Experimental and theoretical results for linear surface- relief grating structures of locally varying depth are presented. The studied gratings result from the superposition of two linear gratings of uniform depth, an example of which is the superposition of two gratings of slightly different k-vectors. The resulting surface profile can exhibit a relatively large-period modulation in profile form and, thus, in diffraction efficiency having especially interesting polarization properties. This periodic variation in diffraction efficiency yields a typical Moire pattern which is seen to alter as the interrogation conditions are varied. For the case of two combined gratings whose individual surface-relief profiles are described by functions f₁ and f₂, the resultant surface-relief profile is described by f₁ + f₂. The basis functions f₁ and f(subscript 2#/ have periods between 0.5 micrometers and 5 micrometers and uniform depths of several hundred nanometers. The basis functions which we studied include sinusoidal, blazed and rectangular gratings.

The paper discusses the development of 2D HOEs for effective laser beam splitting. The relationship between the HOE efficiency and the number of phase levels is investigated. The use of more than eight phase levels is shown to be hardly reasonable because it does not offer any appreciable increase in HOE efficiency, complicates the fabrication and may give rise to many errors. The computer simulation allowed us to predict the effect of fabrication errors and set the requirements on accuracy. The paper also describes a technique of direct e-beam writing of multilevel phase reliefs and control of the relief depth. The technique allowed us to make beamsplitters with parameters agreeing closely with calculated values.

A LiNbO₃ electrooptic grating modulator, which has good wavelength selection and high speed characteristics, is composed of coplanar microstrip electrodes with periodic small fins, a thin SiO₂ buffer layer, and airbridge structure. The refractive index distribution in the modulator is analyzed by considering the linear electrooptic effects. The microwave characteristics are determined using 3D finite difference method (3D-FDM). Numerical simulations indicate that the airbridge structure have good speeding wave up effect. The modulator has quite good selecting wavelength modulation characteristics.

Optical linear transform architectures bear good potential for future developments of very powerful hybrid vision systems and neural network classifiers. The optical modules of such systems could be used as pre-processors to solve complex linear operations at very high speed in order to simplify an electronic data post-processing. However, the applicability of linear optical architectures is strongly connected with the fundamental question of how to implement a specific linear transform by optical means and physical imitations. The large majority of publications on this topic focusses on the optical implementation of space-invariant transforms by the well-known 4f-setup. Only few papers deal with approaches to implement selected space-variant transforms. In this paper, we propose a simple algebraic method to design diffractive elements for an optical architecture in order to realize arbitrary space-variant transforms. The design procedure is based on a digital model of scalar, paraxial wave theory and leads to optimal element transmission functions within the model. Its computational and physical limitations are discussed in terms of complexity measures. Finally, the design procedure is demonstrated by some examples. Firstly, diffractive elements for the realization of different rotation operations are computed and, secondly, a Hough transform element is presented. The correct optical functions of the elements are proved in computer simulation experiments.

We employ conjugate gradient algorithm for designing diffractive phase elements (DPEs) that implement the predefined axial-intensity modulations over a given region. We introduce an error function used for guiding the design of DPEs and appraising their performance. We derive the analytical expression for the gradient of the error function with respect to the phases of DPEs. To demonstrate effectiveness of the related algorithms, we carry out model designs of several DPEs that realize different axial- intensity modulations. For instance, we achieve the designs of the DPEs for focusing incident uniform wave into four foci with equal or unequal spacing between the consecutive foci along the optical axis, and the DPE for realizing sinusoid-like axial-intensity modulation over a given region. We also present the designs of the DPEs for generating pseudo-nondiffracting beams with multiple-segment character. The results show that the designed DPEs can satisfactorily fulfill the practical requirements.

Based on the general theory of the amplitude-phase retrieval problem, we present a new approach for the design of diffractive phase elements (DPEs) to implement beam shaping in the fractional Fourier transform (FRFT) domain. We derive the unitarity transform condition for a FRFT system and find that for the given structural parameters of optical system, the nonunitarity of the discrete FRFT depends on its fractional order. Numerical simulations are carried out in designing the DPEs to convert a Gaussian-profile beam into a uniform-profile beam in 1D optical system and the rotationally symmetric optical system both, for different fractional orders and different parameters of beam. In all the cases studied, our algorithm provide an effective method in designing the DPEs that can implement the beam shaping with a high quality.

A brief summary of both VCSEL technology and guided-mode grating resonant filters (GMGRFs) is presented. We then discuss benefits and issues of integrating the two technologies, emphasizing control of wavelength, polarization, and laser cavity modes. We present a GMGRF design suitable for a 980 nm InGaAs VCSEL and show that a significant loss (-4%) in reflectivity results from the slight loss associated with the minimum mirror conductivity required to inject current through the mirror. Experimental data are presented at 850 mm for gratings designed for and fabricated on fused silica substrates and illustrate that GMGRFs are also very sensitive to other forms of loss such as scatter caused by roughness in the grating lines. We suggest a hybrid approach of a GMGRF on a reduced distributed Bragg reflector stack as a means to circumvent the high sensitivity to loss in the GMGRF.

We have designed, fabricated, and tested hybrid refractive/diffractive optical elements in acrylic and cyclic olefin copolymer polymers. The elements were tested for optical performance before and after various environmental conditions.

Novel Diffractive Optical Elements of MODAN-type open up new promising potentialities of solving the tasks of generation, transformation, superposition and subsequent separation again of different transversal laser modes with high efficiency. We present for the first time a MODAN capable of transforming a Gaussian TEM₀₀ input beam into a unimodal Gauss-Hermite (GH) (1,0) complex amplitude distribution. Now we present new results achieved by combining several MODANs in one optical set-up: The aim of these investigations is to transform a single TEM₀₀ input laser beam into several partial beams, each of them described by a different unimodal GH (n,m) mode structure. After separately modulating these partial beams in time, and subsequent superposing them to again one beam by means of a conventional beamsplitter, this unified multimode beam is permitted to propagate in space. Following that, an `analyzing' MODAN is applied to this transversal multimode beam--a diffractive element which is capable of realizing a spatial modal decomposition of an illuminating beam. For the investigations to be presented here, we restricted ourselves to two unimodal beams and selected as transforming MODANs one element of TEM₀₀-to-GH (1,0) type described and one of TEM₀₀-to-GH (0,1) type. The analyzing MODAN was calculated as a phase-only element using the crossed- gratings method and manufactured with the same technology like the two other elements. Theoretical as well as first experimental results demonstrate promising perspectives for the selected concept.

We show that stoichiometric LiNbO₃ crystal containing nonstoichiometric defects much less than congruent LiNbO₃ exhibit some advantageous properties for the holographic data storage (HDS) applications. This was confirmed by the two-beam coupling experiment and digital hologram test. In order to interpret the high performance of stoichiometric LN, we compared some related parameters such as linear electro-optic constants, photoconductivity and photovoltaic constants between stoichiometric and congruent LN crystals. In all measurements, the stoichiometric crystals grown by the novel double crucible CZ method were found to be more excellent as HDS medium. This superiority was obvious at the geometry using the extraordinary polarization.

Transmission phase gratings of grating constants of 4, 6, 8 and 12 micrometers have been designed and fabricated in glass samples via implantation of helium and nitrogen ions of energies in the 500 keV - 1.6 MeV range, through photoresist masks of thickness of 3.3 micrometers . Both mono- and multienergy implantations have been applied. The gratings have been studied by measuring the diffraction efficiencies. The phase profiles of the lines of the gratings have also been measured directly via interference and phase contrast microscopy and scanning electron microscopy. It was found that the profile of the implanted gratings differed significantly from the quasi rectangular profile of the mask, especially in case of the two finest gratings. The highest first order diffraction efficiencies were around 20%. The dependence of the efficiencies of the gratings on the energy and dose of the implantation have been measured.

We propose the noble method of 3D optical implementation for the multiplication of a matrix by a vector by using the binary phase hologram array designed by computer. The elements of the matrix are transformed into the form of the spatial frequency in the hologram. The fabrication of the hologram is done by the photo-lithographic technique.

An imaging optical system with a short conjugate length (6.6 mm) was designed and fabricated using a pair of replicated binary micro Fresnel lens arrays. Two aperture arrays were placed between the lens arrays to prevent crosstalk images from adjacent lenses in the array. Our imaging optical system also has an off-axis configuration to eliminate the adverse effects of the zero-diffraction order light that is inevitable with diffractive optical elements. First, binary lens arrays were fabricated on a 0.5 mm thick quartz substrate by sub-micron photolithographic and reactive ion etching techniques, and the imaging optical system was constructed from these quartz binary lens arrays. In reading experiments, that quartz lens imaging optical system exhibited an excellent modulation transfer function value of 73% for an 8 line/mm test pattern. Then, replicated binary lens arrays were fabricated on a 0.5 mm thick polycarbonate substrate by employing a photopolymerization (2P method) replication process from a Ni stamper. This Ni stamper was fabricated by electroplating a quartz lens substrate, which was the original master. Then the replicated lens imaging optical system was constructed and also exhibited a good MTF value in reading experiments.

Night-vision relay lens system with a diffractive/refractive hybrid lens which relays the image between the phosphor image plane of an image intensifying tube and a 35 mm film single-lens reflex camera was designed and made. The optical system consists of 5 lenses including 1 diffractive/refractive hybrid lens, whereas the conventional all refractive lens system has 7 lenses. After design and manufacture we compared the optical performances of both two lens systems. Since diffractive/refractive hybrid lens has an excellent feature to correct chromatic aberrations in the broad bandwidth visible spectral region, we could obtain the much higher resolution and better image quality from the lens system with the hybrid lens than those from the conventional lens system. The diffractive surface was fabricated with photolithographic methods to get 8 leveled zone structure and its micro profiles were inspected with scanning electron microscopy and atomic force microscope.

A new, high efficiency diffraction grating configuration for use in the situation of grazing incidence is proposed and analyzed. The structure consists of a flat mirror plane, a thin dielectric film with a grating at the air-film interface. It can advantageously replace corrugation metal gratings in all applications, particularly in high power laser applications using the Littman-Metcalf mounting.

Some of the optical devices work on the basis of light extension in the dielectric environment with refractive index as a periodical function. The following devices belongs to such class: interference filters on reflection, deep holograms, optic waveguides with Bragg gratings imprinted in the fiber core, etc. Interference filters belong to the classic optical devices and are well known. Deep holograms have no wide application at present time except holographic optic elements, and are studied for the application in holographic memory devices with high density of recording and storage of information in the volume unit of storage environment. Optical fibers with Bragg gratings wide created and applied in 1992 - 1997 now find their application in sensors, in-line Bragg reflectors, optical amplifiers, filters, laser sources, etc. But on the RC dependence on wave length spectrum we can see side maximums near the main one. Amplitude of these side tops is less than main top. These tops will deteriorate optical characteristics of devices because they become noise sources. Question arises: can we remove or decrease essentially their amplitude? In the theory of filters on the surface acoustic waves where we met the same problem this question was solved by the way of electrodes apodization. It was to be expected that provided apodization of space grating will show the same results. Under space grating apodization we understand that grating amplitude is not stable but changes according to the definite functional dependence along one of the axis.

We present a design of diffractive phase elements (DPEs) that produce point/ring patterns based on the general theory of phase retrieval. The optical system is illuminated by monochromatic or dual-wavelength light. We carry out numerical simulations. The results show that the designed DPE's can satisfactorily generate monochromatic or color point/ring patterns with the given radii of rings in the above-mentioned illuminating systems. The color of the diffractive patterns can be arbitrarily altered. One of the designed DPE's was fabricated and its performance was measured. Experimental measurement is in good agreement with the numerical simulations. These DPE's suit for the applications in optical space communication.

In this paper a novel optical Fourier transform system for several wavelengths is designed. In the system two techniques are adopted; one is the use of a non-focal diffractive optical element to correct the spherical aberration and get the largest space bandwidth product; the other is the introduction of the concept of harmonic diffractive optical elements to realize Fourier transform for multicolor light. Compared to the traditional optical Fourier transform system, this pure diffractive system can acquire better performance with much simpler structure, and more prospective application in optical signal processing system.

The illumination of the edge of a hologram to generate a reference beam is the most important and difficult problem in making edge-illuminated holograms. We introduce a method for preshaping the reference beam which converts a spot into a broad uniformly illuminated strip, which can be either diverging or collimated, through the use of a combination of cylindrical lenses and slits. The preshaped beam illuminates the edge of the hologram's glass substrate at close to normal incidence. Based on the above, some ways to decrease the reflection loss and to increase the transmissivity in the emulsion are presented. Furthermore, we calculated several cases and gave an approach to find the best beam ratio of the reference to the object wave in edge- illuminated hologram making.

Diffraction gratings are key elements of laser systems with pulse compression. For providing of high peak power subpicosecond pulses these gratings should have a high damage threshold, large aperture and high optical quality. In the present work comparison holographic and ruled gratings for systems of pulse compression is spent. Ruled gratings had spatial frequency 1740 grooves/mm, and holographic--1700 grooves/mm and were covered by gold, that provided 90% diffraction efficiency to the first diffraction order. Measurements of damage thresholds for 1 ps and 0.5 ns pulses have shown that for ruled grating it more than for holographic. It was probably connected to a thicker layer of metal for ruled gratings. To increase of a grating's damage threshold additional multi layer dielectric coatings were used. Computer calculations have shown that by changing of amount, material and thickness of layers it is possible to significantly improve damage thresholds. Experimental measurements have shown that for four layers there is the increase of thresholds in 2 times. Received thresholds show, that for the being available sizes as ruled (170 X 170 mm), and holographic (200 X 400 mm) gratings generation of multiterrawatt laser pulses in CPA laser systems is possible.

High performance phase screens are essential for the focal- plane irradiance profile control in laser-fusion system. A new global/local united search algorithm is presented for constructing continuous phase screens to eliminate the wide- angle scattering. The focal-plane intensity profile fits a 16th-order flat-top super-Gaussian function. More than 98.5% of the incident energy is homogeneously constrained in the desired region. The wide-angle scattering outside (phi) 1 mm in focal plane of focus spots is less than 0.5% of the incident energy.

Holography still stays a laboratory process performed in a deep darkness. However dark rooms and the need to perform multiple operations in deep darkness seem to belong rather to 19th century than to current sophisticated data processing techniques facing 21st century. The possibility to obtain holograms and HOEs practically in any brightly lighted environment avoiding dark rooms is demonstrated. Ultra high resolution holographic media and the technique of momental holography well compatible with lighted environment are used for this purpose. Examples of HOEs, holograms and holographic interferograms made in presence of strong polychromatic light are presented. High quality holographic reconstructions from holograms obtained in diffused daylight as well as in strong sunny illumination of tens of klx are shown. He-Ne, Ne:YAG laser sources and ultra high resolution Russian holographic media PFG-03 or PFG-03C (color) were used in this work.

Current manufacturing processes require rapid, inexpensive and reliable techniques for optical inspections of machinery, products and components. Holography and holographic interferometry in spite of their attractive features are rather rarely used for industrial inspections of products and components due to relative complexity, costs, lengthy multi-stage procedures, need of dark rooms and vibration insulation. The technique of momental holography permits to produce high quality silver halide holograms, HOEs, holographic interferograms and speckle photographs within a few seconds. It is monobath technique with single liquid bath for rapid photoprocessing. No other chemical solutions are required in this case. Quite novel modification of the technique is bathless momental holography which also permits to produce high quality holograms, HOEs, holographic interferograms and specklegrams within a few seconds. No baths with liquid chemicals are used. Bathless holograms, HOEs, holographic interferograms recorded on holographic silver halide media and produced momentally in situ are presented in this work. In situ bathless momental technique is quite inexpensive and very simple. It suits ideally for real time optical inspections which are easily performed without any extra photoprocessing devices located in the recording setup and without special liquid gates for exposure and in situ photoprocessing in the recording setup. Another distinctive feature of technique is the possibility to avoid dark rooms and to work in brightly lighted environment. Thus the most drawbacks of holography are eliminated and real time industrial optical checks of products and components can be simply implemented.

The new technology of the high-efficient large-aperture multilevel diffractive optical elements manufacture is examined. This technology is based on the properties of the laser thermochemical writing of hidden images in chromium films and possibilities of the circular laser photoplotter CLWS-300. The ultra-high resolution interferometric method is used for the hidden image precision alignment.

The photopolymer holographic recording materials, ULSH-500, based upon cationic ring-opening polymerization, has been further optimized for recording in an increased film thickness of 200 micrometers . The dynamic range attained, at least M/# equals 16, is substantially greater than previously reported, while concurrently the inherent low transverse shrinkage and high sensitivity characteristics of the material have been retained. Dynamic range or cumulative grating strength, (Sigma) (eta) _i^0.5, has been determined from co-locationally recorded peristrophic and angle multiplexed plane-wave gratings which exhibit low diffraction efficiencies between about 0.1 and 0.2%. Good Bragg selectivity consistent with the imaged thickness and sinc² function behavior is observed for the multiplexed holograms, and both the angular response and the diffraction efficiency are stable without the need for post-imaging fixing procedures. Sensitivity is in the range of 1 to 10 cm/mJ, and the refractive index modulation achievable during consumption of the accessible dynamic range is n₁ equals 1.3 X 10^-2 at the read wavelength of 514.5 nm.

A method for the design of diffractive beam-shaping elements is presented which extends the finite-element-meshes method proposed by Dresel et al. In particular, the modified method can be applied to non-uniform intensity distributions in the input and output planes. This extension is of practical significance due to the non-uniformity of real laser beam intensity distributions. The method is shown to result in so-called smooth phase functions which are desired for beam- shaping applications to overcome the well-known speckle problem. Transmission functions of diffractive phase-only elements have been computed solving beam-shaping problems of practical relevance. We have demonstrated by numerical simulation experiments that the computed elements perform the desired beam-shaping operations in good approximation.