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Laser Flatness Measuring Instrument

Interferometric measuring instrument TOPOS for the two-dimensional and contactless flatness testing. Due to the four calibrated sensitivity settings of 0.5, 1, 2 and 4 μm per interference fringe, this instrument will not only be suitable for the measuring of reflective surfaces, but in particular for fine-finished surfaces such as lapped surfaces, even with coarser grain, or for finish-ground surfaces. The instrument can be extended to a complete computer-aided measuring system for a two-dimensional determination of the surface shape supplying a quantitative output and a varied graphic representation of the relevant results (picture). The graphics can be output on different printers. The absolute solute measuring accuracy is down to 0,1 μm. The measuring range is up to 100 μm. Automatic measuring procedures can be programmed and stored. Measurements can be stored for comparison with reference surfaces or for the determination of wear.

A laser flatness measuring instrument now permits contact-free flatness
measurement with the accustomed quality of 0.3 microns stripe pattern. This now also permits testing of highly accurate, polished surfaces without
contact. The test results shown on the video monitor can be printed out and
submitted with the workpiece as a proof of quality. This clear advantage is
now a necessity for QA (quality assurance).

In combination with computer evaluation, this clears the way for automation of the entire lapping and polishing process. In this case, handling systems transport the work-piece under the optical system, or from the optical system into the prepared packages.

Figure 68:
Evaluation of a phase pattern and three-dimensional representation of the measured surface.
Planarity error less than 2 microns

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