In ultraprecision machining - metal or plastics cutting with single point natural diamond tools - the most dominant error is the machine vibration. It is shown that this machine vibration is shifted down in frequency by an aliasing principle. The amount of downshift is n times the revolving frequency of the fly cutter. This is shown in principle, in a simulated process and on real surfaces.

Hembrug recently developed the method of tool-normality for machining aspherics on the Super-Mikroturn CNC ultra precision lathe. This method allows the single point diamond tool to be kept perpendicular to the surface and eliminates the influence of tool tip radius error. Due to the perpendicularity of the tool, this method also allows the integration of a dedicated sensor system for in-process measurement. The realisation is carried out by a hydrostatic, numerically controlled precision rotary table, together with a software package for 3-axis interpolation. To measure the surface topography and reflection value of metal optics, a non-contact sensor, consisting of a bundle of glass fibers concentrically arranged is now in development. A number of these fibers are connected to a light source and the remaining fibers are used to transmit the reflected light from the surface. The intensity of the reflected light versus the distance generates a diagram of which the shape characterizes the roughness and the reflection of the measured surface. The integration of such a dedicated sensor into an ultra precision machine tool in combination with the evaluated characteristic diagram makes it possible to obtain data of the shape of surface topography and reflection values performing the first step of an in-process adaptive control system. The paper will deal in greater detail with the development of this new concept of ultra precision machining and measuring problems connected to the process.

The geometrical accuracy and surface roughness of diamond-turned workpieces is influenced by several parameters: the properties of the machine tool, the cutting process and the environmental conditions. A thin-walled electrode made from an aluminium alloy (wall thickness: 1 mm, length: 169 mm, outer diameter: 126 mm) and intended for an electrostatic measuring instrument, serves as an example to show how quasi-optical surfaces with a surface roughness Rα < 10 nm and deviations from roundness of ≤ 5 μm can be achieved when some of these influence quantities are optimized. The cylindrical part of the electrode was turned by means of a rounded mirror-finish diamond tool, the width of the cutting edge being 2 mm, the rake angle -6° and the clearance angle 2°. Compliance with the tolerances of geometrical accuracy was particularly difficult. As age-hardened wrought aluminium alloys cannot be stress-relieved by annealing, or only insufficiently, the geometrical accuracy - in particular the roundness - of thin-walled, rotationally symmetric bodies decisively depends on the state of stress of the workpiece material, on the clamping fixture and on the balanced condition of this clamping fixture.

World wide experience over the last few years has shown that for the efficient economic micro-machining of optical glasses to aspheric profiles, with zero to low sub-surface damage, a high loop stiffness between tool and workpiece is essential, and that the tool penetration must be controllable to better than 100 nm for many materials. This paper analyses the implications of this requirement for the stiffness and accuracy of workhead spindles. The design of a variety of ultra precision air bearing workhead spindles is outlined, and the efficient high speed metrological techniques for test and calibration of such spindles down to 1 nm resolution, is described.

The establishment of Single Point Diamond Machining as a viable production process for metallic, crystalline and plastic optics has resulted in a greater awareness of non-conventional surface geometries from both design and production standpoints. The development by Rank Pneumo Inc. of an Ultra-Precision Aspheric Grinding machine has been prompted by current and predicted market requirements which call for a precision machining process capable of yielding optically smooth aspherical surfaces to a figure accuracy in the order of one wave or less at 632.8nm on workpieces typically no greater than 150mm in diameter.

Interferometric measuring techniques are more and more used for the inspection of mechanical components with "quasi optical" properties. This paper presents a computer-aided interferometric measuring system for measuring optical as well as "non-optical" components.The specifications of the system are discussed, the field of application is demonstrated by various examples of industrial use. In addition to several applications in the field of interferometric investigations of components with reduced sensitivity ( wafers, masks, optical disks, ceramics, etc ), examples for the use of scan interferometry are presented. Scan interferometry allows the measurement of mechanical components with dimensions greater than the field of view of the interferometer. This can be achieved by the combination of interferometric measuring technique with ultraprecision mechanical positioning.

The influences of straightness errors and machine resonances on the surface of faced mirrors are discussed. Measurement results of the machine behaviour are compared with the surface shapes and micro-structure of produced workpieces. A correlation between the measurement results of the machine and the analysed workpiece surfaces is presented in this paper.

The requirements for surface quality of workpieces such as metal-optics are increasing, specially if they are used as optics in high energy laser systems. This fact leads to an ongoing optimization effort of the microturning respectively fly-cutting process with a single point diamond tool. A selection of insufficiently machined workpieces has demonstrated that vibrations at the cutting zone modulate the surface contour. Recent measurements have shown that the static and dynamic compliance of ultraprecision machines has a great influence on these effects. In the past several ultraprecision machines have been studied and the results are presented here statistically. Further examinations have pointed out that it is possible to correlate the measured vibration amplitudes at tool and headstock during the cutting process with the generated texture on the workpiece.

Single point diamond turning (SPDT) is a cost effective method of making severe aspherics in metal. This is particularly true in multi-element systems where accurate mating surfaces can be turned in the same set-up with the optically active surfaces. With current SPDT machines, such aspherics perform satisfactorily in the infrared but tend to scatter sufficient light in the visible that it is difficult to impossible to obtain an assessment of system alignment and image quality using visible light test equipment.

Investigations, using a two-axis vertical-spindle single-point diamond tool lathe to study the facing of discs, showed that, in order to establish and control conditions for cuts approaching 100nm, it was necessary to monitor the spindle for transient run-out and longer-term growth and to measure in-process the orientation of the work-face. Accordingly, an optical (Fizeau) interferometer was incorporated in alignment with the spindle so that orientation and axial motion of the face-plate and/or the work-piece could be observed and recorded and the measured data used for correction. Special requirements and problems associated with using an interferometer to monitor the 'dynamic planarity' of a rotating surface are addressed; instrumental considerations are discussed and results described.

X-ray diffraction methods were developed for the investigation of strain fields in mechanical components of monocrystalline silicon. This local strain fields arise from external forces and from surface defects. Two simple examples of strained silicon are shown in this paper. The average value of the surface region destroyed by slicing with a diamond wheel was 50 μm and by mechanical grinding about 80 μm thick. This destroyed surface region must be removed by an etching procedure, for getting strain free mechanical components.

Moire deflectometry is a versatile technique for measuring various properties of surfaces and transparent objects. The applications of the method to surface analysis include measurements of flatness, roughness, and in-plane and out-of-plane distortions. A microscope mode allows the detection and measurement of scratches and other imperfections. The sensitivity of the instrument is tunable from the millimetric to the interferometric range by a simple mechanical adjustment. This allows the matching of the fringe increment to any desired specification. The deflectometer is highly immune to mechanical shock and vibrations, a feature that allows it to be placed on the production floor. Flat and spherical surfaces may be analyzed in situ in real time. An IBM PC AT compatible computer software package displays contour maps of surface topography, slopes, curvature, roughness, etc.

The draft and design of a polarization-preserving single-mode fibre connection are described. The criteria of the draft were the optimal coupling of laser light with small backlight fraction and the conservation of the laser's polarization state at the fibre end when these ends are prepared according to a simple technique. Two applications and their results are shown.

A model describing the modification of a surface roughness profile due to thin film deposition is presented. Surface smoothing as well as roughening are found to be significant effects. Conclusions which can be drawn from the roughness model with respect to related light scattering make it possible to interpret film scattering experimentally observed.

Traditionally, very high precision mechanical machining is performed using aerostatic or hydrostatic spindles. We describe a different approach, by making use of spindles with active magnetic bearings, which open up new prospects in this field. To test this principle, we have built a machine using a magnetic spindle for machining flat and cylindrical surfaces. Here, we give the results obtained and describe the possible prospects. Design financed by the DRET : La Direction des Recherches et Etudes Techniques.

As we demonstrate, sapphire can be polished by means of colloidal SiO2 (7 nmφ) in water by direct contact to a tin lap to a residual roughness better than 0.3 nm Rz measured with a Talystep profilometer. We use the superpolishing mechanism itself for producing microscopically smooth grooves which can serve for a precision measurement of the very small removal rates intrinsic to the superpolishing process. In order to explain the superpolishing process, we propose the model of hydrothermal wear.

In a scanning x-ray interferometer cut from a silicon crystal the fringe period is equal to the lattice spacing selected (about 0.2 nm), which is well known in the unit of length. It is a practical instrument for high resolution measurements of small displacements, such as occur in investigations of high quality optical surfaces. In combination with an optical interferometer its fine scale having atomic distances as graduation marks, can be used for testing and for calibrating conventional interpolation techniques.

Recently, we have developed efficient optically controllable modulators in AlGaAs that apply band filling or electroabsorption. These reflection modulators typically consist of a GaA1As multi-quantum well (MQW) structure in front of a multi-layered AlGaAs dielectric reflector. Optimizing the performance of the devices requires a precise control of layer thickness and material composition. For analysis of the epilayers grown by molecular beam epitaxy we employ optically reflectometry and X-ray diffraction. Correlating optically measured reflection spectra and numerically computed reflection curves we obtain the optical thickness of individual layers. A simple evaluation method provides resolution of a few nanometers when the periodicity of the structure is larger than 100 nm. For the X-ray studies we employ a double-crystal diffractometer with a germanium-monochromator. From the angular difference of the rocking curves from layer and substrate we determine the layer composition. From the fine structure of the diffraction pattern we can evaluate the thickness of the layers in composed structures. The measurement range is from less than 20 nm to 500 nm allowing for quantum wells to be investigated. In the overlapping range from 100 nm to 500 nm optical and X-ray measurements agree very well and can be used to determine the refractive index. In conclusion, the combination of X-ray diffraction and optical reflectometry provides a powerful tool for characterizing multilayered material systems of optoelectronic and optical applications.

I am certainly pleased to be with you here today, and to speak to you on the subject of international standardization. The work of some of the ISO technical committees, such as ISO/TC 36 "Cinematography", ISO/TC 42 "Photograhy" and, of course, ISO/TC 172 "Optics and optical instruments" may be familiar to many of you and their activities will be presented in your technical sessions. Rather than going into the detail of these technical committees it might be appropriate that, in my capacity as Vice-President of ISO, I present to you an overview of the organization, what it aims to do, with what means, what its achievements are and how it does its job in practice.

In the sixties and seventies, optical items were dealt with in several different Technical Committees of the International Standardization Organization (ISO). TC 10 'Technical drawings' got prepared to day down drawing rules for technical components, TC 22 'Road vehicles' defined terms of physiological optics because of the connection between seeing and driving motor vehicles, TC 59 'Building construction' standardized geodetic instruments, TC 94 'Personal safety - Protective clothing and equipment laid down requirements for sun glasses, and finally Working Group 12 of TC 42 'Photography' was going to work on various optical test methods and requirements for coatings.

Over the last few decades there has been a steady growth of international exchanges in optical production capacity. Differences in national standards for drawings of optical elements have made these exchanges difficult and expensive. Information contained in such drawings, particularly that relating to tolerances, must be translated and converted to the relevant national standard, in order to make it comprehensible at workshop level. Such translation and conversion is often expensive. Clearly, an international standard would help to save time and money.

It is explained why a general interface for optical data between CAD/CAM-Systems is necessary. The requirements for the interface are discussed. The philosophy of a solution is demonstrated and it is shown how to proceed.

ISO Technical Committee (TC) 172 "Optics and Optical Instruments" was organized in June 1978 at the inaugural meeting at Pforzheim West-Germany. TC 172 is composed of nine Subcommittees and the work of the Subcommittee (SC) 1 "Fundamental Standards" was divided into 3 items, for each of which a Working Group (WG) is formed and WG 3 was in charge of preparing the draft standards for "Environmental Test Conditions." The urgent need for that standardization was stressed by one of the U.K. delegates in 1980 at the first meeting of SC 1. However, the actual work of the WG 3 started in 1982. The delay was due to the controversy as to selecting the basic structure of the standard. Another Problem was how to determine the boundary of WG 3's field, because this item extends so widely that interferences with the task of other groups, such as IEC, would be unavoidable. Finally the group decided to divide a big volume of draft into a number of parts and publish them one after another as soon as each of them is accomplished. It was the general agreement of the group members to avoid pursuing the perfectness of the draft too persistently. That seemed impossible because of the complicated character of the field. The prompt publishment of the draft would evoke discussions from the experts in the world which would contribute to improve it. At the end of 1985, draft proposals ISO DP 9022, Optics and optical instruments -Environmental test methods; Part 1 - 14 were accomplished. The working group is still actively working out the additional parts of that DP. In this report the outline of the standard will be reported with the its future prospects.

The variable results of a recent independent assessment of the relative performance of existing national standards relating to surface flaws such as digs and scratches, together with the greater use of laser optics, has led to renewed interest in objective methods for quantifying surface flaws. A code of practice for the measurement of flaws, with traceability to national standards, based on the use of a microscope image comparator, is described. The severity of a flaw is defined here as being proportional to the amount of light it removes from a beam. This code is suggested as a means for resolving disputes when a particular flaw, identified by any convenient method of observation, is found to be near a threshold of acceptance.

Within the International Standardization Organization (ISO) the technical committee (TC) 172, optics and optical instruments, was established in June 1979. Within TC 172 nine subcommittees (SCs) were established. The SC 5 deals with microscopes and accessories. A survey of the present state of standardization activity in SC 5 is given.

The international standardization work in optics is carried out by the ISO TC 172 group. This committee is divided into nine subcommittees. Subcommittee 3, which began its first serious work in 1980, deals with the subject of optical materials and thin film properties.

In the magnificent surroundings of this Congress I would like to develop a short report on the activities of the ISO standardization in a specific sector, that is ophthalmic optics.