离焦

A general formula for computing the OTF of a defocused optical system is derived from the Kirchoff diffraction integration under an approximate condition which is weaker than the Fresnel condition.

本文从基尔霍夫衍射积分公式出发，在弱于菲涅耳条件的近似下，以高斯像面的像差量及系统的离焦量为参变量，导出了便于计算离焦光学系统的OTF的普遍算式。

In the spatial domain,canonical projection of the Wigner distribution function of the associated pupil function to show the insensitivity of the point spread function to the defocus-related aberrations is mainly used,and in the frequency domain,it is shown that the optical transfer function of such a system is also insens.

空域中，主要利用维格纳分布函数的正则投影来分析系统的点扩展函数对离焦像差的变化不敏感特性；频域中，则利用考纽螺线的图解方法来分析系统的光学传递函数对离焦像差的变化不敏感特性。

In the spatial domain, canonical projection of the Wigner distribution function of the associated pupil function to show the insensitivity of the system's point spread function to the defocus-related aberrations is mainly used, and in the frequency domain, it is shown that the optical transfer function of such a system is also insensitive to misfocus through a geometrical description of the so-called Cornu spiral.

空域中，主要利用维格纳分布函数的正则投影来分析系统的点扩展函数对离焦像差的变化不敏感特性；频域中，则利用考纽螺线的图解方法来分析系统的光学传递函数对离焦像差的变化不敏感特性。

On the basis of introduction and constrast of many kinds of analyzing and recovering defocus image technology,we generally discuss the process of the technology.

本论文在介绍了离焦图像分析与恢复的各种技术的基础上，对相应的技术进行了比较，重点论述了离焦图像分析与恢复的步骤。

The other is to analyze the distortion of cavity mirrors leading to defocus aberrations.

得到了离焦像差与腔长的特性关系和离焦像差与腔镜变形量之间的特性关系。

In the article the reason of defocus is analyzed,and the influence of the defocus on the optical measurement is analyzed quantitatively by experiment.

分析离焦产生机理，并通过实验的方法，定量地分析离焦对光测的影响。

The results indicate that multiple reflections are favorable to the increase of depth. When the focal position is above the surface, the absorptive intensity on the front decreases, so the cutting depth decreases. When the focal position is below the surface, the position on the front with the maximum power intensity is downward. The intensity distribution is toward the deeper position, the cutting depth increases. But if the negative focal distance is extremely big, the intensity of the deeper position attenuates sharply with the increase of focal radius and light distances, so the depth deceases.

正离焦切割时，前沿吸收的总激光功率密度减小，切割深度减小；负离焦切割时，最大激光功率密度值的位置下移，使得前沿功率密度分布朝着深部推进，切割深度增加，若负离焦量过大，表面光斑直径和光程增加，更深位置的功率密度减小，切割深度减小；随着激光功率增加、切割速度减小，则前沿弯曲程度减小，被激光直接照射的前沿部位增长，前沿吸收激光功率密度增加，切割深度增加。

Finally, allowable limit of the largest focusing error and the energy distribution of the light spot was given.

通过数值计算，分别得到了在小离焦量和大离焦量时光强沿光轴径向的分布曲线、中心光斑的大小以及在特定范围内总能量随离焦量的变化规律。

Based on the geometrical optics, the thesis first analyzes the basic principles of out-of-focus, summarizes the basic flow of automatic focusing, points out that focusing evaluation function and focusing control strategy are two basic technologies in automatic focusing of image method. The thesis lists most of focusing evaluation functions and explains how to implement different control strategies.

本文首先用几何光学理论分析了离焦产生的基本原理，深入研究了图像法自动调焦的关键技术，指出调焦评价函数和调焦控制策略的选取是图像法自动调焦的两项核心技术，并按类别介绍了已有的各种调焦评价函数、控制策略实现方法。

A new method for a utomatically adjusting the spindle velocity is proposed in the paper. The method juges the extreme point of out-of-focus signal and calculates the time intervals between the adjacent extreme points by means of the characteristics of out-of -focus signal, and finally estimates the band of the out-of-focus signal.

本文提出了利用离焦信号的特点，判断出离焦信号的极值点，并计算相邻极值点之间的时间间隔，最终估算出离焦信号频带，并依据离焦信号的频带自动调节主轴速度的新方法。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。