This PDF file contains the front matter associated with SPIE Proceedings Volume 10315, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.

As optical components' shape becomes more complex, and requirements on the precision get tighter, new, and more versatile polishing processes are required. Conformal, free form or steep concave optics are important examples of optics that are difficult to finish using conventional techniques due to mechanical interferences and steep local slopes. One suitable way to polish such shapes is by using a jet of abrasive/fluid mixture. A fundamental property of a fluid jet is that it begins to lose its coherence as the jet exits a nozzle resulting in instability of the material removal rate, and is therefore unsuitable for deterministic finishing. A method of jet stabilization has been proposed, developed and demonstrated whereby the jet of magnetorheological fluid is magnetized by an axial magnetic field when it flows from the nozzle. It has been shown that a magnetically stabilized jet of MR polishing fluid generates a reproducible material removal function (polishing spot) at a distance of several tens of centimeters from the nozzle. The technology is most attractive for the finishing of complex shapes like free form optics, steep concaves and cavities. Results will be presented showing the ability to use this technique to finish a variety of optical components.

The paper deals with challenges, solutions and results obtained by JENOPTIK Laser.Optik.Systeme GmbH (JO L.O.S.) while contriving and transferring knowledge gained in the field of manufacturing and testing high-end spherical and plan surfaces into manufacturing of complex optical surface shapes. During the last two years notable progress was made in the field of manufacturing optical components with constantly changing curvature and lack of symmetry by linking selected manufacturing equipment and testing methods to each other. We will show present results reached in industrial manufacturing of complex surface shapes on an accepted level of expanse.

A novel hydrodynamic radial polishing tool (HyDRa) is presented. It performs corrective lapping and fine polishing of diverse materials by means of a low-cost abrasive flux and a hydrostatic suspension system that avoids contact of the tool with the working surface. With this tool it is currently possible to polish aspheres and free-form optics of up to 2.5 meters in diameter. It has the advantage of avoiding fallen edges during the polishing process as well as reducing tool wear out and deformation. The functioning principle is based on the generation of a high-velocity, high-pressure abrasive emulsion flux with radial geometry. The polishing process is repeatable and achieves high degrees of precision and accuracy on optical and semiconductor surfaces. An additional advantage of this new tool is the possibility to perform in-process interferometric measurements. Recent results of polished aspheres are discussed.

To realize the image quality of high end objectives, e. g. high NA microscope objectives working in the DUV spectral region the subgroups have to be manufactured with a mechanical precision which is difficult to achieve cost effectively. For high end microscope objectives the accuracy of the diameter of the lens mount must be within 1 µm, the run-out must be met within 1 µm and the distance of the lens vertex relative to the shoulder of the mount must fit within 1 µm. To realize the required precision, today various measurement techniques and production processes are used. Picking up the subgroups on different machining tools and measurement systems will loosen the accuracy. Here, we present the concept and the layout of a new manufacturing tool where we implemented the different measurement techniques in one CNC machining center.

JENOPTIK Laser, Optik, Systeme GmbH (JO L.O.S.) enlarged its product range in the field of cylinder lenses and crystal optics. These components are used in optical measuring technology and in various laser applications. The new cylinder components are a result of the state of the art manufacturing technology. For applications, where the quality of standard cylinders with a surface deviation of PV~Lambda/2 to ~Lambda/5 @632,8nm and tested with a reference glass only is not sufficient, the surface shape can be improved to PV Lambda/10 @632,8nm. The presentation deals with Jenoptik's current state to produce cylinder optics, to reduce remaining surface shape deviations of semi-finished cylinder optics and to test these elements. Based on in-house developed machinery, cylinders are manufactured by means of blocking or drum. The required surface quality in the range of PV~Lambda/10 @632,8nm for cylindrical lenses can be reached by computer aided correction using mrf-polishing techniques in connection with an interferometer test set-up. Therefore, the polishing machine is equipped with an additional axis of movement. The interferometer measurement of the residual surface deviation is done by Computer Generated Holograms (CGH), which are designed and manufactured in-house. CGHs from JO L.O.S. for testing cylindrical lenses can be custom designed starting with F#1.0. They are related to the typical rectangular geometry of cylinder components. Using these measurement techniques, testing is no longer the limiting factor in achieving high quality cylindrical surfaces. JO L.O.S. has all the capabilities of effective manufacturing, testing and correcting cylindrical lenses. Latest results achieved in series production are shown.

The Center of Optics Technology at the University of Applied Science, founded in 2003, is part of the School of Optics and Mechatronics. It completes the existing optical engineering department with a full optical fabrication and metrology chain and serves in parallel as a technology transfer center, to provide area industries with the most up-to-date technology in optical fabrication and engineering. Two examples of research work will be presented. The first example is the optimizing of the grinding process for high precision aspheres, the other is generating and polishing of a freeform optical element which is used as a phase plate.

The technical capabilities of LZOS allow optics manufacturing from the phase of melting and annealing of Astrositall® blanks to their final figuring. Nowadays LZOS is working on the several large contracts, among them are manufacturing of 96 hexagonal segment blanks of 1019 mm x 55 mm of Sitall CO-115M for the SALT (Southern African Large Telescope) primary segmented mirror, and 40 sub-mirrors of Zerodur® for the 6.7 m x 6 m segmented Mb mirror for the LAMOST (Large Sky Area Multi-Object Spectroscopic Telescope) project.

Magneto-Rheological Finishing (MRF®) was originally targeted at the portion of the optical component market that required ultra-high precision levels and/or challenging geometries, e.g., aspheres. While it has certainly shown significant capability and widespread adoption for both of these applications, many of the installed MRF machines are being used to finish plano and spherical optics in the medium (λ/4) to high (λ/10) precision range.

The optical fabrication industry is being pressured to reduce cost and it must respond. Lean Tools can be applied to drive efficiencies that help lower cost. Corning Tropel recently implemented a Lean program called 5S. Significant results were yielded that drove efficiency and enhanced process discipline. Revenue per square foot increased 60% by recovering 10,000sf of floor space and decreasing setup and cycle times.

A new compliant sub-aperture optical finishing technique is being investigated for the removal of mid-spatial frequency artifacts and smoothing of hard polycrystalline infrared ceramics for aspheric applications and conformal shaped optics. The UltraForm concept was developed by OptiPro Systems, Ontario, NY, and is a joint process development effort with the Center for Optics Manufacturing (COM). The UltraForm tool is a pressurized, elastomeric bladder in the shape of a toroid. Finishing pads are attached to the periphery, allowing the use of a wide variety of pad materials and abrasive selections. Experimentation has been conducted using both slurry mixes and fixed abrasive pads. The toroidal tool is rotated while the compliant tool is compressed into contact with the surface. Currently this process has specific interest for the finishing of conformal ALON domes. Also to be discussed will be new versions of the UltraForm Tool, which are currently being developed and tested.

We introduce various factors required for high-precision glass molding, and examples of optical element development, with explaining of the glass molding example by Toshiba Machine glass-molding machine.

We introduce the method of precisely grinding of axis-symmetric aspherical glass-molding dies by using a diamond wheel. Those show how to select vertical-grinding or slant-grinding, how to grind molds with high accuracy and actual grinding results.

Aerostatic spindles are used in precision grinding applications requiring high stiffness and very low error motions (5 to 25 nm). Forces generated during precision grinding are small and present challenges for accurate and reliable process monitoring. These challenges are met by incorporating non-contact displacement sensors into an aerostatic spindle that are calibrated to measure grinding forces from rotor motion. Four experiments compare this force-sensing approach to acoustic emission (AE) in detecting workpiece contact, process monitoring with small depths of cut, detecting workpiece defects, and evaluating abrasive wheel wear/loading. Results indicate that force measurements are preferable to acoustic emission in precision grinding since the force sensor offers improved contact sensitivity, higher resolution, and is capable of detecting events occurring within a single revolution of the grinding wheel.

Aspherical lenses or refractive elements out of optical glass can be produced either by grinding and polishing of glass or by precise molding of glass preforms. The first process is applied for lenses with larger geometries and smaller production quantities. On the other hand, precise molding is used for volume production of lenses within a diameter range between 1 mm and around 30 mm. The addressed products can be found in the consumer markets (digital imaging, digital projection and digital storage). Different preform types can be used for precise molding: polished spherical near shape preforms, polished balls, polished discs and precision gobs. The latter are made directly from the glass melt. This paper describes a newly developed process, which results in fire-polished gobs with very low surface roughness and excellent volume accuracy. Since precision gobs are mostly made for precise molding, they must meet specific process requirements apart form their optical values, such as allowing low molding temperatures and shorter process cycles times. Therefore, this paper also describes the latest results in the development of low Tg glasses, which are designed for the volume production of precision molded optical components. Beside the important parameters like nd, nd as well as Tg, other properties like chemical durability, devitrification resistance, thermal expansion and conductivity coefficients are important for optimizing the precise molding process. The characteristics of three new low Tg glasses in the FK-, PK- as well as SK-region are presented. These glasses are environmentally friendly, since they are free of lead and arsenic.

We describe the construction of elements of an optical materials property database. The database reports micromechanical properties (Young's modulus E, hardness H, fracture toughness Kc) for many optical glasses and crystals. Glass manufacturers included are Corning, Hoya, Schott, and Ohara. The materials included are many types of optical glasses and some optical crystals and polycrystals.

Have you ever wondered how those crazy lens designers come up with those impossible optical manufacturing tolerances? This talk will show one method that lens designers use to define and establish optical tolerances. An interferometric objective lens for testing surface figure will be used as an example to show the differences in tolerance requirements for two different design solutions. Monte Carlo tolerancing will also be explained and demonstrated.

The development of optical design and analysis tools in a CAD software can help to optimise the design, size and performance of tomorrow's consumer produtcs. While optics was still held back by software limitations, CAD programs were moving forward in leaps and bounds, improving manufacturing technologies and making it possible to design and produce highly innovative and sophisticated products. The problem was that in the past, 'traditional' optical design programs were only able to simulate spherical and aspherical lenses, meaning that the optical designers were limited to designing systems which were a series of imperfect lenses, each one correcting the last. That is why OPTIS has created the first optical design program to be fully integrated into a CAD program. The technology is available from OPTIS in an integrated SOLIDWORKS or CATIA V5 version. Users of this software can reduce the number of lenses needed in a system. Designers will now have access to complex surfaces such as NURBS meaning they will now be able to define free shape progressive lenses and even improve on optical performances using fewer lenses. This revolutionary technology will allow mechanical designers to work on optical systems and to shre information with optical designers for the first time. Previously not possible in a CAD program you may now determine all the optical performances of any optical system, providing first order and third order performances, sequential and non-sequential ray-tracing, wavefront surfaces, point spread function, MTF, spot-diagram, using real optical surfaces and guaranteeing the mechanical precision necessary for an optical system.

New manufacturing approaches for the fabrication of aspheres has increased opportunities for using aspheres in a wider range of optical systems. If manufacturability is considered early in the optical design process, the short and long term costs of the aspheric surface can be greatly reduced without sacrificing performance. The optical designer must learn how to select optimum materials for aspheres. Using non-staining glasses, higher index glass types, and softer glass types can help reduce production costs. If the optical designer understands what range of aspheric surfaces can be manufactured, they can constrain the aspheric surface during optimization. The steepness of the aspheric departure (the slope of the aspheric departure) often has a larger impact on manufacturing difficulty than the amplitude of the asphere or the steepness of the base radius. Tolerancing can increase the difficulty without measurably improving optical performance. Finally, the asphere can be designed for ease of metrology. Understanding the options that are available for aspheric metrology will allow the engineer to control tooling and fixturing that is required for testing.

Subaperture stitching is a well-known technique for extending the effective aperture range of phase measuring interferometers. In the past, stitching has successfully been applied to improve the lateral coverage and/or resolution of plano interferometers (including interference microscopes). More recently, QED Technologies has developed a subaperture stitching interferometer (SSI®) for automatic stitching of spherical surfaces, including hemispheres. But stitching can also extend the amount of aspheric departure that can be measured in a non-null test. Conventional interferometers have some capability to measure mild aspheric surfaces without null correction. The interference fringe resolution of the camera limits the asphericity that can be measured, while the difficulty in inferring the surface form from the measured phase degrades accuracy. Therefore, commercially available interferometers can only measure a few micrometers of fourth-order aspheric departure. Furthermore, standard measurement software does not compensate for the aspheric shape or for the interferometer imaging errors present in a non-null measurement. As a result, non-null aspheric measurements are more difficult, and less accurate, than a spherical null test. Examples are presented in this paper that illustrate these issues. Subaperture stitching can extend the testable aspheric departure of a non-null test. This has been demonstrated in the past on annular zones of near-null data. We present a more generally applicable and robust method of stitching non-null phase data, which can provide better accuracy and increased testable aspheric departure over an unstitched test.

Magnetorheological finishing (MRF®) is a deterministic polishing process. Typically, an MRF polishing cycle is used to improve the figure of an optical surface (e.g. reduce the irregularity of a spherical surface to λ/20 PV). The hitmap for this process is based off of a surface (reflection) measurement. However, because MRF polishing is a subaperture process, it is not limited to producing perfectly flat or perfectly spherical surfaces. Indeed, the polishing process can converge to any desired surface shape. This is a particularly useful, enabling feature that can be used to perform transmitted wavefront corrections. One method to produce a perfect transmitted wavefront is to polish perfect surfaces throughout the system, which assumes perfect material homogeneity. In some instances, this can also be accomplished by measuring the transmitted wavefront of an imperfect system, and correcting it by polishing a compensating surface shape into a single surface. By correcting transmitted wavefront data, rather than a surface measurement, this can be a fairly straightforward process. This process can correct for material inhomogeneities, improve system tolerances, and correct prism angles. This paper will begin by giving an overview of transmitted wavefront tests. It will explain how this data can be used to perform a correction by an MRF polishing cycle. Finally, we present some results from corrections of optical systems such as laser rods and prisms.

Current trends in the industry require the need for high volume precision optical assemblies coupled with certifiable 100% Modulation Transfer Function (MTF) inline testing. This is especially true in the highly competitive automotive and cellular phone / PDA markets. This necessity has been particularly problematic for MTF metrology, which is traditionally an expensive and slow endeavor reserved for cost-insensitive low-volume projects. A concept is examined for calculating the MTF of a lens based on its edge response. The edge is tilted with respect to the scanning axis in order to avoid issues stemming from the sampling limit of the detector. This enables us to characterize a large number of field points simultaneously, which greatly increases the MTF measurement speed. The results of the experiments and the noise analysis seem consistent, indicating that this method can be expected to produce less than 4% RMS error within the established operating range. An instrument for MTF analysis has been developed that strikes a reasonable balance between accuracy, throughput, and cost, thus making it practical for a large-volume production quality control environment.

A variety of consumer applications, eg cellphone camera lenses, optical storage devices, digital cameras, etc, are driving the demand for small, high aspheric departure rotationally-symmetric moulded optics, manufactured both in polymer and glass materials. The mould tools for such components are manufactured by ultra-high precision techniques such as single point diamond turning and ultra-precision grinding, and must be accurate to <1/10μm levels for form, and exhibit nanometric surface finish quality. The aspheric forms of such components’ optical surfaces exhibit high departure from best-fit sphere towards their outer edge, which renders this outer region especially critical for optical performance. The high slope of these components at the clear aperture has caused some restrictions on the use of profilometry in the measurement of form across their full diameter. Taylor Hobson designs and manufactures a range of ultra-precision profilometers for use in such industries as aspheric optics fabrication. In order to address the issues described, a new measurement system, Taylor Hobson Form Talysurf PGI 1250, has been developed, which contains new Aspheric Data Fusion Software, as well as Asphero-Diffractive Analysis Software, allowing the entire diametric profile to be analysed to the desired level of accuracy. This development removes the previous limitation of maximum slope for this type of measurement, thus enabling better quality control of high slope, high aspheric departure optics. Measurement data from the Form Talysurf PGI 1250 can be fed back directly to the machine tool, in order to optimize the form of the optical mould.

The LINOS Photonics company has developed a new tactile sensor to measure aspheric surfaces. The sensing device drives along spherical coordinates and the measuring data of a level curve is obtained by the rotation of the lens. The complete asphere of the lens is reconstructed by a number of such level curves. All data is given in a spherical coordinate system. The company provides a software to determine the error between the actual surface and a reference asphere with respect to a cartesian coordinate system. But the algorithm depends on the strong assumption that the peak of the reconstructed asphere is equal to the rotational point of the measuring instrument. Our algorithm expands the existing method. We minimize the distance of the reference asphere to the measuring points in a cartesian coordinate system. To do this, we calculate the optimal rotation and translation of the reference asphere to the measured points. This defines a non-linear optimization problem, which is solved with algorithm of Levenberg and Marquardt. Furthermore, we are able to calculate the Jacobi matrix with respect to the rotation center. The output of the proposed algorithms contains the maximal deviation for each measuring point in z-direction and the variance of the error. Additionally, we determine a pseudo tangential deviation between the reference and the actual geometry by a secant method. Altogether the new algorithm enables us to deliver comparable results for the asphere measuring problem.

In this paper, we suggest a polishing head with a mechanical gimbals-like structure for the optics fabrication. In the small tool polishing processes, several types of polishing mechanism have been tried to get more deterministic and high efficient optical fabrication. The conventional polishing processes to use the contacting pad material of polyurethane or pitch need the higher polishing rate to shorten the overall polishing time for large optics. Therefore, new polishing head mechanism is designed to use the air backpressure and gimbals-like hinge structure to increase polishing velocity. In the following experiment, mechanical adaptability was confirmed both on the flat glass and the convex aluminum surface.

The microlens array is often used for increasing coupling efficiency in vertical cavity surface emitting lasers (VCSELs) to fiber coupling system. Among the various methods to couple VCSEL module with microlenses, a monolithic lithography integration is regarded as better candidate because the process is simple and suitable for mass production. In addition, one can avoid additional assembly process. In the present study, a microlens array with a lens diameter of 40mm and focal length of 150mm was designed to couple a single mode VCSEL array and optical fibers, and tolerance analysis was carried out. A microlens array for VCSEL to fiber coupling was integrated by a UV-transparent mold and a monolithic lithography integration system which utilizes micro UV-molding. Finally, the geometrical properties of the integrated microlens array and the insertion loss of VCSEL to fiber coupling was measured and analyzed.

The output power of high power He-Ne laser with flat discharge tube can be doubled in comparison to the traditional one with same discharge length. For example, the output power of this He-Ne laser of 1.4 meter long can be above 130 mW. This paper introduces and discusses briefly some key technical problems of this laser, including manufacture of flat glass tube and design of the adjustable structure of laser tube.

A new generation of compliant tools and processes called UltraForm Finishing is under development at the Center for Optics Manufacturing (COM) and OptiPro Systems (Ontario, NY). The purpose is to achieve rapid, high quality finishing of hard materials. These compliant tools exhibit a large contact patch that can be up to 1 cm wide. A numerical model was developed to account for finite contact patch geometry on removal for a flat rotating axisymmetric workpiece. This model was used to determine the depth of removal as a function of radial position after the polishing tool has completely traversed the workpiece from its center to a given radial position. The depth of removal was investigated for circular and oval contact patches and a variety of removal functions. A constant removal depth is desired to minimize the induced figure error. Predicted results were compared to experimental measurements of induced figure error.

The Fabrication of Affordable Aspheric Mirrors by Electroforming (FAAME) program seeks to lower the cost of aspheric mirrors by developing electroforming processes suitable for optical-quality electroforms. To achieve this goal, two major areas of improvement were pursued: optimizing the electroforming process and utilizing a multi-generational approach. To improve the process, we studied electroforming variables, identifying key factors that affect an electroform's optical quality. Once the factors were identified, the electroforming process was refined, producing mirrors that met the quality goal of 1/4 wave in the infrared. We drew all of this experience together to demonstrate replication of a wildly aspheric mirror for use in a Trans-Atmospheric Interceptor (TAI).

LZOS is manufacturing the M3 Mirror flat surface for the GRANTECAN Project. The Mirror has an elliptical configuration and axial dimensions of 1521mm x 1073mm. The results of the M3 Mirror figuring and final polishing, testing in the Ritchey-Common layout at two 30° and 60° angles of incidence of a principal ray are presented in the manuscript.

Nowadays LZOS is carrying out work on the manufacturing of the M1 Mirror and M2 Mirror for the VISTA project (Visible and Infrared Survey Telescope for Astronomy) with the 4100mm diameter primary hyperbolic mirror with asphericity about 800 microns and the 1241mm diameter secondary hyperbolic mirror with asphericity about 350 microns. The current status of the work carried out is presented in the manuscript.

Contact mechanics was investigated for compliant tools being developed for UltraForm Finishing. Hertz contact theory predictions were compared with experimental measurements. A high speed camera was used to investigate the size and consistency of the contact spots. The contact pressure distributions were measured with a Tekscan tactile grid system. Preston's equation was used to derive a relation between the pressure distributions and the corresponding removal spots. Experimental results were used to estimate Preston's coefficient for this process.

Double-sided lapping and polishing (DSL) utilizes planetary action with the combination of a top and bottom plate to precisely grind and polish precision, parallel optics. This process is performed primarily with loose abrasive with the parts held in geared carriers (workpiece holders), which glide between a set of flat plates continually changing direction of rotation. Due to the nature of the process it is relatively stress-free in that it induces minimal thermal distortion making it compatible with most optical materials.

The indentation micro-mechanical response of Silicon and CaF₂ are studied and compared by using 3D finite element simulation. The effects of elastic anisotropy and crystallographic symmetry on contact profile, indentation modulus, and dislocation nucleation underneath a spherical indenter are investigated.

EUV lithography promises large gains in resolution as a result of the extremely short wavelength. However, the requirement of aspherical off-axis mirrors dramatically increases the challenge of the optics manufacture relative to refractive designs. For example, because of the short wavelength of only 13.5 nm, a homogenous roughness and RMS values of 2 angstroms and below are necessary for sufficient throughput and high uniformity on these parts, and these specifications can only be achieved obtained through complex polishing processes. Because of these exacting microroughness requirements, fabrication technology is being driven to the exploration of new areas. An example of one of these new technology areas involves the use of nanocrystalline cerium oxide made using a patented plasma arc process that produces particles with very well defined physical properties. Because of the unique manufacturing process, these particles have highly controlled surface chemistry which results in the ability to prepare extremely stable dispersions in water. As such, these dispersion are useful in a variety of polishing processes where a small particle and a tightly controlled particle size distribution are required to access increasingly stringent surface roughness requirements. Carl Zeiss SMT has evaluated a number of cerium oxide slurries manufactured by Nanophase Technologies Corporation for improving polishing processes. The objective was to obtain reproducible low roughness values over a wide range of spatial frequencies. Results show that a significant improvement of the surface roughness was achieved with Nanophase ceria slurry CE-6068 in all spatial frequencies.

Our goal is to better understand the effects of glass mechanical properties, such as hardness, Young's modulus and fracture toughness, on the material removal rate during polishing. We have focused on eleven types of commercial Ohara optical glasses that cover the entire spectrum of the glass table. Conventional polishing experiments were performed to study the correlation between the process parameters (i.e., polishing pad, nominal load and slurry particle size) to the material removal rate and surface roughness. The results demonstrate how a material figure of merit affects the glass material removal rate. We review past results acquired at the Center for Optics Manufacturing as well as the work of others. The data presented demonstrate the controllability of the polishing process based on the known mechanical properties of any glass material.

We present power spectral density (PSD) data measured inside magnetorheological finishing (MRF) spots in orthogonal directions. MRF spots exhibit a distinct grooving pattern that varies for each fluid/material combination. This spot analysis may provide new insights on the material removal process. Issues associated with taking orthogonal PSD measurements are also discussed.

Phase retrieval can be useful in the measurement of optical surfaces and systems. It distinguishes itself through the simplicity of the experimental apparatus, just a detector array which collects light near a focal plane. Aspherics can be measured without null optics. The challenging part of the method is the estimation of the wavefront from the near-focus intensity measurements to reconstruct the wavefront.

The polarization sensitive optical coherence tomography (OCT) system provides useful informations about the biological tissues. The exact tissue parameters measurement and comparison predicts about the malignant and normal tissues. The degree of polarization changes with the depth of tissue samples. We have established the analytical modeling with Jones-Mueller matrix for imaging technique, which experimentally extract the birefringence, depolarization, absorption and scattering information of tissues. The Jones matrix of thermally treated porcine tendon showed a reduction of birefringence from thermal damage. The Jones matrices of porcine skin and bovine cartilage also revealed that the density and orientation of the collagen fibers in porcine skin and bovine cartilage are not distributed as uniformly as in porcine tendon. Birefringence is sensitive to changes in tissue because it is based on phase contrast.

The measurement of radius of curvature through the use of an interferometer can be a very accurate way to understand the properties of an optical surface. This process is completed by observing the distance between the cat's eye and confocal points of an optical piece. This type of measurement process, however, can include a number of errors if not executed properly. This paper presents and explains the major sources of mechanical errors that exist for radius of curvature measurements. The major mechanical errors that may occur are Abbe, cosine, and null cavity error. These errors are presented in a fashion such that they may be easily understood by someone who may not have an extensive optics background. Also, some techniques to test for and assess these errors will be displayed. In order to make extremely accurate measurements, on the order of a nanometer, one must greatly diminish the mechanical errors of a system before examining the effects of environmental errors.

Magnetorheological Finishing (MRF) offers an effective way for correcting transmitted wavefront of lenses. Traditional feedback based methods of polishing and testing a lens until it is tolerance made direct correction of transmitted wavefront difficult if not impossible. Being a feedforward, deterministic process, MRF makes direct targeting and correction of transmitted wavefront possible. The lens must have low spherical aberration, and full aperture metrology is required. The metrology will show the sum of all errors, and all errors are corrected simultaneously by fixing deterministically the transmitted wavefront. Optimax Systems uses this MRF process to correct aspheric lenses in transmission to subwavelength errors.

Optical surfaces are routinely measured using phase-shifting interferometry. The fringe imaging and other interferometer optics introduce distortion into the measurements. Distortion causes a change in magnification as a function of field position, and is often not quantified and calibrated during measurements of optical surfaces. When calculating the figure of an optical surface, systematic errors such as distortion will ultimately limit the accuracy of the measurement. We present a method for improving the accuracy in interferometric measurements using subaperture stitching interferometry. QED's Subaperture Stitching Interferometer (SSI®) is a six-axis computer-controlled workstation that incorporates a standard Fizeau interferometer with our own stitching algorithms. The SSI is a commercially available product that automatically performs inline calibration of systematic errors such as reference wave and distortion. By measuring an optical surface in multiple orientations both on and off-axis, our stitching algorithms are shown to have the ability to measure the distortion (and other systematic errors) in an interferometer, and compensate for these errors automatically. Using the compensators obtained from stitched measurements, distortion values are calculated and plots are shown for several different transmission optics. Theoretical simulations displaying the effects of distortion on surface metrology are shown. Measurements are taken with and without distortion compensators, and the residual difference is analyzed.

Results of a series of single sided lapping experiments designed to develop appropriate conditioning methods for 3M Trizact Diamond Tile fixed abrasives are reported. Trizact™ Diamond Tile is a structured fixed abrasive lapping technology developed by 3M. The Trizact™ Diamond Tile structured abrasive pad consists of an organic (polymeric binder)–inorganic (abrasive mineral, i.e., diamond) composite that is used with a water-based coolant. The effect of platen and conditioner speed on pad wear will be explored for a roller yoke single-side lapping machine. Pad break-in conditioning was studied in detail for a 6 micron Trizact™ Diamond Tile abrasive used to lap soda-lime glass.

Micro aspherical glass lenses are required for electronic devices, optical devices and advanced optical fiber transmission equipments. The glass lenses are manufactured by glass molding method by using micro ceramics dies such as tungsten carbide or silicon carbide (1). Therefore molding dies are most important and they were ground by ultra-precision grinding method with diamond wheel. Recently, the wavelength of used laser is becoming shorter and then the accuracies of the micro molding die are required to be much more precise (2). In this paper, ultrasonic assisted polishing methods/systems were developed in order to finish micro aspherical dies that were ground with micro diamond wheel. In the polishing experiments, the molding die of tungsten carbide was polished with diamond abrasives to test the basic polishing characteristics and the aspheric die was polished with proposed ultrasonic assisted polishing method.