Biomedical subjects

Zeev Zalevsky

Publications and source records attributed to Zeev Zalevsky.

8 recordsLinked to original sources

PubMed2003

Invariant pattern recognition by use of a spatial code division multiplexing approach.

Invariant pattern recognition can be achieved by use of harmonic decomposition, for example circular harmonics are used for rotation invariant recognition. A common problem with such methods is that often only a single term of the harmonic decomposition is used, and it does not contain a sufficient amount of the reference energy. Thus discrimination capability is limited, especially in the presence of noise or other disturbances. By using several terms of the harmonic decomposition together this problem can be solved; this can be achieved by the use of code division filter multiplexing. Several harmonic terms are encoded onto a single filter, and the signal is simultaneously correlated with all of them, hence producing enhanced discrimination capabilities. Here two methods are suggested for such encoding. The first involves multiplexing the filters in the Fourier plane, while the second involves multiplexing in the image plane.

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PubMed2003

Optical transfer function shaping and depth of focus by using a phase only filter.

The design of a desired optical transfer function (OTF) is a common problem that has many possible applications. A well-known application for OTF design is beam shaping for incoherent illumination. However, other applications such as optical signal processing can also be addressed with this system. We design and realize an optimal phase only filter that, when attached to the imaging lens, enables an optimization (based on the minimal mean square error criterion) to a desired OTF. By combining several OTF design goal requirements, each represents a different plane along the beam propagation direction, an imaging system with an increased depth of focus is obtained. Because a phase only filter is used, high energetic efficiency is achieved.

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PubMed2003

Superresolution by use of code division multiplexing.

Traditional methods for superresolution have sacrificed field of view for resolution. These methods multiplexed different parts of signals' spectrum on different carriers, and thus managed to transfer a wider range of frequency, in a manner that is similar to frequency division multiplexing in classical communication. We propose code division multiplexing for such an application, which has been shown to have superior capabilities. To enable such mutiplexing we propose a unique setup that creates an incoherent cosine transform of the image. A theoretical analysis of the setup is obtained and later compared with the empirical results.

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PubMed2003

Filter multiplexing by use of spatial Code Division Multiple Access approach.

The increasing popularity of optical communication has also brought a demand for a broader bandwidth. The trend, naturally, was to implement methods from traditional electronic communication. One of the most effective traditional methods is Code Division Multiple Access. In this research, we suggest the use of this approach for spatial coding applied to images. The approach is to multiplex several filters into one plane while keeping their mutual orthogonality. It is shown that if the filters are limited by their bandwidth, the output of all the filters can be sampled in the original image resolution and fully recovered through an all-optical setup. The theoretical analysis of such a setup is verified in an experimental demonstration.

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PubMed2002

Time multiplexing superresolution based on interference grating projection.

In a previous work done by the authors, it was shown that the superresolution concept based on two moving gratings could be effected by a physical grating attached to the object and a virtual grating. This concept was shown to be very efficient and exhibited features that are helpful in removing some artifacts caused when coherent illumination is used. Furthermore, it simplifies the optical and mechanical modules of the super-resolving system by removing the need for mechanical movement of one grating. However, the system still required the need for moving the first (encoding) grating attached to the input. In this study the encoding grating is replaced by use of a projected grating. This approach simplifies the need for attaching the grating to the input object and thus new applications, such as remote sensing can be considered. The theoretical concept is demonstrated and experimental results are shown.

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PubMed2002

Broad-source holographic reconstruction by use of wavelet encoding.

Reconstructing a hologram with spatially incoherent illumination smears the obtained image. We propose a wavelet based holographic recording process which uses the smearing to obtain a reconstruction with improved spatial resolution when incoherent illumination is applied.

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PubMed2002

Optical generation of fuzzy-based rules.

In the last third of the 20th century, fuzzy logic has risen from a mathematical concept to an applicable approach in soft computing. Today, fuzzy logic is used in control systems for various applications, such as washing machines, train-brake systems, automobile automatic gear, and so forth. The approach of optical implementation of fuzzy inferencing was given by the authors in previous papers, giving an extra emphasis to applications with two dominant inputs. In this paper the authors introduce a real-time optical rule generator for the dual-input fuzzy-inference engine. The paper briefly goes over the dual-input optical implementation of fuzzy-logic inferencing. Then, the concept of constructing a set of rules from given data is discussed. Next, the authors show ways to implement this procedure optically. The discussion is accompanied by an example that illustrates the transformation from raw data into fuzzy set rules.

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PubMed2002

Holographic generalized first-arriving light approach for resolving images viewed through a scattering medium.

We present a generalized holography-based approach with improved spatial resolution for extracting images, viewed through a scattering medium. The various angular directions are encoded either with different wavelengths or by capturing their corresponding images in different time slots. The various encoded images are recorded on a digital hologram with a computer. A digital reconstruction, which includes demodulation of the carrier beam and then a proper decoding algorithm, yields resolved images. The principle is demonstrated by recording image-plane digital holograms. Combining the suggested approach with the first-arriving light technique may further improve the results.

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