大口径非球面系统的共基准加工与检验

针对大口径离轴非球面系统加工与装调的难点,提出了非球面光学系统共基准加工与检测的方法,对该方法的基本原理和实现过程进行了分析和研究。当光学系统的主镜和第三镜面形的RMS值优于λ/10(λ=632.8nm)时,对主镜和第三镜进行共基准装调和测试,并进行背板一体化装嵌,然后利用离子束对其进行一体化共基准加工。结合工程实例,对一大口径非球面系统口径为724mm×247mm的非球面主镜和口径为632mm×205mm的第三镜进行了共基准加工与检测,最终利用离子束共基准一体化精抛光得到主镜和第三镜面形的RMS值分别为0.019λ和0.017λ,满足光学成像。     

矫正规则散光的光学演示模型研制

目的:研制规则散光眼镜片矫正规则散光的光学演示模型。方法:用几何光学成像演示器直观演示规则散光成像、规则散光透镜成像、规则散光透镜矫正规则散光。结果:直接观察到规则散光和散光透镜的成像状态-散光Sturm光锥及散光透镜矫正规则散光的光学效果。结论:规则散光眼镜片矫正规则散光的光学演示模型能观察到规则散光透镜矫正规则散光的光学效果,便于准确理解规则散光成像、规则散光透镜的成像、规则散光矫正的光学原理。     

灵巧聚焦伺服系统的研究

提出了一种灵巧的聚焦伺服信号产生办法,同时,该元件还可以作为反射元件来转折光路。该方法使用倾斜的平板玻璃元件来产生必要的象采用这种方法可以简化光存储系统中光学头的结从理论上对这种方法的可行性进行了分析。制作了试验装置,试验结果证实这种方法是可行的。     

Axis-free correction of astigmatism using bifocal soft contact lenses

Purpose

Pilot study to investigate the feasibility of an axis-free correction approach of regular astigmatism using soft, bifocal contact lenses (CL).

Defocus and twofold astigmatism correction in HAADF-STEM

A new simultaneous autofocus and twofold astigmatism correction method is proposed for High Angle Annular Dark Field Scanning Transmission Electron Microscopy (HAADF-STEM). The method makes use of a modification of image variance, which has already been used before as an image quality measure for different types of microscopy, but its use is often justified on heuristic grounds. In this paper we show numerically that the variance reaches its maximum at Scherzer defocus and zero astigmatism. In order to find this maximum a simultaneous optimization of three parameters (focus, x- and y-stigmators) is necessary. This is implemented and tested on a FEI Tecnai F20. It successfully finds the optimal defocus and astigmatism with time and accuracy, compared to a human operator.     

DDF-Ⅱ型动态聚焦电子枪的研制

在DDF-Ⅰ电子枪基础上，改变电子枪结构，将G5分成三部分，将G52／G53之间的四极场，增加G51／G52之间的四极场，通过改变四极场位置和电子束在主透镜的入射角来减小四角电子束的水平尺寸。调整G51／G52之间水平翼片的长度，让四极场场强达到合适的值，使屏面中心和四角的光点尺寸同时达到最佳。通过反复模拟计算和实验测试，最终确定了能获得满屏良好聚焦性能的DDF-Ⅱ电子枪结构。     

大屏幕彩色显像管电子枪技术

对近年来大屏幕彩色显像管员子枪专有技术进行了讨论,系统分析了电子束形成区、主透镜、会聚透镜系统及动态聚焦方式等。通过计算机模拟、实际效果的比较等手段对各种技术特征进行了全面的总结、评价。     

Characterisation of internal,refractive, and corneal astigmatism in a UK university student population

PurposeThere is a clear benefit in defining internal (IA) and corneal astigmatic error (CA) prior to surgical and other refractive interventions, such as orthokeratology, to minimise risk of unsatisfactory refractive outcomes. Such data would also be of relevance to broader areas of ophthalmic care such as spectacle dispensing and other types of rigid lens fitting. This study offers a detailed characterisation of astigmatic error in a group of university students and specifically investigates compensation of corneal astigmatism by the eye’s internal optics.MethodsFor 176 young-adult participants, objective measurements of refractive error were obtained using the open-view Grand Seiko WAM-5500 autorefractor; corneal curvature and axial length were measured using the Aladdin biometer. Clinical measurements of corneal and refractive astigmatism were converted into vector components J0 and J45; followed by an assessment of corneal astigmatism compensation.ResultsMean total refractive astigmatism (RA), CA, and IA were 0.24 ± 0.32D, 0.46 ± 0.27D and -0.21 ± 0.25D respectively for J0 and -0.05 ± 0.20D, 0.01 ± 0.16D, and -0.06 ± 0.18D for J45. Significant linear correlations were noted between RA, CA, and IA for both J0 and J45 (P < 0.01). A significant linear regression was also noted between axial length and J45 RA and IA, but not CA. Levels of full compensation were low, 7% and 9% for J0 and J45 respectively, however, a complete absence of compensation was also uncommon particularly for J45 (2%).ConclusionsIn general, partial compensation for corneal astigmatism by the eye’s internal optics is noted, but it is unclear whether this is an active compensatory mechanism. Further, larger scale, studies would be required to characterise differences in corneal astigmatic compensation with respect to ethnicity.     

Nanopillar array with a λ/11 diameter fabricated by a kind of visible CW laser direct lithography system

Nanoscale functional structures are indispensable elements in many fields of modern science. In this paper, nanopillar array with a pillar diameter far smaller than Abbe''s diffraction limit is realized by a new kind of continuous wave (CW) laser direct lithography technology. With atomic force microscopy technology, the average diameter of nanopillars on thin OIR906 photoresist film is about 65 nm and the smallest diameter is 48 nm, which is about 1/11 of the incident laser wavelength. Also, the influences of coma and astigmatism effects to the shape and size of nanopillar are numerically simulated by utilizing vector integral. As far as we know, it is the first time that nanopillar array is implemented by a donut-shaped 532-nm visible CW laser. The study presents a new, simple, inexpensive, and effective approach for nanopillar/pore array fabrication.