Arrangement and method for disturbance correction for imaging flow measuring processes

Abstract

A generally time-varying boundary surface between multiple flowing fluids with different refractive indices, for example the boundary surface between water and air with a free water surface, represents an optical disturbance. Optical flow measuring processes that take place through the boundary surface are influenced by this disturbance, which leads to significant measurement deviations or even completely prevents measurement. The invention contributes to solving this technical measurement problem by proposing arrangements (1, 1a, 1') and processes for the instantaneous, hardware-based correction of the optical disturbances caused by a fluctuating boundary surface (211). For this purpose, a wavefront modulator (5) is introduced into the beam of the optical measuring process and, by means of a feedback control, actively compensates for the optical disturbance that is caused. The invention makes it possible to perform optical flow measurements through a fluctuating boundary surface. It is at the same time not restricted to a single flow measuring process but can be implemented in all known imaging processes. The invention can be used in a large number of technical applications. To bementioned by way of example are: liquid-air boundary surfaces, for example in water channels with an open surface; film flows, for example in chemical process engineering for cooling, cleaning or distillation; liquid jets with the surface fluctuating on all sides; measurements in levitated drops or drops adhering on an opaque underlying surface or gas bubbles occurring in liquids. The invention is also suitable for the correction of disturbances due to temperature gradients in combustion processes, pressure gradients, for example in the case of pressure surges, or concentration gradients, forexample in the case of electrolytic processes.

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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