The method for generating temporal flat-top waveform and spatial flat-top profile femtosecond pulse beam by phase and polarization controlling is proposed and demonstrated. Based on direct wave front phase modulating, flat-top spatial intensity distribution can be obtained. Combining a folded 4f zero-dispersion system with a polarization controlling setup, the temporal flat-top waveform is generated. Experimental results indicate that for the input both temporal and spatial Gaussian pulse beam with 363 fs temporal width and 1.5 mm beam waist, the temporal width of the output shaped pulse beam is 1.2 ps and 1.9mm beam waist, and the rms variation is about 9.2%, which prove that the temporal flat-top and spatial flat-top femtosecond pulse beam can be generated effectively.
Camera calibration is a necessary step in 3D vision measurement. Classic technique uses a volume calibration pattern with control points distributing in a 3D space, which is expensive to be made and difficult to be used everywhere. Zhang proposed a planar pattern based calibration method, making the calibration process accessed to almost everyone. Nowadays, consume camera with zoom lens is populated and always used for measurement. Such a camera has the advantage to zoom the lens to get a maximum resolution images for objects with different sizes at an adequate distance. The size of Zhang's planar pattern is fixed, not suitable for a zoom lens. In this paper, a multiple sheets planar pattern is used to deal with this situation. The calibration pattern is made of 1-4 sheets of planar pattern distinguished with coded markers, and the total size .can be modified by changing the distance between the planar sheets or the number of sheets to suit for different lens setting. Such composed calibration pattern is easy used both for laboratory and industrial situation. In the calibration process, one sheet of the planar pattern is first used to get an initial calibration according Zhang's method, and also the initial coordinates of all the control points in the sheets of planar patterns. Then a bundle adjustment algorithm is carried out incorporating of the planar constraints and distance constraints in the planar patterns to obtain a set of precision parameters. Some examples are presented to show the effeteness of the method.
An information field command values emulation system was designed to meet the requirements of testing and emending the information field testing devices. According to form principle of information field command values, the FPGA (Field-Programmable Gate Array) was used to design the emulation system of information field command values, drive the laser to produce simulate information field command values. By comparing the simulate values and the theoretic values, it can be educed that the precision of the simulate values is high enough to verified the feasibility of the emulation system, therefore it can be concluded that the emulation system can meet the corresponding requirements.
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