were taken directly through the glass wall of the bioreactor, which eliminates the need for an expensive NIR immersion probe. Furthermore, the risk of contaminations in the reactor is significantly reduced, as no direct contact with the investigated medium is required. NIR spectra were acquired using two sensor modules covering the spectral ranges 1350-1650 nm and 1550-1950 nm. Based on offline reference analytics, partial least squares (PLS) regression models were established for biomass, PEN, and POX either using data from both sensors separately or jointly. The established PLS models were tested on an independent validation fed-batch experiment. Root mean squared errors of prediction (RMSEP) were 1.61 g/L, 1.66 g/L, and 0.67 g/L for biomass, PEN, and POX, respectively, which can be considered an acceptable accuracy comparable with previously published results using standard process spectrometers with immersion probes. Altogether, the presented results underpin the potential of low-cost microspectrometer technology in real-time bioprocess monitoring applications.

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Diffraction limited mid-infrared reflectance microspectroscopy with a supercontinuum laser

Cited by 54 publications

References 33 publications

Infrared chemical imaging through non-degenerate two-photon absorption in silicon-based cameras

Infrared chemical imaging through non-degenerate two-photon absorption in silicon-based cameras

Sensitivity-Enhanced Fourier Transform Mid-Infrared Spectroscopy Using a Supercontinuum Laser Source

Probeless non-invasive near-infrared spectroscopic bioprocess monitoring using microspectrometer technology

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