In the modem computer-integrated material processing plant statistical process control plays an increasingly important role. A corresponding need for rugged and noninvasive on-line sensors capable of reliable and unattended performance is becoming more and more urgent. Optical sensors are often being adopted for such tasks not only because of their noncontact nature implying an easy adaptability to the automated inspection of continuously moving products at any temperature but also in view of their high response speed intrinsic resolution and increasing ruggedness. Properties which may be probed with optical devices include product features such as geometrical size and shape or surface integrity as well as process parameters such as temperature speed or vibration amplitude. This paper reviews a number of optical sensors which were recently developed at our institute for industrial material online inspection. Examples include surface defect detection 3-D lumber board scanning and infrared temperature measurement either in furnace or during spray deposition. The emphasis is on noncontact techniques well suited to automation and specifically adapted to each particular application with minimum perturbation of the industrial process. 1.

A CCD camera based optical metrology system has been developed for the accurate measurement of a railway locomotive''s wheel movements with respect to the rails. The system is based on the light-sectioning method implemented with four laser diodes projecting light sheets onto the wheel and rail. A high-resolution CCD camera views the four profiles simultaneously using an appropriately folded and combined beam-path. To minimize the effects of ambient light a special narrow-band dielectric filter was designed manufactured and fitted in front of the camera lens. The desired measurement accuracy requires pixel-synchronous acquisition of the CCD video data. This is realized with a custom-built universal CCD data acquistion system with which profile tracking data compression and storage at 12. 5 Hz (half frame-rate) is made possible. A prototype system was built and tested on railway tracks at up to 140 km/h. In laboratory experiments the system surpassed the required measurement accuracies about fivefold attaining an accuracy of 0. 02 mm in relative position and better than 0. 1 mrad in relative angle. 2.

Ion lasers commonly make use of BeO beam tubes because of favorable electrical insulation and high heat conduction properties. The bore along the axis of such a ceramic tube is precisely controlled to length diameter and end-toend straight ness specification tolerances to obtain desired system performance. The capillary''s ma. imum departure from true straight (camber) correlates inversely with lasing eff i ciency. We report here a simple non-contact method and instrument for measuring camber an extension of qual i tative visual inspection practice . A diffusely ii luminated occulting stop is projected so as to almost fill the entrance end of a capil lary. Multiple internal reflections produce a manifold of reasonably sharp concentric virtual rings. We show how qrazinq incidence (paraxial) meridional ray reflec tion optics relates observed nonconcentricity of the first ring to capillary camber. For capillary dimensions of interest (13 mm diameter 8-50 cm lenqth) the sensitivity of camber measurement is approximately 1 mil ( 025 mm). Polaroid pho toqraphy is currently used to record images for camber determination the method lends itself to automation through the use of a CCD camera whereby laser tubes could be inspected serially or in batches. 1.

The alignment of incoming material is one of the most crucial steps in the smooth and even flow of in-line processing systems for many applications. Examples include printed circuit board manufacturing in wave solder body alignment of automobiles for welding quarts or glass substrates for the production of diffraction gratings or lenses and fiber and cable extrusions. Many of these process flow environments use lasers or optical systems to insure accurate alignment immediately before the next processing step occurs. Another prime application involves using optical measuring to align film before deposition on the acetate film used as a substrate. A non-contact three-dimensional inspection system can be used for accurate alignment of the incoming film as well as providing correction constants to the deposition and/or film handling system. Along with the mechanical alignment the dimensional measurement system can find or recognize features or datums on the film to optimize positional alignment within the deposition area rather than only aligning to the relatively coarse position obtained by the using the film (substrate) edges and frame to frame markers. Interfacing the vision system to the external film handling system will be discussed along with the overall system design goals criteria and changes made during to empirical testing.

The Faraday Rotation (FR) and the magnetic properties of single crystals Gadolinium-Bismuth Iron Garnets are investigated in the temperature range covering the magnetic ordering domain. The temperature and Bi content dependences of FR are reported at 1. 15 micron wavelength. These results are compared to the FR induced by lighter rare earth (Ce Nd Pr) substitutions. At room temperature a large increasing of the M. O. efficiency is observed. I -

A broadband optical monitoring system to assist with the control of complex filter designs has been implemented on a newly installed Molecular Beam Deposition (MBD) facility which has been adapted for the growth of optical thin films. When depositing a multilayer structure like a Fabry- Perot etalon with very narrow features whose location depends upon a precise optical thickness the broadband optical monitor is an essential addition to process control. In addition to providing the capability to observe the growth of a sensitive optical feature the broadband optical monitor is used to calibrate other process control methods. This saves a considerable amount of processing time and demonstrates the cost effectiveness of such a system. By the judicious use of broadband optical monitoring a very high degree of control and efficiency is added to MBD processing of optical thin films. 1.

There have been made some attempts to transfer the advantages of FT-JR to industrial use. Commercially available research grade instruments have been large and rather expensive. However in many potential applications only medium resolution is required which means that the mirror displacement in a Michelson type interferometer remains short and computation of the Fourier transform can be executed by a small computer. Medium resolution gives also other advantages in spectrometer design simple source and detector optics less severe requirements for mirror transport and small size. We have used a Michelson type interferometer where the moving mirror is suspended by two flexures and driven by a coil actuator. Displacement of the mirror is monitored using moire transducer which is much smaller and has better thermal stability than the conventionally used HeNe laser. The beamsplitter is a standard CaF2/Si and a thermoelectrically cooled PbSe is used as the detector. In the present prototype data is transferred via parallel bus to a PC/AT compatible computer where the necessary mathematics is done. The spectral range is from 5000 to 1800 cm1 with resolution better than 8 cm1. Interferograins can be recorded several times per second and the computation time for a 2000 point spectrum is 10 seconds. Results of environmental tests carried out for the spectrometer will be presented. The results show that it is possible to construct a simple rugged and inexpensive FT-IR spectrometer

A new type of semiconductor emitter based multichannel spectrophotometer has been designed and tested. The spectrophotometer consists of a small electrically conirolled narrow band light source an optical receiver and microprocessor electronics for data processing. The light source is based on a 32-element GaAs and GaAIAs LED chip array which is connected to a diffraction grating and feedback optics. The source is capable of emitting intensity-stabilized single-beam narrow band light pulses. The wavelength of the light pulse can be selected by the electronics without using any moving parts. The optical mechanical and optoelectronic parts of the source have been integrated to form a compact hybrid construction. Main characteristics have been tested with an experimental 32-channel spectrophotometer designed for the wavelength range 810 nm - 1060 nm. Measured wavelength half-power bandwidths are 8 nm and channel separation is 7. 5 nm. A single spectrum scan can be recorded in 8 ms. 64 scans are averaged by the microprocessor electronics and data is transferred to a PC for a multicomponent spectrum analysis program. Output light power level is better than i05 times the averaged detector noise level. The wavelength range used is optimized for near infrared transmittance (NIT) analysis of agricultural products. 1.

This paper discusses the advantages that can be achieved by using integrated multichannel detectors instead of the traditional filter wheel construction in process analyzers and presents four accomplished applications. Integrated multichannel detectors include several parallel detector elements each equipped with a specific interference filter and a Peltier cooler in one hermetic package. Advantages gained by filter integration are good withstanding of ambient stresses and low price due to small size. Multichannel detectors enable the use of different chopper techniques and rugged miniature and highly reliable analyzer constructions. Furthermore multichannel detectors provide exactly simultaneous measurement at each wavelength. This minimizes noise caused by rapid variations in fast moving nonhomogeneous process streams. The first application described is a two wavelength water monitor designed for on-line measurement of water content in lubricating oils. It has to meet high temperatures and high relative humidities in production plant environments. The oil analyzer is an advanced instrument that continuously measures oil content of water effluents in marine and land based applications. The peat moisture meter is a rugged portable NIR instrument constructed without any moving parts. Finally a four-wavelength NIR reflectance instrument is described. In a pilot application in a wood grinding plant the instrument with fibre optics is used to achieve a true in-line moisture measurement of the pulp stream having a speed of 15 - 40 rn/s and temperature of 125 - 145 OC. 1.

A Laser transducer has been designed and built which can be used for field measurement of structural vibrations in the audible frequency range. The main design features of the laser transducer are the use of Acousto-Optical Modulators for generation of a frequency offset in the interferometer the use of optical fibers and an increase of the modulation index of the offset frequency and the dynamic range of the frequency demodulator. A detection limit of 5lO ms ''/JHz was realized with this non-contact transducer which is much lower than that of commercially available instruments. 1 .

It had been considered that the use of optical systems in potentially explosive atmospheres did not constitute an explosion risk. It has been established that very small objects heated electrically or optically can ignite such atmospheres. This paper summarises work carried out by the author and others to investigate the effects of power object size the nature of the flammable gas or vapour and the nature of the heated object. It has been shown that for all the gases and vapours tested with both catalytic and non-catalytic objects an apparent ignition boundary exists. The use of tethered objects and free" falling dust particles has shown that there is an apparent safety margin between the two cases. The work included objects which are inert combustible or metallic to determine the effect of target material on the power required to cause ignition of the flammable gas or vapour and flammable materials having a range of ignition temperatures and ignition energies. 2.

The efficiency of plasma assisted deposition processes such as reactive ion plating with regard to the densification of the deposited thin films depends strongly on the arrival rate ratio of ionized species (atoms molecules) to the total influx of vaporized coating material. While it is relatively easy to measure ion beam currents produced by an auxiliary ion beam source (for example a Kaufman gun) it is much more difficult to measure ion currents in plasma processes. Typical probe measurements change the plasma conditions almost instantaneously. An optical fiber Faraday ring ammeter initially developed for space plasma research provides for a non-invasive measurement of ion currents present in plasma assisted deposition processes. We will be discussing the principles and the potential use of such a device in a high vacuum box coater equipped for low voltage reactive ion plating deposition. 1.

An optical-fibre sensor based on the phase of the signal reflected from a stack of 5i02/Si3N4 layers grown on silica in LPCVD is described in detail. This sensor is an example of a rather straightforward embodiment within the wide range of possible reflection-based optical fibre sensors. The various options allowing more refined solutions matched to the measurement problem are discussed in more general terms. 1.

This paper describes a fiber-optic interferometer which uses two laser diodes in a modified Mach-Zender configuration for testing aspherical surfaces with phase shift technique and a possibility to implement two wavelength technique. Experimental results show that this type of interferometer is very useful for in-process control directly on a diamond turning machine, the test element still attached to the chuck.

A signal processing method is proposed for optical nhase measurement from spatial carrier frequency interference fringe pattern. The intensity model of the interference pattern is adapted to the measured intensity array of the interferogram using a parameter-adaptive estimation algorithm to identify the model parameters. The algorithm is implemented in a digital interferogram analysing system for applications in precision surface microprofilometry and roughness measurements. 1.

The application of high energy lasers for material processing requires a high beam quality. This is e. g. determined by the image quality of the optical elements used for beam guidance and shaping. Up to now in the construction of the elements several influencing parameters that occur during laser processing were largely neglected. Reasons for this are the limited knowledge about the operational performance of optical elements for high power lasers (up to 25 kW) and the difficult measurement of the occuring deformations and displacements. Responsible for the deterioration of the desired image properties of the optical elements are on the one hand manufacturing inaccuracies and on the other hand statical dynamical and thermal process forces. Statical forces result from the mounting of the optical components and the applied coolant pressure. Dynamical forces can occur due to vibrations of the mechanical components of the beam guidance and fluctuations of the coolant pressure. The absorption of a small part of the incident laser radiation leads to a heatup of the optical element resulting in a time and spacedependent deformation of the optics. The statical dynamical and thermal deformations and displacements occur simultaneously. A systematic analysis of the operational behavior requires a separated consideration of these parameters. Only this proceeding can lead to a weighting of the influencing parameters. Using holographic interferometry such a separated consideration of the different influences becomes possible. It

Increasing use of electrooptical imaging and detection systems in thermography high density information storage laser instrumentation and X-ray optics has led to a pressing need for machinecompatible sensors for the measurement of surface texture. This paper reviews recent advances in the use of deterministic and parametric noncontact methods for texture measurement and justifies the need for objective simple and yet precise means for displaying the microfinish of a machined surface. The design of a simple two channel phase contrast microscope is described which can be calibrated by test pieces and used as a means for optimising the process parameters involved in the generation of high quality surfaces. Typical results obtained with this technique including dynamic range and ultimate sensitivity are discussed. 1 . NEED FOR SURFACE METROLOGY Surface quality has a direct influence on product acceptability in many different industries including those concerned with optoelectronics and engineering. The influence may be cosmetic as with paint finish on a motor car body or functional for example when excessive wear rates may occur in a bearing surface with inadequate oil retention. Since perfection can never be achieved and overspecification can be costly it is clearly necessary to be able to define thresholds of acceptance in relation to different situations. Such thresholds do of course require agreed methods of measurement with traceability to national standards. The current trends in surface metrology are towards higher

Parameters which describe the surface topoqraphy in terms are the spatial frequencies the qr of the siope They will become hiqher values f the object under investigation is a rough sample. The range of these parameters what can be detected is limited by the method o measuremnt including signal evaluation. The aim of this paper is to deal w)th the range of these parameters using the method of spatial heterodyne technique: I

A novel method for simultaneously measuring of form and roughness of the diamond turned surfaces has been developed. A laser beam has been applied to scan the surface under test the scattering patterns have been received by a CCD array with 2048 sensor elements the deviation of the specular reflection gives the information of the surface slope which can be integrated to yield the surface form. The surface roughness is described by scattering pattern. Furthermore the scattering patterns can also be used to diagnose the working conditions of the machine which is used to manufacture the optical surface under test. Finally some factors which have influences on the light scattering method have also been discussed. I .

The influences of thermal expansion of the cutting tool on the shape deviations of faced metal-mirrors are discussed. Measurement results of the temperature behaviour of the cutting tool during machining are compared with the surface shape of produced workpieces. Correlations between the measured temperature variations and the generated surface profile are presented in this paper. 1.

In micro machining. as in conventional machining. often machine vibration limit the attainable surface quality. The picture of the machine vibration created on the worked surface follows an aliasing principle. The exciting vibration undergoes a frequency and amplitude transformation. The transformed vibration is passed to the emerging surface. The relationships between cutting parameters. vibration frequency of the machine structure and the shape of the emerging surface are examined. The results show that for particular conditions of vibration frequency and cutting parameters the effects of machine vibration on the emerging surface are minimal. Knowledge of these relationships allows the optimization of the obtainable surface quality. 1.

In this paper the equations that describe off-axis conic surfaces for a four axis approach to non-axisymmetric surface generation are derived. In addition considerations that minimize the fourth axis range of motion are reviewed. An example using a well known segmented astronomical mirror is used to illustrate these considerations.

Sensitivity in speckle metrology is interpreted in the terms of the spatial frequency which is encoded in the double-exposure specklegram. The spatial frequency distribution in specklegrams depends on the character of the object surface and on the configuration of the recording system. Optimization of the optical transfer function of the recording system and treatment of the sample surface so as to broaden the spatial frequency bandwidth are two key approaches for sensitivity enhancement. The objective speckle method offers a capability for accurate optical recording of the specimen surface details. Finely polishing an object surface and replication of a high frequency grating onto the specimen surface yields a fully defined high frequency spectrum. Experimental results demonstrate that the sensitivity of speckle metrology can be controlled within wide margins from values typical of geometric moire to those comparable to moire interferometry. 1.

The ability of moire deflectometry to measure surface quality is compared to other optical probes. The comparison is done using the amplitude - wavelength (A - W) diagrams introduced by Stedman. Two modes of analysis allow the extension of the amplitude and wavelength ranges over many orders of magnitude. In the flatness mode, the actual profile is calculated from the fringe slopes using an adaptation of the phase shift method. The range of amplitudes covered by this mode is from around A = 100 nm (at wavelengths down to 50 jim) to over 100 jim at W = 50mm. In the roughness mode the autocovariance function is calculated from measurements of fringe contrast versus sensitivity (or shear) of the instrument. Resolution extends to several nanometers of amplitude and a few microns in wavelength. The tunable sensitivity of the moire deflectometer allows a considerable overlap between the flatness and the roughness modes of operation. Both fringe shifts and contrast are measured from the same deflectogram thus yielding a dynamic range much wider than those of other optical methods. The above figures refer to the Rotlex Optics OMS -400 which is a general purpose instrument. The A -Wranges may be extended in certain directions by building more specialized instruments based on the same technique. However, such extensions may reduce the range in other portions ofthe A -W space. The method is demonstrated using various types of surfaces.

The growing face of LIJO3 crystal was studied by means of ellipsometry and interferometry . izi situ. Two phenomena were observed: the existence of solution boundary layer adjacent to the growing face and the formation of zonar defect structure of the crystal. The thickness of the boundary layer is estimated to be about 50 nm. Refraction index of the layer is 0. 02 higher than that of the bulk solution. The formation of zonar structure was observed in the form of spontaneous inclusion of quasi-two-dimensional layers in the growing crystal. Mean distance between them was estimated to be 10 aim. 2 .

The results achieved by 3oviet specialists over the past 3-5 years in the field o technology of finish machining of optical parts are presented. 1 .

Abstract not available.