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Today, the vibration analysis of laminated structures represents an important field in engineering metrology. To perform non-invasive vibration measurements in industrial environments, optical methods are a preferable choice. Electronic Speckle Pattern Interferometry is a method, which permits full field and non-contacting displacement or deformation measurements. The experimental measurement of the resonant frequencies for the piezoceramic material is generally performed by impedance analysis. In this work, Electronic Speckle Pattern Interferometry (ESPI) technique is proposed for studying vibration of piezoceramic/nickel circular laminated plates. The circular membrane is a composite made of a nickel alloy disk with thickness 0. 1 mm and diameter 32 mm, to which a piezoceramic disk, with the same thickness and a smaller diameter (24 mm) is bonded. The time average frame subtraction technique is improved by subtracting two Bessel fringe patterns at two different amplitude levels. A brief analysis of the techniques and some preliminary experimental tests are presented.

Many deconvolution techniques have been proposed in literature based on the knowledge of the Point Spread Function or on its estimation from the observed image. In this paper, we propose an alternative approach, which performs a local inversion through an iterative technique. The proposed iterative deconvolution combines accuracy with fast execution and it is well suited for fast hardware implementation. A discussion on the convergence of the algorithm is also presented in the paper. A novel approach to the deconvolution in medical imaging is proposed. Although its efficiency has been demonstrated in the work only for improving lateral resolution, it can easily be applied to full 2-dimensional deconvolution. The proposed technique has local characteristics and can operate on a limited number of data at a time with great advantage for memory storage requirements; further, it is well suited for a fast hardware implementation because only multiplications and summations are used in the algorithm. The feasibility of an alternative technique for the medical image deconvolution is analyzed theoretically; experimental results are also presented. The results are compared with those obtained by a conventional Fourier-based method.

We present the design and realization of two optical front- ends in the bandwidth 0.5-10 GHz and with a transimpedance gain greater than 60 dB. The two amplifiers implement a lossy matching architecture with an interstage matching and a matched feedback architecture with a frequency controlled local feedback. We realized two hybrid circuits on an alumina substrate. A p-i-n photodiode has been placed on a ceramic substrate together with the three stage amplifier block. We propose a comparison between the two architecture taking into account the effects of the photodiode hybrid assembly. The parasitic link effects on the expected performances of the different architectures. We firstly measured on the photodiode hybrid circuit to verify its model: the response was not as flat as expected from the datasheet. Therefore we had to equalize the photodiode frequency response by means of an input reactive network.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.