Search

In this paper,several aspheric testing methods for different fabrication steps and their new research progresses are introduced. Especially,we emphasis on the testing methods for precision polishing step,in which subaperture stitching interferometric testing and non-null partial compensating testing method are described in detail. Moreover,several combined interferometric testing methods which perform well in measuring large and steep aspherics are introduced. In addition,we provide a general description of free-form surface testing. The further development of aspheric surface testing methods is also prospected.

Based on the environment and nekton data obtained from seasonal surveys in Lidao artificial reef(AR) and control zones of Shandong province between May 2009 and February 2010,this paper analyzed the species composition of nekton community in the two zones.Variations on temporal-spatial distribution patterns and community structure of nekton community were determined by using Margalef′s species richness index,Shannon-Wiener diversity index,Pielou′s evenness index.The relationships between abiotic environmental variables and nekton community pattern were investigated with gradient analysis,combining Monte Carlo test to determine limiting factors affecting nekton community structure of artificial reef zones.A total number of 18 fish species belonging to 15 families and 8 orders were collected during the surveys.Sebastes schlegeli,Hexagrammos otakii and Hexagrammos agrammus were the most abundant species.S.schlegeli was the absolutely dominant species in weight composition of catch(41%).The species number and catch of nekton at AR were higher than that at the control site,but the difference was not significant(P0.05).The highest average CPUE by season of investigation zones appeared in the reef zone near shore(NA) and reached 830.24 g/(net·d) during the surveys.It was noted that the parameters of community structure were highest in spring or autumn.However,no significant differences were found in community structure parameters between artificial reef zones and the control zones(P 0.05).Cluster analysis showed that similarities among quadrats of different zones were relatively high in spring,summer and winter,while similarities among quadrats between the reef and control zones off shore in autumn and all zones in spring were higher than those NA and control zones.37.1% of the variation in composition of nekton community was explained by water temperature in the RDA analysis,which suggested water temperature was main explanatory factor(Monte Carlo test P=0.002).The water temperature and depth were key environmental variables for temporal-spatial variation of nekton community structure in Lidao artificial reef zones.

To accurately measure the transmission directions of high power laser beams from a laser independent expanding beam system in the laser launching system,the equipment for measuring the parallelism error of independent expanding beam system is designed.Firstly,based on the speciality of the independent expanding beam system and the IR laser,the equipment uses a high resolution IR CCD for measuring and imaging.Then,the mechanical structure of the equipment is constructed by using aluminum alloys with light quality and high rigidity,and its activity parts are building on a linear moving platform with high precision.On the basis of the high resolution CCD and the precise displacement platform,the equipment can implement the dynamic and static measurement.The experimental results show that the equipment works stably and reliably and measuring precision is better than 2″.It satisfies the requirements of the laser launching system,and can provide basis for the assembly and application of the expanding beam systems.

Wavefront coding system is a new type of optical-digital two-step imaging system.The cubic phase mask is used to get asymmetric point spread function and the intermediate blurred image which nearly the same in a considerable depth of field.Combined with spatial domain optical imaging modeland kronecker product,an image restoration algorithm which based on the Bi-CGSTAB(BiConjugate Gradient Stabilized) and antireflective boundary conditions was used in the digital decoding part of the wavefront coding system.This algorithm have advantages such as small computing amount,high computing speed and nearly no boundary effect.The new algorithm was optimized and transplanted with the characteristics of parallel computing for the platform of TMS320DM642.The whole platform consists of image capture module,image display module and external memory module.By a specially designed optical system,the experiment imaging the human and object with the object distance of 1 m,5 m and 10 m.From the experimental result of middle blurred images,the effect of this new algorithm on the platform of TMS320DM642 is good,and it gives the possibility to realization of the truly portable and practical of the wavefront coding system.