Optical Fibers for Mid‐Infrared Spectrometry

Lendl, Bernhard; Mizaikoff, Boris

doi:10.1002/0470027320.s2702

Cited by 5 publications

(8 citation statements)

References 53 publications

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“…Therefore, care should be taken when coupling the light in and out of the fiber. 34 A major advantage of optical fibers is their flexibility, it should however be noted that the more the fiber is bent, i.e., the smaller the bending radius, the lower the transmission. This decrease in transmission is due to the fact that the conditions for internal reflection are fulfilled less and less.…”

Section: Introductionmentioning

confidence: 99%

“…Transmission ranges depend on material properties: the lower wavelength limit is determined by electronic absorption (band gap edge), while the higher wavelength limit depends on the multi-phonon edge. [32][33][34] Furthermore, transmission depends on losses due light scattering within the material, impurities, and material defects. The numerical aperture (NA) or acceptance angle of the fiber, which in turn depends on the critical angle for total internal reflection, i.e., the ratio of refractive indices of core material (within which the light is guided) and the surrounding medium (often an appropriately chosen cladding layer, or the coating).…”

Section: Introductionmentioning

confidence: 99%

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Comparison of Fiber Optic and Conduit Attenuated Total Reflection (ATR) Fourier Transform Infrared (FT-IR) Setup for In-Line Fermentation Monitoring

et al. 2016

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The performance of a fiber optic and an optical conduit in-line attenuated total reflection mid-infrared (IR) probe during in situ monitoring of Penicillium chrysogenum fermentation were compared. The fiber optic probe was connected to a sealed, portable, Fourier transform infrared (FT-IR) process spectrometer via a plug-and-play interface. The optical conduit, on the other hand, was connected to a FT-IR process spectrometer via a knuckled probe with mirrors that had to be adjusted prior to each fermentation, which were purged with dry air. Penicillin V (PenV) and its precursor phenoxyacetic acid (POX) concentrations were determined by online high-performance liquid chromatography and the obtained concentrations were used as reference to build partial least squares regression models. Cross-validated root-mean-square errors of prediction were found to be 0.2 g L (POX) and 0.19 g L (PenV) for the fiber optic setup and 0.17 g L (both POX and PenV) for the conduit setup. Higher noise-levels and spectrum-to-spectrum variations of the fiber optic setup lead to higher noise of estimated (i.e., unknown) POX and PenV concentrations than was found for the conduit setup. It seems that trade-off has to be made between ease of handling (fiber optic setup) and measurement accuracy (optical conduit setup) when choosing one of these systems for bioprocess monitoring.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Comparison of Fiber Optic and Conduit Attenuated Total Reflection (ATR) Fourier Transform Infrared (FT-IR) Setup for In-Line Fermentation Monitoring

et al. 2016

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“…Potential uses include not only laser surgery, but also numerous applications in infrared spectroscopy, thermal imaging, sensing and infrared countermeasures [1][2][3][4]. The HCWs structure is composed of a hollow glass capillary tube with a metallic/dielectric structure deposited inside the bore [5].…”

Section: Introductionmentioning

confidence: 99%

Single mode operation with mid-IR hollow fibers in the range 51-105 µm

Sampaolo¹,

Patimisco²,

Kriesel³

et al. 2015

Opt. Express

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Single mode beam delivery in the mid-infrared spectral range 5.1-10.5 μm employing flexible hollow glass waveguides of 15 cm and 50 cm lengths, with metallic/dielectric internal layers and a bore diameter of 200 μm were demonstrated. Three quantum cascade lasers were coupled with the hollow core fibers. For a fiber length of 15 cm, we measured losses down to 1.55 dB at 5.4 μm and 0.9 dB at 10.5 μm. The influence of the launch conditions in the fiber on the propagation losses and on the beam profile at the waveguide exit was analyzed. At 10.5 µm laser wavelength we found near perfect agreement between measured and theoretical losses, while at ~5 µm and ~6 µm wavelengths the losses were higher than expected. This discrepancy can be explained considering an additional scattering loss effect, which scales as 1/λ 2 and is due to surface roughness of the metallic layer used to form the high-reflective internal layer structure of the hollow core waveguide. 37(9), 2454-2458 (1998). 10. J. Kriesel, G. M. Hagglund, N. Gat, V. Spagnolo, and P. Patimisco, "Spatial mode filtering of mid-infrared (mid-IR) laser beams with hollow core fiber optics," Proc. SPIE 8993, 89930V (2014). 11. https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=7062#SingleMode.

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“…1,2 The materials used to fabricate infrared-transmitting fiber optics are generally divided into three broad categories: glass, crystalline, and hollow waveguides (HWGs). 3 Crystalline fibers include both polycrystalline (PC) fibers, such as silver halides, and single-crystal (SC) fibers, such as sapphire. The most common type of HWG is the hollow glass waveguide constructed using a glass capillary possessing a metallic-dielectric inner surface.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Silver Halide Fiber Optics and Hollow Silica Waveguides for Use in the Construction of a Mid-Infrared Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Spectroscopy Probe

Damin

Sommer

2013

Appl Spectrosc

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Advances in fiber optic materials have allowed for the construction of fibers and waveguides capable of transmitting infrared radiation. An investigation of the transmission characteristics associated with two commonly used types of infrared-transmitting fibers/waveguides for prospective use in a fiber/waveguide-coupled attenuated total internal reflection (ATR) probe was performed. Characterization of silver halide polycrystalline fiber optics and hollow silica waveguides was done on the basis of the transmission of infrared light using a conventional fiber optic coupling accessory and an infrared microscope. Using the fiber optic coupling accessory, the average percent transmission for three silver halide fibers was 18.1 ± 6.1% relative to a benchtop reflection accessory. The average transmission for two hollow waveguides (HWGs) using the coupling accessory was 8.0 ± 0.3%. (Uncertainties in the relative percent transmission represent the standard deviations.) Reduced transmission observed for the HWGs was attributed to the high numerical aperture of the coupling accessory. Characterization of the fibers/waveguides using a zinc selenide lens objective on an infrared microscope indicated 24.1 ± 7.2% of the initial light input into the silver halide fibers was transmitted. Percent transmission obtained for the HWGs was 98.7 ± 0.1%. Increased transmission using the HWGs resulted from the absence or minimization of insertion and scattering losses due to the hollow air core and a better-matched numerical aperture. The effect of bending on the transmission characteristics of the fibers/waveguides was also investigated. Significant deviations in the transmission of infrared light by the solid-core silver halide fibers were observed for various bending angles. Percent transmission greater than 98% was consistently observed for the HWGs at the bending angles. The combined benefits of high percent transmission, reproducible instrument responses, and increased bending tolerance indicated HWGs should be preferred in the construction of a fiber/waveguide-coupled ATR probe.

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Optical Fibers for Mid‐Infrared Spectrometry

Abstract: The sections in this article are Overview Introduction to Infrared Transparent Fibers General Considerations On Mid‐Infrared Optical Fibers Losses in Optical Fibers Measurement of Optical Losses Brief History Infrared Fiber Optic Materials Solid‐Cor… Show more

Cited by 5 publications

References 53 publications

Comparison of Fiber Optic and Conduit Attenuated Total Reflection (ATR) Fourier Transform Infrared (FT-IR) Setup for In-Line Fermentation Monitoring

Comparison of Fiber Optic and Conduit Attenuated Total Reflection (ATR) Fourier Transform Infrared (FT-IR) Setup for In-Line Fermentation Monitoring

Single mode operation with mid-IR hollow fibers in the range 51-105 µm

Characterization of Silver Halide Fiber Optics and Hollow Silica Waveguides for Use in the Construction of a Mid-Infrared Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Spectroscopy Probe

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