Flatness is often decisively important for functional surfaces, with examples including components with sealing surfaces used in pressure and vacuum technology, as well as transparent films for displays, semiconductor elements, metal surfaces and ceramic surfaces. Determining percentage contact areas is a simple and reliable process too. In this context, the TopMap systems allow you to measure large surface areas and thus get fast, complete characterization of the workpiece.

Polytec is a world leader in technology for optical topographic measurement of large areas with nanometer precision. Determining parallelism, flatness, radii, steps, angles and other parameters are typical tasks for this technology. The areas to be examined are often situated in subjacent holes or differ a great deal in terms of height. But this is an easy task for Polytec’s systems in contrast to other optical measuring methods, such as coherent interferometry.

In many cases, the complete topography of a workpiece or object has to be checked, as is the case, for example, with the shock absorber component shown here or with other precision workpieces in the automotive industry, in aerospace development or in precision mechanics. Ceramic components, imprints, safety features and even forensic evidence can be analyzed with nanometer accuracy using white-light interferometry. Also, the demands placed on the warping and deformation of components such as printed circuit boards are forever growing as dimensions continue to shrink.

Oberflächenparameter

Very often, mechanical designs for workpieces include specifications for defined parameters such as roughness or ripple. White-light interferometers can acquire 3D profiles that require a very long measuring time if acquired using tactile processes within a few seconds, particularly for flat parameters. Such parameters – take the percentage contact area or frequency distributions, for example – can be determined quickly and easily. Roughness can be optically determined too, but the values can deviate from the results of tactile measurements to which the drawing dimensions and standards often refer. However, new guidelines for calibrating white-light interferometers give the user the assurance that the measured values can be traced back to calibration standards. Optical measurements also make roughness parameters available. Often, for instance, it is sufficient to decide whether the surface of e.g. dynamic sealing surfaces is too rough – which would lead to high friction losses – or too smooth, which could result in excessive adhesion.

A large vertical adjustment range is often the key to determining parallelism, height differences or angles between several surfaces. The TopMap series offers adjustment ranges of up to 70 mm, or 50 mm that can be used to measure surfaces that are separated from one another by large steps or are situated inside holes. The TopMap systems’ telecentric light beam path avoids shadowing effects.

Surface metrology integrated into production lines are highly effective. Testing samples at an early stage of the production cycle and identifying trends can significantly reduce production costs. White-light interferometers of the TopMap series are suited to use in a metrology chamber, located near the production line or installed directly in-line. The TopMap In.Line is the dedicated measuring system for production testing right in the manufacturing process. The compact sensor can be used in various mounting configurations in the production line and measures preset specifications like flatness or waviness within short cycle times and with complete coverage.

Determining the amount of material removed plays a key role when it comes to wear measurements. In this situation, the surfaces are often very jagged and the light reflected back shows great intensity differences. The SmartSurface scanning technology incorporated into the TopMap systems guarantees optimum results in such cases, too. Wear and tear studies are also traditional tasks for topography measurements. Examples of such tasks include performing a root cause analysis when brake disks have suffered wear and tear.

In industrial production, compliance with specified tolerances has to be checked as often as possible. This helps to ensure that defective parts are eliminated before any further processing steps are taken and that unnecessary costs are avoided. White-light interferometers can be used to quickly examine large areas of many surfaces for the number of defects, form deviations, ejections, missing connections or break-offs. Processes can be permanently or randomly monitored too. In many cases, the complete topography of a workpiece or object has to be checked.

NC machines often have to be properly adjusted to ensure that parts are manufactured to the required flatness and curvature values. Checking workpieces at an early stage during machine set-up helps to save both time and money. During this process, the relevant parameters are checked before production is started and the processing machines’ settings are optimized. Machine operation can also be monitored with ease.