An Algorithm for Fresnel Diffraction Computing Based on Fractional Fourier Transform

The fractional Fourier transform (FrFT) is used for the solution of the diffraction integral in optics. A scanning approach is proposed for finding the optimal FrFT order. In this way, the process of diffraction computing is speeded up. The basic algorithm and the intermediate results at each stage are demonstrated

On a Direct Approach to the Solution of Inverse Optical Problems

The evaluation from experimental data, of physical quantities, which enter into the electromagnetic Maxwell equations, is described as inverse optical problem. The functional relations between the dependent and independent variables are of transcendental character and numeric procedures for evaluation of the unknowns are largely used. Herein, we discuss a direct approach to the solution, illustrated by a specific example of determination of thin films optical constants from spectrophotometric data. New algorithm is proposed for the parameters evaluation, which does not need an initial guess of the unknowns and does not use iterative procedures. Thus we overcome the intrinsic deficiency of minimization techniques, such as gradient search methods, Simplex methods, etc. The price of it is a need of more computing power, but our algorithm is easily implemented in structures such as grid clusters. We show the advantages of this approach and its potential for generalization to other inverse optical problems

Modeling Optical Response of Thin Films: Choice of the Refractive Index Dispersion Law

Determination of the so-called optical constants (complex refractive index N, which is usually a function of the wavelength, and physical thickness D) of thin films from experimental data is a typical inverse non-linear problem. It is still a challenge to the scientific community because of the complexity of the problem and its basic and technological significance in optics. Usually, solutions are looked for models with 3-10 parameters. Best estimates of these parameters are obtained by minimization procedures. Herein, we discuss the choice of orthogonal polynomials for the dispersion law of the thin film refractive index. We show the advantage of their use, compared to the Selmeier, Lorentz or Cauchy models

Minimum Mean Square Error Approach in Images Processing for Full-field Displacements and Deformation Measurements

A vision system is applied to full-field displacements and deformation measurements in solid mechanics. A speckle like pattern is preliminary formed on the surface under investigation. To determine displacements field of one speckle image with respect to a reference speckle image, sub-images, referred to Zones Of Interest (ZOI) are considered. The field is obtained by matching a ZOI in the reference image with the respective ZOI in the moved image. Two image processing techniques are used for implementing the matching procedure: – cross correlation function and minimum mean square error (MMSE) of the ZOI intensity distribution. The two algorithms are compared and the influence of the ZOI size on the accuracy of measurements is studied

Information Modelling of Two-Dimensional Optical Parameters Measurement

A method for measurement and visualization of the complex transmission coefficient of 2-D micro- objects is proposed. The method is based on calculation of the transmission coefficient from the diffraction pattern and the illumination aperture function for monochromatic light. A phase-stepping method was used for diffracted light phase determination

JORDANIAN ZEOLITIC TUFF AS A RAW MATERIAL FOR THE PREPARATION OF SUBSTRATES USED FOR PLANT GROWTH

One of the problems faced in front of industry for potting media is limited amount of quality row materials (mainly peat) for unlimited production of quality substrates in the future. The using of natural minerals for production of substrates or as amendments for existing substrates is possible solution for this problem. The natural zeolites with their specific properties – high CEC, high content of macro and microelements are one of good alternatives to the traditional potting media. Each zeolite deposit has unique chemical composition, physical and mechanical properties. That is why obligatory preliminary condition for their successful application in agriculture is caring out of biological study with agricultural plants for determination of the optimal parameters of chemical and physicochemical properties of the substrates

JORDANIAN ZEOLITIC TUFF AS A RAW MATERIAL FOR THE PREPARATION OF SUBSTRATES USED FOR PLANT GROWTH

One of the problems faced in front of industry for potting media is limited amount of quality row materials (mainly peat) for unlimited production of quality substrates in the future. The using of natural minerals for production of substrates or as amendments for existing substrates is possible solution for this problem. The natural zeolites with their specific properties – high CEC, high content of macro and microelements are one of good alternatives to the traditional potting media. Each zeolite deposit has unique chemical composition, physical and mechanical properties. That is why obligatory preliminary condition for their successful application in agriculture is caring out of biological study with agricultural plants for determination of the optimal parameters of chemical and physicochemical properties of the substrates

SKELETAL AGE ASSESSMENT IN PATIENTS WITH TRANSVERSE MAXILLARY DEFICIT UNDERGOING RAPID MAXILLARY EXPANSION

Aim: The study was governed by two main goals: 1) To assess the skeletal maturation of young patients who were undergoing orthodontic treatment with rapid maxillary expansion; 2) To compare their chronological age with their skeletal maturation stage. Material and methods: Lateral cephalometric radiographs of 74 patients were randomly selected and analyzed. The sample included 51 girls and 23 boys in late mixed and permanent dentition, with an average age of 13.2 (± 2.24) in the range from 9 to 17 years. The assessment of skeletal maturation followed the cervical vertebral maturation (CVM) methods of Baccetti et al. and Lamparski. Results: The results showed 53% consistency and 47% discrepancy between the chronological and skeletal age of the patients. In the age group 9-13.5 years, the discrepancies reached 73.5%. The difference in percentages was statistically significant, p <.001. The discrepancies tended towards higher skeletal age: 80% in the whole sample and 86.25% among patients aged 9 - 13.50 years. The difference between the patients classified in higher and lower stages of skeletal age was statistically significant, p <.001. Conclusion: Chronological age is an unreliable indicator of growth potential in adolescent patients before and after growth spurt. The discrepancy is particularly prominent in patients before growth spurt, where skeletal age suggests a higher level of maturation than predicted by the patients’ chronological age

JORDANIAN ZEOLITIC TUFF AS A RAW MATERIAL FOR THE PREPARATION OF SUBSTRATES USED FOR PLANT GROWTH

One of the problems faced in front of industry for potting media is limited amount of quality row materials (mainly peat) for unlimited production of quality substrates in the future. The using of natural minerals for production of substrates or as amendments for existing substrates is possible solution for this problem. The natural zeolites with their specific properties – high CEC, high content of macro and microelements are one of good alternatives to the traditional potting media. Each zeolite deposit has unique chemical composition, physical and mechanical properties. That is why obligatory preliminary condition for their successful application in agriculture is caring out of biological study with agricultural plants for determination of the optimal parameters of chemical and physicochemical properties of the substrates