We demonstrate that computer-generated diffractive optical elements can be used to synthesize the infrared spectra of real compounds. In particular, we describe a modified phase- retrieval algorithm that we have used to design diffractive elements of this type and we present experimental results for a diffractive optic which is capable of synthesizing the infrared spectrum of HF between 3600 cm^-1 and 4300 cm^-1. The reflection-mode diffractive optic consists of 4096 lines, each 4.5 micrometers wide, at 16 discrete depths relative to the substrate (from 0 to 1.2 micrometer), and was fabricated on a silicon wafer using anisotropic reactive ion-beam etching in a four-mask-level process. We propose the use of such elements to replace reference cells in a new type of correlation spectroscopy that we call 'holographic correlation spectroscopy.' Storage of a large number of diffractive elements, each producing a synthetic spectrum corresponding to a different target compound, in compact disk-like format, will allow a spectrometer of this type to rapidly determine the composition of unknown samples. Further, this approach can be used to perform correlation- based measurements of hazardous or transient species, for which conventional correlation spectroscopy is impractical.

A planar micro lens array, in which a surface-relief micro lens array is built into the glass substrate using a stamping replication method, has been developed for parallel optical components. The planar micro lens array has completely flat surfaces on both sides, and therefore other parallel optical devices can be monolithically composed in tandem. Furthermore, a high thermal reliability for axial alignment is made possible by the adoption of the same material of the substrate as that of the others. In this paper, we review the fabrication method of this planar microlens array using a stamping replication method and discuss the advantages of its use with liquid crystal displays.

A new formulation of the modal method by Fourier expansion (MMFE), that uses the correct rules of Fourier factorization, for crossed surface-relief gratings is presented. By numerical examples, the new MMFE is shown to converge much faster than the old MMFE. For the first time the MMFE is used to produce convergent numerical results for metallic crossed gratings. In addition, the new formulation uses a general non-rectangular Cartesian coordinate system, which gives the MMFE greater generality and in some cases the ability to save computer memory and computation time. Two matrix truncation schemes, the customary parallelogramic truncation and a new circular truncation, are considered. Numerical experiments show that the former is superior.

A novel approach for designing quasi non-diffracting beams is presented. When using these beams for scanning images, the resulting signals have low contrast levels that are maintained over distances far exceeding depth-of-focus distances obtainable with Gaussian beams. A system using two phase-only diffractive optics filters separated by a free space region is sufficient to generate such beams. Gerchberg-Saxton algorithms are applied for determining the phase functions necessary for transforming the input laser beam into the desired beam distribution. The characteristics of the beams are presented.

The Talbot effect is known as a very effective means to illuminate an array of micro-optical components. In this paper, we analyze the Talbot effect along optical multimode slab waveguides with respect to array illumination and present some experimental results. The analysis is based on (1) the seemingly infinite reproduction of the waveguide aperture in the aperture plane caused by kaleidoscopic total reflections in the waveguide walls, and (2) numerical evaluations of the Fresnel-Kirchhoff diffraction formula. The aperture function is generated by phase elements that are based on Ronchy-type phase gratings with a phase step of 180 degree. The analysis is carried out both for mirror waveguides and dielectric waveguides. The experimental verification of the calculated results was obtained by placing a binary phase grating close to the aperture of a rectangular quartz-glass dielectric waveguide.

High-speed calculation of hologram is very important to realize the continuous real-time holographic 3D-TV. We are studying computer systems and algorithms for the high-speed calculation of hologram. We have proposed three high-speed calculation systems of Fresnel-hologram. But, they didn't come up to real-time holographic 3D-TV when the object is complex. In this paper we have proposed holographic-stereogram calculation system using the graphic-accelerator and the digital-signal-processor (DSP) system. Holographic-stereogram calculation time doesn't depend on complexity of the object. A fast-Fourier-transform of object is calculated fast using the DSP system. We make clear that the continuous real-time holographic 3D-TV will be realized in the near future.

Digital pixel holography on the basis of scalar diffraction theory has an effective security function in anti- counterfeiting technology. The digital pixel hologram is in reality a diffraction element. The digital pixel hologram is a laser lithographic image to produce high efficiency volume phase only computer generated holographic diffraction grating. The use of the Postscript language program and the chaos fractal patterns generating program as an interface between the mathematical coding and the laser lithographic device is effective, since this model has flexible and powerful security function for anti-counterfeiting technology. The Postscript files and chaos fractal patterns generating program can control the lithographic system which has a Postscript and chaos fractal patterns generating interpreter.

The calculation formula of the far-field diffraction pattern for mm-wave diffraction antenna with a continuous phase structure is derived by current-distribution method. The simulation calculation using this method is compared with the experiment results for a diffraction antenna prototype operating at 8 mm wavelength. The simulation results coincide well with the measured data.

The DARPA-funded Consortium for Optical and Optoelectronic Technologies for Computing (CO-OP) recently completed the first DOE Foundry run delivering ten samples to each of nineteen users, each with a unique design. The binary optics process was used to provide a maximum of eight phase levels at a design wavelength of 850 nm. Averaged over all users and all samples, an etch depth error of one percent and alignment accuracy within 0.25 micron were achieved. This paper summarizes the details of the process results.

Diffractive optical elements (DOEs) of the kinoform type have been fabricated on DuPont photopolymer by using a gray scale mask technology. The fabricated DOEs have high diffraction efficiency and low noise. Compared with the conventional DOE fabrication the new process is rather simple and does not involve expensive capital equipment such as mask aligners and dry etching systems, and can be extended to mass production.

Replication technologies such as embossing, molding and casting in polymer materials are highly attractive for the fabrication of surface-relief diffractive optical elements (DOEs) and are expected to become key technologies for their production in the future. They have very high resolution, typically in the nanometer range, and allow the fabrication of large area, complex microstructure by low-cost, high volume industrial production processes. This paper gives a summary the current main replication technologies for surface microstructure and discusses their extension to a wider range of DOE microstructures, involving developments such as the replication of deeper and higher aspect ration microstructure and the maintenance of an optically precise form for critical surfaces such as imaging DOEs. Examples and recent results for DOE fabrication by replication technology are presented. New possibilities resulting from the combination of replication technology with other processes such as dry etching and thin film coating are discussed.

A new photopolymer holographic recording material, ULSH-500, based on cationic ring-opening polymerization, has been further optimized to achieve low transverse shrinkage without sacrificing sensitivity. The extent of transverse (z) and lateral (x) shrinkage was determined explicitly in this study for a range of slant angles, in volume holograms which were recorded to near saturation and in holograms of low diffraction efficiency. (Delta) K_x/K_x and (Delta) K_z/K_z, which represent the physical material shrinkage in the grating vector plane, were ascertained by (1) direct measurement of the differential angle changes in the reference and signal beam angles necessary to achieve Bragg matching and (2) measurement of the average refractive index. The accuracy of this method was primarily limited by the exactness in determining the angle of peak efficiency in the Bragg selectivity curve. It is demonstrated that the peak angle can be established to within a small fraction of a degree. It is shown that the assumption of anchoring and thus uniaxial shrinkage, as embodied in the conventional fringe rotation model, cannot be applied for the photopolymer, ULSH-500, under the recording conditions used herein.

Diffractive optical elements (DOEs) have proven to be useful components in optical interconnection and routing systems, especially where volume, weight and design flexibility are important. We show that it is possible to increase the functionality of DOEs by making them polarization-selective. For the fabrication of these polarization-selective DOEs we have used two wet etched anisotropic calcite substrates, joined together at their etched surfaces with their optical axes mutually perpendicular. An index-matching polymer was used to fill the gap between the two substrates and ensures that each of two incident orthogonal polarizations sees only one of the two etched surface relief patterns. We show that such structure is much less sensitive to fabrication errors than earlier presented configurations with an air gap, and we explain the restrictions on the choice of the index-matching polymer. Furthermore we present the experimental results we have obtained for polarization-selective on- and off-axis Fresnel lenses with different focal points dependant on the polarization of the incident beam, polarization-selective gratings which deflect an incident beam in different directions dependant on polarization, and polarization- selective computer-generated holograms generating different images in their Fourier plane for different polarizations. For these binary-phase elements we have measured first order diffraction efficiencies ranging from 30% to 40% and contrasts between the two polarizations up to 500:1.

Broad beam neutral ion machining is investigated as a process for patterning submicrometer features. An ion machining system (IMS) has been designed and constructed to conduct the ion machining experiments on large samples using an 11 cm diameter ion source. A series of experiments were conducted with this broad beam argon ion source impinging on photoresist-masked silicon and glass substrates. A calibration mask with representative features characteristic of those used in diffraction gratings compact discs, and magneto-optical storage devices has been produced and used to evaluate the achievable pattern resolution of the photoresist layer. Several photoresists have been used to generate sub-micrometer features, and their performance as mask materials is compared.

Switchable holograms in polymer-dispersed liquid crystals are now being considered for a variety of applications in which transmission loss, cross-talk, and on/off dynamic range are important issues, particularly as devices are stacked in tandem. Switching voltage and speed also remain as important considerations. All of these characteristics are related to the properties of materials comprising the switchable grating as well as the microscopic morphology. In this paper we explore these material-structure-property relations and examine trade-offs in device parameters. It appears that low optical scattering and wide dynamic range approximately 40 dB are achievable while retaining microsecond switching times. Further reductions in switching voltage will require research in the interfacial anchoring and order parameter of the liquid crystal droplets.

E-beam lithography (EBL) is a powerful tool in optics. Optician can use the progress in EBL to fabricate optical components and systems with novel functions. However, EBL is dominated by microelectronics. Therefore the demands of optics are not always met by the exiting EBL technology. Some possibilities as well as limits of EBL in optics are discussed at the example of diffractive optics.

Dichromated gelatin layers (DCG) facilitate the design and fabrication of large format holographic optical elements (HOE) of high optical quality and diffraction efficiency. The HOEs are used for the fabrication of spectrally selective solar concentrators and as glazing materials for daylighting and passive sun control in buildings. The suitability of HOEs in these applications depends upon the achievable bandwidth, operating central wavelength, dispersion characteristics and low absorption losses. The HOEs are fabricated on glass or plastic film substrata in a DCG-layer of 5 to 30 micrometer thickness. The layer thickness and the gradient ar precisely controlled during the layer deposition and drying (plus or minus 1 micrometer and 0.1 micrometer/cm for standard layer of 10 micrometer thickness). The production process is based on the fabrication of high quality master holograms that are copied by dry copying procedure. The current manufacturing facilities allow the fabrication of 1 m² HOEs on glass substratum and a continuous production of HOEs on plastic substratum with a width of 20 cm and length of 50 m. This technology is also used to fabricate holograms for instrumentation optics in metrology and for optical interconnects in multichip modules. The fabricated HOEs exhibit the desired operational characteristics: high diffraction efficiency, small Braggshift, large bandwidth and a central wavelength that may be freely selected over a wide spectral range. In this paper, we present the results from the experimental investigation and theoretical analysis of large number of holograms of the transmissive and reflective types. We discuss the attained angular and wavelength spectra, bandwidths, wavelength shifts and the diffraction efficiencies as functions of the holographic parameters. The HOEs are made for technical applications and are designed to operate in the 300 nm - 1500 m spectral range.

Computer-generated holograms are limited by conventional lithographic fabrication capabilities which rely on accurate deposition, exposure, and developing of photosensitive chemicals. We present an alternate fabrication technology that uses a focused laser beam to write patterns by inducing a thermochemical change in a bare metal film. The patterns are developed using a single etching step that dissolves the non- exposed metal. The thermochemical writing method allows holograms to be directly written onto large-diameter, thick, and non-flat substrates, requiring no intermediate steps that compromise the ultimate accuracy. Circular patterns for optical testing were written using a polar-coordinate laser writer. The laser power and control requirements are shown to be modest and the etching is shown to be tolerant of temperature and concentration variations. The technology is demonstrated with the fabrication of CGHs up to 136 mm in diameter used for optical testing.

The application of continuous-tone photomasks for fabrication of diffractive optical elements with a deep phase relief is explored. Results of computer simulation for technological process are reported and compared with experiment. The experimental testing of offered technique was carried out on thick AZ4562 photoresist layers. The possibility of deep phase relief fabrication has been proven. The application of the new technique to fabrication of multiorder diffractive elements is discussed.

An optical device is presented that uses the highly wavelength dispersive nature of diffractive optics to provide a means of either removing a small waveband of incident radiation from a scene, to function as a tunable notch filter, or passing only a small waveband of incident radiation from the scene, to function as a tunable bandpass filter. A prototype design example is presented along with preliminary performance analysis.

In order to fulfill the need of high astronomical observation spectral resolution, we are developing a new stationary interferometric spectrometer: heterodyne holographic spectrometer (HHS). It utilizes the configuration of a Twyman- Green interferometer with two arms adjusted for zero path difference and with a plane diffraction grating replacing one of the arm mirrors. So, it combines the multi-advantages of traditional spectrometers: SGS and FTS (slit grating spectrometer and Fourier transform spectrometer), and avoids their disadvantages, especially in the observation with telescope. We get its experimental result in the laboratory and have a simple discussion on its application prospect in astronomy.

A photorefractive beamsplitter (PRBS) is introduced as an alternative to a polarizing beamsplitter (PBS) for coupling optical power into reflective modulators in a free-space optical interconnection (FSOI) system. The PRBS uses a single diffraction grating recorded in a photorefractive material to redirect the incident laser light into the first diffraction order and onto the modulators. Reflected interconnection light not matching the Bragg angle criteria transmits through the beamsplitter uncoupled. Experimental results show that the PRBS provides better uniform transmission for off-axis beams than the currently used PBS.

Electronically switchable Bragg gratings (ESBG) based on holographic polymerized polymer/liquid crystal composites have been described by Sutherland et al. We present an overview of potential applications to waveguide based fiber optic NXN crossconnect and waveguide selective (WDM) crossconnect devices. Various proposed waveguide grating devices are described, and silicon and glass/polymer fabrication paths are outlined. Recent experimental results are summarized. ESBGs are a promising new technology for efficient, large N scalable, moderate speed reconfigurration switches for fiber optic networks.

Highly efficient diffractive grating based on doped photorefractive crystal Bi₁₂TiO₂₀ have been applied for measurement of displacement after mechanic and temperature loading without application of external electric field. The diffraction efficiency of the doped crystal is discovered in non-optimized optical set up 100 times as much as that of the undoped crystals. Practically unlimited number of grating cycles of write, erase and read have been performed without optical damage and external electric or temperature fields. High adaptivity of this grating to external influence fields allows creation of a new optical development of small size diffractive dynamic elements -- DDE in contemporary optical engineering.

This paper discusses the use of diffractive optical elements for optical interconnection in digital computers. The demonstration of these elements, called holographic optical interconnect elements (HOIEs), in an FFT processor is described from three perspectives: system architecture, major enabling technology (smart pixel arrays and HOIEs), and component and system packaging. The FFT processor is based on free-space optical interconnects between a pair of smart pixel arrays, thereby using the advantages of free-space optics to realize the global connectivity requirements of the FFT algorithm. An emphasis is placed on the computer generated holographic elements that establish the free-space paths between the smart pixel arrays.

A novel scheme is proposed to introduce continuous-level phase shift using only binary (two-level) surface-relief grating- like structures. The desired phase shift is invoked by purposely dislocating the grating groove position along the direction perpendicular to the grating grooves. Based on this method, both free-space and guided-wave computer-generated holograms (CGHs) can be constructed. Design and experiments are presented in order to demonstrate the effectiveness of the proposed scheme.

Holographic interferometry has been successfully employed to characterize the materials and behavior of diverse types of structures under stress. Such applications of holographic technique offer some of the most effective methods of modal and dynamic analysis available. The technology is non- destructive, real-time, and definitive in allowing the identification of vibrational modes, displacements, and motion geometry. Structures and processed materials can be analyzed with very low amplitude excitation and the resultant data can be used to adjust the accuracy of mathematically derived structural models. Holographic interferometry has offered a powerful tool to aid in the primary engineering and development of advanced complex composite materials. One such material is a graphite-epoxy fiber reinforced polymer matrix composite. This type of material is finding increased use in advanced aerodynamic, automotive, and other highly mobile platforms. Avionic and undersea applications especially, must consider environments where extremes in vibration and mechanical stresses can affect both operation and structural stability. These are ideal requisites for analysis using advanced holographic methods in the initial design and subsequent test of such advanced structures and materials. Specialized variations of holographic technology have also been applied to define dynamic and vibration related structural behavior. This has been particularly useful in characterizing dynamic parameters of advanced components composed of composite materials. Holographic methods are non- destructive, real-time, and definitive in allowing the identification of minute displacements, and motion geometries. Such effects are directly indicative of various types of induced mechanical, thermal, and acoustic structural stress related to hidden structural anomalies and defects. Such information is often crucial to the determination of mechanical configurations and designs as well as operational parameters of structures composed of advanced engineering materials.

A system has been built and is now being tested that can inject a very high power. pulsed yttrium aluminum garnet (YAG) laser beam into a multimode fiber without damaging the fiber. This design is quite tolerant to changes in the laser beam quality and alignment errors, thereby making the system largely maintenance free. This beam-injection architecture is expected to be useful for medical and industrial applications.

Arbitrary chirped gratings that are very difficult to fabricate by photoresist process or electron beam lithography can be realized by a bent waveguide through a uniform periodic grating. The approximate condition that the system is equivalent to a big chirped grating is deduced. The curve function of bent waveguide can be got by resolving an integral equation. A novel binary chirped grating that could be used as an integrated optical component having combined functions of demultiplexer and focusing lens is also described. Coupled- mode theory is used to compute the efficiency of grating.

We describe a new holographic optical element to improve the image's quality of a reflective liquid crystal displays (LCDs). This new holographic reflector consists basically of 2 layers: a volume type transmission hologram layer and a metallic reflection layer. Compared with conventional reflectors for reflective LCDs, a high optical efficiency can be obtained because the hologram is able to concentrate the reflected light to the observer's eyes. Also, it avoids the problems of glare in the LCDs by deviating the reflected incident light (used for display) away from the direction of the direct reflection light. The transmission hologram's low wavelength selectivity permits us to obtain a near white color reflector for reflective LCDs which for multiple applications is the preferable color for the background.

A novel transmission structure of holographic color filters is introduced. The device is based on the natural characteristics of angular color dispersion in transmission holograms, and the optical reciprocity interacting with two same transmission structure. The type of holographic color filters, differed from before, is composed of two same structure of transmission holograms which are laminated on the both side of transparent substrate. The first transmission hologram diffract normally incident white light, generally emitted from metal halide lamp, into transparent substrate with angular color separation. The diffracted beams transmitted through substrate and are separated for different R, G, B wavelengths. At last, the different R, G, B beams normally couple out with the second hologram as same structure as first one due to optical reciprocity. A light beam matrix mask (LBM) is presented to produce R, G, B pixel, and provided an approach in LCD application.

Based on the characteristics of the Fourier and inverse Fourier transform of special functions, a double binary optics composite system is proposed to realize focusing with high uniformity, which is insensitive to the distortion of the input laser beam. Yang-Gu's algorithm combined is used for optimization design. The deviation caused by diffraction is corrected by iterative optimization. High quality focus with efficiency higher than 90%, uniformity better than 3% (rms), filling factor (FF) higher than 90% is obtained. Simulation calculation shows that it is a promising way to complement ICF uniform illumination.

Based on scalar diffraction optics theory, a new type of mm- wave antenna-diffraction antenna is described in this paper. It has the advantages of thinner thickness, lighter weight and design flexibility. The design theory and space shadow are discussed in detail, and the measured results are presented. The results show that the properties of this kind of antenna are closed to paraboloid reflector.

The synthesis and fabrication of efficient holographic beamsplitters are considered in the paper. Various methods of computer design of two-dimensional binary and multistep holographic beamsplitters are described. The best efficiency achieved was 80 - 85%, the variations in beam intensities being less than 1%. A specially designed beamsplitter whose beam intensities vary from 0 to 7 is presented by way of example. A high-precision e-beam lithography technique was used to make beamsplitters for the visible spectral range. E- beam lithography allowed the realization of phase distribution with errors less than 2%. The effect of different kinds of phase errors on the beamsplitter efficiency and on variations of beam intensities is discussed. The value of allowable errors is determined. All these factors permitted us to make beamsplitters whose efficiency differs by just a few percent from the design efficiency.

The spectral properties of corrugated waveguide structures comprising a thin high index waveguiding layer, and a thick lower index slab volume are reported. It is shown that a wavelength filter based on this structure can be realized. Laser generation in the structure with an active thick slab is experimentally demonstrated. Several possible schemes of distributed feedback are discussed.

A new versatile method to measure the focal length of conventional imaging lens, Fourier transform objective and linear scanning objective using laser as light source is reported, which uses a holographic grating and thin laser beam, and the measurement accuracy is analyzed and relative issues are discussed in the paper. The method has the advantages of versatility, high measurement accuracy, no complex auxiliary needed and easy adjustment. In addition, the spherical aberration of the lens undertest can also be obtained from the same set of testing data by some transformation and processing.

The design principles of inexpensive compact holographic read- only memory (CHROM) based on plastic card and its construction are discussed. CHROM capacity reaches 6 Mbyte.

The concept of optimized waveguide mode control elements allows for the design of improved components such as mode converters and waveguide transitions. This concept can also be applied to the realization of a new type of waveguide phase shifter through the modification of a waveguide geometry. Some examples for the optical control of a waveguide dimension in several different types of waveguide are provided. These designs require accurate numerical electromagnetic solvers and the use of nonlinear optimization tools, resulting in an iterative process where constraints such as bandwidth and manufacturability can be imposed.

Making multiplex holograms is not so popular in general laboratory because of its complicated optical system set-up and its costly optical components. But there are still many areas for multiplex hologram making and research, such as color multiplex hologram, flat multiplex hologram and multiplex hologram duplication. You cannot do the set-up just by try and error, since ways of optical components combination are so many and each component has so many specifications. You must get it well designed and then buy the components to build the system. Equations were derived to link the optical components for good imagery. A flow chart is developed. Based on it, a computer program can be written. With known film height and width of different formatted movie films, known distance from viewer to hologram, known distance from cylindrical lens to hologram, i.e., the radius of the cylindrical multiplex hologram, and with distance of cylindrical lens to spherical lens adjustable, you can get not only the specifications of the two main components, the large spherical lens and the cylindrical lens, but also all the other required parameters for the optical system set-up. Besides, optical paths of imaging are taken into consideration, horizontally and vertically. We believe, to multiplex hologram makers and researchers, it will help

Dynamic liquid surface measurements by non-distirbing technique based on the usage of Talbot effect for two cases, are described: measurements of the water surface disturbed by ultrasound radiation pressure; measurements of the form, thickness and velocity of the oil films spread on the water or solid surfaces. Measurements of the form and wettability angles of drops on the same surfaces.