focal ratio

英 [ˈfəʊkl ˈreɪʃiəʊ]

美 [ˈfoʊkl ˈreɪʃioʊ]

网络  焦比; 焦距比; 焦比大

英英释义

noun

• the ratio of the focal length to the diameter of a (camera) lens system
  Synonym:f numberstop numberspeed

双语例句

• Determination of Focal Mechanism by Using SH and P Wave Amplitude Ratio
  利用SH波和P波振幅比测定中小地震的震源机制
• Moreover, the amount of the focal shifts depends on the Fresnel number of the focusing lens, the spatial coherence of the partially coherent light and the central obstruction ratio of the annular lens etc.
  并且，焦移量不仅依赖于透镜外半径的菲涅耳数，还依赖于部分相干光的空间相干度和中心拦截比。
• The application of focal mechanism determinations of moderate-small earthquakes in Yunnan Province using the first motion and amplitude ratio of P and S wave
  用P波、S波初动和振幅比计算中小地震震源机制在云南地区的应用
• Determination of focal mechanism using SH to p amplitude ratio
  用SH波和P波振幅比确定震源机制解
• It designs two estimating experiments to obtain the focal length value corresponding to the minimum CCD focal length, from which the ratio of the CCD focal length to its optical equivalent is derived.
  设计两种测量CCD等效焦距的实验方法，分别利用物像距离与物像长度的比例关系和平行双目成像原理，得到与CCD焦距极值对应的等效焦距。
• The results indicated: the imaging distance of PS transformation related mainly to focal length of imaging lens, the system magnifying power related mainly to the ratio between the imaging lens focal length and holographic lens focal length.
  推导表明，PS变换成像的距离是较稳定的，主要与成像透镜焦距有关，系统放大率主要与成像透镜焦距和全息透镜焦距之比有关；
• The results show that the focal, field and remote precursory anomalies are of the following characteristics: The spatial distribution of anomalies is inhomogeneous, the distribution of anomalous monitoring stations of focal precursors is concentrated, and the anomaly ratio can reach 90%;
  结果表明，源、场、远兆异常有如下特征：异常空间展布不均，源兆空间内异常监测点展布“密集”、异常比例可达90%；
• Using geometry theory and the Monte Carlo method study its 'geometric optical characteristics and focal plane density distribution, and consider influence of different error on geometric concentrating ratio and the flux density distribution.
  利用几何学原理和MonteCarlo方法研究新型多平面太阳能聚光器的几何光学特征及焦平面能流密度分布，分析不同综合误差对几何聚光比及能流密度分布的影响。
• It has many advantages to determine the focal mechanism by using SH and P wave amplitude ratio, but requires highly for the distribution of stations.
  用SH波和P波振幅比测定地震震源机制具有诸多优点，但它对台站布局要求较高。
• The focal ratio of the Cassegrain system for the telescope is F/ 10 and the plate scale is 20 ″/ mm.
  该望远镜卡焦焦比为F/10，底片比例尺为20〃/mm，无畸变象场约为1平方度天区。