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Precision Instrument and Mechanology    Follow    
  This is an Open Access Journal Open Access journal
     ISSN (Print) 2304-1811 - ISSN (Online) 2304-182X
     Published by World Academic Publishing Homepage  [28 journals]
  • Optical Design and Optimization of CCTV Monitor Lens
    • Abstract: Optical Design and Optimization of CCTV Monitor Lens
      Pages 128-131
      Author Xuezhu Lin,Guohua Cao,Lijuan Li,Xin Yang
      A CCTV monitor optical system was designed by using Zemax (optical design and analysis software). The effective focal length of the system is 5 mm, the F-number and the full field of view angle is 2.8 and 70° respectively. The image sensor of the lens is 1/2 in CCD, whose pixel size is 6.5 um×6.5 um. To achieve the lens with the feature of compact structure and wide field of view (FOV), an inversed telephoto system is used to be compressed and simplified. Based on the characteristics of CCTV lens, a certain degree of field curvature is allowed to exist to keep a higher resolution. The result shows that only 5 spheric lenses can meet the requirements. The MTF value is above 0.3 within 0.7 FOV at the Nyquist frequency, the MTF values are all above 0.5 at the 1/2 Nyquist frequency. As various components are spherical mirror, the system with simple form and compact structure has the practical application value.
      PubDate: 2013-10-29
       
  • Fractional Axicon as a New Type of Diffractive Optical Element with
           Conical Focal Region
    • Abstract: Fractional Axicon as a New Type of Diffractive Optical Element with Conical Focal Region
      Pages 132-143
      Author Svetlana N. Khonina,Andrey V. Ustinov,Sergey G. Volotovsky
      We theoretically investigated the transverse parameters and the depth of the focal region formed by a lensacon (a tandem of a lens and an axicon). In this case the focal spot size becomes variable and it can be smaller than when optical elements are used separately. The concept of a new phase diffractive optical element (DOE) – fractional axicon – is introduced. It has a fractional dependence on the radial coordinate. Depending on the value of the power the fractional axicon allows to form either a decreasing scale or an increasing scale Bessel beams with a corresponding field depth extension. In the former case the fractional axicon is similar to the lensacon and in the latter case it is similar to the logarithmic axicon but there is no singularity in the centre. Thus, the offered element expands a set of the optical elements forming “light strings” actively used in metrology.
      PubDate: 2013-10-29
       
  • Improving the Optimization Performance of NSGA-II Algorithm by Experiment
           Design Methods
    • Abstract: Improving the Optimization Performance of NSGA-II Algorithm by Experiment Design Methods
      Pages 144-151
      Author Shidong Qiao,Xiang Dai,Zhong Liu,Jincai Huang,Guangying Zhu
      NSGA-II is an effective multi-objective optimization algorithm and how to further improve its optimization performance is an interesting but difficult problem. The Orthogonal Array method(OA) and the Taguchi method are two important kinds of experiment design methods. In this paper, the classical genetic operators are individually replaced by these experiment design methods to generate new individuals in NSGA-II. This results into two hybrid NSGA-II algorithms, whose optimizing ability is approved by the experiments on the typical multi-objective test functions, and the algorithm combined with Taguchi method is better than the other one with OA, while the calculation complexity of the former is a little higher. In fact, the differences between NSGA-II and the two hybrid algorithms are just the operations to generate new individuals, and the hybrid algorithms do not change any other operations of NSGA-II, which makes them easy for implementation.
      PubDate: 2013-10-29
       
 
 
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