Polymer microtips manufactured at the end face of standard optical fibers have been used for effectively coupling with a selected antiresonant fibers (ARFs). Four tested ARFs had similar geometry, 7 capillaries placed around the central air core. It was shown how such coupling structure modified the ARFs spectral characteristics. Applying polymer microtip successfully excited additional bands. Illumination of the ARF with a microtip that operates as a microlens causes a change in numerical aperture and mode number.
Mycoplasma synoviae (MS) infection in poultry is a serious global epidemiological and economic problem. Usually, MS pathogen is responsible for respiratory disease, infectious synovitis and the eggshell apex abnormalities (EAA). The EAA may lead to an increase in the incidence of cracks and breaks of eggshells which often are reason of microbial infections and higher water vapor loss during the entire incubation process. All these problems can cause higher embryonic mortality and lead to significant economic losses. Most of eggs with EEA posses characteristic deformation of an eggshell, however, a number of those eggs infected by MS may be omitted during visual inspection. To prevent such situation a combined Full-Field OCT (FF OCT) and spectral technique for detection of MS infected pieces is proposed. After a numerical processing from a recorded transmittance spectra of a eggshell a few parameters are calculated. Those parameters describe the shape of the transmittance spectrum understood for example as the directional coefficient of a line matched to a graph, or maximum amplitudes of changes in a specified range of wavelengths. Analyses of those parameters allow shells assignment into one of two groups – eggs coming from healthy and MS infected poultry. Data obtained from FF OCT allow more precise evaluation of MS influence on the eggshell, for example changes in the micropores, which are responsible for proper embryo – environment gas exchange [1]. Authors present a new approach to food quality testing which in near future may be applied to reduce the egg production losses caused by MS in the commercial poultry industry.
Graphene nanoplatelets exhibit high potential for current engineering applications, particularly in context of conductive inks for organic and flexible electronic. Electrodes for organic displays are expected to be transparent in the visible part of electromagnetic spectrum.
Thus this study aimed at full-field transmission measurements in the visible wavelength range. The paper presents transmission characteristics of different graphene samples. Samples, prepared using spray coating methods contained 3 types of deposited inks. Each of them was based on different concentration and size of graphene nanoplatelets. Moreover, they had various numbers of layers. Such materials were characterized by different parameters, like distribution of deposited carbon nanoparticles which is influencing layers homogeneity, resulting in different optical properties.
Further, this research tries to establish a robust indicators characterizing examined samples. Authors built in Institute novel scanning optical system with fiber-based, compact spectrometer instead of other expensive techniques used for material characteristic in nanosciences i.e. high-resolution scanning electron microscopy. An optical scheme, design of system and technical parameters are described.
Performed examinations show, that number of parameters derived from our measurements, strongly correlate with physical properties of deposited inks. Authors estimated surface roughness, homogeneity and distribution of nanoparticles agglomerates within the deposited layers.
Presented results suggest, that this novel cost-effective, simple optical method of materials characterization especially in production of graphene nanoplates coatings can be promising in concern of repeatability assessment and optical properties.
Optical coherence tomography (OCT) is noncontact and nondestructive interferometric method which allows visualization of internal structure of an investigated sample. Till now it has found many applications in measurements of biological tissues, technical materials and conservation of art. Optical coherence tomography in full-field configuration is a great technique for visualization of subsurface structures of measured sample with high resolution. In this technique, en-face data acquisition is applied, which allows application of microscope objectives with high numerical aperture while the depth of field is not a problem. These objectives allow obtaining ultra high transverse resolution like in traditional microscopy. Additionally, light sources with broad spectrum, like low cost incandescent lamps (i.e. halogen lamp), allow measurements with micrometer scaleaxial resolution. In this paper the authors present application of full-field optical coherence tomography with a Linnik microscope for the thickness measurement of layers in flexible display with electrodes made of graphene and carbone nanotubes. Thicknesses of layer have a huge impact on the display parameters. There is a correlation between the thickness of the graphene layer and its electrical resistance. Graphene is a new and very promising material which is durable, flexible and has a good adhesion to diverse substrates. It gives a theoretical possibility to create flexible electronics, such as graphene bendable screens. Using OCT we can evaluate the quality of printed layers and detect subsurface defects.
Polymer substrates which are covered with a thin layer of graphene nanoplatelets or carbon nanotubes have a big potential for modern engineering, especially in organic electronics. The main advantage of those materials is transparency in the visible part of the electromagnetic spectrum. This property creates a possibility of using these materials to produce electrodes in flexible screens and light sources. It is necessary to know the transmission characteristics of these materials to assess their usefulness in optoelectronics. In the article authors present the results of the conducted research on the transmittance characteristics of different samples. The samples contained different deposited substances. They had various diameters of the graphene nanoplatelets, one group contained carbon nanotubes. Samples had 50 or 100 layers. The authors examine the influence of these parameters on ink transmittance and ink transmittance uniformity. These analyses are a base for future research on flexible carbon electrodes, especially for applying them in production of flexible organic displays and light sources.
An algorithm for interpolation of central fringe position in low-coherence interferometry measurements is presented. The algorithm is based on a polynomial curve fitting. Fast calculation of interpolation is possible due to the use of an NVIDIA Compute Unified Device Architecture (CUDA) technology, which allows independent analysis of different points of a high-resolution detector matrix on separate cores of a graphics processing unit (GPU). The dependency of the method’s accuracy on the spectral width of the light source is checked. The computation times on a GPU are compared with those achieved with a multicore central processing unit, showing nearly 30 times faster calculations when using CUDA technology. The algorithm accuracy is tested by measuring a flat glass surface with two different cameras—an ordinary CCD camera and a cooled EMCCD camera. Finally, the algorithm is applied to measurements of a populated optical fiber connector array prototyped using deep proton writing technology.
Recently the new type of light source has been introduced to the market. Organic light emitting diode (OLED)
is not only interesting because of the low applying voltage, wide light emitting areas and emission efficiency. It gives
the possibility to create a light source of a various shape, various color and in the near future very likely even the one that
will change shape and spectrum in time in controlled way. Those opportunities have not been in our reach until now.
In the paper authors try to give an answer to the question if the new light source -OLED - is suitable for interferometric
purposes. Tests cover the short and long term spectrum stability, spectrum changes due to the emission area selection.
In the paper the results of two OLEDs (red and white) are shown together with the result of an attempt to use them
in an interferometric setup.
Although low coherence interferometers are commercially available (e.g., white light interferometers), they are generally
quite bulky, expensive, and offer limited flexibility. In the paper the new portable profilometer based on low coherence
interferometry is presented. In the device the white light diode with controlled spectrum shape is used in order to
increase the zero order fringe contrast, what allows for its better and quicker localization. For image analysis the special
type of CMOS matrix (called smart pixel camera), synchronized with reference mirror transducer, is applied. Due to
hardware realization of the fringe contrast analysis, independently in each pixel, the time of measurement decreases
significantly. High speed processing together with compact design allows that profilometer to be used as the portable
device for both in and out door measurements. The capabilities of the designed profilometer are well illustrated by a few
application examples.
This paper presents novel application of Low Coherence Interferometry (LCI) in measurements of characteristic
parameters as circular pitch, foot diameter, heads diameter, in extremely small cogged wheels (cogged wheel diameter
lower than θ=3 mm and module m = 0.15) produced from metal and ceramics. The most interesting issue concerning
small diameter cogged wheels occurs during their production. The characteristic parameters of the wheel depend strongly
on the manufacturing process and while inspecting small diameter wheels the shrinkage during the cast varies with the
slight change of fabrication process.
In the paper the LCI interferometric Twyman - Green setup with pigtailed high power light emitting diode,
for cogged wheels measurement, is described. Due to its relatively big field of view the whole wheel can be examined
in one measurement, without the necessity of numerical stitching. For purposes of small cogged wheel's characteristic
parameters measurement the special binarization algorithm was developed and successfully applied.
At the end the results of measurement of heads and foot diameters of two cogged wheels obtained by proposed
LCI setup are presented and compared with the results obtained by the commercial optical profiler. The results
of examination of injection moulds used for fabrication of measured cogged wheels are also presented. Additionally,
the value of cogged wheels shrinkage is calculated as a conclusion for obtained results.
Proposed method is suitable for complex measurements of small diameter cogged wheels with low module
especially when there are no measurements standards for such objects.
One of the most important challenges in multiple-fiber connectors is to achieve accurate fiber positioning, i.e. to
ensure that the fiber end facets coincide with the front facet of the connector plate. Therefore, it is crucial
to increase the accuracy of the assembly process of fiber connectors. We present the population of a plastic
multi-fiber connector designed for optical interconnect applications with silica fiber, with a good uniformity of
fiber protrusion across the array of ±2.5-μm. To this end, an interferometric setup for in situ monitoring of
fiber tip positions during the insertion phase was developed. It ensures an accurate fiber tip position at the
fiber connector's front facet and across the fiber array in cases where post-insertion polishing is not possible.
Furhermore, our setup can provide us with insight into the influence of the curing process (e.g. shrinkage) on
the tip position during the fiber fixation step and allows us to assess the fiber facet quality. We compare the
fiber tip position measured in situ using our setup with the position measured off-line using a commercial white
light interferometer, showing a deviation smaller than 5%.
Deep Proton Writing (DPW) is a rapid prototyping technology allowing for the fabrication of micro-optical and micro-mechanical
components in PMMA, which are compatible with low-cost replication technologies. Using DPW, a high-precision
2D fiber connector featuring conically-shaped micro-holes for easy fiber insertion, was realized. When
populating these fiber connectors by fiber insertion and fixation, a critical issue is the accurate control of the fiber
protrusion. The use of laser interferometry to measure the fiber's facet position with respect to the connector surface to
within a few micrometers, is inconvenient in view of the measurement range as compared to the fiber dimensions. In this
paper, we propose an interferometric method for in-situ monitoring of the fiber insertion depth, based on the
phenomenon of low temporal coherence light interference in a Twyman - Green setup. In addition, achieving a few
micrometers measurement range with low coherence light requires vertical scanning of the sample under test. The design
of the experimental setup and the achieved measurement results are shown and discussed.
In the paper the multiwavelength interferometer with automatic data analysis based on phase fraction method is
described. It is used to extend measurement range without losing sensitivity, especially to calibrate long gauge blocks.
Numerical simulations and experimental work results have been shown to confirm proper functioning of this method.
However, stabilization of environmental conditions and light sources has significant influence on correctness of
measurement results. To match those requirements measurement system, which will be built for Polish Central Office of
Measures, has been designed. This design is based on Twyman-Green interferometer and assumes usage of two highly
stabilized laser sources. Optical and mechanical design of this system has been shown. Moreover, system for monitoring
and stabilization of environmental conditions is required.
Today there exist different commercial and proprietary micro-optics measurement instruments for the characterization of micro-optical components and microlenses in particular. However there is often a lack of a complete quantitative optical characterization of the latter components. Therefore we will focus in this paper on the optical characterization of spherical microlenses. Moreover the results of the performed round robin within the European 6th FP Network of Excellence on Micro-optics "NEMO" will allow us to select the most appropriate instrumentation tools for characterizing refractive spherical microlenses.
Optimization of the optical quality of optical-grade germanium components requires an in-depth investigation of the different contributions to the optical loss in germanium. In this paper we therefore focus on this optical characterization. We give an overview of possible characterization techniques to determine surface roughness, surface/bulk absorption and refractive index inhomogeneities and we highlight the obtained optical characteristics. To conclude we select the most appropriate non-destructive characterization tool for each optical parameter.
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