Interference of light has numerous metrological applications because the optical path difference (OPD) can be varied at will between the interfering waves in the interferometers. We show how one can desirably change the optical path difference in diffraction. This leads to many novel and interesting metrological applications including high-precision measurements of displacement, phase change, refractive index profile, temperature gradient, diffusion coefficient, and coherence parameters, to name only a few. The subject fundamentally differs from interferometry in the sense that in the latter the measurement criterion is the change in intensity or fringe location, while in the former the criterion is the change in the visibility of fringes with an already known intensity profile. The visibility can vary from zero to one as the OPD changes by a half-wave. Therefore, measurements with the accuracy of a few nanometers are quite feasible. Also, the possibility of changing the OPD in diffraction allows us to use Fresnel diffraction in Fourier spectrometry, to enhance or suppress diffracted fields, and to build phase singularities that have many novel and useful applications.

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A b s t r a c t. The effect of laser priming at different irradiation times on canola yield and its components under saline conditions were investigated. The results showed that laser priming had a positive effect on yield and its components and caused yield increase under saline conditions. Increase in salt levels had a negative and significant effect on seed yield, number of seeds per pod, number of pod per plant, pod length and plant height. The results showed that 45-min laser priming had the strongest effect on yield and yield components and reduced significantly the adverse effects of salinity. By contrast, laser radiation applied for 60 and 75 min, resulted in a dramatic decrease in yield and its components. Correlation coefficients between the attributes showed that canola yield had a positive and significant correlation with plant height, number of seeds, pod per main branch and lateral branches, length of pod and number of lateral branches. Effects of laser and salinity were significant on lateral branch pod length but not on main branch pods.K e y w o r d s: canola, laser irradiation, salt stress, yield, yield components INTRODUCTIONSalinity is known to adversely affect productivity of most crops worldwide (Ashraf, 2009) because their biomass and seed yield are significantly suppressed by this abiotic stress (Munns and Tester, 2008). Globally, more than 770 000 km 2 of lands are salt-affected by secondary salinization: 20% of irrigated land and about 2% of dry land agricultural land (Yildirim et al., 2006). In Asia, after pervious USSR, China, India and Pakistan the largest amount of saline soils belong to Iran (Szabolc, 1989). Canola represents its highest yield in proper and desirable soil conditions. However its growth, yield and oil yield can be reduced significantly by environmental stresses such as drought, salinity, water logging etc. Therefore, canola yield may reduce under saline soils (Ashraf and Mc Neilly, 2004).Among the various methods of priming it seems that there is little information about physical methods. But in recent years, interest in the use of physical methods of plant growing stimulation has increased (Carbonell et al., 2000;Dinoev, 2006;Hernandez et al., 2010; Vasilevski, 2003). Also in recent years the use of laser radiation in biology and agriculture extended widely and rapidly. Hernandez et al. (2006) reported that laser radiation increased the emergence speed and percentage, dry mass of seedlings and, ultimately, significantly increased the yield of laser radiated seeds. In the case of physical treatment the energy introduced in the cell creates conditions for molecular transformations and, as a result, the necessary substances are provided for the cell (Aladjadjiyan, 2007).The purpose of this experiment was to study different laser intensities for priming canola seeds as well as to measure how different densities of laser radiation affect canola yield and performance under salt stress conditions. MATERIALS AND METHODSThe experiment was conducted as factorial in the compl...

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The transport-of-intensity equation (TIE) is applied in the reconstruction of two interfering wavefronts by analyzing the interference patterns and their derivatives along their common propagation directions. The TIE is extended from one wave to two waves and is then applied to calculate the phase of the interference field. Finally, the phase shift concept is applied to reconstruct the phase distribution of two waves. The consistency of the method is verified by simulation.

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This paper presents a technique for reconstructing two interfering wavefronts by analyzing their 3D interference field pattern. The method is based on the numerical inverse problem and will present a robust algorithm for reconstructing of wavefronts. Several simulations are done to validate the proposed method.