Arrangement and method for interference correction of imaging flow measurements

Abstract

Optical interference is generated by often time-varying boundary surfaces between flowing fluids with different refractive indices, such as a boundary surface between water and air with an open water surface. Optical flow measurement processes through boundary surfaces are affected by such disturbances, which can lead to significant measurement deviations or may even completely prevent the performed measurements. The present invention helps to solve this metrology problem by proposing an arrangement (1, 1a, 1') and method for instantaneous and hardware-based correction of optical disturbances caused by undulating boundary surfaces (211). To this end, a wavefront modulator (5) is introduced into the beam path of the optical measuring method, which modulator actively compensates for optical disturbances by means of a control system. The invention enables light flow measurements through undulating boundary surfaces. It is not limited to a single flow measurement technique, but can be implemented in all known imaging methods. The invention can be used in a variety of technical applications. Some examples include: liquid-air boundary surfaces, such as in water channels with open surfaces; thin-film flow, such as in process technologies for cooling, purification, or distillation; fluid jets, whose surfaces undulate on all sides; Measurement of air bubbles present in suspended droplets or droplets or liquids adhered to opaque substrates. The invention is also suitable for correcting disturbances due to temperature gradients in combustion, pressure gradients such as in pressure fluctuations or concentration gradients such as in electrolytic processing.

Description

technical field [0001] The present invention relates to an arrangement and a method for interference correction of a flow measurement method, in particular an arrangement and a method for interference correction of an imaging flow measurement method. Background technique [0002] Many treatments in chemical engineering involve fluids with different refractive indices separated by boundary surfaces. This boundary surface typically changes with time. The resulting refractive index fluctuations represent time-varying fluctuating optical disturbances. This can greatly reduce the performance of the optical measurement method or make the measurement impossible at all. For example, in an open surface in a pool where waves may form, light rays are randomly refracted at the water-air boundary surface, and using this boundary surface to measure flow velocity in water is heavily affected by disturbances. Fluctuating boundary surfaces are therefore a major challenge for flow measurem...

AI Technical Summary

Problems solved by technology

Scattering of light on tissue results in multiple reflections, which prevent any defined boundary surfaces from forming

Disadvantageously, the correction of optical distortions on the retina can thus only be performed in sections, ie line by line and thus on a small scale, since the first module has a line scanner for scanning the eye for this purpose

It is therefore impossible to correct the entire field of view instantaneously

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