25 August 2018 Interferometric velocity measurements through a fluctuating interface using a Fresnel guide star-based wavefront correction system
Hannes Radner, Lars Büttner, Jürgen Czarske
Author Affiliations +
Abstract
To improve optical measurements, which are degraded by optical distortions, wavefront correction systems can be used. Generally, these systems evaluate a guide star in transmission. The guide star emits well-known wavefronts, which sample the distortion by propagating through it. The system is able to directly measure the distortion and correct it. There are setups, where it is not possible to generate a guide star behind the distortion. Here, we consider a liquid jet with a radially open surface. A Mach–Zehnder interferometer is presented where both beams are stabilized through a fluctuating liquid jet surface with the Fresnel guide star (FGS) technique. The wavefront correction system estimates the beam path behind the surface by evaluating the incident beam angle and reflected beam angle of the Fresnel reflex with an observer to control the incident angle for the desired beam path. With this approach, only one optical access through the phase boundary is needed for the measurement, which can be traversed over a range of 250  μm with a significantly increased rate of valid signals. The experiment demonstrates the potential of the FGS technique for measurements through fluctuating phase boundaries, such as film flows or jets.
© 2018 Society of Photo-Optical Instrumentation Engineers (SPIE) 0091-3286/2018/$25.00 © 2018 SPIE
Hannes Radner, Lars Büttner, and Jürgen Czarske "Interferometric velocity measurements through a fluctuating interface using a Fresnel guide star-based wavefront correction system," Optical Engineering 57(8), 084104 (25 August 2018). https://doi.org/10.1117/1.OE.57.8.084104
Received: 7 May 2018; Accepted: 7 August 2018; Published: 25 August 2018
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Cited by 2 scholarly publications.
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KEYWORDS
Wavefronts

Velocity measurements

Interfaces

Calibration

Liquids

Stars

Interferometry

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