| The Integral Field Unit(IFU)is an optical device that can realize the collection of three-dimensional celestial spectrum information.It can obtain the two-dimensional position information of the spectrum and the wavelength information of the spectrum at the same time.Solar physicists are committed to building large-scale coronagraphs to observe the evolution of the corona and the distribution of the corona’s magnetic field in order to predict the catastrophic weather in space and study the impact of solar storms and corona changes on the earth.In the design of the coronagraph,the K-mirror sector scanning is used to scan the corona by partitions,and then the light of each sector is coupled to the optical fiber of the IFU through the microlens array.Based on the construction of a large-scale coronagraph,this thesis designs an IFU microlens array suitable for the K-mirror sector scanning field of view.The microlens array has the characteristics of high filling rate,low aberration,energy homogenization and good optical fiber input focal ratio uniformity.It solves the problem that the energy contained in different microlens units is not equal when the coronagraph is observing the energy of the coronal magnetic field.Taking advantage of the characteristics of multiple imaging in the optical theory of the microlens array and the independence of each unit in the microlens array when imaging,a sector microlens array is designed.Each lens unit in the microlens array is sector,achieving a100% lens filling rate.The application wavelength of the lens array is 515～660 nm,the total number of microlens units is 510,the field of view corresponding to the observation sky is30",and the output focal ratio of the IFU is ≥F/6.The single side length of the single lens is not less than 300 μm,the number of layers of the microlens array is 15 layers,and the area ratio of the outermost single lens to the innermost single lens is between 1.2 and 1.3.In order to align the optical fiber array with the micro lens array with high precision,the microlens array is optimized,and the light of each single lens can be completely coupled into the optical fiber by using an optical fiber with a core diameter of 35 μm.Two optimization methods are proposed in the thesis.One is to adjust the curvature of each layer of lens to make the back focal length of each layer close.The maximum image spot radius is 3.022 μm,and the energy contained in the enclosing circle with the core center as the center radius of 17μm exceeds 90%.Another solution is that each layer of sector single lens is cut from a round lens of the same curvature.The maximum image spot radius of the obtained sector lens is1.993 μm.For each lens unit,more than 90% of the energy is concentrated in the containment circle with a radius of 15 μm with the core center as the center.This thesis mainly focuses on the relevant design of the sector microlens array in the sector IFU system.This design will provide the design direction for the sector microlens array in the sector coronagraph in the future.As a pre-research work,the finished product of this design can test the scientificity and rationality of the sector IFU system.As a key element in the IFU system,the microlens array will play a vital role in the performance of the optical system.This thesis mainly conducts related application research for the design of the large coronagraph,and proposes a new type of fan for real-time observation of the coronal energy distribution.The microlens array is designed and the related structure is optimized,and it satisfies the 100% lens filling rate. |
