換句話說，不同大小的顆粒在通過激光光束時其衍射光會落在不同的位置，位置信息反映顆粒大小；ruguotongyangdadekelitongguojiguangguangshushiqiyansheguanghuiluozaixiangtongdeweizhi，jizaigaiweizhishangdeyansheguangdeqiangdudiejiahoujiubijiaogao，suoyiyansheguangqiangdudexinxifanyingchuyangpinzhongxiangtongdaxiaodekelisuozhandebaifenbiduoshao
，rutu 2 所示。這樣，如果能 夠(gou)同(tong)時(shi)測(ce)量(liang)或(huo)獲(huo)得(de)衍(yan)射(she)光(guang)的(de)位(wei)置(zhi)和(he)強(qiang)度(du)的(de)信(xin)息(xi)，就(jiu)可(ke)得(de)到(dao)粒(li)度(du)分(fen)布(bu)的(de)結(jie)果(guo)。實(shi)際(ji)上(shang)激(ji)光(guang)衍(yan)射(she)法(fa)就(jiu)是(shi)采(cai)用(yong)一(yi)係(xi)列(lie)的(de)光(guang)敏(min)檢(jian)測(ce)器(qi)來(lai)測(ce)量(liang)未(wei)知(zhi)粒(li)徑(jing)的(de)顆(ke)粒(li)在(zai)不(bu)同(tong)角(jiao)度(du)（或者說位置）上shang的de衍yan射she光guang的de強qiang度du，使shi用yong衍yan射she模mo型xing，再zai通tong過guo數shu學xue反fan演yan
，然ran後hou得de到dao樣yang品pin顆ke粒li的de粒li度du分fen布bu。檢jian測ce器qi的de排pai列lie在zai儀yi器qi出chu廠chang時shi就jiu已yi根gen據ju衍yan射she理li論lun確que定ding
，在zai實shi際ji測ce量liang時shi，分fen布bu在zai某mou個ge角jiao度du（或位置）上的檢測器接收到衍射光，說明樣品中存在有對應粒徑的顆粒。

ranhouzaitongguogaiweizhidejianceqisuojieshoudaodeyansheguangdeqiangdu
，dedaosuoduiyinglijingkelidebaifenbihanliang。danshi，keliyansheguangdeqiangduduijiaodudeyilaixingshisuizhekelilijingdebianxiaoerjiangdi

，rutu 3 suoshi。dangkelixiaodaojibainamishi
，qiyansheguangqiangduiyujiaodujihuwanquanshiquyilaixing，jicishideyansheguanghuifenbuzaihenkuandejiaodufanweinei，erqiedanweimianjishangdeguangqianghenruo，zhewuyizengjialejiancedenandu。

如何實現對 1 微米以下及寬粒徑範圍（一般幾十納米到幾千微米）的樣品的測量是激光衍射法粒度儀的技術關鍵。概括起來
，目前有以下幾種技術和光路配置被采用：
1
、多透鏡技術
duotoujingxitongzengzaiershishijibashiniandaiqianbeiguangfancaiyong
，tashiyongfuliyeguanglupeizhijiyangpinchifangzaijujiaotoujingdeqianfang，peiyouduogebutongjiaojudetoujingyishiyingbutongdelijingfanwei
，rutu 4 suoshi
，youdianshishejijiandan，zhixuyaofenbuyujishidufanweidejiaopingmianjianceqi，chengbenjiaodi。quedianshiruguoyangpinlijingfanweikuandeshihouxuyaogenghuantoujing
，butongtoujingdejieguoxuyaopinhe，duiyixieweizhilijingdeyangpinyongyigetoujingceliangshikenenghuidiushixinhaohuoduiyuyouyugongyibianhuadaozhideyangpinlijingbianhuabunengjishifanying。

duoguangyuanjishuyeshicaiyongfuliyeguanglupeizhijiyangpinchizaijujiaotoujingdeqianfang
，yibanzhiyoufenbuyujishidujiaodufanweidejianceqi
，weilezengdaxiangduidejiancejiaodu
，shigaijianceqinenggoujieshoudaoxiaokelideyansheguangxinhao
，zaixiangduiyudiyiguangyuanguangzhoudebutongjiaodushangzaipeizhidiyihuodierjiguangqi，rutu 5 所(suo)示(shi)。這(zhe)種(zhong)技(ji)術(shu)的(de)優(you)點(dian)是(shi)隻(zhi)需(xu)分(fen)布(bu)於(yu)幾(ji)十(shi)度(du)角(jiao)度(du)範(fan)圍(wei)的(de)檢(jian)測(ce)器(qi)，成(cheng)本(ben)較(jiao)低(di)

，測(ce)量(liang)範(fan)圍(wei)特(te)別(bie)是(shi)上(shang)限(xian)可(ke)以(yi)比(bi)較(jiao)寬(kuan)
，缺(que)點(dian)是(shi)分(fen)布(bu)於(yu)小(xiao)角(jiao)度(du)範(fan)圍(wei)的(de)小(xiao)麵(mian)積(ji)檢(jian)測(ce)器(qi)同(tong)時(shi)也(ye)被(bei)用(yong)於(yu)小(xiao)顆(ke)粒(li)測(ce)量(liang)，由(you)於(yu)小(xiao)顆(ke)粒(li)的(de)衍(yan)射(she)光(guang)在(zai)單(dan)位(wei)麵(mian)積(ji)上(shang)的(de)信(xin)號(hao)弱(ruo)
，導(dao)致(zhi)小(xiao)顆(ke)粒(li)檢(jian)測(ce)時(shi)的(de)信(xin)噪(zao)比(bi)降(jiang)低(di)
，這(zhe)就(jiu)是(shi)為(wei)什(shen)麼(me)多(duo)光(guang)源(yuan)係(xi)統(tong)在(zai)測(ce)量(liang)範(fan)圍(wei)上(shang)限(xian)超(chao)過(guo) 1500 weimizuoyoushi，ruoyaotongshibaozhengjiweimiyixiaxiaokelidezhunqueceliang
，xuyaogenghuanduanjiaojudejujiaotoujing。lingwai
，duotoujingxitongzaiceliangyangpinshi，butongdejiguangqishiyicikaiqi
，erzaiganfaceliangshi，youyukelizhinengyicixingtongguoyangpinchi，zhiyouyigeguangyuannengbeiyongyuceliang，suoyiyibancaiyongduotoujingjishudeganfaceliangdelijingxiaxianhennandiyu 250 納米。


3、多方法混合係統

多duo方fang法fa混hun合he係xi統tong指zhi的de是shi將jiang激ji光guang衍yan射she法fa與yu其qi它ta方fang法fa混hun合he而er設she計ji的de粒li度du儀yi
，激ji光guang衍yan射she法fa部bu分fen隻zhi采cai用yong分fen布bu於yu幾ji十shi度du角jiao度du範fan圍wei的de檢jian測ce器qi，再zai輔fu以yi其qi它ta方fang法fa如ru PCS deng
，yibanjiweimiyishangyongjiguangyanshefaceliang，erjiweimiyixiadekeliyongqitafangfaceliang

，lilunshangjianglijingxiaxianqujueyufuzhufangfadexiaxian，zhezhongfangfadeyoudianshichengbendi，zongdeceliangfanweijiaokuan，danyinweibutongdefangfasuoyaoqiudezuijiadeceliangtiaojianruyangpinnongdudengdoubuyiyang
，tongchangnanyijiangu，lingwaiyouyubutongfangfajiancunzaidexitongwucha，zailiangzhongfangfadeshujunihequyuwangwangjiaonandedaolixiangdejieguo，chufeiceliangqianyijingzhidaoyangpinlijingzhiluozaiyanshefafanweineihuofuzhufangfadefanweinei。lingwaiduofangfahunhexitongxucaiyonglianggebutongdeyangpinchi，zheduiyushifacelianglaijiangbushiwenti，yinweiyangpinkeyixunhuan，danduiganfaeryanyangpinzhinengyicixingtongguoyangpinchierbunengxunhuan，bu能用兩種方法同時測量
，因而多種方法混合係統在幹法測量時的粒徑下限隻能到幾百納米。

4、非均勻交叉大麵積補償的寬角度檢測技術及反傅裏葉光路係統feijunyunjiaochadamianjibuchangdekuanjiaodujiancejifanfuliyeguangluxitongshiershishijijiushiniandaihouqifazhanqilaidejishu，caiyongfanfuliyeguanglupeizhijiyangpinchizhiyujujiaotoujingdehoumian
，zheyangshijianceqizaijidadejiaodufanweineipailie，yibanzhenzhengwulijiancejiaodukeda 150 度，從而使采用單一透鏡測量幾十納米至幾千微米的樣品成為可能，光路示意圖如圖 6 所(suo)示(shi)，在(zai)檢(jian)測(ce)器(qi)的(de)設(she)計(ji)上(shang)采(cai)用(yong)了(le)非(fei)均(jun)勻(yun)交(jiao)叉(cha)而(er)且(qie)隨(sui)著(zhe)角(jiao)度(du)的(de)增(zeng)大(da)檢(jian)測(ce)器(qi)的(de)麵(mian)積(ji)也(ye)增(zeng)大(da)的(de)排(pai)列(lie)方(fang)式(shi)
，既(ji)保(bao)證(zheng)了(le)大(da)顆(ke)粒(li)測(ce)量(liang)時(shi)的(de)分(fen)辨(bian)率(lv)也(ye)保(bao)證(zheng)了(le)小(xiao)顆(ke)粒(li)檢(jian)測(ce)時(shi)的(de)信(xin)噪(zao)比(bi)和(he)靈(ling)敏(min)度(du)。無(wu)需(xu)更(geng)換(huan)透(tou)鏡(jing)及(ji)輔(fu)助(zhu)其(qi)它(ta)方(fang)法(fa)就(jiu)可(ke)測(ce)量(liang)從(cong)幾(ji)十(shi)納(na)米(mi)到(dao)幾(ji)千(qian)微(wei)米(mi)的(de)顆(ke)粒(li)

，即(ji)使(shi)是(shi)幹(gan)法(fa)測(ce)量(liang)，其(qi)下(xia)限(xian)也(ye)可(ke)達(da)到(dao) 0.1 微米。這種方法的缺點是儀器的成本相對於前麵的幾種方法而言偏高。


二、 激光粒度儀選購
jiguangliduyizhuyaoyouguangxuejiancexitong，fensanjinyangxitongjikongzhifenxiruanjianzucheng，erguangxuejiancexitongyoubaokuoguangyuan，guanglujijianceqidengguanjianbufen。zaixuanzejiguangliduyishiyaotebiezhuyiyixiajidian：
1、 光源
光源主要有氦氖氣體激光器和半導體固體激光器兩種，氦氖激光器具有線寬窄，單色性極好，
bushougongdiandianyabodongjiwendubianhuadeyingxiang，wendingxinggao，tebieshijinxienianlaimifengdengjishudefazhan

，qishiyongshoumingyoulehendatigao，suoyisuiranhainaijiguangqicunzaitijida，xugaoyagongdianjijiagegaodequedian，danrengranbeiyixiegaoduanyiqicaiyong。erbandaotijiguangqijuyoutijixiao，gongdiandianyadi，shiyongshoumingjiaochang，xiangduihainaijiguangqieryanjiagedidengyoudian，danqidansexingcha
，xiankuankuan
，wendingxingyishouwendubianhuajigongdiandianyuanbodongdeyingxiangdengquedianyexianzhiletazaiyiqizhongdeyingyong
，dangrankeyiyujiandeshisuizhebandaotiguangyuanjishudetigao，bandaotigutijiguangqijianghuibeigengduodeshiyongyuliduyi。lingwaiyaozhuyideshi，jiguangqibochangduiliduceliangdeyingxiang，dangkelijiaoxiaoshi


，genjuruilisanshelilun，sansheguangqiangyulijingdeliucifangchengzhengbi，eryuguangyuanbochangdesicifangchengfanbi，suoyixuanyongduanbochangdejiguangqigengnengtigaoxiaokelijianceshidexinhaoqiangdujixinzaobi。
2、 在zai光guang路lu配pei置zhi上shang，前qian麵mian已yi有you所suo提ti及ji，主zhu要yao需xu要yao考kao慮lv的de是shi儀yi器qi是shi否fou有you穩wen固gu的de光guang學xue平ping台tai
，是shi否fou有you自zi動dong對dui光guang功gong能neng，是shi否fou無wu需xu更geng換huan透tou鏡jing就jiu可ke以yi測ce量liang寬kuan的de粒li徑jing範fan圍wei
；如果需幹法測量，粒徑測量範圍下限是否能達到 0.1 微米而同時上限可達 1000 微米以上。
3、 檢測器是激光粒度儀的最關鍵部件之一，好的檢測器成本有時會占到整個粒度儀成本的四分之一以上，在 ISO13320 激光衍射法國際標準 6.7 章zhang節jie中zhong特te別bie提ti到dao檢jian測ce器qi對dui儀yi器qi靈ling敏min度du和he分fen辨bian率lv的de影ying響xiang，所suo以yi在zai選xuan擇ze時shi不bu能neng隻zhi考kao慮lv檢jian測ce器qi中zhong檢jian測ce單dan元yuan的de數shu量liang
，還hai要yao看kan檢jian測ce器qi的de幾ji何he形xing狀zhuang，排pai列lie方fang式shi，檢jian測ce單dan元yuan的de麵mian積ji及ji其qi真zhen正zheng的de物wu理li檢jian測ce角jiao度du。
4
、yangpinfensanjinyangxitongshibaozhengyangpinzhengquefensanhejinyangdezhongyaofujian，shifafensanjinyangqixuyaoyouneizhichaoshenghejiaobanjizugouliliangdexunhuanbengzuihaoshilixinbeng，ganfafensanjinyangqixuyaoyouzhendongjinyanggongneng
，qiliuyaliketiao，butongrongliangdeyangpinpankexuan。lingwai，zaiyangpinceliangguochengzhongyangpinyoushihuibukebimiandizhanfuzaiyangpinchidechuangkoushang
，suoyiyangpinchishifourongyichaixieqingjieyefeichangzhongyao。
5、 軟件是用於儀器控製和數據分析的，數據采集速度越快越好。在 ISO13320 guojibiaozhunzhong，tebietichuruguokelilijingxiaoyujishiweimi，xucaiyongmishililun
，shuruzhengquedeyangpinzheshelvhexishoulvyibiannenghuodegengweizhunquedejieguo，suoyizairuanjianzhongxuyaoyouyibanwuzhideguangxuecanshujizheshelvhexishoulvdeshujukubingnengbuchongshuruzhexieguangxuecanshu。lingwai，shujushuchugongneng，yonghubaogaogeshishejigongneng
，liangchengkuozhangongnengdengyeshibukehuoquedeyinsu。ruguozaiyouzhongwenruanjianhezhongwenshuomingshu，duidabufenzhongguoyonghulaishuogengshihaodexuanze。
6
、 最後要提到的一點就是有關激光粒度儀測量的準確度和重現性或精度等指標，這些指標應該是針對標準樣品（如 NIST 可溯源的乳膠顆粒等）的某些特征值（如 D50,D10, D90 等），如果隻在儀器樣本上簡單地標上 0.5%或更小而不指明針對性，勢必會誤導用戶，所以用戶在看到這些指標時，有必要確認其針對性和具體含義。