Fourier components phase accumulation in observation of an object with an orbital telescope

1Kornienko, YV, 1Lyashenko, I, 1Pugach, VV, 1Skuratovskiy, SI
1O. Ya. Usikov Institute for Radiophysics and Electronics of the National Academy of Sciences of Ukraine, Kharkiv, Ukraine
Kinemat. fiz. nebesnyh tel (Online) 2020, 36(1):68-84
Start Page: Instruments and Devices
Language: Ukrainian

In the case of astronomical observations from the surface of the Earth it is difficult to obtain high resolution images due to the distorting influence of the atmosphere. There are two groups of methods for overcoming this influence. First ones are not interfering into the process of image forming, they are related to the processing of already registered images. The methods from the second group represent the construction of specific observational instruments. Putting the instrument out of the atmosphere also may be considered as a method from this group. In this case there is no atmosphere influence, and it is assumed that obtaining the images with diffraction-limited resolution is possible without additional efforts. The factors that may lead to phase distortions while observing with an orbital multi-mirror telescope are discussed. As a method for removing them the total phase accumulation method is proposed. It is designed for compensating the distortion of Fourier component phases, caused by the Earth’s atmosphere. Assumptions as to the statistics of phase distortions, used for its development, are quite general ones and not interfering for its application to space observations. Computer modeling is used to demonstrate the technique effectiveness and studying its possibilities in processing of images from a multi-mirror space telescope. Using of modeling as an instrument for research is motivated by the high cost and complexity of the real experiment, and the requirement of the correct image of an object for evaluating the method error. The aperture configuration of James Webb telescope under construction is used for modeling. The modeling was used to explain the different behavior of phase distortions between space observations and the observations from Earth’s surface. It is demonstrated that in case of space observations the total phase accumulation is required instead of the main phase values accumulation either. It is found that the dependence of the reconstruction error on the number of accumulated images has not monotonous behavior.

Keywords: complete phases accumulation, image processing, multi-mirror telescope, phase distortions, spaceborn observations

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