New developments with the focus-wavelength encoded optical profilometer are reported in the area of applications to surface contouring. Longitudinal chromatic dispersion of a suitably designed lens as a probe is exploited to obtain distance information between the probe and the surface. After proper scanning, the surface topography is recovered.

Transmitting and illuminating optical surfaces are machined by different processes. Grinding and polishing technologies are mainly used for glass or other non metallic materials to get the right surface figure and optical function. Milling processes like "fly-cutting"using a single point crystal diamond tool are major processes to machine metal optics. The static, kinematic and dynamic behaviour of inserted machining tool is responsible for the design quality of the optical products. Testing and analyzing methods to describe the dynaknic compliance behaviour of machine tool are well known for common milling, turning and grinding machines. This paper describes an improved testing method to analyze undulation problems on micro-machined surfaces for precision machines. The process influencing machine behaviour is recognized by the frequency depending com-pliance characteristic. A non contact laser vibration measurement is used to registrate vibrating machine tool parts. Measuring methods like modal analysis are applied to give a good impression of machine tool deformation behaviour. Results of different tests are presented. An illustration for plottable test statements will be given for a precision milling machine. Selected parts of the machine structure were rebuilt and improved the dynamic behaviour of the tested machine. Increasing undulation marks and a good surface figure are recorded on process tests.

In micromachining of aspherical surfaces the diamond tools are used in a zone extending over a certain segment. This zone is minimized in the spherical generator type machine, but it must be found and located by knowing edge quality over the entire length. Our method of verifying edge sharpness over the entire tool radius as well as the circularity (form) consists in viewing with a micro-interferometer a plunge cut trace produced in the real tool-workpiece configuration. This allows to set a partially defective tool for optimum machining conditions. One can also set for best cutting depth, because certain tool damages on the rear phase become effective only with deeper cuts. This will be illustrated. The micro-interferometer plunge cut inspection allows to detect material vibration, chatter and crossflow of material.

The use of common machine tools for the production of optical elements having aspheric shapes and the computational approximation thereof have been described by Erickson1 and Watt , who patented an aspherical machine concept involving stationary coordinate setting in a spherical generator, which equals Erickson's approach superimposing a dynamic control. This machine type was developed in Europe by Protop and was reported on at several DGaO meetings. In English literature it is described in ref.3.

The production task for very large metal mirrors by micromachining has been addressed by various manufacturors on this SPIE forum. We as a machine tool builder have since years focussed on providing air-bearing turn-tables of diameters from lm up to 5m diameter. With less than 1μm departure from planarity and roundness these - tables are used not only for metrology but for machining of such large mirrors specifically.

Measurement of radii of curvature (cv, cc) in the 'ange 1 to 30 m is hardly possible using available metrology equipment. An ancient method' of long radius measurement is reevaluated and adapted to in situ measurments on spherical generators . Finding the auto-collimation position is eased by strioscopic interferometry which at the same time allows Foucault- and interferometric surface testing. Radii typical in high power lasers from 1 - 30 m are subject to this type of radius measurement. The inaccuracy is in the order of dR/R = 0,05 %.

SOPELEM is equipped with a high precision diamond turning MOORE machine to manufacture our own aspheric components. We present results obtained with this process along with the tests carried out. Several applications with INFRA-RED systems are shown, in spectral bandwidths : 3 to 5 microns and 8 to 12 microns.

The objective lens is a single element glass lens with one aspheric replicated surface and one flat surface. The manufacture of the aspheric surface by means of replication is suitable for high quality mass-production.

The design of a diffraction-limited aspheric lens for optical disc systems is discussed (f=4.5 mm, NA=0.45, wavefront distortion less than 0.045 wavelength rms). The design for mass-production is a mono-aspheric lens consisting of a piano-convex glass body with a correction layer of ultraviolet-curing lacquer. The optical quality of the lens is measured with a phase-stepped interferometer. A few details of the interferometer are given and the aberrations of the mass-pruduced lenses are discussed.

A diffraction-limited bi-aspherical readout lens for the digital audio disc system has been designed and developed based on a high-precision lens replication process using UV-polvmerizable coatings. This single element read-out lens consists of a hall-shaped quartz substrate with two aspherical replicated coating surfaces. The design of the bi-aspherical lens is presented and its production described. The optical performance of the lenses proved to be reasonable with an rms-OPD of 0.055 λ, the primary lens aberration being spherical aberration.

Towards the end of 1985, the last finishing touch was made to the flight mirrors for the German ROSAT X-Ray Satellite. On the basis of the results available, the procedures actually applied and those considered at the various production stages are assessed. A. comparison is made between these procedures and those used for the HEA0-B mirror system in order to illustrate the advantages and disadvantages between them. Key features are: support of the mirror during grinding, polishing and measuring, diamond-wheel grinding of the mirrors, surface finish and slope, error correction.

An automated aspheric polishing machine has been constructed using a readily available microcomputer, off-the-shelf servomotors and controllers, and other commercially available mechanical components. A computer model of the polishing process was developed and used to investigate the effect of various tool shapes and motions on the polishing process and the shape of the material removal profile. Suitable tool shapes and motions were determined from the model. A microcomputer controlled aspheric polishing machine was designed to produce these motions. Software was developed to control the servomotors, monitor the process, calculate material removal profiles, and interface with the user. Examples of precision aspheric surfaces fabricated using this process are presented. Other possible uses and future developments are also discussed.

A commercial coordinate measuring machine has been modified to provide surface profile measurements of one meter optics to an accuracy of 50 microinches. Additional calibration of specific surfaces provides an accuracy of 15 microinches. Data acquisition and analysis software is discussed.

The design and underlying theory is given for an aspheric singlet lens capable of operating, with minimum sphero-chromatic aberration, over a range of pre-selected wavelengths. The performance of the lens is compared with a conventional aspheric (based on Fermat's principle) using finite ray tracing techniques. The use of the lens as a focusing element in a multi-wavelength high-power laser is evaluated. Finally, comments are made on its manufacture and testing and its performance compared with theoretical prediction.

We have been involved for a number of years with the design and production of a range of aspheric lenses, both singlets and doublets, for use as focusing elements for high power lasers. The paper gives a brief resume of the design and manufacture of such lenses but concentrates on the final testing and performance. A critical discussion is given on the effect of surface imperfections on the quasi-far field performance of the lens and compares this with an assessment of the lens based on its focal properties.

The theory developed for perturbed apsheric singlets is used to design a minimum aspheric component optical circuit for use in VLSI. The specification is for a circuit with optical reduction of 10:1 with flat field imaging of a 100mm diameter object field and a resolution of 0.5μm or better. A discussion of the minimising procedure is given together with the theoretically expected performance of the circuit using numerically generated holograms.

This paper discusses preliminary investigations of a novel interferometric approach in testing cylindrical optics that makes use of an optical fiber as a cylindrical reference surface.

Two-wavelength holography and phase-shifting interferometry are combined to measure aspheric surface contours with a variable sensitivity. In this technique, the surface is effectively tested at a synthesized longer equivalent wavelength ^λeq = ^λa^λb|^λa - ^λb| using measurements made at wavelengths ^λa and ^λb where the difference of the phases measured for ^λa and ^λb yields the modulo 2π phase at ^λ_eq. A mask of point apertures is placed over the detector array in order to resolve closely spaced fringes. This technique has an rms repeatability of ^λ_eq/100. Limits to this technique are discussed and results are shown.

This paper proposes the use of a simple two-scale model of surface roughness for testing and specifying the topographic figure and finish of synchrotron-radiation mirrors. In this approach the effects of figure and finish are described in terms of their slope distribution and per spectrum, respectively, which are then combined with the system point spread function to produce a composite image. The result can be used to predict mirror performance or to translate design requirements into manufacturing specifications. Pacing problems in this approach are the development of a practical long-trace slope-profiling instrument and realistic statistical models for figure and finish errors.

Laser-guided weapons delivery systems are now well known. Such systems, termed laser designator/sensors, are optical devices which usually include a laser and a near-infrared TV camera, in combination with autotracking capability, a direct-view optical telescope system, and a forward looking infrared (FLIR) nighttime imaging/tracking system. One of the major potential sources of error in optical devices is misalignment of optical elements, particularly optical devices in helicopters and tanks where operating environments are quite severe. Alignment is maintained by boresighting with an optical sub-system called a bore-sight module. The boresight module is optically coupled with the particular designator sensor and tracking system. Most boresight module components provide greatly relaxed angular tolerances that are achieved with Risley prisms. Nevertheless, the problem of their accuracies is not completely solved. While vibrational and weight load errors have been considered, the problem of thermal changes leading to variations in results has gone unsolved. This paper discusses a solution to the thermal distortion problem by providing a zero expansion transfer device, spanning two widely separated optical apertures for mutual boresighting. The boresight module renders two parallel lines of sight in visible, near and far infrared spectra by retro-reflection and auto-collimation. The reflective collimator has diamond-turned aspheric surfaces.

This work presents an attempt to develop a new procedure to evaluate surface roughness through the utilization of the spectral densities of laser speckles by image processing techniques. Preliminary results indicated a trend in which the peak of the spectral density would shift towards a lower frequency for higher surface roughness. This trend has not, however, been conclusive in another experimental setting which attempted to magnify that trend. This inconsistency may have been attributed to the possibility that the results were defining a finer pitch roughness rather than coarser pitch roughness which the specimens were considered at. Further studies are then required on the specific state of the specimens by using other conventional techniques. The work, however, indicates a possible potential for this spectral density technique by laser speckle image processing to evaluate surface roughness conditions.

Research Optics & Development, Inc. is using a slope tracing profilometer to measure the figure of optical surfaces which cannot be measured conveniently by interferometric means. As a metrological tool, the technique has its greatest advantage as an in-process easurement system. An optician can easily convert from polishing to measurement in less than a minute of time. This rapid feedback allows figure correction with minimal wasted effort and setup time. The present configuration of the slope scanner provides resolutions to 1 micro-radian. By implementing minor modifications, the resolution could be improved by an order of magnitude.