Fiber-optic Sensors

Fiber-optic sensors of minimized dimensions may substitute tactile stylus systems in industrial production measurement technology. They scan the measuring object along a well-defined trajectory and the measured distance changes are displayed and analyzed in a 3D coordinate system.

The measurement technology group deals with interferometric fiber-optic sensors, which reach nanometer resolution. A micro-lens focuses light on the surface of the measuring object. The reflected light is again coupled into the fiber and analyzed.

The method of phase modulation uses a periodical change of the path length either in the reference or in the measuring arm of the interferometer and turned out to be very robust. The measuring frequency is twice the frequency of the path length modulation and, thus, data rates of more than 100 kHz are achieved with little effort.

S. Hagemeier, K. Bittner, F. Depiereux, P. Lehmann
Miniaturized interferometric confocal distance sensor for surface profiling with data rates at ultrasonic frequencies
Meas. Sci. Technol. 34 (2023) 045104

S. Hagemeier, S. Tereschenko, P. Lehmann
High-speed laser interferometric distance sensor with reference mirror oscillating at ultrasonic frequencies
tm - Technisches Messen, 86 (2019) 164-174

S. Hagemeier, M. Schake, P. Lehmann
Sensor characterization by comparative measurements using a multi-sensor measuring system
J. Sens. Sens. Syst., 8 (2019) 111-121

M. Schulz and P. Lehmann,
Measurement of distance changes using a fibre-coupled common-path interferometer with mechanical path length modulation,
Meas. Sci. Technol. 24 (2013) 065202 (8pp)