Multiple wavelength interferometry for distance measurements of moving objects with nanometer uncertainty

作者：Kuschmierz R^*; Czarske J; Fischer A

来源：Measurement Science and Technology, 2014, 25(8): 085202.

DOI：10.1088/0957-0233/25/8/085202

• interferometry
• absolute distance and velocity measurement
• moving objects
• measurement uncertainty

Optical measurement techniques offer great opportunities in diverse applications, such as lathe monitoring and microfluidics. Doppler-based interferometric techniques enable simultaneous measurement of the lateral velocity and axial distance of a moving object. However, there is a complementarity between the unambiguous axial measurement range and the uncertainty of the distance. Therefore, we present an extended sensor setup, which provides an unambiguous axial measurement range of 1 mm while achieving uncertainties below 100 nm. Measurements at a calibration system are performed. When using a pinhole for emulating a single scattering particle, the tumbling motion of the rotating object is resolved with a distance uncertainty of 50 nm. For measurements at the rough surface, the distance uncertainty amounts to 280 nm due to a lower signal-to-noise ratio. Both experimental results are close to the respective Cramer-Rao bound, which is derived analytically for both surface and single particle measurements.

• 出版日期2014-8