Study On Image Technology Of Optical System Of Fizeau-type Sparse-aperture

The spatial angle resolution is a important criterion for evaluating the detectingperformance of telescope optical system. In certain wave band, it is must to enlargethe diameter of aperture for gaining higher angle resolution, but limited by theoptical material, machining technics, cost, weight and volume, a large filled aperturesystem is very difficult to be manufactured. So, people want to search new theories,new method and new technologies, and the technology of optical system of sparseaperture is one of the important approaches for realization of super resolutionobservation of telescope optical system.This paper discussed the theory of improving system resolution with the imagetechnology of optical system of sparse-aperture, research sub-aperture array adaptedto the photoelectricity theodolite, built the experimental system of interference imageof double apertures, successfully finished the theory validating experiment.Firstly, introduce the research background and the developing status of the imagetechnology of optical system of sparse-aperture, introduce the sort of optical systemof aprse aperture and the main study contents. Analysed the image theory of opticalsystem of sparse-aperture, the formula of PSF and MTF were given, introduced themain aperture arrays and their MTF distribution, and the means of performanceevaluating of array was discussed.Secondly, three arrays——Golay-3type, Y type and equilateral pentagon type, which were adapted to photoelectricity theodolite, were found from the known arrayand the performance of these arrays were analysed. According to the result, theGolay-3array have the biggest sub-aperture, the difference between the maximumand minimum cut-off frequency of the Y type array is the biggest, the distribution ofMTF of equilateral pentagon type is most close to the circle. As all the known arraycould only adapted in the inside of tracking shelf, a new array, named quasi-crossarray, was invented, which apertures distribute in the inside and outside of trackingshelf. According to the result, the MTF distribution of quasi-cross array close tocircularity, and the equivalent aperture is bigger than2.7times of sub-aperture.Thirdly, briefly introduced the7kind of imaging aberration of optical system,mainly analysed the theory of achromatic and apochromatic, discussed the threeerror in the process of ray combination and their influence in the imaging. Theoptical system of Fizeau sparse aperture of multi-aperture was decomposed intothree sub-system designed independently. Structure of sub-aperture was thecassegrain type with achromatic collimated lens. There were two kind of raycorrector to be choosed. The ray combiner had5piece lens and was apochromatic.Any kind array could be realized by combined the sub-systems logical.As a example,the cut-off frequency and equivalent aperture of Golay-3type was calculated.Finally, based on the imaging thoery of optical system of Fizeau sparse-apertureand multi-aperture structure, the experimentation system of imaging system theotyvalidation of double-aperture was built. This system could realized interferenceimaging of double-aperture and validated the influence on system PSF by the pistonerror. From the experimentation result, it could be found that the resolution of doubleaperture system outclassed the single sub-aperture resolution, about2times, and theinfluence on the PSF, begot by the piston error, was accordant to the conclusion oftheory analysis and emulation in the main.