A novel raytracing method through parabolic axial gradient index lenses is presented. The study is based on developing the exact solution of the differential ray equations with initial conditions set by refraction at the first surface. The analysis offers potential benefits in reducing the computation effort and increasing the raytracing accuracy.

Compared to the holographic elements, the binary optical element (BOE) is more flexible and powerful in its design, functionality and fabrication. Better optical performance, with the advantages of compactness, lightweight, and low cost, is possible if the BOE based optical system is made monolithic. In this paper a monolithic planar-binary integrated optical visor with two couplers is proposed, designed and analyzed. One of the couplers directs the light into the glass slide substrate so that the light can travel within a planar passage via total internal reflection; the other couples the light out of the optical plate and into the wearer's eyes. Meanwhile, a binary lens array is adopted on the surface of the input end, so the visor can serve its imaging function with minimal geometrical aberrations. A bi- blazed diffractive structure of BOL is proposed to correct the chromatic aberrations and achieve achromatic imaging over the visible range.

Atomic force microscopy and other advanced metrology tools now allow detailed determination of the groove profiles and surface morphology of diffraction gratings and other diffractive structures. Modern electromagnetic models allow prediction of the efficiency performance of diffraction gratings in many applications. In addition, tools exist to predict the scatter from low roughness mirrors such as are used for ultraviolet to X-ray optical systems. We describe a program to apply these tools and software developed using commercial off the shelf tools such as IDL and PcGrate to a highly selected set of diffraction gratings developed for the HST/STIS instruments. Both efficiency and scatter predictions are compared with experimental data.

Guided-mode resonance refers to a sharp resonance effect in waveguide gratings where efficient energy exchange between reflected and transmitted waves occurs in a small parameter (wavelength, angle, or refractive index) range. High- efficiency optical reflection filters are obtainable using zero-order waveguide gratings based on this effect. In this paper, a new type of high-contrast (high efficiency and low- sideband) guided-mode resonance reflection filter is studied theoretically and experimentally. Low-reflection sidebands and symmetrical resonance lineshapes are achieved by incorporating thin-film Brewster effects for a TM-polarized incident wave. Experimental results verifying the feasibility of this concept are presented.

We have characterized the performance of high quality micro- jetted microlenses with diameters ranging between 109 microns and 400 microns, with focal lengths ranging between 135 microns and 540 microns. We have found that single drop 109-micron diameter microlenses perform close to their diffraction limit. However, the larger lenses, made with multiple droplets show rapid increase in spherical aberration as the diameter of a lens increases.

Polymer dispersed liquid crystals are generally described as a system with an isotropic liquid crystal (LC) droplet distribution in a polymer matrix. Using masked ultraviolet light and/or applied electric field a structured polymer/LC phase separation can be achieved. One technological advantage is the potential for integrated polymer/LC devices. This approach can be used to manufacture miniature switchable optical components such as diffractive gratings and switchable microlenses. We investigate switchable diffractive gratings based on a structured polymer/LC system. LC director modeling is used to take into account the polymer regions and electric field orientation when the device thickness is comparable with the electrode period. Optical diffraction properties are compared with results of the theoretical modeling.

The Oak Ridge National Laboratory has been instrumental in developing ultraprecision technologies for the fabrication of optical devices. We are currently extending our ultraprecision capabilities to the design, fabrication, and testing of micro-optics and MEMS devices. Techniques have been developed in our lab for fabricating micro-devices using single point diamond turning and ion milling. The devices we fabricated can be used in micro-scale interferometry, micro-positioners, micro-mirrors, and chemical sensors. In this paper, we focus on the optimization of microstructure performance using finite element analysis and the experimental validation of those results. We also discuss the fabrication of such structures and the optical testing of the devices. The performance is simulated using finite element analysis to optimize geometric and material parameters. The parameters we studied include bimaterial coating thickness effects; device length, width, and thickness effects, as well as changes in the geometry itself. This optimization results in increased sensitivity of these structures to absorbed incoming energy, which is important for photon detection or micro-mirror actuation. We have investigated and tested multiple geometries. the devices were fabricated using focused ion beam milling, and their response was measured using a chopped photon source and laser triangulation techniques. Our results are presented and discussed.

The influence of the surface-active substances (SAS) on the evolution process of the charged surface instability has been investigated. It is indicated that the presence of the SAS grows the critical space frequency of deformation, which allows the SAS using for the resolving power growing of the information phototermoplastic carriers, destined for the recording of the optical imagines.

A well-known advantage of injection molded plastic optical components is the possibility of integration of an optical function and a mechanical mount. The optical part can be positioned accurately with respect to well-defined references of the mechanical mount. The optical function does not have to be restricted to one optical surface. In principle any combination of lenses, mirrors and/or beam splitters is possible. The metrology of these combined optical functions is often not trivial. Commercial available measuring equipment in general has difficulties when the different optical functions are tightly toleranced with respect to each other and when less common types of optical surfaces are involved. In this paper three examples of multi function optical components are presented. One of these examples, a double mirror, is elaborated in detail in terms of metrology. The orientation of both mirrors with respect to the mechanical references is tightly toleranced. The same holds for the orientation of the mirrors with respect to each other. The shape of one of the mirrors is so accurate that the reflected wave front is diffraction limited. The other mirror is an off axis paraboloid. The specially developed measurement tool, based on the autocollimator principle, the obtainable measurement accuracies and the calibration procedure will be described. Also the product accuracies realized with injection molding of this component in mass production will be presented.

Traditionally, optical storage has been unable to compete with magnetic storage in the hard disk drive market because multiple heads and disks could not be integrated in a small volume. Optically-assisted Winchester technology overcomes this problem using a fiber-optic delivery system to carry light to multiple recording heads, each of which utilizes several micro-optical components. The small size of the recording head presents design challenges difference from those usually faced in the optical storage industry.

Optics and optical subsystems are playing a larger role in consumer electronics. With that role comes extraordinary developments in size and weight reduction as well as high volume manufacturing methods, driving down both cost and size. Optical elements, as well as lasers and detectors will be fabricated lithographically and configured using the packaging technologies developed for ICs and multi-chip modules. A miniature laser-based optical sensor recently developed for a particularly low cost, high volume application takes advantage of these advanced fabrication methods. The application is the LS120TM disk drive which features a conventional magnetic floppy disk with an optical tracking servo to permit a much finer magnetic track pitch on the media. The 120 MB disk drive has been in the desktop computer market for several years. but the recent effort to develop a smaller version for laptop and notebook computers required major size and mass reduction in the optical sensor. For desktop personal computers, the standard drive bay is 25.4mm high. The standard LSl201M drive features an optical tracking head which is large. with macroscopic lenses, difIractive elements., lasers and detectors which are assembled into a molded chassis [1]. Extension of LS120Thi technology to laptop computers required reducing the drive height to fit in a 12.7 mm slot. This necessitated a significant reduction in the size and mass of the optics head. The device would be required to have the structural integrity to carry the electrical leads for servo interfacing while maintaining precise alignment to the magnetic head. The new size and mass constraints required a fundamental change from the conventional optical system construction. The new sensor was produced using Integrated Micro-Optical System (IMOS) technology [2]. In IMOS. the optical elements are lithographically generated with integrated alignment and bonding features. The source and detector elements are assembled into the system at the chip level, using flip-chip techniques to mechanically and electrically connect them.

In high power laser system, such as laser forming, the requirement for the intensity distribution of the focused laser profile must be top head, steep edge, low side lobe and concentrated high power performance in the main lobe. Such uniform illumination can be realized by the Diffractive Optical Element (DOE), because the DOE has many advantages, such as high light efficiency of pure phase modulation, strong flexibility of phase distribution design and so on. In some application field, uniform illumination is needed on the plane non-perpendicular to the optical axis and the DOE designed by conventional method which only involves the focal plane is difficult to realize such uniform illumination on the planes which are at angles of 30 degree(s), 45 degree(s), 55 degree(s) with the optical axis. To obtain good illumination uniformity on the inclined plane, based on the method of designing a DOE with long focal depth, an indirect design principle is proposed to realize such uniform illumination, by designing the phase distribution of the DOE to make uniform illumination on three planes at right angles with the optical axis, then the uniform illuminations on the incline planes are assured. A hybrid algorithm based on hill-climbing and simulated annealing is utilized for phase design which exploits the ability of strong convergence of the hill-climbing and the global optimization potential of the simulated annealing sufficiently. Simulated results show the non-uniformity on the incline planes at angles of 30 degree(s), 45 degree(s), 55 degree(s) with the optical axis are 5.91%, 4.00%, 3.38%, respectively.

A new method is proposed for the analysis of singlemodes and multimodes planar gradient waveguides, with arbitrary distribution of the constant dielectric (epsilon) (y). The method designated (alpha) k permits the calculation of the propagation constants, critical frequencies and the TE and TM modes. The method allows one to determine the distribution of (epsilon) (y) from experimental model or from a theoretical model. In this work two theoretical models of the distribution of (epsilon) (y), that permit to simulate and analyze the assorted cases of planar optical waveguides are proposed. The (alpha) k method, can be used to draw the refractive index profile, based upon the values of the propagation constants obtained experimentally.

Computer generation of Diffractive Optical Elements is a method of considerable value since it allows an user encoding of complex optical functions (e.g. lens arrays). As a rule, Computer Generated Holograms (CGH's) are thin amplitude transmission elements. The duplication of such holograms on a photopolymerizable film leads to thick phase holograms with higher diffraction efficiencies. Indeed, the incident optical information is recorded as a modulation of the refractive index. A great advantage of polymerizable materials over other recording systems it that no chemical or heating post-treatment is required once the hologram was recorded. Swelling and shrinkage effects, that are a feature of wet development processes are, thus, avoided. The different methods of duplication taken into account are conventional holographic recording, contact copying and direct imaging of CGH's on polymer layers. Advantages and drawbacks of the three methods will be discussed. The characteristics of the photopolymer developed in the Mulhouse laboratory, such as low degree of optical aberrations and high diffraction efficiency, make it possible to achieve attractive and promising results.

High-resolution holographic gratings have been prepared in glass by photodeposition of iron oxide, principally Fe₂O₃, in Si-based porous glasses followed by thermal consolidation to a nonporous glass. A comparison of the properties of the holographically prepared gratings with those produced by direct laser writing in similar glasses show a significant improvements in the uniformity of the deposited gratings and their optical performance.

A new method for solving the dispersion problem of Diffractive Optical Elements (DOEs) is suggested. By aligning two DOEs made of different dispersive materials, the optical path differences as a function of the wavelength can be controlled. Applying this concept, a combined achromatic DOE can be designed for applications that require wavefront control using different wavelengths or wideband light sources. Numerical and simulation results are presented.

A simple microlens array fabrication process based on chalcogenide glass As-Se and As-S photoresists is described. Specific properties of chalcogenide photoresists important for microlenses preparation and the parameters of fabricated spherical and cylindrical microlens arrays are measured and discussed.

Dry photopolymerizable thin films are used to fabricate diffractive optical elements for application in the infrared wavelength region. The polymer solution consists of polyvinyl alcohol (PVA) as a binder, acrylamide (AA) as the monomer base, triethanolamine as a coiniciator, and methylene blue as a photo sensitizer. Such PVA/AA thin films are prepared on glass substrates by graving settling and drying in the dark for about 15 hours, leading to film thicknesses of about 50 microns. The drying of the films is controlled by permanent weighting of the samples. In this way a defined water content can be adjusted, and the sample properties are well reproducible. The photopolymer films are exposed with a laser beam writing system, consisting of a focused helium neon laser beam and computer controlled linear stages that move the photopolymer film in its plane with a resolution of one micron. Computer-generated diffraction patterns are reproduced directly into the photosensitive films. Regulation of the laser illumination is achieved by controlling the speed of the linear stages. The formation of the relief structure with amplitudes up to 10 microns, i.e., 20 percent of the film thickness, takes place in the dark by self-development without the need of wet chemical processing. As a last processing step, the samples are illuminated homogeneously to passivate the photo sensitizer and to fix the obtained relief structure.

A microoptical beam transformation system for coupling a high power laser diode bars into multimode optical fibers is introduced. The key components are a gradient-index cylindrical lens for the collimation of the fast-axis radiation and an array of blazed gratings for beam deflection of the single emitter bundles in the slow-axis. Excellent optical performance and high numerical aperture is required for the cylindrical lens. The lenses are fabricated by Ag⁺/Na⁺ ion exchange and exhibit diffraction-limited performance up to N.A. equals 0.5. The array of blazed gratings is produced by e-beam lithography in a variable dose writing mode. The diffraction efficiency into the desired order is higher than 85% for each element. Using these elements coupling of more than 60% of the output power of a 19 emitter high power laser diode bar (P_out equals 20 W) into a 200 micrometers fiber of N.A. equals 0.2 is achieved. Applications in fiber laser pumping, solid state laser pumping as well as laser soldering and plastic welding are discussed.