A precise, non-contact measuring of structures, thickness and form deviation is of decisive importance for modern production methods. A measuring unit is described which senses the structures to be measured with a 1 μm Laser Focus employing the principle of dynamic focusing. An automatic focusing device with a precision of <2 nm provides constant 'contact' with the surface and the required lens movement is transformed into an analog displacement signal. Maximum vertical steps of up to 600 μm can be assessed. The highest measuring frequency is >600 Hz. In addition to a short introduction to the measuring principle, special emphasis is laid on practical applications in the sectors of glass material, roughness standard samples, diamond turned surfaces and soft materials.
"Evaluation Of A Commercial Microtopography Sensor", Proc. SPIE 0802, In-Process Optical Metrology for Precision Machining, (1 January 1987); doi: 10.1117/12.967117; https://doi.org/10.1117/12.967117