Micro system currently is the mainstream of application and demand of the field of micro fabrication of civilian and national defense. Compared with the macro assembly, the requirements on location accuracy of the micro-assembly system are much higher. Usually the dimensions of the components of the micro-assembly are mostly between a few microns to several hundred microns. The general assembly precision requires for the sub-micron level. Micro system assembly is the bottleneck of micro fabrication currently. The optical stereo microscope used in the field of micro assembly technology can achieve high-resolution imaging, but the depth of field of the optical imaging system is too small. Thus it’s not conducive to the three-dimensional observation process of the micro-assembly. This paper summarizes the development of micro system assembly at home and abroad firstly. Based on the study of the core features of the technology, a program is proposed which uses wave front coding technology to increase the depth of field of the optical imaging system. In the wave front coding technology, by combining traditional optical design with digital image processing creatively, the depth of field can be greatly increased, moreover, all defocus-related aberrations, such as spherical aberration, chromatic aberration, astigmatism, Ptzvel(field) curvature, distortion, and other defocus induced by the error of assembling and temperature change, can be corrected or minimized. In this paper, based on the study of theory, a set of optical microscopy imaging system is designed. This system is designed and optimized by optical design software CODE V and ZEMAX. At last, the imaging results of the traditional optical stereo microscope and the optical stereo microscope applied wave front coding technology are compared. The results show that: the method has a practical operability and the phase plate obtained by optimized has a good effect on improving the imaging quality and increasing the depth of field.
Reflective zoom system is widely used in the design of large size, wide spectral, high resolution system due to its great superiority in compacting size, system weight, aperture size, free chromatic aberration and thermo-stability. But for coaxial system, its disadvantage of obstruction renders the FOV (field of view) and light utilization rate unsatisfactory. Thus, to make the secondary and tertiary mirror off-axial is a good choice for optical designers. However, there are two problems in the alignment of off-axis zoom optical system. First, the Seidel aberration theory is not applicable for a system without rotational symmetry. Second, it is hard to control the misalignment status when zoomed. To solve this problem, the vector aberration theory is selected to analyze the off-axis three-mirror zoom system. When small perturbation is applied to the system, coincident with the alignment in reality, the residual aberration varies along with the movement of secondary and tertiary mirror. As the result, aberration character of misalignment three-mirror zoom system is provided, which offers guidance for misalignment determination and makes sure of the normal operation of the zoom system. This paper makes description of our experiment on an off-axis three-mirror zoom system and furnishes the figure of sensitivity in different zoom position. The conclusion may provide a reference to the vector aberration theory study on off-axis three-mirror zoom system and computer aided alignment.