|M.Sc Student||Rosenblatt Florence|
|Subject||Measurement Methods for Aero-Optical Phenomena and|
Restoration of Images Distorted by Them
|Department||Department of Aerospace Engineering||Supervisor||Professor Josef Stricker|
In the first part of our work we propose a new method for quantitative measurement of schlieren images: the heterodyne schlieren system. This method is based on the measurement of phase differences between two photo-detector signals as compared to intensity variations that are measured in the conventional schlieren method.
It is shown, both theoretically and experimentally, that measuring the phase shift between the two signals is an accurate way of evaluating the refractive-index gradients of a phase object. The system is sensitive, accurate; automating is possible.
In the second part of our work we propose a concept to restore, on board of flying aircrafts, images that have been blurred by aero-optical effects which are due to the turbulence around the aircraft. We suggest a system composed of three subsystems to accomplish the tasks of the restoration process. The three tasks are: to measure the aero-optical effects, to image a far away object and to restore the real image of the object using the data obtained from the two first parts of the system. Those three tasks have to be carried out almost instantaneously. The first subsystem is a conventional schlieren system; images of objects that are far away from the aircraft, are taken by the second subsystem which is a regular imaging system. The restoration process is carried out, without a priori knowledge of the object, by the third subsystem which is composed of computational equipment. We carried out laboratory experiments of blurred objects caused by frozen turbulence and restored them accurately.