单击此处编辑母版标题样式单击此处编辑母版文本样式第二级第三级第四级第五级u cu cup u mu mudu bu busu bu bugu bu budu cu cut u gu gumu bu bun duckgunjugmugnutrughuttub
43 激光束的变换绝大多数激光器发出的光束,为满足特定的实验需求,在投入使用之前,都要在谐振腔外部,通过一定的光学系统变换成所需要的形式。34节表明,高斯光束在自由空间中的传播特性与球面波不同,通过光学系统时,仍有和球面波不同的传输特性。本节将讨论高斯光束的变换特性,具体地说,就是研究高斯光束的聚焦、扩束和准直。这些问题在实际中经常遇到。例如,激光打孔需要对激光光束进行聚焦,全息摄影需要将激光进行
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第一级Unit2-PART1 colors and numbers颜色和数字 Describing a lost item描述一下丢失物品Lost and found 失物招领Laura: Excuse meLost and found:Can I help youLaura: Ah yes Im looking for a and found: What color is your bagLa
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Unit 4 Part 1The Powerful Gift of Love上海交通大学出版社Language in UseEnhancement of Language Abilities Unit 4Language Skills Development上海交通大学出版社Focus1translation1 The president ___________________________
牛津小学英语6BUnit 6 Planning for the weekend(Part A) plan 计划A: What are you going to do this weekend Are they at school today 2. What are Gao Shan and hi
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Unit7 After schoolPlay a game:Is he / she … ing…?Are they… ing…?Think and guess:What am I doing?Are you …ing…?Yes, I am/ No, I’mfather is cooking in thebrother is playing in themother is doing somesis
从而 在一定程度上反映了二维随机变量(XY)中的分量X与Y 的某种相互关系 Cov(X X) = D(X) Cov(X Y) = Cov(Y X) Cov( aX bY ) = ab Cov(X Y) a b 是常数 Cov(X1X2 Y)= Cov(X1 Y) Cov(X2 Y) 补充: Cov(X a )=0
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