Precision Fibre Angle Inspection for Carbon Fibre Composite Structures Using Polarisation Vision

This paper evaluates the precision of polarisation imaging technology for the inspection of carbon fibre composite components. Specifically, it assesses the feasibility of the technology for fibre orientation measurements based on the premise that light is polarised by reflection from such anisotropically conductive surfaces. A recently commercialised Sony IMX250MZR sensor is used for data capture by using various lighting conditions. The paper shows that it is possible to obtain sub-degree accuracy for cured and dry woven and unidirectional materials in ideal conditions, which comprised dark field illumination. Indeed, in ideal conditions, the average relative angles can be measured to an accuracy of 0.1–0.2°. The results also demonstrate a precision of the order 1° for more general illumination, such as dome illumination and ambient lighting, for certain material type/lens combinations. However, it is also shown that the precision varies considerably depending on illumination, lens choice and material type, with some results having errors above 2°. Finally, a feasibility study into the inspection of three-dimensional components suggests that only limited application is possible for non-planar regions without further research. Nevertheless, the observed phenomena for such components are, at least, qualitatively understood based on physics theory.

Artifacts in metallography: dust.

The article discusses the identification of dust particles on the surface of metallographic samples. It is noted that the volume of literature on metallographic artifacts is very small one. This is due to the fact that the Russian – language literature of the metallographic direction was wtitten long ago when the structure was fixed using the photographic method on photographic plates or film. The complexity of the process and the lack of photographic materials excluded the generation of information about metallographic artifacts.Modern metallographic complexes capture structure images digitally. Therefore, in addition to images of the structure, it is possible to record sample preparation artifacts without restrictions. Dust particles on the surface of metallographic sections and their difference from non-metallic inclusions are illustrated. The use of dark-field illumination and polarized light to identify artifacts is considered. Some effects arising from metallographic etching are illustrated.

Multiangle Long-Axis Lateral Illumination Photoacoustic Imaging Using Linear Array Transducer

Photoacoustic imaging (PAI) combines optical contrast with ultrasound spatial resolution and can be obtained up to a depth of a few centimeters. Hand-held PAI systems using linear array usually operate in reflection mode using a dark-field illumination scheme, where the optical fiber output is attached to both sides of the elevation plane (short-axis) of the transducer. More recently, bright-field strategies where the optical illumination is coaxial with acoustic detection have been proposed to overcome some limitations of the standard dark-field approach. In this paper, a novel multiangle long-axis lateral illumination is proposed. Monte Carlo simulations were conducted to evaluate light delivery for three different illumination schemes: bright-field, standard dark-field, and long-axis lateral illumination. Long-axis lateral illumination showed remarkable improvement in light delivery for targets with a width smaller than the transducer lateral dimension. A prototype was developed to experimentally demonstrate the feasibility of the proposed approach. In this device, the fiber bundle terminal ends are attached to both sides of the transducer’s long-axis and the illumination angle of each fiber bundle can be independently controlled. The final PA image is obtained by the coherent sum of subframes acquired using different angles. The prototype was experimentally evaluated by taking images from a phantom, a mouse abdomen, forearm, and index finger of a volunteer. The system provided light delivery enhancement taking advantage of the geometry of the target, achieving sufficient signal-to-noise ratio at clinically relevant depths.

Dark-field microscopy enhance visibility of CD31 endothelial staining

A simple dark field microscopy technique was used for visualization of blood vessels in normal human renal tissues and carcinoma. Phase contrast condenser ring apt for high power objectives was combined with a 10x objective in order to create a dark field illumination of the specimens examined. The endothelial lining of the vessels had been stained by using CD31 monoclonal antibodies combined with conventional peroxidase immunohistochemistry. The final DAB addition used for this technique induced an intense light scatter in the dark field microscope. This scattered light originating from the endothelial lining made the walls of the bright vessels easily detectable from the dark background.

Surface morphology, magnetic resonant and antistatic properties of 07S11-KVfabric coated with stainless steel

A study of the mixed 07С11-KВ fabric (produced by Mogotex) with a coating of steel 12X18H10T, obtained by the method of pulsed cathode arc deposition in a vacuum of 3.5×10–3 Pa, was conducted. It is shown that optical microscopy has a number of advantages in studying the surface morphology of such objects as compared to scanning electron microscopy. The most contrast image is formed using dark-field illumination. When coating is applied, a droplet phase is formed, the droplet sizes vary from 2 to 10 microns. By the method of electron paramagnetic resonance, it has been established that the spectrum of coated fabric has an asymmetrical spectral line with a width of 101 mT, which indicates a high concentration of magnetic resonance centers and a significant resonant absorption of microwave energy. Resonant absorption at low magnetic fields is determined by clusters of iron, nickel, chromium, titanium, etc., with weak nonresonant absorption. The specific surface resistance of the fabric (side 1 / side 2) is 3.3×105 ohm and 5.6×105 ohm, respectively.