Fourier ptychography (FP) has emerged as a powerful tool to improve spatial resolution. In order to apply FP technique to long-distance imaging for example remote sensing, many factors have to be overcome, such as diffraction, noise, turbulence and so on. In this paper, we mainly aims at studying the influence of atmospheric turbulence on FP technique, and using iterative algorithms to restore high-legible image and eliminating the residual errors, so it will meet or reach the diffraction limit of imaging system. The optical imaging systems which work in atmospheric circumstance will face the problem of imaging through atmospheric turbulence, which causing the blurring of image and badly impact the imaging capability of optical systems. We combine the FP with the theory of adaptive optics to achieve the effective recovery of the long-range target, which is subject to the effect of atmospheric turbulence. In this work, we firstly introduce a Fourier Series (FS) atmospheric phase screen generator to simulate the atmospheric-induced wave front phase distortions and represent the wave front phase as a two dimensional periodic function. Both the spatial and temporal correlations between wave-front phase screens separated by time and/or angle are properly modeled. And using the adaptive optics， we complete the correction of the atmospheric turbulence in large distance imaging through the developed algorithm. Then we propose using laser arrays coupled with coherent illumination as an effective method of improving spatial resolution in long distance images. We emulate a laser arrays realized by optical fiber conduction and also show that appropriate phase retrieval based reconstruction algorithm which can be used to effectively recover the lost high resolution details from the multiple low resolution acquired images. Finally we analyze the effects of the atmospheric turbulence on the reconstructed image quality. The results prove that under the influence of atmospheric turbulence at outer scale of 1-m, inner scale of 0.1-m, Fourier ptychographic reconstruction can obtain good image quality for object 200 meters far away. The spatial resolution is increased six-fold.
As a new kind of optical imaging technology, polarimetric imaging can be able to identify the target that may be difficult to conventional ones and can reduce the influence of stray and complex environment. It can efficiently increase the detection dimension of the information and increase capability of target imaging and recognition by imaging the polarization properties of the optical wave. The dissertation researches a type of simultaneous polarization imaging optical system with divided aperture. This system is adopted the identification system of polarization and morphological feature, which can improve the ability of space target classification and recognition. It also can be used as a space-based space target imaging system, which can be used for the classification and recognition of space target. Polarization optical system is adopted the structure mode of two-mirror reflecting systems and field correction mirror, pupil division and four zoning registration scheme of array CCD detector. The system technical parameters are F#/12.5, EFL 1500mm, FOV 0.47°. The size of CCD pixel is 12μm×12μm. The system can detect the light of 0°/45°/90° and visible light for 450-850 nm spectrum. It reached the conclusion that optical system imaging quality is close to the diffraction limit at the Nyquist frequency 41.70lp/mm though simulation test, the system can meet the imaging requirements.
An off-axis three-mirror detection system with a large field of view is designed in order to improve the space target detection capability. The optical system is a Cook-TMA with the focal length of 127mm, the F number of 2, the field angle of 25° × 25° and the spectral range of 400-700nm. The primary mirror and the tertiary mirror of the off-axis three mirror system are all designed by free form surfaces: the primary mirror is characterized by Zernike polynomial and the tertiary mirror is described by XY polynomial. At the same time, we analyze the related characteristics of Zernike polynomial and XY polynomial. The results show that the free form surfaces have great advantages in improving the field of view and the imaging quality of the off-axis optical system. The system has high energy concentration and good imaging quality, which can capture and track the target in a wide range is suitable for wide area target monitoring.
For 640 pixel×512 pixel cooled staring focal plane array detector, a VisSWIR wideband continuous zoom optical system with 7X zoom range is presented based on the pattern of the negative zoom group and compensating lens group. The zoom system provides continuous changed in the field of view from narrow to the wide. The zoom optical system works in the range of 0.4μm~1.7μm, F number is 4, the pixel of the detector is 15μm. It realizes 20mm~140mm continuous zoom with a smooth zoom path and provided high image quality with the whole zoom range, the zoom ratio is 7:1. The modulation transfer function(MTF) for the system is above 0.5 within the whole focal length range at spatial frequency of 34lp/mm and it almost approaches the diffraction limit. RMS value of spot diameter was investigation, the maximum distortion value is less than 5% and the surface type of all lens applied is spherical. Moreover, the cam curve after optimization is given by the optical design software Code V macro. The design results provide that the zoom system has the small size, high resolution, excellent image quality and the smooth cam curve etc.