Back to Blog
Silica HCFs were manufactured using the stack and draw technique, where capillaries are manually assembled into a hexagonal structure prior to draw. As the mode propagates in the microstructured fiber hollow-core, the effect of the silica’s high material absorption is minimized owing to the low overlap (<1%) of the guided mode with the glass. Lately, pure silica HCFs have been investigated 14. ![]() However, the coating procedure is relatively cumbersome and used toxic materials. In initial attempts, mid-IR HCFs have been fabricated by coating the inner surface of a capillary tube with a metallic film and dielectric material. Such fibers have been already exploited for numerous applications in infrared spectroscopy such as laser surgery, gas sensing, label-free biological sensing, thermal imaging and infrared countermeasures 9, 10, 11, 12, 13. Thus, the search for optical fiber operating in the mid-IR has focused on materials that have high transmittance in the wavelength range λ = 2–20 μm such as chalcogenide glasses, heavy metal fluorides, polycrystalline silver halides (AgX), single-crystal sapphire, and tellurium halides (TeX) 6, 7, 8, which still requires extraordinary purification processes and are extremely hard to handle.Īn alternative approach relies on the use of hollow-core fibers (HCFs) such as photonic bandgap fibers and anti-resonant fibers, where light is confined within the hollow-core, greatly decreasing the influence of the material optical properties. Since the invention of laser sources in the mid-IR range spectral region (2.5 to 25 μm), there has been a growing interest in the development of optical fibers transparent at these wavelengths for applications in chemical, biological and atmospheric sensing 1, 2, 3, 4, where the unique molecular absorption associated to the excitation of specific fundamental vibrational and rotational modes allows for an accurate chemical fingerprinting 5.Īlthough over the last 3 decades silica optical fibers have become the backbone of optical communications and distributed optical sensing, they cannot guide light in the mid-IR as the silica network has strong overtone absorptions above 2 μm, resulting in an overall attenuation that increases for increasing wavelengths. Thermal imaging at the fiber facet performed within the wavelength range 3.5–5 µm clearly indicates air guidance in the fiber hollow-core. The final PETG fiber outer diameter was 466 µm with a hollow-core diameter of 225 µm. The structured plastic fiber preforms were fabricated using commercial 3D printing technology and then drawn using a conventional fiber drawing tower. Guiding is provided by the fiber geometry, as PETG exhibits a material attenuation 2 orders of magnitude larger than the HCF propagation loss. In this paper, we demonstrate a Polyethylene Terephthalate Glycol (PETG) hollow-core fiber (HCF) with guiding properties in the mid-IR. Traditionally, research was directed towards materials with low absorption in the mid-IR region, such as chalcogenides, which are difficult to manipulate and often contain highly toxic elements. It is verified by experiments that this algorithm can realize the detection of defects in the optical fiber preform.Mid-infrared (mid-IR) optical fibers have long attracted great interest due to their wide range of applications in security, biology and chemical sensing. ![]() Finally, the location, size and category of the defect are calculated by tracking information. Further, the defects are tracked through the full-angle image and the tracking information is recorded. Then, the boundary of the optical fiber preform in the full-angle image is determined by the proposed algorithm and the full-angle image is preprocessed. First, rely on the optical fiber preform defect detection experimental platform to obtain the full-angle image of the optical fiber preform. ![]() This paper proposes a defect detection method for optical fiber preforms based on machine vision. However, manual inspection is slow and subjective, and problems such as missed inspections and false inspections are extremely easy to occur, which seriously affects the quality of products. Most domestic manufacturers use manual visual inspection and comparison with tool cards for defect detection. In order to ensure reliable product quality, fiber optics need to be detected for defects during the manufacturing process.
0 Comments
Read More
Leave a Reply. |