会计学Thesekindsofopticalelementsarecalledprisms.Theprisminfig.4.9iscalledPentaprism(五角棱镜(léngjìng))Fig.4.10showstheappearanceofaright-angleprism.Itisatrianglecylinder(三角柱体).Theplaneorsectionwhichisperpendiculartoeachprismiscalledmainsection(主截面(jiémiàn)).Therayslieinthemainsectionwillliestillinthesamesectionafterpassingthroughtheprism.＊BasicdefinitionIncidentface：ACEmergingface：BCWorkingface：AC,BC,ABRidge楞：theintersectionlineofworkingfaceMainsection(主截面(jiémiàn),光轴截面(jiémiàn))：ABCface＊Equivalentactionofprism＊Conclusion＊unfoldingofprismTheprismmustbedemandedtomeettworequirements:Methodsofunfolding:＊Sometipicalprisms4.4.2Pentaprism(五角棱镜(léngjìng))4.5roofsurfacesandroofprisms(屋脊(wūjǐ)面和屋脊(wūjǐ)棱镜)Inordertogetanimagesimilartotheobject,twosurfacesat90°whoseintersectionliesinthehypotenuse(斜边)canbeusedtoreplaceoneofthereflectingsurfaces.Thesespecialsurfacesarecalledroofsurfaces(屋脊(wūjǐ)面).Aprismcontainingroofsurfacesiscalledroofprism(屋脊(wūjǐ)棱镜).Whatistheroleoftheroofprism?Fig.4.18Principleofroofsurface4.6imagingpropertyofparallelglassblockandprismsizecalculation光线移动的距离随入射角的不同而不同同样也随平板(píngbǎn)的厚度不同而变化上式表明:ΔL′因不同的I1值不同而不同.即从具有不同入射角的各条光线经平行平面板折射后，具有不同的轴向位移量，这就说明，同心光束经平行平面板后变为非同心光束，成像是不完善的。也可以看出平行平面板的厚度(hòudù)d愈大，成像不完善程度也愈大。§4-7determinationofimageorientationsformirrorsandprisms4.7.1mirrorandprismsystemwithsinglemainsectionAccordingtothemirrorimagingproperties,theobjectandtheimagearesymmetricaltothemirror,sotheorientationofz’inimagespacewillbeasthesameasthatofzintheobjectspacenomatterhowmanyreflectionshavehappened.However,ifthereisaroofsurfaceinthesystem,accordingtotheroofsurfaceproperty,theorientationsz’andzwillbereversed.Inthiswaywecaneasilydeterminetheorientationofz’inamirrorandprismsystemwiththesinglemainsection.Firstofall,supposethereisnoroofsurfacesinthesystemandmeansz’willbethesameorientationasz.onthiscondition,ifthetotalnumberofthereflectorsiseven,theimagewillbesimilartotheobject,y’andyhavethesameorientationiftheorientationofaxisx’coincideswithx,asshownin