This PDF file contains the front matter associated with SPIE Proceedings Volume 8489, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

In recent years, the trend within the molded optics community has been an overall advancement in the capability to diamond grind molds using a variety of grinding techniques. Improvements in grinding equipment, materials and tooling have enabled higher quality ceramic and carbide molds and thereby lenses. Diamond turned molds from ductile metals are still used prevalently throughout the molding industry. Each technology presents a unique set of advantages and disadvantages whether used for precision injection molding of plastic optics or precision glass molding. This paper reviews the manufacturing techniques for each approach and applicable molding process. The advantages and disadvantages of each are compared and analyzed. The subtle differences that exist in optics molded from each technique and the impact they have on the performance in various applications is reviewed. Differences stemming from tooling material properties, material-specific minor defects, as well as cutting and grinding process-induced artifacts are described in detail as well as their influence on the roughness, waviness, and form errors present on the molded surface. A comparison with results between similar surfaces for both diamond grinding and diamond turning is presented.

One of the limits of a conventional multiphoton microfabrication is its low throughput due to the sequential nature of scanning process. In this study, a multiphoton microfabrication system based on spatiotemporal focusing and patterned excitation has been developed to provide freeform polymer microstructures fast. The system integrates a 10 kHz repetition rate ultrafast amplifier featuring strong instantanrror device generating designed patterns at the focal plane. As the result, three-dimensional freeform polymer microstructures using Rose Bengal as the photoinitiator are created by sequentially stacking up two-dimensional (2D) structures layer-by-layer. The size of each 2D fabrication area can be larger than 100 × 100 μm². Compared with scanning process or fixed mask pattern generation, this approach provides two- or three-fold fabrication speed and freeform microstructures. Furthermore, the system is capable of optical sectioning the fabricated microstructures for providing 3D inspection.

Optical injection molded parts are used in many different industries including electronics, consumer, medical and automotive due to their cost and performance advantages compared to alternative materials such as glass. The injection molding process, however, induces elastic (residual stress) and viscoelastic (flow orientation stress) deformation into the molded article which alters the material’s refractive index to be anisotropic in different directions. Being able to predict and correct optical performance issues associated with birefringence early in the design phase is a huge competitive advantage. This paper reviews how to apply simulation analysis of the entire molding process to optimize manufacturability and part performance.

We have investigated the light collection and collimation properties of both Fresnel lenses and the nonimaging (TIR) “cones” typically used with LEDs. We have measured the integrated light output and its spatial distribution, and we have also measured the sensitivity of these two parameters to misalignment between the optic and the LED. We find that for a given distance from the LED to the front of the optic, a Fresnel lens can produce a narrower (better collimated) beam than can a nonimaging “cone.” Various design and manufacturability factors must be weighed when determining which solution to choose for a given illumination problem, and some of these are discussed.

This work presents the fabrication of a high fill factor Fresnel microlens array (MLA) by employing a low-cost homebuilt maskless exposure lithographic system. A phase relief structure was generated on a photoresist-coated silicon wafer, replicated in Polydimethylsiloxane (PDMS) and electrostatically bonded to a glass substrate. Optical characterization was based on the evaluation of the maximum intensity of each spot generated at the MLA focal plane as well as its full width at half maximum (FWHM) intensity values. The resulting FWHM and maximum intensity spot mean values were 50 ± 8% μm and 0.71 ± 7% a.u , respectively. Such a MLA can be applied as Shack-Hartmann wavefront sensors, in optical interconnects and to enhance the efficiency of detector arrays.

Plastic lenses are widely used in visible imaging systems and provide a number of advantages including reduced weight. However, their use in the short-wave infrared (SWIR) has been limited due to the presence of strong material absorption bands occurring at wavelengths above 1 micron. This paper explores the viability of using plastic optics in broadband SWIR imaging applications and the efficacy of using plastic lenses as a method of weight reduction. A design study is presented to reveal combinations of plastic and glass lenses suitable for aberration correction. Weight savings is quantified via a comparison to glass lenses to investigate the trade-off between using lower density plastic materials and the faster F/#s (i.e. larger lenses) required to compensate for the signal loss caused by their absorption.

Reactive mesogen retarders or waveplates provide new opportunities for flexibility in the design of optical systems requiring polarization control. These true zero order retarders are less than 10 microns thick and can be used either as a free standing film or they can be coated as a film on other optical elements such as lenses or mirrors. The slow axis direction can be patterned to form small, even microscopic, discrete retarders or continuously varied to make radial or axial polarizers. We describe in detail the properties of these new optical retarders.

Deformable mirror is a very important reflective component in optical system, which can vary the focal length while the surface deform. Nowadays several type of material were used as deformable mirror, such as liquid lens and MEMS deformable mirror. MEMS deformable mirror have been developed in our group and shows the potential. However, the problem of high actuation voltage is not easy to solve. In this thesis, we proposed using low voltage applied material, which is called Ioic-Polymer Metal Composite (IPMC) with the advantage of low applied voltage but high actuation performance. Arbitrary-shaped electrode IPMC was successfully fabricated by simply covering a shadow mask during electroless plating. Maximum central displacement of ellipsoid-shaped electrode IPMC can be achieved up to 350 μm under 2.5 volts applied. We believe this technique can be used in optical system as a deformable mirror in the future.

The rapid development and adoption of digital technology is leading to an increase in demand for smaller, faster digital data devices and faster digital telecommunication networks. This trend requires increased network bandwidth to handle large amounts of data and seamless integration of network devices with compatible end-user devices. This need is being met by using fiber-optic and photonics technology, infra-red (IR) signals to transmit information, and is fundamental changing the communication industry, thereby creating a need for new polymeric materials. New ULTEM* polyetherimide (PEI) and EXTEM* thermoplastic polyimide (TPI) resins meet the material requirements for the optoelectronics industry. These resins have building blocks enabling IR light transmission without degrading signal quality. They can be injection-molded into thin, precision optical lenses and connectors. ULTEM* resins are been widely used in this industry as fiber-optic components in trans-receivers. EXTEM* resins are amenable to lead-free soldering (LFS), a greener industrial assembly process. While still being IR-transparent, EXTEM* resin is an ideal material for LFS capable substrates, connectors and lenses. An optical product portfolio has been developed and is being presented as a solution to the opto-electronics component industry and some of the successful applications therein.

With its chemical resistance and easy structurability, polyimide (PI) makes for a fine candidate for membranes of tuneable optical systems. Disadvantages of the material are its high absorption coefficient and its mechanical stability, which prevents high deflections of the membrane. To improve the optical capabilities of the material, different variations of processing of the membrane are used. For fabrication of the PI membrane, a photosensitive PI precursor is used. The precursor is spin coated on a 4" Si wafer. After a prebake, the wafer is exposed to UV light. To manipulate the optical properties, different types of postbake are investigated. Afterwards, the backside of the wafer is structured by Deep Reactive Ion Etching (DRIE). Thus, a temporary photoresist etching mask is manufactured by photolithography on the wafer backside. Circular structures with a diameter of 2 mm are then etched through the wafer to fabricate the membranes. The absorption coefficient of the different manufactured membranes is measured. For future use of the membrane as part of a variable optical system, a FEM-Model is built to predict the behaviour of the membrane under mechanical loads, especially considering strains and stresses induced by the different postbake types. The results of the FEM-Model are compared with experimental data obtained via digital image processing methods. Comparative data using different membrane materials are also presented to compare the performance of the PI membrane.

With the array of thin-film coated polymer based optics currently in use within the optoelectronic and photonic industries the need for finger print reducing coatings has drastically increased. Due to the peak-to-valley micro structure of thinfilms fingerprint oils and other airborne particulate are prone to create disruptive optical interference within films, which negate their overall effectiveness in transmitting light and or data. Our approach in combating this issue is a deposition process that is capable of being deposited on numerous injection-molded and cast sheet polymer formulations to help reduce the appearance of fingerprint oils on optically and cosmetically critical components. In many cases, such vacuum-applied coatings improve the optical performance of polymers by improving the visual acuity of the display through the drastic reduction of fingerprint oils and airborne particulate. This presentation will focus on the full spectrum of thin-film coatings that are currently being deployed to polymer optics in order to combat smudging and fingerprints on polymer optics and displays.

Precision glass molding (PGM) directly into metallic structures is a process similar to the plastic injection molding process of insert molding, however fundamental differences exist due to the processing temperatures, nature of materials and manufacturing requirements. Despite some limitations, insert precision glass molding (IPGM) extends many benefits to the product designer. IPGM occurs at the glass transition temperature of the glass therefore materials must be matched by their thermal properties so that undue stress is not exerted on the glass during processing or significant inherent stress left in the part after processing. Either of these conditions could lead to cracking, birefringence or failures due to thermal cycling during operation. This paper will discuss the techniques and specific design considerations that must be taken into account when designing for IPGM. Design aspects such as interface diameters, wall thicknesses, aspect ratios and material properties will be analyzed. The optical and mechanical performance and properties of the glass and holder assembly will also be reviewed, including strength of the assembly, quality of the sealing interface (hermeticity), optical to mechanical alignment and impact on optical quality. The review includes both chalcogenide and traditional oxide based moldable glasses.

Today isothermal precision molding of imaging glass optics has become a widely applied and integrated production technology in the optical industry. Especially in consumer electronics (e.g. digital cameras, mobile phones, Blu-ray) a lot of optical systems contain rotationally symmetrical aspherical lenses produced by precision glass molding. But due to higher demands on complexity and miniaturization of optical elements the established process chain for precision glass molding is not sufficient enough. Wafer based molding processes for glass optics manufacturing become more and more interesting for mobile phone applications. Also cylindrical lens arrays can be used in high power laser systems. The usage of unsymmetrical free-form optics allows an increase of efficiency in optical laser systems. Aixtooling is working on different aspects in the fields of mold manufacturing technologies and molding processes for extremely high complex optical components. In terms of array molding technologies, Aixtooling has developed a manufacturing technology for the ultra-precision machining of carbide molds together with European partners. The development covers the machining of multi lens arrays as well as cylindrical lens arrays. The biggest challenge is the molding of complex free-form optics having no symmetrical axis. A comprehensive CAD/CAM data management along the entire process chain is essential to reach high accuracies on the molded lenses. Within a national funded project Aixtooling is working on a consistent data handling procedure in the process chain for precision molding of free-form optics.

The increasing market demand for LED illumination requires new design approaches for the replacement of conventional recessed luminaries. In this paper we present a series of glass reflectors covering a broad range of beam angles between 10° and 40°. The key feature of this development is the identical size of all reflectors making a modular set-up possible complying to a Zhaga-standardized LED module. The reflector dimensions are comparable to halogen MR16 lamps and allow an immediate use in existing downlight systems. Here, we present light technical measurements of these reflectors and compare the performance to already existing MR16 LED retrofit solutions.

While conventional line generators consisting of rotationally symmetric glass lenses have been widely used for many applications, their optical performances can be improved by using sophisticated optics. Here we report the advantages of our line generators and production technique. We utilize free-form glass lenses to focus laser beams on entire regions of arbitrary-curved surfaces. High energy efficiency is achieved by reducing the size of tool marks left on the lens surfaces. An advanced manufacturing process for free-form surface on carbide materials is briefly discussed.

For LED lighting applications, Fresnel lenses or TIR lenses are frequently made of optical plastics. Glass, however, can offer a number of advantages, including higher resistance to heat, to UV light, and to chemicals like solvents. In this work, several glass materials for transmission optics are compared. The transmittances are evaluated, including Fresnel losses and absorption, as well as shifts of the chromaticity coordinates and of the color rendering index. TIR lenses made of Suprax borosilicate glass and polycarbonate are compared concerning their contour accuracies and their resulting photometric properties like luminous intensity distributions, luminous fluxes, and chromaticity distributions.

Concentrator PhotoVoltaic (CPV) solar energy systems concentrate the sun 500 - 1,000 times or more, in order to take economic advantage of the most advanced and efficient solar cells. The two prevalent system architectures use either reflective glass optics - such as based on a Cassegrain telescope design - or a refractive plastic system - either an acrylic or silicone-on-glass Fresnel lens - for concentration. Both systems have their advantages in areas of performance and durability. Both system designs manufacture their optics by low-cost processes that are unavailable to the other material system. These contrasts are reviewed. The refractive system embodies a simpler optical concept, requiring a single Fresnel lens rather than two concentrating mirrors. However, the reflective, glass system uses the greater design sophistication to provide a greater acceptance angle, which yields tolerance benefits in both manufacture and installation; and also provides faster optics without suffering the spectral aberrations of the refractive systems. Both glass and plastics are low-cost commodity materials. The long-term durability of optical glass is more firmly established than for optical plastics. And light transmission through optical plastics is attenuated by absorbance in both the UV and IR regions, in regions where such light is harvested by efficient multi-junction solar cells.