Optical System Design For Wide-angle Of The Unmanned Airborne Grating Imaging Spectrometer

With the improvement of the importance about spatial information, conventionalsatellite and aerial remote sensing technology has been difficult to meet the applicationof emergency monitoring with the requirements of high resolution and fast time.Low-altitude UAV remote sensing system provides a new way for the special demand.Imaging spectrometer is an effective method for earth observation, which can obtainthe space and spectral information of the scene at the same time. It is loaded on thelow-altitude UAV after being miniaturized and lightweighted, which will fullyintegrate the advantages of the UAV and the imaging spectrometer, such that itbecomes a flexible means for earth observation.The paper is based on the optical system design of visible near-infrared (VNIR)hyperspectral imaging spectrometer from450nm to1000nm wavelength range withwide FOV and large relative aperture. The paper concentrates on the followingcontents:1) Firstly, the development of imaging spectrometer is introduced. Moreover, theresearch content is clarified. Then, the relevant theories of imaging spectrometer aredescribed, which provide theoretical basis for the optical system design of imagingspectrometer.2) Spectral imaging system with a convex grating is finally selected according tothe design index of the imaging spectrometer. Multiple structure optimization isadopted to realize the final design. Then, the MTF and SPOT are used to evaluate theperformance of the design, which shows that the spectral imaging system has a goodimaging performance, and satisfies the requirement of miniaturization and lightweightdesign.3) A double gaussian refractive system is selected as the initial structure of thedesign for the characteristics of wide FOV and large relative aperture and small focallength of the foreoptics. In the process of the design, the numerical aperture matching is considered with spectral imaging system. The telescopic system meets therequirement in image space. A two-layer HDOE with negative dispersive characteristicis used to eliminate chromatic aberration and the secondary spectrum within the widespectral band in the process of optical system design. All kinds of primary aberrationare corrected and balanced. The diffraction efficiency of two-layer HDOE is analyzed.The final design has a good imaging performance. Furthermore, it satisfies therequirement of miniaturization and lightweight design.4) In order to match the spectral imaging system and foreoptics system well, theideas of multiple structure optimization design is used again for the integrative design.The whole optical system has a good imaging performance according to the MTF andSPOT for evaluation of optical performance.It is proved that the optical systems designed and simulated in the optical designsoftware CODE V have good imaging qualities and satisfy the requirement ofminiaturization and lightweight design in the Low-altitude UAV.