Freeform Surface Graded Optimization of Deformable Mirrors in Integrated Zoom and Image Stabilization System Through Vectorial Ray Tracing and Image Point Freezing Method

Abstract

Integrated zoom and image stabilization system based on deformable mirrors (DMs) has advantages of miniaturization, rapid response and low energy consumption. Integrating the two capabilities on one DM-based imaging system poses considerable challenges. First, limited DM stroke will result in limited changeable aberration correction value for zoom and image stabilization. Second, the DM-based off-axis imaging system suffers a simple relative movement between optical axis and objects caused by carrier vibration may result in complicated optical system aberrations. To address these challenges, a reasonable assignment of the changeable aberration correction value for zoom and image stabilization is needed. Image stabilization and aberration correction in DM-based off-axis imaging system, should be considered when translation or rotation occurs. To troubleshoot the assignment issues of the correcting aberrations, we propose a graded optimization method which comprises two steps. To troubleshoot the image stabilization and aberration correction issues, we introduce vectorial ray tracing method and image point freezing principle to transform the aberration correction problem into an optimization problem of image coordinates. With the proposed method, we construct practical integrated freeform surfaces of DMs for a space camera with three mirrors. The sagittal heights of designed DM surface profiles are limited within their available stroke.

A Method to Increase the Field of View of an Imaging Optical System

“…smooth constraint term used to suppress noise and ringing effect, f ˆis the approximate solution of the object, g is the image received by the detector, γ is the weights of smooth constraints, C is the Laplacian Operator, and p corresponds to different norm types. Finally, we use the ADMM (alternating direction method of multipliers) method to obtain the optimal solution f ˆof (11) and complete the image restoration.…”

“…( 3) and ( 4) are combined to calculate the wavefront aberration and construct the generalized pupil function, and the Fourier transform is used to obtain the PSF model. Finally, the theory proposed by Filip Sroubek [30] and others is used to decompose the PSF model established in the previous step by a singular value to obtain the base filter matrix B and the coefficient matrix M. Combined with the blurred image g received by the detector, it is possible to establish (11). The flow chart of the method is shown in Fig.…”

“…This requires a linear array detector to receive the image and obtain the rectangular field of view by scanning and swinging [10]. In order to realize the imaging of an off-axis three-mirror optical system with a rectangular field of view (expanding the field of view in the Y-direction), scientists use free-form surface optical elements in the system to correct off-axis aberrations and increase the field of view [11][12][13][14][15][16][17][18]. Optical free-form surface is a non-rotational symmetric surface, which is different from the traditional surface types such as spherical surface, quadric surface and even aspheric surface.…”