In our previous works, we presented a zoom system and image stabilization design based on deformable mirrors (DMs). According to the high bandwidth and free edge characteristics of the piezoelectric deformable mirror (PDM), we tested the system’s image-stable capability. We found the PDM could realize some tilt displacements while keeping a certain stable surface shape, it could obtain higher image stabilizing precision when integrated with the traditional mechanical image stabilization systems. In the design of the image stabilization system, the PDM’s tilt displacement range is a key factor for consideration. So in this paper, we carried out a tilt displacement range testing experiment by using the OKO’s 37-channel PDM. We measured and analyzed the variation of the tilt displacements in optical image stabilization process, and calculated the maximum tilt angle as the PDM surface shape was stabilized. We built an experimental platform consisting of a fixed target, an imaging system based on PDM, and a CCD camera. We used the ZYGO interferometer as an evaluation instrument to measure the surface shape stability. When the PDM surface had a tilt displacement, the image point of the fixed target on the camera sensor shifted correspondingly. The tilt angle of the PDM could be obtained by calculating this shift. The results showed that the maximum tilt angle of the PDM was 0.2mrad. The paper also analyzed the experiment errors when concerning about the off-axis error of the PDM deflection center.
In this paper we propose a ray tracing method in 3-D space. This method, based on ABCD ray transfer matrices in 2-D spacey, is deduced to establish the matrix expression for ray tracing in 3-D space. In order to solve the attitude control problem of the plan mirror in image stabilization system, we construct a mathematical model to describe the ray passing process from incident plane, mirror reflection, to the next optical plane. Two 2*2 ABCD submatrixes, for two 2-D subspaces, have been used to describe the propagation rules of ray in a 3-D space. Furthermore, the stabilization formula has been deduced. In this way, the offset angle for stabilization and coordinate of ray in space can be got. With the simulation experiments, we verified the effectiveness and accuracy of this mathematical model. The method we put forward has the characteristics of universal and simple. This 3-D ray tracing method could be further applied to other optical area.
A four-group stabilized zoom lens design of two focal-length-variable elements was discussed in our early work. The focal-length of the zoom system could be adjusted by tuning the surface shape of focal-length-variable element. In this paper, we propose to use the deformable mirror (DM) as the focal-length-variable device, and then we need to control the DM to forming the required surface shape and analyze the errors between actual surface and theoretic surface. This lays the foundation for analyzing the focusing zoom errors of the stabilized zoom lens in the zoom process. This paper firstly introduces a DM flatten method applied for using OKO Technologies’ Piezoelectric Deformable Mirror (PDM) and analyzes the high order errors of flattened surface with the help of ZYGO interferometer. Then we study the method of DM control to form sphere surfaces with different curvature. The analyses of the high order error of the actual surface and the measurement of the curvature range of the sphere surface are also included in this paper.
A novel approach is proposed to extract the tree crown from remote sensing image.The method is based on
Reversible Jump Markov Chain Monte Carlo sampler(RJMCMC), and improved data term is developd to describe the
tree crown, and jump and diffusion strategy of sampling is employed to optimize the energy function. Similar or better
extracting result is achieved with great efficiency , and the pre-segmentation is not need. The mothod is verified on
remote sensing images