Li Junchang

Application of Eliminating Zero-order Diffraction Light in Wavefront Reconstruction of Inverse Diffraction Computation

According to the Collins formula and its inverse diffraction computation, this paper presents an algorithm for reconstructing the object wavefront of a numerical holograph. To improve the quality of wavefront reconstruction, a technique of eliminating the zero-order diffraction light is introduced, which is achieved by subtraction of two intensities of the interference patterns. The computer simulation and image processing show that the method of eliminating the zero-order diffraction beam can be applied to the wavefront reconstruction of inverse diffraction computation.

The research of Digital Holographic Object Wave Field Reconstruction in Image and Object Space

For conveniently detecting objects of different sizes using digital holography, usual measurements employ the object wave transformed by an optical system with different magnifications to fit charge coupled devices (CCDs), then the object field reconstruction involves the diffraction calculation of the optic wave passing through the optical system. We propose two methods to reconstruct the object field. The one is that, when the object is imaging in an image space in which we reconstruct the image of the object field, the object field can be expressed according to the object-image relationship. The other is that, when the object field reaching CCD is imaged in an object space in which we reconstruct the object field, the optical system is described by introducing matrix optics in this paper. The reconstruction formulae which easily use classic diffraction integral are derived. Finally, experimental verifications are also accomplished.

From UML-RT Models to a Graphical Design Environment of Real-time Multitasking

Presents guidelines of mapping UML-RT models to design models of a graphical design of real-time multitasking environment component-based in order to overcome easy translation UML-RT structure models into the high-level architecture models of this design environment, and transformation UML-RT State Diagram behavior model into its execution models. First, concepts of UML-RT modeling structure, State Diagram behavior modeling and the design environment are presented. Second, specific guidelines and constrains of translation UML-RT models to the environment design models are proposed. Finally, an example is given to illustrate mapping methods between them.

Analysis of reliability of subpixel displacement estimations used in digital speckle correlation method (DSCM)

This paper discusses the precise estimation of interpolation and gradient algorithm which search subpixel displacement by digital speckle correlation method. We obtain these results which the displacement estimations of subpixel are affected by speckle design, interpolation formula, estimated function etc. The theory precision of the quadratic interpolation and the gradient method are analysed by mathematics theory and numerical computation. We ameliorate all formula on discrete integral aspect for computing subpixel displacement. The experiments show that the computational results of the new formula are more stable than the general method.