According to the updated scientific predictions, the advancements in the conventional computer chip technologies will cease sometime between 2010 and 2020. This is prophesied to happen as a result of the fact that conventional computers usually use transistors in order to implement logic gates, which are employed as their computational basic elements. To increase the speed of computers, there are great efforts to decrease the physical size of the transistors in order to shorten the time of electricity paths through them. Using the updated technologies, transistors with the size of 60 nanometers across can be mass-produced. According to the quantum mechanics, below a scale of about 20 nanometers, electrons are unpredictable. This means that the size-reduction of the transistors cannot proceed much further since the electrons passing through them may not be controlled well.
Optical computing may present a promising alternative to the conventional computing as we know it today. The capabilities of a massive parallelism, high speeds, cost effective data-storage and the elimination of wiring are only part of the attractive advantages that optical computing presents. The fact that much knowledge has been already accumulated in this field during many years and the reality that only recently commercial companies rediscovered the great opportunities this field presents, may make optical computers to become practical very soon. It is obvious that the development of an optical processor, which is the main part of an optical computer, is going to change the entire world of computers and electronic devices that are used presently.
The current research work aims to explore new holographic methods for optical computing and processing. This is going to be done by using two different approaches. The first approach investigates methods for building special-purpose optical processors that are designed to solve specific types of problems, whereas the second approach investigates methods for optical logic gate implementation that can be the basic elements in any digital optical processor.
During the past decade, optical imaging through scattering medium has proved to be a powerful technique for many applications. It is especially effective in medical diagnostic, since it is safe, noninvasive and low-cost compared with the conventional radiation techniques. Based on a similar principle of the fly’s visual system, we show a novel method of optical imaging through scattering medium. An image of bones hidden between two biological tissues (chicken breast) is recovered from many noisy speckle pictures obtained on the output of a multi-channeled optical imaging system. The operation of multiple imaging is achieved using a microlens array. Each lens from the array projects a different speckled image on a digital camera. The set of speckled images from the entire array are first shifted to a common center and then accumulated to a single average picture in which the concealed object is exposed.
Optical coherence profilometry and tomography are fundamentally new types of optical imaging that generate high resolution images using echoes of light. They have a number of features that make them attractive for a broad range of applications, including the fact that they enable real time, visualization of microstructures in a nondestructive manner. Most existing methods of optical coherence profilometry and tomography are based on the physics of temporal coherence. Our recently invented method is based on the spatial, rather than the temporal, coherence phenomenon.
Therefore, the proposed interferometric system is illuminated by a quasi-monochromatic spatial incoherent source instead of a broadband light source. The surface profile is measured by means of shifting the spatial degree of coherence gradually along its longitudinal axis while keeping the optical path difference between the measured surface and a reference plane constant. Currently, we explore novel methods to use the 3-D properties of the coherence function for analyzing surface profiles.
3-D optical correlators open opportunities for processing 3-D images directly and rapidly. Targets distributed in 3-D space can be recognized or tracked by optical correlators in the same fast and parallel manner that the well-known two-dimensional correlators have demonstrated for the past three decades. Recently we have developed a few methods to perform spatial 3-D electro-optical correlation. We have proposed an electro-optical pattern recognition system, which can identify an object and its location in the three-dimensional observed space. These novel methods enable one to implement many operations of signal processing on three-dimensional images.
Optical technologies have recently been employed in data security. Compared with traditional computer and electrical systems, optical technologies offer primarily two types of benefits. (1) Optical systems have an inherent capability for parallel processing, that is, rapid transmission of information. (2) Information can be hidden in any of several dimensions, such as phase or spatial frequency; that is, optical systems have excellent capability for encoding information. Recently we have proposed several security systems that are based on existing optical correlators but has some additional benefits over those of the present generation. These systems have better security level more functions and they might be useful for more purposes.
Recently we have started to explore the field of longitudinal holography. Longitudinal holography is the method to shape the light distribution along the propagation axis. While an ordinary hologram is a transmission mask, typically employed to construct a desired transverse image, the longitudinal hologram is a special transmission mask that is used to achieve a desired longitudinal light distribution. For example, by inserting the longitudinal hologram in the propagation path of the laser beam, its divergence can be avoided so that the beam radius remains constant along an arbitrary axial distance. Currently we extend our research to the 3-D computer generated holography. The goal of this project is to find efficient methods of computing synthetic holograms, which are capable of creating artificial 3-D images in the observer eyes.
Recently we have developed a novel method of hologram recording. We suggest a process that produces a computer-generated hologram of real-life three-dimensional images, outside laboratory conditions and in incoherent white light illumination. The 3-D objects are recorded from a few angles by a conventional digital camera giving an end result of a holographic picture with "real life" qualities. This method might lead to developing of a general-used holographic camera for outdoor photography.