KEYWORDS: 3D modeling, Bone, Image segmentation, Data modeling, Skull, Visual process modeling, 3D printing, Tomography, Rapid manufacturing, Manufacturing
The article is devoted to the development of a method for manufacturing models of cranial implants using full-scale prototyping by means of extrusion 3D printing. According to the results, specialized software was developed that allows building a geometric model of cranial implants with the maximum degree of automation, performing spatial visualization of the volume model of the implant and generating initial data to create the corresponding full-scale model.
This work devoted the perspective cutting edge technology, method and device for progressive united data and power supply transmission for neutrall and null- interaction application in signal transmission networks. The method of organization, a mathematical model and a structure of fiber-optical data-power interfaces-channels (FODPIC) ,orientated to specialized application and tasks of the incorporated transfer of the information and energy by light are presented. This provides a new possibilities for stabilities transmission of measurement and computing signals and data flows under conditions of influence electromagnetic fields and other potential negative factors for signals. Also it provides a united power supply transfer to low power consumption electronics and devices, through light stream and combines it with information optical signals through new modification of WDM method.
This paper presents the introduction about fiber periodic structures which have a ability to coupling light from fiber core to cladding, their principles and applications. Paper also presents the detail description of particular example of TFBG spectral response for changes of fiber bending in range of curvature radius from 30 to 7 mm. The area of observed cladding mode resonances is changing due to strengthening of fiber curve with simultaneous core mode independence for this quantity. The ghost mode which is resonance closest to Bragg mode wavelength also stands out with transmission loss dependency from fiber bending which is also described.
Authors have worked out a nonstationary signal analysis method on an example of research of laser lines. This method disclosed relationship between signal approximation coefficients and geometry signal characterizations (for instance, energy center, moment of inertia). Examples, which is demonstrating an application of this method for exact coordinate determination problem in laser line at displacement compensation in laser imaging are present.
The method of compensation of output signal temperature drift in an optical methane concentration measurer has been improved, which allowed to expand the operating temperature range to +55°C preserving regulated metrological characteristics. In the proposed method, in contrast to the existing ones, compensation is made for the temperature-caused change of the constant component of the output signal not by the static polynomial, but by the functional dependency of LED optical radiation intensity change on voltage drop change in it. The improved method of compensation in the measurer using hardware and software components has been implemented, which made it possible to evaluate metrological characteristics of the measurer and its efficiency. During the experimental research of the methane concentration measurer in question, it has been obtained the value of the additional absolute measurement error of methane concentration, which does not exceed the regulated magnitude of the basic error (±0.20vol%), which fully meets the requirements for these measurers under conditions of coal mine atmosphere.
This paper presents the spectral properties of chirped tilted Bragg gratings (CTFBG) written on photosensitive optical
fiber by using phase mask technique and excimer laser. The dependencies of manufactured structures spectra on three
various values of chirp: 0,1 nm/cm, 1 nm/cm, 10nm/cm and gratings tilt angle in 0° to 2,5° range with 0,5° change have
been shown in all combinations. Influence of temperature changes in -40°C to 180°C range on measured spectra have
been investigated. We showed the dependencies of CTFBG spectral parameters in various cases of periodic refractive
index variations angle and different chirp values given in manufacturing process.
The optical-electronic system for measuring of geometrical parameters of micrometrical objects is a difficult process that requires the observance of certain features designing or improvement. The observance of that will provide a higher measurement accuracy compared with the accuracy metrics of measurement that were developed without compliance with these design features. Every feature of the design reduces the error of the functioning of individual nodes of the system or errors in nodes under the influence of various internal or external factors. When reducing or eliminating each factor of occurrence of the error, respectively, will increase the overall measurement accuracy. In this work, the result of introducing measurement error for each factor is determined experimentally and proved the correctness of such actions.
Experimental researches of the measurement error to the stage of compliance with subtleties in the improvement of the opto-electronic system was 10 ± 1.5 μm, and after improvement with considering of the specifics of the design measurement error of geometrical parameters was 10 ± 0,33 μm.
Photodynamic cancer therapy is used as an alternative or in combination with conventional treatments. PDT involves three key components: a photosensitizer, a light source and tissue oxygen. The combination of these three components leads to the chemical destruction of any tissues which have either selectively taken up the photosensitizer or have been locally exposed to light. In our research we used Charge-coupled device (CCD) spectrometers to measure intensity of the fluorescence signal. Devices allow receiving and processing signal in a CCD structure at a wide range of wavelengths. We have established a system for measuring the fluorescence of tumor tissue. These results are important for determining the dose of laser radiation and optimal time for laser action without damaging healthy tumor.
Melanoma skin is difficult to diagnose in the early stages of development despite its location outside. Melanoma is difficult to visually differentiate from benign melanocytic nevi. In the work we investigated parameters of human intact skin in near-infrared range for different racial and gender groups. This allows to analyze statistical differences in the coefficient of diffuse reflection and use them in the differential diagnosis of cancer by optical methods subject.
Optical sensing systems has a not weakening research and development in recent years. Because of its unique properties of being unsusceptible to electromagnetic interference, having wide range of operational temperature and having extreme small physical dimensions, optical fiber sensors has increasing acceptance. Fiber Bragg Gratings (FBG) is the most frequently used type of optical sensor types because of its huge multiplexing potential and potentiality of being embedded into composite material (e.g. in structural health monitoring) or attached into measured structure. Embedding or attaching FBG into an inhomogeneous environment, spectral characteristic of the sensing grating do not retain full symmetry, which is due to related differences in the distribution of the axial stress of the grating. When periodicity of the grating is constant, the peak of FBG reflection spectrum should be narrow and sharp. An inhomogeneous axial strain distribution will cause a distorsion in measured transmission or reflection spectrum. This paper shows an distorsions in FBG reflection spectrum measured from sensor attached on surface with welded joint. The sensor strain-to-wavelength shift processing characteristics obtained for homogeneous and welded steel samples were compared.
KEYWORDS: Fiber Bragg gratings, Sensors, Digital signal processing, Signal to noise ratio, Denoising, Demodulation, Filtering (signal processing), Interference (communication), Digital filtering, Optical filters
Spectrum reflected or transmitted by fiber Bragg grating (FBG) in laboratory environment usually has smooth shape with high signal to noise ratio, similar to Gaussian curve. However, in some applications reflected spectrum could included some strong noise, especially where sensing array contains large number of FBGs or while is used broadband, low power source. This paper presents a possibility for extraction fiber Bragg grating peak wavelength from spectra with weak signal to noise radio with most frequently using digital signal processing algorithms. The accuracy of function minimum, centroid and Gaussian fitting methods for peak wavelength detection is compared. The linearity of processing characteristics of extended FBG measured for reference high power and second, low power source is shown and compared.
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