The experienced lens designer is well aware of the potential advantages aspherics can afford. Within the last few years, machines specifically designed for the CNC machining and polishing of glass aspheres have become commercially available through several manufacturers. This has brought down manufacturing cost to the point that designs incorporating aspheres can be used to reduce system cost compared to all spherical designs. (That is aspheres are no longer used just to save space and weight at the expense of cost.) Not all aspheres are equally manufacturable, however. Arbitrary choices at the beginning of a design can have major impact on manufacturing cost and limit final "as built" performance. This paper considers factors in designing ground and polished (as opposed to molded) glass aspheres which may not be obvious to even the experienced lens designer accustomed to using spherical surfaces or who has dealt with diamond turned aspheres. Factors considered include the surface shape, how the shape is specified, how the surface is to be tested and how it is toleranced. Emphasis will be placed on medium priced components where practical considerations are important.

Today, most optical surfaces are assigned tolerances on power and irregularity, as well as on surface defects (scratch and dig), but usually not on peak surface slope error. This situation reflects concern for the types of error that typically occur with the classical, grind-and-polish method of fabricating lenses. Sometimes, RMS tolerance types are used to control the difference between a surface and the intended, ideal surface. With the propagation of new fabrication methods, new types of surface error - or, at least, types of surface error that were not previously prevalent - are increasing in importance. In particular, this is true for processes such as diamond turning and computer-controlled, local polishing, both of which are used for the fabrication of aspheric surfaces and aspheric mold inserts. In this paper, we examine the use of "peak slope error" as a criterion for specifying optical surface. In the first part of the paper, we look into cases in which the traditional tolerance types for form error are insufficient, and examine when and where surface slope errors (as opposed to surface height errors) are important In the second part of the paper, we look at how tolerances for slope error can be calculated.

The main objective of this article is to introduce a novel power device for electrical-assisted micro-grinding, which could reduce the ambiguities reported and experienced during grinding. For example, the device's software is equipped with a knowledge database that automatically sets suitable electrical parameters for the instructed fine grinding parameters. The parameters are controlled throughout the process in order to achieve the stringent specifications required for further advanced polishing processes or establishing mirror surface finish on optical components.

We study material removal mechanisms of commercially available hard optical materials, with respect to their micromechanical properties, as well as their response to different manufacturing techniques. The materials of interest are heterogeneous materials such as Ni-based (nonmagnetic), Co-based (magnetic), and binderless tungsten carbides, in addition to other hard optical ceramics such as ALON, polycrystalline alumina (PCA), and silicon carbide (SiC). Our experimental work is performed in three stages, emphasizing the contributions of each material’s microstructure to its mechanical response. In the first stage, we identify and characterize material physical properties, such as E-Young's modulus, H_v-Vickers hardness, and K_Ic- fracture toughness (either by microindentation techniques, previously published models, or vendors’ data base). In the second stage, we examine the ability of these materials to be deterministically microground and spotted with magnetorheological finishing (MRF). The evolution of the resulting surface topography is studied using a contact profilometer, white light interferometry, scanning electron microscopy, and atomic force microscopy. In the third stage, we demonstrate that subsurface damage (SSD) depth can be estimated by correlating surface microroughness measurements, specifically, the peakto- valley (p-v) microroughness, to the amount of material removed by an MRF spot.

For many years, Chemical Mechanical Planarization (CMP) has enabled the fabrication of highperformance multilevel integrated circuits for the electronics industry. While CMP techniques are now being used in the manufacturing of optical devices, the concepts and mechanisms of CMP are not yet fully understood by the optics industry. In this paper, an overview of CMP fundamentals and the potential benefits and challenges of using a CMP approach in producing optics will be presented. Examples across several applications will be discussed.

Optical glasses exhibit very different properties during manufacturing process. Densification of glass under pure pressure dramatically changes the material removal mechanism. In glasses with densification, the densification inhibits the propagation of subsurface damage but also masks subsurface damage. Densification is the primary form of subsurface damage at ductile removal mode, like polishing, when material can be densified with pure pressure.

Conventional mechanical grinding and lapping processes impart substantial sub-surface damage (SSD) in optical substrates. SSD is usually mitigated by subsequent grinding and lapping with progressively smaller grit size which removes the damage from the previous step but leaves behind SSD damage of its own. The last remnants of SSD are removed in the final polishing step, which ends up being the longest process step. For some high laser fluence glass optics, BOE etch is used as an intermediate step between the grinding steps in order to arrest further propagation of SSD. No such easily implemented wet-etch chemistry exists for silicon carbide (SiC) optics. Reactive Atom Plasma (RAP^TM, a novel non-contact, atmospheric pressure plasma based process, has been shown to reveal and mitigate sub-surface damage in optical materials. Twyman stress tests on milled SiC substrates demonstrate RAP's ability to mitigate this stress. We will show how the RAP process can enhance and accelerate the fabrication of SiC optics.

UltraForm Finishing (UFF) is a new deterministic subaperture computer numerically controlled (CNC) polisher. Because UFF uses a compliant tool, the desired depth of removal is achieved by adjusting the tool crossfeed velocity. Algorithms for determining an optimum crossfeed velocity profile that satisfies tool velocity and acceleration constraints have been derived for flats, spheres, and mild aspheres. The solutions were validated experimentally. The removal function that characterizes the interaction between a particular tool and part material is evaluated by making a removal spot for one set of process parameters. Its variations, as a function of the process parameters, are predicted by using Hertz contact theory and the Preston equation. Additional algorithms were developed for the evaluation of part and spot metrology inputs and for tool path generation to prevent tool-part collisions.

We have investigated various means and methods for processing large Sapphire Windows for use as a multi-spectral pod window. The only available Sapphire in the large dimensions required to date has been A-plane grown Sapphire, which proves to be challenging to maintain both surface and figure simultaneously. Our approach is to break the process into two distinct stages; initial conventional polish which brings in the figure and final post processing which brings in the surface without effecting figure. Using this type of approach we report on our initial findings with regards to Chemical Finishing, and Ion Beam Finishing. We also extended our results to include a comparison of Sapphire to Alon.

Modern optical designs often include components with shapes more complicated than simple spherical and plano surfaces. These shapes, which include conformal, steep concave, stepped and free form surfaces, are often difficult to finish with conventional techniques due to mechanical interference and steep local slopes. A suitable approach to polishing these shapes is to use a jet of fluid containing an appropriate abrasive. However, a fundamental property of a fluid jet is that it will begin to lose its coherence once it exits the nozzle. This instability results in an unpredictable removal rate of the fluid jet, which makes it unsuitable for use in a deterministic finishing process. A method of jet stabilization whereby a jet of magnetorheological (MR) fluid is magnetized by an axial magnetic field when it flows from the nozzle has been demonstrated and implemented into the Magnetorheological Jet (MR Jet^TM) finishing process. The magnetically stabilized jet of MR polishing fluid produces a stable and reproducible material removal function (polishing spot) at a distance of several tens of centimeters from the nozzle making MR Jet an attractive technology for the finishing of complex shapes such as free form optics, steep concaves, and cavities. Recent results will be presented showing the ability to use this technology to finish a variety of shapes and materials including glass, metals, and ceramics.

We present a material removal rate model for MRF of optical glasses using nanodiamond MR fluid. The new model incorporates terms for drag force, polishing particle properties, chemical durability and glass composition into an existing model that contains only terms for the glass mechanical properties. Experimental results for six optical glasses are given that support this model.

The manufacturing of precision aspheres has traditionally been a long-lead-time, labor-intensive process that is made even more expensive by the need for specific process expertise, dedicated tooling for polishing, and dedicated nulls for metrology. These challenges have limited the widespread use of optical aspheres. New technology is currently being developed to enable flexible and lower-cost manufacturing of precision aspheres, without the need for dedicated tools or null optics. Subaperture Stitching Interferometry (SSI®) combined with Magnetorheological Finishing (MRF®) enable a flexible and deterministic approach to finishing precision aspheres in a wide variety of materials and geometries. MRF systems use highly stable, subaperture tools that perfectly conform to the changing curvature of aspheric optics during the polishing process. This enables a single machine to process plano, spherical, and aspheric surfaces (both convex and concave) without the delays and costs associated with maintaining and switching between sets of dedicated tooling. SSI systems mathematically "stitch" together subaperture measurements to generate high-resolution, high-precision, fullaperture aspheric surface measurements. By locally nulling and using maximum pixel resolution over a subaperture, the SSI extends general-purpose, null-free interferometry to aspheres with departures from best-fit-sphere on the order of 100ë. When these technologies are combined with either the latest grinding and pre-polishing or diamond-turning technology, fast, flexible prototyping, or small-batch production of precision aspheres is available at an attractive cost.

A new polishing concept combines two award winning technologies for polishing and fine correction of optical surfaces.

New optical designs containing freeform optics have recently begun appearing in systems. Applications have incorporated parts ranging in size from small (e.g.: ~5 – 10 mm rectangles) to large (e.g.: astronomical applications). To meet these needs, QED Technologies recently introduced two solutions using its Q22-Y and Q22-950F platforms. Magnetorheological Finishing® (MRF®) is a production proven technology for deterministically finishing symmetric parts (flats, spheres, and on-axis aspheres) using a rotational toolpath, and rectangular flats and cylinders using a raster toolpath. The new freeform toolpath expands the raster capabilities of the Q22-Y and Q22-950F machines to include spheres, aspheres, off-axis sections, and true freeform geometries. The freeform raster toolpath was first introduced on a meter-class optic platform, the Q22-950F. As optics grow in size, the mass typically scales as well. This in turn increases the demands on the machine dynamics to meet rotational polishing requirements. The raster freeform toolpath solution greatly reduces the machine dynamics and is employed to polish a wide variety of part shapes, sizes, and geometries. A similar version of the toolpath was subsequently implemented on the smaller Q22-Y platform. This paper will compare the implementations on each platform, describe the benefits of the toolpath for existing and new applications, and present results from demonstrations on the two platforms.

Traditionally, optical surface specifications have been given for figure and finish. Surface figure covered the low spatial frequencies and finish covered high spatial frequencies. Scratch/dig was used as a cosmetic specification for the quality of the surface. In the more recent past, advances in optical fabrication have enabled production of more complex surface shapes. This has led to a greater need to specify surfaces across a continual spatial frequency spectrum. In this paper we discuss metrology considerations and calculations necessary to produce surfaces to such requirements, including an example with measurements. The results are applicable to various surface specifications including amplitude spectral density, power spectral density, structure functions, or slope specification. The results also are applicable to a variety of optical metrology methods.

For spherical lenses, 3D in-process metrology is rather simple. Surface form may be tested in reflection using a test plate or a tower interferometer, and the polisher can rapidly assess the progress of the polishing process. For aspheric lenses 3D surface metrology is not easy. It often requires expensive, long lead time holograms or diffractive optical elements, a powerful interferometer and labor intensive setup by a skilled test technician. All of these factors combine into repeatability errors and suspect results. Looking deeper, there are specific geometries where it may be advantageous to look THROUGH the lens rather than AT the lens. Testing and correcting the aspheric lens as it is used, in transmission, addresses some of the shortcomings of traditional 3D surface metrology. This presentation will compare and contrast transmission testing versus surface testing for aspheric lenses. It will list specific cases where Optimax Systems chose transmission testing over surface metrology and the reasons for the choice. Additionally it will touch on the techniques and results of this transmission testing.

Spherical-reference objectives, retrace error correction and environmental (vibration) compensation are incorporated into a scanning white light microscope to enable high-precision measurements of precision optics over a mid-spatial frequency range from 1 and 500 mm^-1. The complete metrology platform with automated calibration and positioning demonstrates a measurement repeatability of less than 65pm, while achieving a global uncertainty of less than 100pm for surfaces up to 450mm in size and aspheric departures up to 2 &mgr;m/mm. Keywords: Interferometry, optics, aspheres, metrology.

Traditionally, the most accurate measurements of aspheric surfaces have relied on interferometric null tests. These usually require "null correction" optics, which often take significant time and expense to design and fabricate, and are specific to a particular asphere prescription. Alignment and calibration of the null correction optics can also be quite difficult. Thus there is a significant benefit to a flexible, accurate, "operator-friendly" alternative to the null test. Testing aspheres without null correction (using a spherical wavefront) has been very limited. A typical interferometer can acquire only a few micrometers of fourth-order aspheric departure before the interference fringes become too dense to resolve. Other "non-null" issues include accounting for the part's aspheric shape and optical aberrations of the interferometer. QED's SSI-ATM addresses these limitations, allowing a standard Subaperture Stitching Interferometer (SSI®) to automatically measure mild aspheric surfaces. The basic principles of how subaperture stitching enhances asphere capability are reviewed. Furthermore, SSI-A measurements from real aspheres are presented, along with null test measurements where available.

Using a high resolution two-dimensional angle sensor, 3D-Deflectometry determines the local slopes of an aspheric surface. The sensor scans the surface in spherical coordinates thus measuring the deviation from a reference sphere. A new fault tolerant software algorithm transfers slope information into surface topography data simultaneously correcting for systematic errors of the instrument. In this way various surface types can be characterized; convex and concave standard shapes as well as toric or even free form surfaces.

A new method for measuring the surface of aspheric optics using a combination of two interferometric technologies is presented. The metrology method provides a 3D measurement with high data density in a short measurement time without the need for special tooling. The measurement technique is inherently insensitive to ray trace error and can be used on the shop floor. It covers a large range of aspheric departures and delivers very small measurement uncertainties.

The Technology Demonstration Mirror (TDM) is designed to be a 1.8 m diameter off-axis primary mirror with a highly aspheric surface. This TDM development effort was targeted at demonstrating technology relevant to the chronographic Terrestrial Planet Finder (TPF) mission. A 2D Lorentzian Power Spectral Density (PSD) function was a requirement used for specifying the mid-spatial frequency content, between 0.025 cm^-1 and 0.5 cm^-1, of the interferometricallymeasured TDM. The objective of this study was to develop a 2D PSD algorithm with improved immunity to spatial frequency noise relative to full aperture PSD approaches. The Welch Overlapping Sub Aperture (WOSA) PSD algorithm was identified for its strong variance-reducing characteristics inherent in the averaging of multiple PSDs. Results of this study showed that the variance in the WOSA PSD is roughly an order of magnitude lower than that of the full aperture PSD. The impact of window type, low-frequency pre-filtering, and RMS scale factors on the PSD results are also considered.

Long measurement times can be a bottleneck in an optics production environment. Ideally the measurement time will be quicker than polishing times. Large aperture and high precision parts, however, tend toward slower measurement times. Additionally, such parts usually need dedicated and expensive test setups. In 2004, QED Technologies introduced the Subaperture Stitching Interferometer (SSI®) to automatically stitch spherical surfaces (including hemispheres) up to 280 mm. The system also reduces measurement uncertainty with in-line calibration of systematic errors. With stitching, measurement time is a variable that can impact measurement uncertainty. The user can control such parameters as lattice design, systematic error calibration, and acquisition speed to optimally balance measurement speed and quality. We empirically demonstrate the trade-offs between measurement uncertainty and cycle time on the SSI.

Here I describe results of a method for reducing the influence of vibrations in PSI using the spatial information in the interference intensity images to achieve as much as 100X reduction in induced surface distortion for small-amplitude vibrations. The interference patterns are first normalized for the distribution in illumination across the field of view by measuring the empty-cavity intensity distribution of light reflected from the reference surface prior to measuring the object. The technique then determines the phase increments between acquired frames by comparing the measured interference intensity patterns, and then uses these increments to recalculate a vibration-corrected profile. This approach does not require spatial carrier fringes and maintains full lateral sampling resolution. The method can be applied to any PSI acquisition, and is compatible with most surface shapes encountered in optical testing, including flats, spheres and mild aspheres. Unlike carrier-fringe techniques, as few as one or two interference fringes are sufficient for calculating the phase increments.

Aspheric lenses are of increasing importance in the production of compact imaging systems. High volume productions of such imaging systems demand fast test systems to check the quality of the lenses. The measurement of the modulation transfer function has its limitation for aspheric lenses that are used to correct a lens system for good image quality, but does not have good imaging capabilities as a single lens. Measuring the wavefront of aspheric lenses with a Shack-Hartmann sensor gives a flexible tool to determine the properties of the lenses. We present measurement principle, capabilities and different configurations of the lens testing system WaveMaster® of Trioptics GmbH.

This technical summary presents the fiber-optics interferometric sensor LISE and its applications in the optics industry. The summary explains the measurement principle (Section 1), describes the hardware system components (Section 2) and gives results of an experimental accuracy validation (Section 3). Section 4 illustrates the application of the sensor as a metrology tool for optics manufacturing.

The measurement of the Modulation Transfer Function (MTF) has become the most accepted test in the range of quality control of optics. Years ago only high quality optics like e.g. satellite or professional camera objectives have been MTFtested. Nowadays even simple optical systems like cell phone cameras objectives are 100% tested. But not only single objectives have to be tested. If a perfect objective is badly aligned with respect to the sensor the result will be a bad MTF too. Therefore it is also recommended for the final camera inspection to measure the total MTF of the system objective plus sensor (CMOS or CCD). TRIOPTICS developed a MTF equipment to measure the MTF on 9 different field positions and different object distances of a complete camera in a few seconds. The system comprises a special target generator with slanted crosses as targets and new developed software to grab images and to calculate the MTF of the complete camera in realtime.

Lens centration tolerances are an essential consideration in optical design and assembly, and achieving them is a fundamental phase of optical fabrication. The tolerances for centration may be expressed in any of several different ways (including wedge, edge thickness variation, beam deviation, image decenter) by the designer or draftsperson; and may then be measured in the shop according to a different set of parameters (including wedge, edge thickness variation, beam deviation, surface reflection orbits, edge lateral runout) depending on available equipment and methods. The necessary conversions between expressions are subtle, easily misunderstood, and not readily available. The available literature is not entirely consistent. This paper provides definitions, diagrams, explanations, derivations, and conversions between the various expressions. Aspheric lenses have additional datum features and are not addressed in this paper.

The optical imaging quality of objectives is mainly influenced by the errors of the mechanical alignment of the single elements. TRIOPTICS has developed a new technology called MultiLens® in order to measure the centering error of single lenses as well as complete objectives. It is possible to measure the tilt of each single optical surface inside of a mounted objective with highest precision. We achieve accuracies in the range of an arc second. During the measurement the deviation of each centre of curvature with respect to a reference axis is measured. These data are further processed in order to provide the shift and tilt of an individual lens or group of lenses with respect to a given reference axis. The knowledge of the centering error can be used to align actively single optical elements. Applications mainly include the measurement of cell phone and digital camera lenses. However, any type of objective lens from endoscope up to very complex objective lenses used in microlithography can be measured with highest accuracy.

We present an automatic bonding station which is able to center and bond individual lenses or doublets to a barrel with sub micron centring accuracy. The complete manufacturing cycle includes the glue dispensing and UV curing. During the process the state of centring is continuously controlled by the vision software, and the final result is recorded to a file for process statistics. Simple pass or fail results are displayed to the operator at the end of the process.

Recent market demands for free-form optics have challenged the industry to find new methods and techniques to manufacture free-form optical surfaces with a high level of accuracy and reliability. Production techniques are becoming a mix of multi-axis single point diamond machining centers or deterministic ultra precision grinding centers coupled with capable measurement systems to accomplish the task. It has been determined that a complex software tool is required to seamlessly integrate all aspects of the manufacturing process chain. Advances in computational power and improved performance of computer controlled precision machinery have driven the use of such software programs to measure, visualize, analyze, produce and re-validate the 3D free-form design thus making the process of manufacturing such complex surfaces a viable task. Consolidation of the entire production cycle in a comprehensive software tool that can interact with all systems in design, production and measurement phase will enable manufacturers to solve these complex challenges providing improved product quality, simplified processes, and enhanced performance. The work being presented describes the latest advancements in developing such software package for the entire fabrication process chain for aspheric and free-form shapes. It applies a rational B-spline based kernel to transform an optical design in the form of parametrical definition (optical equation), standard CAD format, or a cloud of points to a central format that drives the simulation. This software tool creates a closed loop for the fabrication process chain. It integrates surface analysis and compensation, tool path generation, and measurement analysis in one package.

The addition of a high resolution encoder to the spindle of a standard diamond turning lathe has allowed for precision control of angular rotation. With three precision controlled axes, (rotational C, linear X and linear Z), tool path programs can be defined in cylindrical coordinates, which enables the production of freeform geometries. Optical designers are now exploring complex shapes that were previously unachievable. These shapes range from long radius toroids to freeform wavefront corrector plates. From a manufacturing point of view, interfacing between optical design programs, fabrication equipment, and metrology equipment often proves to be the most difficult part of the production process. The optical design must be translated into a tool path for the diamond turning lathe, and in some cases the design must be imported into the metrology software for surface comparison. The purpose of this report is to inform the reader about some of these manufacturing challenges using one specific example: a freeform phase plate that suppresses diffraction in an astronomical image and enhances searches for extrasolar planets around nearby stars. Designed by Johnan Codona and Roger Angel from the University of Arizona, this ZnSe lens has many ridges and valleys that have been optimized to reduce the 4 micron wavelength light observed from a nearby star to a level that makes planet detection possible. The phase plate had an aperture of 4.44mm and was placed on a 12.7mm diameter 4mm thick substrate. Surface feature size was approximately 2.5 micron peak-to-valley. In on-sky testing, the optic attenuated diffracted light from the star approximately 100 fold.

Interest in micro-optical components for applications ranging from telecommunications to life sciences has driven the need for accessible, low-cost fabrication techniques. Most micro-lens fabrication processes are unsuitable for applications requiring 100% fill factor, diameters around 1 mm, and scalability to large areas with millions of lenses. We report on a flexible, low-cost mold fabrication technique that utilizes a combination of milling and microforging. The technique involves first performing a rough cut with a ball-end mill. Final shape and sag height are then achieved by pressing a sphere of equal diameter into the milled divot. Using this process, we have fabricated molds for rectangular arrays of 1-10,000 lenses with apertures of 0.25-1.6 mm, sag heights of 3-130 &mgr;m, inter-lens spacings of 0.25-2 mm, and fill factors of 0-100%. Mold profiles have roughness and figure error of 68 nm and 354 nm, respectively, for 100% fill factor, 1 mm aperture lenses. The required forging force was modeled as a modified open-die forging process and experimentally verified to increase nearly linearly with surface area. The process is easily adapted to lenticular arrays. Limitations include milling machine range and accuracy.

This article deals with prediction of birefringence and changes in refractive index in polymer optical parts due to the injection molding process using finite element analysis. The simulation includes analysis of mold filling, packing and cooling as well as post-molding deformations (warpage). The geometry of a part and runner systems is represented by a 3D tetrahedral mesh. The material model includes non-linear viscoelasticity in the liquid (molten) and solid (frozen) domains. The simulation predicts the distribution of birefringence and refractive index over the part as well as integral retardance for light coming from an arbitrary direction. Verification experiments for PMMA and COP moldings show reasonable agreement with the numerical results.

Silicon targets as a single source for reactive magnetron sputtering provide a variety of advantages. The single-target approach offers, for example, the possibility to build very compact sputtering systems. The implementation of pulsed power results not only in non-arcing sputtering conditions but also in deposition of dense dielectric layers with smooth surfaces. Various film materials can be deposited simply by using different gases such as argon, as well as the reactive gases nitrogen and oxygen. In the visible range (380nm-780nm) silicon-oxides, silicon-nitrides and all kinds of siliconoxy- nitrides with a refractive index range of 1.44-2.05 can be used for many different optical thin film coatings. Pure silicon and silicon-sub-oxides with refractive indices up to 3.5 can be applied for coatings in the near infrared (NIR)/ infrared (IR)-region. High deposition rates of up to 2 nanometers per second, in combination with short pumping times of about 3-5 minutes, lead to extremely fast coating cycles. The machine concept and several possible applications, as for example Bragg mirrors and narrow band-pass filters in the NIR, will be presented. Anti-reflective coatings fabricated by this method have Vickers hardness values higher than 1000 HV and show superior scratch-resistance. Furthermore it is possible to produce Nd:YAG laser mirrors with high laser damage thresholds.

Optical systems often require compensation during operation to accommodate environmental and process changes. Compensation usually involves the movement of a lens element insitu. Different optomechanical designs are used to in order to meet the volume, optical and environmental systems requirements on a case by case basis. Two opto-mechanical designs are presented and compared. The performance and service requirements dictate the methodology used, including component design, flexure construction, actuation and control system. Included will be design constraints, prototype testing, manufacturing issues and implementation problems.

Polymer optical fibers replace the traditional communication media as copper and glass in short distance communication systems step by step, because of their economical and easy-manageable advantages. POFs are used in various fields of optical communication, e.g. the automotive sector or the in-house communication. The best available technologies are single mode communication systems. The use of only one wavelength for communication limits the bandwidth. For prospective scenarios, this traditional technology is the bottleneck of bandwidth, e.g. for HDTV with IP-TV. One solution to overcome this limitation is to use more than one wavelength over one single fiber, this is so-called WDM (wavelength division multiplexing). But this multiplexing technology requires two technical key-elements: a multiplexer, which combines the multi-wavelengths signals into one fiber and a demultiplexer at the end of the network to separate the colored signals. In this paper computer simulation of the design of several demultiplexer patterns will be shown. The following realization of the demultiplexer will be done using injection molding. This technology offers easy and very economical processing. These advantages make this technology the first choice for optical components in the low-cost array. All components, the dispersive units and focusing elements, can be fabricated by means of injection molding and microinjection molding.

This paper, presents a novel low-cost, compact, rugged, optical rotational sensor. The optical sensor is based on optical navigation technology, which measures changes in position by optically acquiring sequential surface images (frames) through a CCD array and mathematically determining direction and magnitude of angular displacement. Further the efficiency of the system was tested by placing the sensor 2mm above a circular disc; it was moved through a known angle. A stepper motor and a rotary stage were chosen as the references for providing the rotary motion. It was found that sensing larger radii which corresponds to a higher resolution, the scale factor of the displacement vector increased proportionally, thereby demonstrating good linearity. It was also observed that slower sensitivity (rotation rate) had a higher accuracy pointing to a trade off between frame rate and accuracy of measurement. The sensor has a resolution of 0.12° and a best accuracy of 99%.The sensor would find applications in Inertial Navigation systems and autonomous robots.

Paraboloidal mirror surfaces transform plane wavefronts into spherical ones and vice versa. This allows us to perform an interferometric measurement of its shape without the need of compensating optics or a CGH. From measurement's point of view there are good preconditions to manufacture high accuracy paraboloidal surfaces. On the other hand machining has to deal with the aspherical deviation to the best-fitting sphere. Depending on the amount of this deviation and the material of the mirror, different machining technologies are applied to bring the surface into paraboloidal shape. Off-axis paraboloids provide even more challenges in machining. There are two accepted approaches for manufacturing off-axis precision paraboloids. One way is to figure and polish a rotationally symmetric part with subsequent separating the off-axis elements from the parent paraboloid. On the other hand you can machine the single parts right from the start. In this case the surface is a kind of freeform. In this paper we discuss the manufacturing of on-axis and off-axis paraboloidal mirrors applying various methods.

Geometry and motions of double-sided machines are described. Expressions for the time evolution of part orbits about the laps are developed, and orbits charted.

In the 70's Leistner [1] demonstrated that PTFE (Teflon) coated substrates, when used instead of pitch coated substrates, have the ability to produce polished surfaces with low surface roughness (<2A°) and high flatness (<&lgr;/100). Their PTFE tool was made by painting and curing several layers of PTFE on a glass ceramic substrate, a time and labor intensive process. Over the years there has been an increase in the number of formats in which PTFE can be purchased. One such format is that of thin PTFE sheets with an adhesive backing. The potential of this user friendly PTFE format to replace pitch was investigated. A thin sheet of PTFE was adhered to metal substrate and used to polish a glass workpiece. Different polishing set-ups were investigated and the resulting surface finish measured. Best surface roughness values obtained on optical glass polished with an alumina based slurry was R_rms = 0.49nm (Zygo interferometer 50x). Under the same conditions a pitch tool produced a surface roughness value of R_rms >1.1 nm (Zygo interferometer 50x). The material removal rate with pitch tooling was approximately five times greater than that achieved using the PTFE sheet. While the results are not as good as that produced by Leistner, the work does illustrate the potential of an off the shelf PTFE sheet as a polishing pad. Should the entire process be further optimized lower surface roughness values should be obtainable.

The concept for polishing optical elements with a process called VIBE is presented. Application to non uniformly sloped optics such as aspheric shapes is detailed. Initial results on spherical surfaces are presented. A few technical challenges to be overcome are outlined.

Nano-sized particles with well defined geometries and size distributions suitable for polishing glass and glass ceramics are readily available. Understanding how effective these particles are at removing material and smoothening surfaces during pitch polishing processes is essential for process optimization and achieving better surfaces. This paper details work conducted to measure how effective sub-micron sized particles are at polishing and to isolate the influence of process chemistry and slurry density on the material removal rate (MRR). The paper also details how modifying the slurry pH affects the polishing coefficient of friction (CoF). Fused silica was polished on a synthetic pitch polishing tool with a range of different polishing slurries. Slurries tested included 40nm diameter ceria based slurries with varying density and pH, and both 20nm and 750nm diameter ceria based slurries with fixed density and pH values. Findings include that a) the material removal rate decreases with particle size and decreasing slurry density, b) the surface finish is not strongly dependent on particle size, c) slurries with a pH of 7 are most effective in removing material, while slurries with a pH value of 4 have the lowest MRR, and finally that d) the polishing CoF is greatest at pH 4 and lowest at pH 10. The results indicate that while process chemistry is very influential when polishing with submicron sized particles, the actual nature of the interaction between the abrasive, the workpiece and the tool requires further investigation.

Opticians have for years kept polishing pitch in electrified containers called "pitch pots" that keeps it in at an elevated temperature. The temperature is adjusted to achieve the desired pitch viscosity. When pitch is desired, the optician will remove the cover, reach into the pot and scoop out a glob of pitch with his hand. However, without thinking, most opticians will "fold over" or "push aside" the top layer of pitch to select pitch from deeper in the pot. This paper documents the change in temperature as the distance from the top surface increases. It also shows the effect of insulating the top cover.

LPI Precision Optics Ltd. in Hong Kong has successfully produced some very complex prototype freeform optics and mold inserts by using Nanotech 350- FG five axis diamond turning machine. One of such typical optics is an LED car head lamp, which consists of several non-symmetrical freeform surfaces. In order to make these surfaces, we have developed in-house special software which can combine 3D freeform surface with DT parameters to generate slow tool servo program for diamond turning. The software can generate program not only for single freeform surface or multiple freeform surfaces but also for freeform lens arrays. The produced freeform surfaces were measured by 3D interferometer and compared with the designed CAD models. The form deviation was around 5 um and the surface roughness was within 10 nm. Diamond milling was employed to fabricate more complicated multifaceted freeform surfaces. The milling program was optimized by means of UG software. Processing parameters and details are to be discussed in the paper.

The success of fabrication of optical coatings depends on a proper choice of a theoretical coating design and on the choice of monitoring strategy that provides low thickness errors for the chosen design. Software tools described in this presentation help an optical coating engineer to investigate a potential manufacturability of a given theoretical design when various monochromatic monitoring strategies are applied. This may help to reduce or even eliminate test deposition runs required for a successful coating fabrication.

Durable silicon–silicon nitride films have been created that exhibit low angle shift and reduced s and p polarization separation. The more common silicon dioxide – metal oxide films often have performance problems at large angles. They are inherently sensitive to angle of incidence and thus are prone to alignment issues and cone angle effects of the incident light. In contrast, silicon–silicon nitride films have much higher average optical indices and thus are ideal for applications were spectral form and placement are critical at large angles of incidence and when cone angle considerations are important. In addition, the difference in the spectral performance between the s and p polarizations is greatly reduced with silicon–silicon nitride films, offering more alignment flexibility when polarized sources are required. The silicon–silicon nitride films were found to be environmentally durable, and can be applied to a variety of substrates and substrate geometries, including plano, spherical domes, and complex parabolic surfaces.

A new photopolymer composite containing triazine monomer and photochromophore was explored as a holographic recording media that show color change after holographic recording. Photopolymer films prepared by mixing s-triazine (ST) methacrylic monomer, photochromic dye, aromatic acrylic monomer, binder polymer, and photo initiator were sensitive to a visible light and polymerized upon excitation with a visible laser light. The real-time diffraction efficiency was determined and correlated to the polymerization of the film. The diffraction efficiency in the presence of photochromophores was similar to that without them. After holographic recording to generate 3D image, an external light source was introduced to change the color of the recorded area. The color change from the 3D image was visible and reversible.

The current trend that calls for miniaturization of the optical components used in digital and cellular phone cameras will continue to play an important role. Aspherical lenses are taking on greater importance because a single asphere can be used to replace several spherical lenses and, thus, reduce the overall size and weight of the optics. At the same time, aspheres allow for an improved image quality and a higher resolution of the phone camera system.

Nowadays trends, which have the most pronounced impact on the development of new optical glasses, are miniaturization, noise reduction, the trend to increase optical performance of consumer optics and the requirement to be in accordance with nowadays environmental regulations or trends. This generates increasing demand for glasses with • high refractive index • low dispersion • improved transmittance in the UV-blue area • low glass temperature suitable for the mass production of precision molds • anomalous partial dispersion

The fast development of sensors with high sensitivity and growing pixel numbers for the IR range drives the development of suitable optical systems. This is enforced by the growing demands of the defense and security sector. JENOPTIK LASER, OPTIK, SYSTEME GmbH serves this market based on many years of experience. The product spectrum contains all usual types of optical components. Most of the typical IR transmitting and reflecting materials are machined. The quality scale reaches from medium to high-end, where the latter is mostly needed for defense applications. High-efficiency, highly durable and environmentally stable anti-reflection coatings for the complete spectrum of substrate materials are developed and produced in-house. JENOPTIK is developing and manufacturing custom-tailored lens systems and electro-optical modules for civil and military applications. This includes optical modules for IR cameras and for long range surveillance and target recognition, which fulfill the highest demands with respect to imaging quality, aperture, stray light, compactness, and durability. The testing and the verification of performance parameters include interferometrical testing, transmission, scattering, and MTF measurement at working temperature. A combination of design, manufacturing and measurement techniques is needed for the fabrication of IR lens systems meeting the highest performance requirements.

OptiPro Systems has developed a new finishing process for the manufacturing of precision optical components. UltraForm Finishing (UFF) has evolved from a tire shaped tool with polishing material on its periphery, to its newest design, which incorporates a precision rubber wheel wrapped with a band of polishing material passing over it. Through our research we have developed a user friendly graphical interface giving the optician a deterministic path for finishing precision optical components. Complex UFF Algorithms combine the removal function and desired depth of removal into a motion controlled tool path which minimizes surface roughness and form errors. The UFF process includes 5 axes of computer controlled motion, (3 linear and 2 rotary) which provide the flexibility for finishing a variety of shapes including spheres, aspheres, and freeform optics. The long arm extension, along with a range of diameters for the "UltraWheel" provides a unique solution for the finishing of steep concave shapes such as ogives and domes. The UltraForm process utilizes, fixed and loose abrasives, in combination with our proprietary "UltraBelts" made of a range of materials such as polyurethane, felt, resin, diamond and others.

The fabrication of different spherical and aspherical optical surfaces often presents various challenges. Additionally, the fabrication of freeform optics presents special and often unique challenges beyond standard rotationally symmetric components. Consequently, not all freeform optics can be manufactured utilizing standard methods. Diverse manufacturing techniques are necessary depending on part size, surface frequency content, surface slopes, and required materials. These techniques could include single point diamond machining using our slow slide servo technique, fast tool servo machining, raster fly-cutting, micro-milling, and freeform deterministic grinding. There is a recognized need in the industry to simplify and improve the production of aspheric and freeform optical surfaces. Recognizing this demand Moore Nanotechnology Systems has developed an innovative new software tool called NanoCAM™. This presentation will describe the latest advancements made at Moore Nanotechnology Systems to integrate the entire production cycle in one comprehensive software tool that can interact with all systems from optical design tools, to production machines as well as measurement equipment. NanoCAM™ solves the complex challenges involved with freeform machining, and the result is improved product quality, simplified processes, and enhanced performance. NanoCAM™ is designed to be used with the Nanotech 250UPL, Nanotech 450UPL, and Nanotech 350FG as well as the Nanotech Fast Tool Servo (NFTS-6000).

In the manufacturing business, there is one product that matters, money. Whether making shoelaces or aircraft carriers a business that doesn't also make a profit doesn't stay around long. Being able to predict operational expenses is critical to determining a product's sale price. Priced too high a product won't sell, too low profit goes away. In the business of precision optics manufacturing, predictability has been often impossible or had large error bars. Manufacturing unpredictability made setting price a challenge. What if predictability could improve by changing the polishing process? Would a predictable, deterministic process lead to profit? Optimax Systems has experienced exactly that. Incorporating Magnetorheological Finishing (MRF) into its finishing process, Optimax saw parts categorized financially as "high risk" become a routine product of higher quality, delivered on time and within budget. Using actual production figures, this presentation will show how much incorporating MRF reduced costs, improved output and increased quality all at the same time.

UCM-AG manufactures Ultrasonic Cleaning Machines for highest quality requirements. The company has the know-how for cleaning and supplies cleaning systems together with the cleaning process. With a UCM of Switzerland Cleaning System, the customer gets the system itself, the cleaning process with a guarantee for the specified result but also all auxiliary equipment needed for perfect results. Therefore UCM also supplies fixtures, linkage to existing automated fabrication facilities water treatment plants etc. Thus the UCM customer gets a turnkey installation – ready to operate and including know-how. UCM of Switzerland will describe the latest technology in ultrasonic precision cleaning on the example of a recent and sophisticated installation. The installation consists of three interlinked cleaning systems which operate completely automated. The 1st system is designed for pre-cleaning to remove waxes, pitch and protection lacquers with environmentally friendly solvents which are non hazardous to the health of the operators. The 2nd system cleans the parts prior to inspection and operates with neutral or slightly alkaline detergents. The 3rd system is designed for final cleaning prior to vacuum coating and perfect results are required. It combines cleaning tanks and DI-Water rinse with lift out and vacuum dryer. The installation combines the latest technologies in ultrasonic cleaning for precision optical components. The system employs multi frequency immersed ultrasonic transducers and special rinsing technologies The complete installation will be explained in detail; the concept in its whole, the lay out, the particular setup of each cleaning system etc. will be shown and explained together with construction particulars of the complete installation.

A new, comprehensive course of study in optical fabrication and testing has been created and is available to companies, schools, and individuals. It is aimed at aspiring and practicing precision opticians. The author is collaborating with OptiMax to further enhance presentations through animation and videography. Additional modules are being created. The need for such a course, and its goals and syllabus, are described.

We present experimental results for a low-coherence, dual-wavelength metrology system capable of measuring simultaneously both optical thickness and surface figure. The system measures optical thicknesses as thin as 12 microns to as wide as 12 mm with an accuracy of 0.1 microns. The current system scans at a resolution of 50 microns, which is limited by the spot-size of the measurement beam. We validate that SLCDI yields results in agreement with traditional interferometry and demonstrate its ability to measure aspheric “saddle” mirrors and complex three-dimensional surfaces.