Refractive microlenses with more than 50 microm sag are fabricated using grayscale lithography. Mechanical assembly features are made simultaneously alongside the microlenses to facilitate high precision assembly of miniature optical systems. The microlens elements are formed using lithographic patterning of photosensitive hybrid sol-gel glass requiring no etch transfer to the substrate material. Grayscale lithography enables the straightforward patterning of aspheric lenses and arbitrary surfaces within the material depth. Lessons learned in the design of a grayscale photomask are described. Characterization of the fabricated lens elements is reported including lens shape, surface quality, and image quality of a complete assembled imaging system.

This letter presents a method to fabricate high quality, high refractive index titanium oxide thin films by applying liquid phase spin-on deposition combined with low temperature annealing. The synthesis of the liquid form titanium oxide material is carried out using a sol-gel synthesis technique. The material can be annealed at low temperature (150 C degrees ) to achieve relatively high refractive index of 1.94 at 632.8 nm wavelength, whereas annealing at 350 C degrees results in index of 2.03 at 632.8 nm. Film depositions are demonstrated on silicon substrates with 0.5% uniformity in thickness. Refractive indices and extinction coefficients are characterized over a broad wavelength range to demonstrate the optical performance of this novel aqueous phase spin-on deposited hybrid titanium oxide material.

The synthesis of directly UV-photopatternable pure and antimony-doped organo-tin materials is presented. UV-photopatternability has been achieved by using the synthesized benzoylacetone modified tin and antimony 2-isopropoxyethoxides. Photopatterned pure and antimony-doped organo-tin films are crystallized by thermal annealing in order to obtain conductive SnO2 and Sb:SnO2 thin films. The molar ratio between benzoylacetone and metal alkoxides has to be 2 in order to obtain crack-free, good-quality structures. The effects of UV-irradiation, increasing antimony doping level and benzoylacetone concentration on the electrical properties of the single-layered films are analyzed. The highest obtained conductivity was 20 S/cm. Benzoylacetone concentration and UV-irradiation has only a negligible effect on the film electrical conductivities.

Hybrid glass materials are used in the photolithographic fabrication of optical and optomechanical structures. Two different photolithographic hybrid glass processing methods are. described. The first one is referred as photolithographic patterning and the second as direct photolithographic deforming of hybrid glass materials. No etch transfer of the photoimaged structures is needed. In the latter method even the chemical development step can be excluded from the fabrication. Fabrication of lens-arrays gratings and other binary structures is presented. The synthesized hybrid glass materials feature minimum optical transmission of 97% at wavelengths ranging from 450 nm to 1600 nm and refractive index of, e.g., 1.53 at 632.8 nm. The photolithographic patterning resulted in structure. heights in excess of 180 mum with rms surface roughness values ranging from 10 to 45 nm. The direct-photolithographic deforming resulted in structure heights in excess of 27 mum with rms surface roughness values ranging from 1 and 15 nm.

We introduce a process for applying directly UV photopatternable materials and processing methods for the fabrication of binary diffractive optical elements. We design and model a binary axicon-an optical element that produces an almost diffraction free beam at a specified distance from the element. We also synthesize sol-gel-based hybrid 1 glass materials and tailor their processing parameters to fit to the demands of the axicon design. A grating periodicity of 2 mm, an 850-nm structure depth, and certain morphological properties are required to meet the design parameters. The materials are synthesized using zirconium(IV)isopropoxide, methacrylic acid and methacryloxypropyltrimethoxysilane as deposition material precursors. We determine the morphological and shape characteristics of the fabricated axicons as a function of the lithographic exposure parameters. The optical characteristics of the axicons are measured in terms of the axial and radial intensity profiles. The difference between the modeled and measured results is explained. (C) 2002 Society of Photo-Optical Instrumentation Engineers.

This paper introduces the usage of directly UV-photopatternable sol-gel based materials and the processing methods for the fabrication of binary diffractive optical elements. We designed and modeled a binary axicon - an optical element, which produces almost diffraction free beam in a specified distance from the element. We fabricated sol-gel based hybrid-glass materials and tailored their processing parameters to fit the demands of the axicon design. Resolution of 2 microns, film thickness of 850 run, and certain morphological properties were required. The materials were derived from zirconium(IV)isopropoxide, methacrylic acid, and methacryloxypropyltritethoxysilane. We determined the morphological and line quality of the fabricated axicons as a function of the UV-irradiation dose. In addition, we measured the optical characteristics of the axicons in terms of the axial and radial intensity profiles. The reasons for the differences between calculated and measured values are discussed.

Free-space IR transmission provides high bandwidth and good security with small-sized and low-cost links, for instance, for high-bit-rate wireless LANs. Some robustness against shadowing is achieved using diffuse channels, but disadvantages are high path loss and multipath propagation. We use ray-trace simulation software to analyze IR channels in realistic office rooms. Simulations are performed to test the methods and to specify the bandwidth and power budget requirements of diffuse links. Both diffuse and specular reflections as well as shadowing effects due to furniture are considered. Based on the study, novel Monte Carlo ray-tracing software, such as ASAP (Advanced System Analyses Program), are suitable for analyzing the multipath dispersion and the optical power budget of infrared links in realistic indoor environments. The simulations also reveal the benefits of quasidiffuse link configurations, which are composed of multibeam transmitters with restricted beam divergences as well as of detectors with narrow fields of view. For implementation of multibeam transmitters we design an array-type diffractive element that modifies the beams of a 2-D vertical-cavity surface-emitting laser (VCSEL) array. A single element providing the largest 50-deg illumination angle is fabricated for demonstration, The measured diffraction efficiency is in fair agreement with the calculated one after considering the properties of the real VCSEL beam. (C) 2002 Society of Photo-Optical Instrumentation Engineers.

We report on the fabrication of transparent, conductive and directly photopatternable, pure and Sb-doped tin dioxide thin films. Precursors used were antimony(III)isopropoxide and a photo-reactive tin alkoxide synthesized from tin(IV)isopropoxide and methacrylic acid. The synthesis of methacrylic acid modified tin alkoxide was monitored in-situ using IR- and ESI-TOF mass spectroscopic techniques. Sb-doped organo-tin films were deposited via single layer spin coating. After deposition the films were patterned via photopolymerization, using a mercury I-line UV-lamp. All investigated materials could be patterned with 3 W features. After development in isopropanol, the films were annealed in air, in order to obtain crystalline and conductive films. The electrical conductivities of the annealed thin films with, and without, UV-irradiation were determined using a linear four-point method. The direct photopatterning process was found to increase the film conductivity for all the Sb-doping levels tested. The mechanisms for the increased conductivity were characterized using AFM, XPS and XRD techniques.

Direct lithographic patterning of lenslet arrays with tens sags up to 75 mum and opto-mechanical structures with thickness up to 118 mum is demonstrated, using negative tone hybrid glass materials and greyscale and binary photomasks, The hybrid glass material features a maximum extinction coefficient of 2.0 x 10(-4) mum(-1) between 450 and 1600 nm, a refractive index of 1.531 at 632.8 nm and an estimated Abbe number of 45. The patterned structures exhibit rms surface roughness between 10 to 45 nm.

Direct photolithographic deforming of hybrid glass films is used to fabricate optical structures. The structure is fabricated in polyethylene-oxide-acrylate modified hybrid glass films with (1) binary and gray-scale photomasks using a mercury UV-lamp exposure and (2) maskless UV-laser patterning. Fabrication of isolated lenslets, lens arrays, and gratings is presented, including the associated exposure patterns. The hybrid glass material yields light-induced deformation peak-to-valley (p.v.) heights up to 12.8 microm with mercury UV-lamp exposure and p.v. deformation heights up to 6.8 microm with 365-nm UV-laser exposure. The fabricated lenslets' surface data are presented as Zernike-polynomial fit coefficients. Material synthesis and processing-related aspects are examined to understand and control the material's deformation under exposure. The hybrid glass material exhibits a maximum spectral extinction coefficient of 1.6 x 10(-3) microm(-1) at wavelengths ranging from 450 to 2,200 nm and has a refractive index of 1.52 at 632.8 nm. The fabricated structures exhibit rms surface roughness between 1 and 5 nm.

In this paper, we describe the progress toward the development of miniaturized imaging systems with applications in medical imaging, and specifically, detection of pre-cancer. The focus of the article is a miniature, optical-sectioning, fluorescence microscope. The miniature microscope is constructed from lithographically printed optics and assembled using a bulk micro-machined silicon microoptical table. Optical elements have been printed in a negative tone hybrid glass to a maximum depth of 59 /spl mu/m and an rms surface roughness between 10-45 nm, fulfilling the requirements of the miniature microscope. Test optical elements have been assembled using silicon-spring equipped mounting slots. The design of silicon springs is presented in this paper. Optical elements can be assembled within the tolerances of an NA=0.4 miniature microscope objective, confirming the concept of simple, zero-alignment assembly.

In this paper, we report the effect of direct UV photopatterning on the compositional and morphological characteristics, and hence the conductivity, of antimony-doped tin dioxide thin films (55-70 nm) prepared using wet-deposition techniques. Direct UV photopattern-ability was achieved using methacrylic acid modified tin(IV) isopropoxide and antimony(III) isopropoxide as precursors. Spin-on deposited films were lithographically patterned using a UV light source (I line) with a contact mask. After developing, the structures were thermally converted to crystalline, conductive pure and Sb-doped tin oxides. The effect of the UV irradiation on the chemical composition, surface morphology, and crystal size of the fabricated films was investigated using XPS, AFM, and XRD, respectively. We found that the UV irradiation lowered the crystallization temperature, increased the crystal size in the pure or slightly doped samples, and resulted in a more homogeneous Sb dopant distribution. The increase in crystal size was found to correlate with a large increase in conductivity (up to 1500%).

Hybrid (organic-inorganic) glass materials, synthesized by the hybrid sol-gel method, are demonstrated to have potential for fabrication of micro-optical and opto-mechanical structures by UV patterning in a single step. The Figure, an SEM image, shows a microlens array photolithographically patterned in hybrid glass material using a grayscale photomask.

Sol-gel technology was used to fabricate two types of near-infrared absorbing dye-doped polyceram coatings for eye protection purposes against laser radiation. Tolerance of polycarbonate visors against mechanical and chemical stresses may be enhanced by using these coatings. The visible light transmission maxima of high-quality 35 and 25 μm-thick spray-coated polyceram coatings were 70% and 90% for methacrylic and propyl functionalities, respectively. Optical densities at 1064 nm were 4 and 2.

We have used non-sequential ray tracing as a simulation tool to model micro-optical systems. Ray tracing can be used to model micro-optical systems as long as the wave nature of the light is not dominant Non-sequential ray tracing takes inherently into account the aberrations of the optical system and enables the modeling of scattering and stray light effects. We have used measured scattering properties of a hybrid-glass lens material to model scattering in an example imaging micro-optical microscope system. We have also used non-sequential ray tracing to model a straight and a bent light-guide that can be used as chemical sensors. Modeling estimates the amount of light going through the optical system to the detector and shows the paths of the rays leaking out from the system.

Hybrid glass materials are used in the photolithographic fabrication of optical and opto-mechanical structures. Two different methods are introduced. The first one is referred as photolithographic patterning and the other as direct photolithographic deforming of hybrid glass materials. Fabrication of isolated lenslets, lens arrays, gratings and other binary structures is presented. The hybrid glass material used in the photolithographic patterning features a maximum spectral extinction coefficient of 2.0 X 10-4 micrometers -1 between 450 nm and 1,600 nm and a refractive index of 1.53 at 632.8 nm. The fabricated structures feature large convex lens sags (up to 100 microns) with rms surface roughness values ranging from 10 to 45 nm, when the photolithographic patterning is applied. The hybrid glass material used in the direct photolithographic deforming exhibits a maximum spectral extinction coefficient of 1.6 X 10-3 micrometers -1 at wavelengths ranging from 450 nm to 2200 nm and a refractive index of 1.52 at 632.8 nm. The fabricated structures exhibit rms surface roughness between 1 and 5 nm, when direct photolithographic deforming is applied. These materials and methods are highly promising for micro- optics fabrication.

The transient and steady state performance of organic light-emitting devices (OLEDs) has been investigated with a view towards suitability for pulse sources. The rise and fall times of the electroluminescence of the different structures and materials were afforded special attention. The tested devices cover single and multi-layer structures with different layer thicknesses. Both molecular and polymeric-based devices were tested. Molecular materials used in the OLEDs were N,N'-bis(3-methylphenyl)-N,N'-diphenylbenzidine (TPD) as a hole transporter, tris-(8-hydroxyquinolate) aluminum (Alq(3)) as an electron transporter/emitter and 4,7-diphenyl-1,10-phenanthroline (BCP) as a hole blocking material. Poly(2-methoxy, 5-(2'-ethyl-hexoxy)1,4-phenylene-vinylene) (MEH-PPV) and poly(3,4-ethylenedioxythiophene)/poly(styrene) (PEDOT/PSS) were the polymeric materials used in the devices. The effect of the driving voltage on the response time and the current density in transients was under investigation. In addition, changes in the response time were studied, when the bias voltage was applied.

Liquid phase deposition of sol-gel method derived hybrid glass materials is utilized for fabrication of UV light deformable thin films. The hybrid glass material undergoes a surface-relief deformation when exposed to UV light. The observed deformation phenomenon is in the form of a physical expansion of the exposed areas. The maximum deformation when the material was patterned as a sinusoidal grating was 643 nm. The hybrid glass material features an index of refraction of 1.52, rms surface roughness of 2.25 +/- 0.83 nm after processing, and extinction coefficients of 1.2 10(-3) mum(-1) and 0.47 10(-3) mum(-1) at wavelengths of 633 nm and 1550 nm, respectively.

Liquid-phase deposition of sol-gel method derived hybrid glass materials is utilized for fabrication of UV-light-sensitive thin films. The hybrid glass material undergoes a surface-relief deformation when exposed to UV light. The observed deformation phenomenon is in the form of a physical expansion of the exposed areas. The UV light induced surface expansion of the hybrid glass film was used to fabricate near-sinusoidal diffraction gratings with periods of 24 microm, 18 microm, 12 microm, and 9 microm. The maximum deformation when the material was patterned as a diffraction grating was 0.685 microm. The hybrid glass material features an index of refraction of 1.52 at 632.8 microm, rms surface roughness of 2.2 +/- 0.8 microm after processing, and extinction coefficients of 1.2 x 10-3 microm-1 and 0.47 x 10-3 mm-1 at wavelengths of 633 nm and 1550 nm, respectively.

We present the design and fabrication of miniaturized light sources for micro-optical systems using organic Light emitting diodes (OLEDs). These devices can be integrated on a micro-optical table (MOT) using various backplanes. Acceptable angular uniformity of emitted radiance, and a brightness of more than 30,000 cd/m(2) can be readily achieved with OLEDs having areas ranging from 0.0003 cm(2) to 0.0363 cm(2).