Three basic types of membrane hydrophone made from the piezoelectric polymer polyvinylidene fluoride (PVDF) are described. These have been developed as instruments for the characterisation of ultrasonic fields in the megahertz frequency range. Performance properties such as sensitivity, directional response, membrane reflection, linearity and signal-to-noise ratio are considered for various devices made from films of thicknesses between 0.006 mm and 0.080 mm and with active elements from 0.5 mm to 4 mm diameter.

https://iopscience.iop.org/article/10.1088/0022-3735/16/8/019/pdf

PVDF membrane hydrophone performance properties and their relevance to the measurement of the acoustic output of medical ultrasonic equipment

A row vector when left-multiplied by a column vector produces a two-dimensional rank-one matrix in an operation commonly called an outer product between the two vectors. The outer product operation can form the basis for a large variety of higher order algorithms in linear algebra, signal processing, and image processing. This operation can be best implemented in a processor having two-dimensional (2-D) parallelism and a global interaction among the elements of the input vectors. Since optics is endowed with exactly these features, an optical processor can perform the outer product operation in a natural fashion using orthogonally oriented one-dimensional (1-D) input devices such as acoustooptic cells. Algorithms that can be implemented optically using outer-product concepts include matrix multiplication, convolution/correlation, binary arithmetic operations for higher accuracy, matrix decompositions, and similarity transformations of images. Implementation is shown to be frequently tied to time-integrating detection techniques. These and other hardware issues in the implementation of some of these algorithms are discussed.

Optical processing using outer-product concepts

http://ieeexplore.ieee.org/iel5/10277/32710/01533869.pdf

The Vector Imaging Convolver

Resistivity, photoresistivity and magnetoresistance in sharp zincblende-wurtzite phase transition in CdS nanoparticles

http://ieeexplore.ieee.org/iel5/10276/32709/01533707.pdf

Experimental Confirmation of Two-Dimensional Acoustic Processing of Images

http://ieeexplore.ieee.org/iel5/10275/32708/01533423.pdf

Two-Dimensional Fourier Imaging of Light Using Acoustic Pseudo Beam Steering

Strain-induced modulation of photoconductivity in thin polycrystalline films of cadmium sulfide

http://ieeexplore.ieee.org/iel5/10280/32713/01534432.pdf

A. Mahapatra

Papers

Two-Dimensional Fourier Imaging of Light Using Acoustic Pseudo Beam Steering

The Vector Imaging Convolver

Strain-induced modulation of photoconductivity in thin polycrystalline films of cadmium sulfide

Experimental Confirmation of Two-Dimensional Acoustic Processing of Images

Low Frequency Acoustic Propagation in Anisotropic Thin Polymer Films