会计学训练课变成＂我猜我猜我猜猜猜＂的节目(jiémù)了教学(jiāoxué)参考书激光(jīguāng)英语激光(jīguāng)英语激光(jīguāng)英语Text1fundamentalsoflasers2、Atomicsystemssuchasatoms,ions,andmoleculescanexistonlyindiscreteenergystates.Achangefromoneenergystatetoanother,calledatransition,isassociatedwitheithertheemissionortheabsorptionofaphoton.ThewavelengthoftheabsorbedoremittedradiationisgivenbyBohr’sfrequencyrelation原子系统(xìtǒng)，诸如原子、离子和分子，只存在于分立的能态，从一个能态到另一个能态的变化称为跃迁，它伴随着光子的发射或吸收.波尔频率关系式给出了吸收或发射辐射的波长。3、whereE2andE1aretwodiscreteenergylevels,V21isthefrequency,andhisthePlanck'sconstant.AnelectromagneticwavewhosefrequencyV21correspondstoanenergygapofsuchanatomicsystemcaninteractwithit.E2一E1=hv21式中，E2,,E1是两个(liǎnɡɡè)离散的能级，v21为频率，h是普朗克常量，与这一原子系统的能隙相对应的是频率为u21的电磁波，该电磁波与原子系统能够相互作用.4、Atthermalequilibrium,thelowerenergystatesinthematerialaremoreheavilypopulatedthanthehigherenergystates.Awaveinteractingwiththesubstancewillraisetheatomsormoleculesfromlowertohigherenergylevelsandtherebyexperienceabsorption.在热平衡时，材料中处于下能态的粒子数远比上能态的多，电磁波与其发生相互作用，使原子和分子从低能级上升(shàngshēng)到高能级，即为吸收.5、Theoperationofalaserrequiresthattheenergyequilibriumofalasermaterialbechangedsuchthatenergyisstoredintheatoms,ions,ormoleculesofthismaterial.Thisisachievedbyanexternalpumpsourcewhichtransferselectronsfromalowerenergyleveltoahigherone.激光器运转要求改变激光材料的能量平衡，使能量存储于该材料的原子、离子或分子之中.通过(tōngguò)外部泵浦源使激光材料中的粒子从低能态跃迁到高能态.6、Thepumpradiationtherebycausesa"populationinversion”Anelectromagneticwaveofappropriatefrequency,incidentonthe"inverted"lasermaterial,willbeamplifiedbecausetheincidentphotonscausetheatomsinthehigherleveltodroptoalowerlevelandtherebyemitadditionalphotons.Asaresult,energyisextractedfromtheatomicsystemandsuppliedtotheradiationfield.Thereleaseofthestoredenergybyinteractionwithanelectromagneticwaveisbasedonstimulatedorinducedemission.泵浦辐射导致“粒子数反转”.使频率适中的电磁波入射到该“反转的”激光材料上，入射光子将促使高能级的原子降落到低能级而发射出附加的光子，形成光波放大。最终，能量从原子系统出来，供给到辐射场.原子系统与电磁波相互作用而释放出原先(yuánxiān)存储的能量，这是以受激发射或感应发射为基础的.7、Statedverybriefly,whenamaterialisexcitedinsuchawayastoprovid