TOPOS interferometric measuring systems for non-contact flatness measurement of finish-machined parts

TOPOS interferometers operate according to the principle of grazing incidence of light. The flatness of also rougher parts can be measured, which show no more fringe pattern with optical flats or Fizeau-interferometers. Based on the interference pattern a computer calculates the flatness of the test object. Next to lapped or ground parts also polished parts can be measured. The parts may consist of diverse materials:

• metal (steel, aluminium, bronze, copper, etc.)
• ceramic (AL₂O₃, SiC, SiN, etc.)
• plastic material
• etc.

The interferometers can be placed in the production line, close to the processing machine. The absolute accuracy is up to 0.1µm over the entire measurement area.

Innovative arrangement of the measurement instruments

TOPOS interferometer have a reference surface at the bottom of the instrument and thus above the test object. Thereby, the measurement is performed without any contact and with an air gap between the test object and the reference surface. Due to this arrangement the TOPOS flatness measurement instrument has the following advantages:

• due to the non-contact measurement, there is the maximum protection of the reference surface, which reduces the maintenance costs substantially
• oil and other lubricants cannot reach the reference surface and/or reach into the flatness measurement instrument
• additionally the TOPOS flatness measurement instrument may be equipped with an encapsulation which provides further protection against dust or oil-bearing production environments

Measurement of large rings and surfaces

Due to the non-contact measurement, it is possible to expand the TOPOS flatness measurement instrument by a rotary or cross table in order to measure larger parts.

Simple adaptation to parts with different characteristics

With the TOPOS interferometer there is the option to select between 4 different calibrated sensitivity values. This enables the user to adopt the measurement to the flatness and roughness of the test object. The TOPOS 100 also allows a measurement with high numbers of data points of small parts due to the zoom lens.