bluuebunny/crossref_metadata_2025 huggingface dataset:
Absolute Measurement of Spherical Surfaces
Authors: Creath Katherine , Wyant James C.
Published: February 2023

The absolute measurement of spherical surfaces is important with optics specified to be less than 1/20 of a wavelength peak-to-valley. A number of techniques have been described in the literature.1-5 A technique widely used with phase-measuring interferometry was first described by Jensen,2 and then further discussed by Bruning,3 Truax,4 and Elssner et al.5 This technique has the advantage of giving the absolute shape of the sphere under test independent of the reference surface and diverger optics as long as the test surface is aligned correctly. The main disadvantage of this technique is the requirement that the test surface be aligned so that it can be rotated and keep the fringe pattern unchanged. A simpler technique has been developed which does not require this precise alignment and requires only two measurements. The result is not exactly an absolute measurement, but as long as the test surface has even symmetry, the test can be absolute. This paper will discuss this new technique and compare it to Jensen's technique.
Optical Shop Specifications
Authors: Walsh Kenneth F.
Published: February 2023

This tutorial will explore the process of establishing the specifications for optical components. It is intended to help the Optical Shop Supervisor or Process Engineer gain a better understanding of the reasons behind the specifications sent to the shop by the designers. The factors considered by the Optical Designer and Engineer in selecting materials, finishes, and tolerances, as well as the consequence of excessive variance from specification.
Replicated Mirrors for High Fluence Laser Application
Authors: Novaro Marc , Berger Michel , Floch Hervé , Roussel André
Published: February 2023

Molded metallic mirrors manufactured by the so-called Optic-Replication Technique (ORT) are developed since a quite long time (ref 1-2-3) for various applications. Such mirrors are particularly attractive when attempt are made to consider large number of identical components associated with a low cost investment.
Fabrication of the first pair of optics for the Advanced X-ray Astrophysics Facility (AXAF)
Authors: Reid P. B. , Gordon T. E. , Magida M. B.
Published: February 2023

The first two mirrors for the Advanced X-Ray Astrophysics Facility (AXAF) have been successfully fabricated and tested. We have demonstrated figure convergence rates previously unseen on large precision optics. These results were based on developing a unified systems approach to fabrication and testing aided by the extensive use of analytical models. This paper presents a summary of the optic requirements, the fabrication process, metrology used, and results.
Correction of Short Spatial Wavelength Errors Using Ion Beam Figuring
Authors: Allen Lynn N.
Published: February 2023

Considerable interest exists for correcting spatial wavelength surface figure errors on the order of 1 to 2 cm on large and small optical elements. These errors can result from conventional processes that cause print-through (i.e. optical quilting) on lightweighted optics, severe zonal or rolled edges on non-symmetric geometries, or short wavelength errors on small optics. Ion beam figuring, which is extremely efficient for correcting low-order aberrations, has also been utilized to correct these errors. Several examples of this capability will be presented.
Advanced Optically Black Baffles
Authors: Seals Roland D.
Published: February 2023

Baffles in optical systems are internal surfaces that control or suppress stray radiation, typically using geometrically designed vanes and surface morphology. Baffles perform a major role in determining the signal-to-noise level of many optical systems. While a few commercially available baffle materials meet optical requirments, current industrial baffle materials do not meet survivability and endurability needs; i.e, thermal, mechanical, and chemical stability requirements. The major problem is the generation of particles from the baffle surfaces during transport and operation which degrade the image quality.
Challenges for the U.S. Precision Optics Industry
Authors: Trotta Patrick A.
Published: February 2023

The U.S. optics industry is in a period of challenges. The challenges are not driven by optics technology, but by external factors such as government, regulation, quality and standards issues, and restructuring of the workplace and the market.
Optical Fabrication Laboratory: Introductory Training for Optical Engineering Students
Authors: Jacobs S. D. , Kubath K. , Maltsev A.
Published: February 2023

Students in the BS and MS programs at The Institute of Optics may elect to take a one-semester laboratory course, taught by a master optician, which introduces them to optical glasses and the classical techniques for fabricating optical components. Over the past few years, several projects and new pieces of testing equipment have been added to the laboratory in order to expose optical engineering students to modern fabrication issues not previously covered. Students now investigate subjects such as glass melting and forming, the evolution of stress-birefringence during annealing, the relationship between a glass type's optical properties and its ease of fabrication, the estimation and measurement of subsurface damage, and new instruments for determining the figure and smoothness of finished parts. This paper describes some of the projects in the laboratory and gives examples of results generated by the students during the 12 three-hour laboratory sessions held weekly throughout the semester.
A Method for Polishing SPDT Aspheric Surfaces
Authors: Parks Robert E.
Published: February 2023

Single point diamond turning is a cost effective method of making aspheric optics for use in the infrared. Because the technique leaves fine grooves or tool marks in the surface of the turned part, diamond turned aspherics are not generally suited for use in the visible spectral region without post polishing of the turned surface. If this polishing is not done the surface exhibits a rainbow-like scattering that is objectionable in the final optical system.
“Snap Together” Directed Energy Threat Protection System
Authors: Rajic S. , Elnicki M.E. , Chen W. , Maxey L.C. , Rogers J.E.
Published: February 2023

In recent years the American military has gained an appreciation for the global directed energy threat. While an elegant solution to the agile spectral threats will likely become available around the turn of the millennium, a practical near term solution is needed. A system employing a penetrable mirror can fulfill the requirements for both broadband spectral protection and near term availability. Typically a very stringent requirement for directed energy protection systems is a tightly focused spot size. This requirement necessitates precision manual alignment which can be negated with the use of a snap together design.
Center for Optics Manufacturing Overview
Authors: Pollicove Harvey M. , Moore Duncan T.
Published: February 2023

The Center for Optics Manufacturing (COM), established at the University of Rochester's Institute of Optics, is a strategic collaboration of APOMA (American Precision Optics Manufacturers Association), several academic institutions (Arizona, Central Florida and Rochester), and the U.S. Army Materiel Command. This focused cooperative alliance is forging the optics industry's course for modernization and continuous improvement through original development programs that will determine the next generation of optics manufacturing technology.
Lens Blocking Method for Opticam
Authors: Novak Robert , Marro Marlene , Tipps Joe D. , Czajkowski Walter , DeMarco JoAnn , Salamon Peter A. , Matchett David , LeBlanc Glenn
Published: February 2023

A UV-curing 'cold' blocking adhesive has been developed by Loctite Corporation for use with the Opticam SM. The adhesive is a significant advance in the lens blocking process, as it eliminates heat-induced blocking strain; the most significant problem encountered with current hot pitch blocking methods. The new cold blocking adhesive is complemented by a new Kennametal lens blocking adapter tool and chucking system. The tooling offers substantially improved alignment and transfer between the lens adapter and machine; at considerably lower cost. The lenses are deblocked in heated water and detergent solution, eliminating the environmental concerns of the current method.
"Removing the 'Islands of Technology' in Optical Manufacturing"
Authors: Czajkowski Walter
Published: February 2023

Many of today's optical manufacturing processes and technologies remain isolated islands, insulated from many of the concepts of computer integrated manufacturing. The benefits derived from applying the principles of concurrent engineering and CIM into the optical design and manufacturing communities will be explored.
"Eliminating the Barriers Between (Optical) Design and Manufacturing"
Authors: Tipps Joe D.
Published: February 2023

Many benefits are derived from linking the design and manufacturing disciplines together. The benefits include reduced time to market, lower unit manufacturing cost and improved product quality. However, in most optical shops a wall still remains between design and manufacturing.
Calculation of wavefront aberration coefficients for non-circular or obscured pupils
Authors: Selberg Lars A.
Published: February 2023

Optical designers sometimes find it desirable to specify the performance of an optical system or its components in terms of the specific wave aberrations. The calculations for these aberrations from interferometric data typically use the Zernike polynomials which are defined over a circular pupil with no obscurations. When confronted with a part for which the clear aperture is elliptical or rectangular or has a central obscuration, this type of specification must be examined more closely on two counts. First, what is the legitimate interpretation of such a specification when used for such a pupil? Second, when measuring the part, how is the aberration coefficient to be calculated so as to be repeatable?
Harmonic Phase Shifting Interferometry
Authors: Saxer Christopher , Moore Duncan T.
Published: February 2023

The technique of harmonic phase shifting interferometry (PSI), originally developed by Joseph Miceli in 19821, is a quasi-heterodyne method to continuously measure the optical phase of a point in an interferogram. The optical phase of the interferometer reference arm is modulated with the sum of prescribed amplitudes of a sine wave and its second harmonic. The interference phase at the detector is directly related to the electrical phase of the detected signal's fundamental frequency component. Harmonic phase-shifting interferometry may be executed by using a piezoelectric transducer (PZT) to shift the reference surface of the interferometer and a lock-in amplifier to measure the phase of the detected signal. Phase measurements may be made with peak reference arm phase changes less than 3λ/4, where λ is the wavelength of the light source, using either polarized or unpolarized light. This technique is best suited to single point measurements and line scans of interference patterns since each detector produces a continuous signal from which the interference phase must be extracted.
Polished Substrate Surface and Cleaning Study for Coated Optic Quality*
Authors: Tesar A. , Eickelberg W. , Koons K. , Davis K.
Published: February 2023

The optical substrate-coating interface is established by (1) the original polished condition of the substrate; (2) the substrate cleaning process; and (3) the environment of the coating process. The substrate-coating interface affects the coating adhesion properties, is where most coating defects and scatter sites are thought to initiate, and in some instances may control the structure of the coating as it is deposited. Often features appear on an optic after coating which could not be observed after cleaning and prior to coating. Because of the wide variety of possible substrate materials, surface problems, and contaminants, cleaning processes are constantly evolving. Our study has clearly shown that the coating appearance is dependent not only on the cleaning method, but especially on the initial character of the substrate surface.
Machine Vision System for Measuring Subsurface Damage
Authors: Greivenkamp John E. , Chang Matthew T.
Published: February 2023

The dimpling technique is widely used to measure subsurface damage SSD. The ground surface is first acid etched to open up the fractures. A dimple is polished into the surface by a sphere of a known diameter, and the diameters of the circular zones with and without visible subsurface fractures are measured to determined the damage depth. The measuring system consists of a microscope with a reticule and a linear translation stage. The diameters of the various zones are visually interpreted and measured. The dimpling technique provides a direct measurement of SSD, as opposed to other techniques where the SSD is implied from other properties such as scattering. The manual measurements associated with this technique are tedious and requires a trained operator to identify the deepest fracture.
Computer Controlled Small Tool Polishing
Authors: Baumler Mark
Published: February 2023

In 1991 an existing 2.5 meter gantry polishing machine was modified to provide the necessary motions and control for Computer Controlled Small Tool Polishing (CCSTP). Five axes of Computer Numerical Control motion are used to correctly position the polishing tool on the optical surface with a maximum slope of 30 degrees. Combined with a 2-axis polishing spindle, Eastman Kodak has integrated 7-axis of motion to increase the flexibility of its polishing process. The 2-axis polishing spindle provides controlled pad pointing and a high speed orbital motion. The capabilities of the machine and some actual optical figuring results from the CCSTP process will be discussed.
Benefits of the ISO 10110 Optical Drawing Standard
Authors: Parks Robert E.
Published: February 2023

The greater breadth and explicitness of the ISO 10110 optical drawing standard allows more optically pertinent parameters to be shown on drawings than was previously possible.
Mechanical Properties of Bronze/Diamond Bound Abrasive Materials: Models and Experiments
Authors: Zhou Yi-Yang , Funkenbusch Paul , Gracewski Sheryl , Lambropoulos John
Published: February 2023

The thermomechanical properties of abrasive materials may have a significant effect on the mode of material removal during deterministic microgrinding, as well as on the amount of material removed. For example, Izumitani [1986] has shown that the polishing rate of glass has a strong dependence on the hardness of the abrasive particles via the abrasive particle sintering temperature, and that, for a given glass, there is a polishing agent that maximizes the material removal rate via the dependence of the polishing rate on the creep compliance of the optical polishing agent.
Coolant Performance in Bound Diamond Ring Tool Grinding of K7 Optical Glass
Authors: Puchebner B. E. , Feltz A. , Ng W. , Jacobs S.D.
Published: February 2023

There are a number of commercial coolants available to the metal cutting industry. These coolants have been optimized for the various properties of specific metal types, and instructions are available for their use [1,2]. Recently, coolants advertised to be designed especially for the optical industry have become available. A grinding study to evaluate the performance of several metal and glass grinding coolants is being conducted at the Center for Optics Manufacturing. This paper presents some recent results for K7 optical glass.
Electrolytic In-process Dressing (ELID) on the Opticam PM
Authors: Lindquist Arne , Golini Don
Published: February 2023

Typical fabrication of optical glass prisms involves a number of shaping, lapping, and polishing steps done in an iterative process. Initial rough shaping is usually performed with diamond saws (molded blanks for high volume). Processing to near net shape generally involves using bound diamond surface grinders and specialized tooling, with numerous blocking steps needed to complete all facets. Loose abrasive lapping or additional stages of finer surface grinding are required to prepare the prism blank for polishing, particularly to meet specifications for precise angular requirements. Difficult tolerances usually necessitate final finishing of one or more prism facets prior to near net shaping of the remaining facets. This introduces problems associated with protecting the finished optical surfaces from damage or staining.
The Scanning Force Microscope as a Tool for Studying Optical Surfaces
Authors: Bennett Jean M. , Jahanmir Jay , Podlesny John C. , Balter Tami L. , Hobbs Daniel T.
Published: February 2023

Traditional instruments that have been used to study optical surfaces include the Nomarski microscope, various types of optical and mechanical profilers, scanning electron microscope, and transmission electron microscope. Although most of these instruments are sensitive to very small height variations, they have limited lateral resolution. Hence, features such as tiny scratches, closely spaced structure of metal and dielectric films, tiny laser damage craters, and impact craters from space debris cannot be seen by the traditional surface characterization instruments. With the advent of the scanning tunneling microscope in 1982 followed by a variety of scanning probe microscopes, new characterization tools have become available for studying optical surfaces. The scanning tunneling microscope has limited usefulness since it requires that the sample surface be conducting. Most optical samples and their multilayer film coatings are insulating. Even metals such as aluminum, copper, silicon, beryllium, and molybdenum, all of which have optical applications, are covered with layers of native oxide, making them nonconductive. Fortunately the scanning force microscope (SFM), formerly called the atomic force microscope (AFM), is ideally suited for studying optical surfaces.1 It uses a pyramidal silicon nitride probe with a tip radius ~400 Å, which contacts the surface with very light loading, approximately 1000 times smaller than the loading used with the highest performance commercial mechanical profilers. Under suitable conditions, the SFM can show structure on high quality optical surfaces that has rms heights down to the subangstrom level and lateral dimensions of a few tens of angstroms. The SFM can resolve lateral dimensions ~1000 times smaller than those resolved with most optical profilers and ~100 times smaller than is possible with the best mechanical profilers.
Subsurface Damage: Comparison of Automated and Visual Measurements
Authors: Chang Matthew T. , Greivenkamp John E. , Lindquist Arne , Rich Tim M.
Published: February 2023

An automated PC-based machine vision system has been developed for measuring subsurface damage in glass based on the ball dimpling method [1,2]. The software automatically processes an image of the dimple and returns the SSD value. This paper provides a preliminary comparison of the result from this system and the result obtained by conventional visual measurements.
Testing an Unknown Off-Axis Conic Mirror
Authors: Stahl H. Philip
Published: February 2023

To fully characterize an unknown off-axis conic mirror requires knowledge of its optical axis vertex distance from the center of the segment, radius of curvature, conic constant, and surface figure error. No single test can provide all of this information. There are too many unknowns. To acquire the required knowledge, both a conjugate null test and a center of curvature test must be performed.
IR Interferometric "Wire" Test of Aspherics
Authors: Anderson David S. , Burge James H.
Published: February 2023

Aspherization of strong aspheres can be guided without a null lens by measuring the local radius of curvature of discrete zones using IR interferometer fringes.
Improved Measurement of the Topography of High Precision Optics
Authors: Sullivan Paul , Evans Christopher , Parks Robert
Published: February 2023

The aim of the project is to investigate the potential of expanding the instrument measurement bandwidth of a traditional phase measuring interferometer (PMI) using a comparatively simple optical/software modification. This would offer the benefit to users of gaining increased measurement bandwidth within a single measurement set-up.

Specifically the design is aimed at detecting (and measuring the locations of) higher frequency components than are traditionally measured. These components are those that arise from the general roughness and pits and scratches within the figure of the surface geometry. The principle of the technique is to make a two part measurement and then to examine the two measurements either individually or in combination. The first measurement is simply the conventional interferogram analysis. The second measurement involves introducing additional optical components (lenses and a spot mask) into the optical path and then re-measuring the phase map. Software is then used to analyze the resultant images.

This paper describes the design and construction of a “bread boarded” set-up of the test instrument. It includes some preliminary test measurements demonstrating the functionality of the system.
Optical Surfaces Processing Methods
Authors: Nikolov I.D. , Stancheva D.M.
Published: February 2023

A mathematical model for polishing solid crystal surfaces is proposed. Method of wafes processing is offered. A suitable method and control device for surfaces on the processing machine is presented. The use of electronic–beam technologies and magnetic fluid polishing of optical surfaces is recommended. Analysis of the experimental results is done and the state of processed optical surfaces is investigated.
Fabrication Of Micro Optical Elements With Spherical And Aspherical Surfaces
Authors: Rusan V.V. , Arhipova L.N. , Ivashevskii S.N. , Karapetyan G.O.
Published: February 2023

It is well known, that employment of mechanical treatment to manufacture the micro optical elements (diameter ≤2mm) with spherical surfaces of small radius or aspherical surfaces is connected with considerable difficulties and is very expensive. One of the effective methods of solving this problem is precise pressing (or molding) of glass blanks, Blanks placed between the male and female molds were heated and pressed 1,2. Molded micro elements do not demand mechanical treatment. But in this case, practically, a very complicated problem is substituted for only slightly complicated one. It means that considerable efforts are made to prepare male and female mold surfaces. They are precise mechanical treatment, the coating of surfaces by high temperature resistant multi layer coats and so on. At the beginning of our study the main question under investigation was: "Can we develop the technique that allows to produce micro optical elements with spherical and aspherical surfaces without or with simplest mechanical treatment of both the glass blanks and the molds?” In this talk two techniques of fabrication curvilinear surfaces of micro optical elements without mechanical treatment have been considered.
Metrology of transparent flats
Authors: de Groot Peter
Published: February 2023

When a transparent flat plate with parallel surfaces is illuminated with laser-based interferometer, the resulting interference pattern is a complex mixture of fringes created by reflections from both the front and back surfaces of the plate.1,2 Figure 1 is an example of an interferogram for an optical wedge with perfectly flat surfaces. In order to do meaningful metrology on such an object, the common practice is to either thinly coat the front surface with a high reflectivity material, or defeat the back-surface reflection by applying some kind of index-matching coating. It would be desirable to dispense with these kinds of surface treatments for regular inspection and testing, particularly for process control in a production environment.
Phase-Shifting Interferometry at High Frame Rates
Authors: Modisett David
Published: February 2023

A high-frame-rate (208Hz) camera has been interfaced to an existing phase-shifting interferometer in order to reduce the effect of vibration in measurements of large optics.
New Interferogram Analysis Procedure Based On Optimisation
Authors: Guse F. , Kross J.
Published: February 2023

For the quantitative analysis of interferograms being of Michelson- or Fizeau-type, fringe pattern analysis or phase-shifting techniques are commonly applied. With fringe pattern analysis, a wavefront is evaluated from only one interferogram, but the "permitted" interferograms are restricted to open fringes. The phase-shifting technique allows the analysis of a greater variety of interferograms, but requires a correlation of three or more measurements.
Computer Integrated Manufacturing Tools for the Optics Industry
Authors: Tipps Joe
Published: February 2023

An industry-wide Opticim (optics computer integrated manufacturing) System will provide the means to intelligently integrate (concurrent engineering) optical design, engineering and manufacturing activities. Design, engineering and manufacturability decisions determine the total product life cycle cost, and cost control is most effective when issues are resolved in the early stage of the optical system development cycle.
Defocus Measurement Using A Liquid Crystal Point Diffraction Interferometer
Authors: Mercer Carolyn R. , Creath Katherine
Published: February 2023

A liquid crystal phase-stepped point diffraction interferometer (LCPDI) has been developed to measure optical wavefronts[1]. A locally generated reference beam is generated by diffraction from a microsphere embedded in a thin liquid crystal layer. Phase shifting is achieved by applying a voltage across the birefringent liquid crystals to shift the phase of the object beam without affecting the reference beam. The intended application for this instrument is the measurement of phase objects, such as optical elements and slowly varying fluids.
Some new error-compensating algorithms for phase-shifting interferometry
Authors: Schmit Joanna , Creath Katherine
Published: February 2023

5- and 6-frame algorithms derived using an extended averaging technique have significantly less sensitivity to phase shift miscalibration and detector nonlinearities than commonly-used algorithms.
Phase Shifting Diffraction Interferometry for Measuring Extreme Ultraviolet Optics
Authors: Sommargren Gary E.
Published: February 2023

Extreme ultraviolet projection lithography operating at a wavelength of 13nm is based on all reflective imaging systems made up of three to five multilayer coated mirrors. If these imaging systems are to achieve diffraction limited performance, the deviation of the wavefront from spherical in the exit pupil must satisfy the Maréchal condition of λ/14 rms where λ is the operating wavelength. The wavefront error must therefore be less than l.0nm rms. If the imaging system is made up of four mirrors, the error contribution from each mirror is then less than 0.5nm rms (assuming uncorrelated errors) which means the surface figure must be less than 0.25nm rms (due to the doubling of the error on reflection).
Surface Roughness Generation Mechanism of Ultraprecision Grinding with Cup-Typed Resinoid-Bonded Diamond Wheels
Authors: Namba Y. , Shiokawa M.
Published: February 2023

The ultraprecision surface grinder1) having a glass-ceramic spindle of extremely-low thermal expansion has been developed, and very smooth surfaces better than conventional optically-polished surfaces can be obtained2) on various optical materials by cup-typed resinoid-bonded diamond wheels and the ultraprecision surface grinder. There are 3 grinding modes in grinding of optical glasses, such as the fracture mode, ductile & fracture mode and ductile mode3). The ductile mode grinding of NbF1 optical glass can be obtained by using a resinoid-bonded wheel having diamond grains less than 20 μm in grain size. There is no micro-crack observed under the surface ground in the ductile mode. The ground surface roughness less than 0.2nm rms or 2nm Rmax has been obtained on BSC7(BK7) glass sample with a SD3000-75-B wheel. So, there is big possibility of actualization that optical glasses will be finished into optical components by the ultraprecision grinding without polishing.
Precision Lens Manufacturing in China
Authors: Czajkowski Walter , Chang Jeremy
Published: February 2023

In a country which has become one of the leaders in world wide consumer export, China is now becoming a formidable force to reckon with in precision optical fabrication. This paper will explore some of the experiences encountered in establishing a high volume lens manufacturing facility in Mainland China.
Null correctors for 6.5-m f/1.25 paraboloidal mirrors
Authors: Burge J. H. , Murgiuc D. , West S. C.
Published: February 2023

The instruments used to interferometrically measure the optical surfaces of the 6.5-m f/1.25 primary mirrors for the University of Arizona telescope projects must compensate over 800 μm surface departure from the best fitting sphere. The errors in the optical test must not contribute more than 0.04 arc seconds FWHM to the final image and the conic constant must be held to 0.01%. This paper presents an overview of the instruments used to measure these giant mirrors to such high accuracy.
Adaptation of Traditional Grinding Force Models to Cylindrical Cup Grinding
Authors: Venkataraman Natarajan , Gans Roger F.
Published: February 2023

The dynamics of grinding is less well investigated than other machining processes. In particular, the cylindrical cup grinding process used in optical manufacturing has received little attention. Our interest in this arises from the observation of rose-petal shaped marks called cutter marks during microgrinding glass lenses. Since microgrinding is a finish grinding process supposed to reduce greatly the amount of material to be removed in the polishing stage, it is important to find the cause of, and to eliminate, these cutter marks.
Aspheric Surface Metrology - Where Do We Go From Here?
Authors: Greivenkamp John E. , Lowman Andrew E.
Published: February 2023

The routine testing of aspheric optical components remains an elusive goal for the optical engineer. While significant improvements in the art of aspheric testing (especially in the use computer-generated diffractive nulls) have occurred over the last several years, the usual aspheric test situation still requires specialized null optics with relatively long lead times and added cost. As a result, the use of precision aspherics have been limited to situations that can afford or amortize these costs: large programs such as telescopes, high-volume products, or very specialized instruments. The irony is that these limitations are occurring at a time when manufacturing technology is capable of producing an ever-increasing variety of surface types and specifications, and sometimes these surfaces can be fabricated economically even in small quantities.
Precision Interferometric Characterization to Accurately Test Aspheric Surfaces
Authors: VanKerkhove Steven , Michaloski Paul
Published: February 2023

Interferometric surface testing of optical components such as spheres and flats can be performed quite routinely with conventional interferometry where high accuracy can be achieved by incorporating reference subtraction or more complicated absolute characterization techniques. Aspheric null lens tests suffer from an inability to use reference subtraction or absolute calibration techniques to separate rotationally symmetric aberrations that exist between the test setup and the aspheric surface. Furthermore, zonal positioning errors that exist when imaging from surface to camera can be accounted for with conventional tests, but the zonal location of irregularities is crucial in the correction of aspheric components during the fabrication process. The interferometric null test bench must be designed, built, and characterized with high precision to achieve accurate aspheric surfaces.
Image Degradation due to the Opticam Manufacturing Process
Authors: Kotha Anita , Harvey James E.
Published: February 2023

The demand for modernizing the precision optics manufacturing industry has led to the development of a new generation of computer controlled precision machining process known as deterministic microgrinding at the Center for Optics Manufacturing (COM) at the University of Rochester in cooperation with the American Precision Manufacturers Association (APOMA). The Opticam (Optics Automation and Management) machine is a closed loop computer-integrated grinding and polishing system that generates and fine grinds blanks to an optical specification and centers to final dimensional requirements. The entire process excluding any post-polishing takes approximately five minutes. The optical elements fabricated by this precision machining process exhibit residual tool marks in the shape of periodic radial grooves which are orthogonal to the nature of surfaces machined by single-point diamond turning process where the surfaces exhibit azimuthal periodic grooves.
A Fabrication Plan for Ultra Thin Mirrors for NGST
Authors: Miller Steve , Burge Jim , Cuerden Brian
Published: February 2023

A fabrication technique has been developed at the University of Arizona which incorporates the well understood method of fabricating rigid optical components and a method of supporting thin glass substrates so that their flexible nature is transparent to the optician2,3. Fixing the shell to a rigid monolithic blocking body eliminates the problems of handling and the deflection of the substrate under the forces of polishing. This approach has been demonstrated by the fabrication of shells 1/2 meter in diameter and 2 mm thick. The U of A is currently manufacturing a shell which is 2 meters in diameter and 2mm thick as a demonstration for the NGST4.For space applications, the coefficient of expansion of the material at cryogenic temperatures is of concern. For this reason, a borosilicate material (Schott Borofloat) has been selected as the mirror substrate because it has a CTE of zero at 35°K. In this particular case, the selection of material generated the need for adaptation of the earlier process.
Speculation on Ultrasonic-Assisted Grinding with an Engineered Wheel
Authors: Hashimoto H , Imai K , Dornfeld D , Blaedel K
Published: February 2023

The ability to perform high-quality, shear-mode grinding of brittle materials such as glass critically depends on an adequate flow of coolant through the contact zone between the tool and the workpiece. A long contact zone limits the induction of coolant and thereby promotes high temperatures in the contact zone where heat is generated. For workpiece materials like glass, the high temperature and subsequent quenching causes surface and subsurface damage. High temperature of the wheel also tends to promote faster wheel wear. In contrast, short contact lengths tend to reduce the temperature of both the workpiece and the wheel. For some grinding geometries, where a long contact length is difficult to avoid, an alternative is to excite the wheel at ultrasonic frequency, which also admits coolant between wheel and workpiece. Results are shown of grinding force with and without ultrasonic excitation and the analyses of the resultant surfaces.
New NC Data Generating Method Including Tool Wear Compensation in ELID (Electrolytic In-Process Dressing) Grinding
Authors: Moriyasu Sei , Nakagawa Takeo , Yamagata Yutaka , Ohmori Hitoshi
Published: February 2023

Recent demands for ultraprecision machining has been for higher precision. The ELID grinding technique is widely known as a method which produces high precision ground surfaces in a short period of time.1) Aspherical optics, one typical example of super precision parts, require not only good mirror surface finish but also high form accuracy.2) But it involves considerable difficulty to achieve both good mirror surface finish and high form accuracy. The authors have proposed a new form control system for achieving high form accuracy regularly and efficiently in aspherical ELID grinding, and successful results could be obtained through some experiments3),4). But there had been some conditions, under which the profile errors could not converge because the radius of the grinding wheel decreased by the wear. This paper proposes a new form compensation method which can be applied to the condition under which the grinding wheel is much worn.
Development of Mirror Surface Slicing Machine Installed with Grinding System using Metallic Bond Diamond Blades and Electrolytic In-Process Dressing (ELID)
Authors: Ohmori Hitoshi , Moriyasu Sei , Kim Hwa Young
Published: February 2023

Recently with a rapid advance of new material industry, the new materials such as ceramics and glass are increasingly applied to precision machine parts and optical parts etc.. Therefore, requirements of advanced slicing technique for precision slicing of these materials having the features of hardness and brittleness is gradually increasing. Generally, the slicing method using metallic bond diamond blades is using for the slicing of the hard and brittle materials. However, since the diamond blades of upper grits size #200 cannot be used due to the loading of blades etc., it is difficult to achieve the good slicing surface with high quality. In order to achieve the good slicing surface with high quality, post processing operations such as polishing and lapping must be carried out after slicing operation. Therefore, to obtain simultaneously excellent slicing surface such as mirror surface without the post processing operation, development of advanced slicing technique using a metallic bond diamond blade with fine grain size is essential. ELID (Electrolytic In-Process Dressing) is a new grinding technique which the protrudent gains of wheel is controlled and maintained by assistance of the electrolytic in-process dressing(ELID) and especially possesses the excellent capabilities for the fine or mirror surface grinding of hard and brittle materials1). Many studies on various grinding techniques applying ELID grinding have been reported until now2),3). In this study, ELID-grinding slicing technique to realize fine and mirror surface slicing of hard and brittle materials is proposed. A mirror surface slicing machine installed with the proposed ELID-grinding slicing system is developed and its performance is evaluated.
Recent Advances in Optics Manufacturing in China
Authors: Czajkowski Walt
Published: February 2023

Optical manufacturing competency and capability in mainland China will be explored. Factors influencing the all important cost versus quality decisions will be reviewed.
Topographic Inspection of RPG Contact Lenses by Laser Triangulation
Authors: Costa Manuel F. M.
Published: February 2023

Optical triangulation (Figure 1.) as a non-destructive test method extensively proved its usefulness on the dimensional and topographic inspection of a large range of objects and surfaces.
Fabrication of the SubReflector for the Large Millimeter Telescope (Gran Telescopio Milimétrico)
Authors: Renero-C. Francisco-J. , Cardona-N. Octavio , Cardona-N. Roberto , Vázquez-M. Sergio , Cornejo-R. Alejandro , Islas-G. Carlos , Romero-A. Jorge
Published: February 2023

Astronomers use telescopes to study the universe in the different spectrum regions. The dimensions of telescopes, to research in the millimeter region, are too big. Thus, fabrication of such instruments is a challenge work. The “Gran Telescopio Milimétrico (Large Millimeter Telescope, which will be called LMT) is a Cassegrain Telescope, which diameter of the primary reflector is 50 meters and the subreflector is a hyperbolic surface which diameter is 2.57 meters, and it is been developed to observe in the millimeter region. The subrelector surface must be fabricated with an accuracy of 13 µm (rms). Furthermore, the subreflector must achieve the so-called wobbling, meaning that the subreflector cannot be so heavy, but enough stiff to be wobbled. In this work, we describe the fabrication technique for the subreflector.
Aspherical ELID Grinding Technique for X-ray Mirrors
Authors: Moriyasu Sei , Nakagawa Takeo , Yamagata Yutaka , Ohmori Hitoshi
Published: February 2023

X-ray optics is advancing rapidly and being applied to numerous fields. X-ray mirrors may serve as one of the most important devices giving tremendous influence on the performance of a whole system. X-ray mirrors require for higher precision than any other parts. But the technique which produces such mirrors has yet to be established. In this paper the applications of the ELID grinding technique1),2), which is known widely as a method for producing high precision ground surfaces in a short period of time, are described for X-ray mirrors.
Point Diffraction Interferometry: A EUV Projection Lithography System Alignment and Qualification Tool
Authors: Naulleau Patrick , Goldberg Kenneth A. , Lee Sang , Bresloff Cynthia , Attwood David T. , Bokor Jeffrey
Published: February 2023

Extreme ultraviolet (EUV) projection lithography is currently being developed to achieve sub-100 nm critical dimension pattern transfer. Such severe performance requirements place unprecedented demands on phase measuring interferometry which must provide a measurement accuracy of ~ 1 Å based on acceptable wavefront tolerances of ~2 Å. Furthermore, since these lithography systems utilize resonant reflective structures, the interferometry must be performed at the operational wavelength, which is in the 5 nm to 15 nm range.
Technology development and selected applications for the ductile grinding of aspherical surfaces
Authors: Klocke F. , Hambücker S.
Published: February 2023

Glass, an ancient yet innovative material, has always held a particular fascination. We are surrounded by glass in almost all areas of life, in the home by window glass, television and computer screens, by wine glasses etc., and by high-tech products such as glass fibres, micro-optics, aspherical precision lenses etc. The problems involved in machining all types of glass are summed up by the expression: "Glass retains its shape until it reaches breaking point" which, at the same time defines the dominant characteristic of float and optical glass. The brittle nature of glass is the major influencing factor on the material removal mechanism when glass parts are machined using diamond wheels with metallic bonds. Glass chips are removed by inducing fractures. Under certain boundary machining conditions, however, it is possible to achieve a viscous flow of the glass material. This principle is known as ductile material removal. By producing a very finely-structured surface, the ductile grinding process reduces or eliminates the need for a polish-finishing operation. This paper describes the dominating parameters on ductile chip formation and illustrates some special applications.
Diamond Turning of Optical Glass - New Technologies for the Machining of Micro-Optical Elements
Authors: Klocke F. , Rübenach O.
Published: February 2023

Optical products will continue to be particularly interesting from an economic point of view. However, in addition to the established markets, solutions in the field of micro-technology will increase in importance. The use of complex micro-lenses in laser technology (high-performance diode lasers), in information technology (fibre couplers) and in medical technology (endoscopy) are examples of such applications.
Modern Production Methods for Complex Surfaces
Authors: Karow Hank H.
Published: February 2023

Over the past five years, several optical production methods have been perfected to the point where they can now be reliably used for cost effective production of complex optical surfaces. Most of the improvements were made in production machines that now rely heavily on the use of CNC controllers. Concurrent improvements in metrology complemented these developments.
Stylus Profilometer with an Optical Reference
Authors: Clark Stephan R. , North-Morris Michael , Greivenkamp John E.
Published: February 2023

Three-dimensional or x-y-z stylus profilometers are a well-established method for measuring non-rotationally symmetric aspheric surfaces.1 In this paper, the design of a three-dimensional stylus profilometer that uses an optical reference surface is presented. The benefits of using this reference structure are also discussed.
Multilayer Filter Coatings with Improved Environmental Stability
Authors: Martin Peter , Pawlewicz Walter , Coult David , Jones Joseph
Published: February 2023

In this paper we report on reactively sputtered optical coatings which are remarkably stable in wavelength performance after extensive temperature cycling and humidity exposure. This exceptional environmental stability makes them particularly well suited for use in optics systems subjected to harsh environments for extended time periods.
Ion-Assisted Deposition of Optical Thin Films: Low Energy vs. High Energy Bombardment
Authors: McNeil J. R. , Al-Jamaily G. A. , Barron A. C.
Published: February 2023

In the fabrication of high quality optical coatings, proper stoichiometry is an important requirement. In particular, metal oxide films should be free of suboxides or metal that could increase absorption in the film. However, decomposition of the film starting material during deposition is a common problem, and in the case of metal oxides this is often severe. Because of this, various techniques of reactive deposition have been developed over the last decade to improve the film stoichiometry. One such technique that has received attention lately is ion-assisted deposition, in which a beam of oxygen ions is directed onto an optic during film deposition.
Automated Vacuum Coating Plant for IR-Optical Coatings
Authors: Herrmann R. , Klug W. , Zöller A. , Zueltzke W.
Published: February 2023

Microprocessor controlled coating plants gained more and more market shares during the past few years because they increase the yield of the coating processes and allow additional cost savings by running several machines by only one operator or by completing a run during the night. These cost savings are especially pronounced in the case of infrared coatings with runs of up to 8 hours.
Methods of all-dielectric bandpass design
Authors: Baumeister Philip
Published: February 2023

There are two types of all-dielectric bandpass filters: (a) The mutual passband type; and, (b) The multiple cavity type.
Simulating Quarterwave-Layers
Authors: Herrmann R.
Published: February 2023

Multilayer antireflection coatings often make use of layers with refractive indices which do not occur in nature. There exist several methods to simulate such layers by a combination of two given materials. One of the first methods had been patented by GEFFCKEN /1/ who proposed to simulate a quarterwave-layer with a required refractive index by at least a three layer combination. ROCK /2/ patented antireflection coatings in which a first quarterwave-layer is replaced by only two layers.
New Algorithms for Synthesised Design of Optical Filters
Authors: Seeley J.S. , Lim Y.K. , Wu S.Y.
Published: February 2023

Improvements have been made to two design-algorithms used in micro­computing (Seeley 1983).
Wave Optics at λ = 1 Å
Authors: Patel J. R. , Golovchenko J. A.
Published: February 2023

Many years ago Wiener, in a classical wave optics experiment, demonstrated the presence of standing waves upon reflection of monochromatic light from a polished metallic surface. That similar phenomena can be demonstrated at wavelengths four orders of magnitude lower in the x-ray range is less well known. Using the appropriate geometry and detectors the presence of x-ray standing wavefields can be directly demonstrated. For x-rays the standing wavefield is not fixed but can be moved. This attribute allows accurate atom location studies at or near crystal surfaces.