中國(guo)計量科(ke)學研究院(yuan)在建立我國(guo)961.78℃以上溫區國(guo)際溫標(ITS-90)的基礎上，研制了用作溫標傳遞標準及精(jing)密測溫的新型精(jing)密光電高溫計。
鑒于(yu)鎢帶燈和(he)黑體(ti)爐在(zai)溫(wen)標(biao)(biao)(biao)傳(chuan)遞中的(de)重(zhong)要(yao)地位(wei),新(xin)型光(guang)電高(gao)溫(wen)計(ji)(ji)具(ju)備測(ce)(ce)量目標(biao)(biao)(biao)小(xiao)和(he)輻射(she)源尺寸效應(Size-of-sourceeffect)小(xiao)的(de)特(te)點(dian)。新(xin)基準(zhun)光(guang)電溫(wen)度(du)(du)(du)比較儀在(zai)設(she)計(ji)(ji)時使其主要(yao)參數與國(guo)(guo)際建議一致;同樣,新(xin)光(guang)電高(gao)溫(wen)計(ji)(ji)在(zai)被(bei)測(ce)(ce)目標(biao)(biao)(biao)形狀、面積、受光(guang)立體(ti)角、儀器(qi)光(guang)譜(pu)帶寬等參數及儀器(qi)結(jie)構上與國(guo)(guo)家基準(zhun)比較儀保持基本(ben)一致,以避免(mian)因基準(zhun)和(he)標(biao)(biao)(biao)準(zhun)儀器(qi)的(de)差異在(zai)溫(wen)度(du)(du)(du)量值(zhi)傳(chuan)遞的(de)過程中產生顯著(zhu)的(de)系(xi)統誤(wu)差。由于(yu)該高(gao)溫(wen)計(ji)(ji)的(de)光(guang)電探測(ce)(ce)器(qi)輸出與被(bei)測(ce)(ce)目標(biao)(biao)(biao)的(de)光(guang)譜(pu)輻射(she)亮度(du)(du)(du)呈(cheng)現很(hen)好的(de)線性關(guan)系(xi),并(bing)在(zai)我國(guo)(guo)首次將原地測(ce)(ce)量有效波長(chang)方法(fa)應用于(yu)傳(chuan)遞溫(wen)標(biao)(biao)(biao)的(de)高(gao)溫(wen)計(ji)(ji),因此,可直接(jie)由內部微控制器(qi)依據普(pu)朗克定律計(ji)(ji)算被(bei)測(ce)(ce)溫(wen)度(du)(du)(du);具(ju)有數字濾波、自動暗電流修(xiu)正及發射(she)率修(xiu)正等功能(neng),具(ju)備GPIB接(jie)口功能(neng),便于(yu)組成(cheng)自動化測(ce)(ce)試系(xi)統。
該高(gao)溫(wen)(wen)(wen)計(ji)在660nm波長(chang)、900℃時溫(wen)(wen)(wen)度(du)(du)分辨率(lv)為(wei)(wei)0.01℃;在800℃～2200℃溫(wen)(wen)(wen)度(du)(du)范圍、置信水平(ping)為(wei)(wei)0.99時,擴展不(bu)確定度(du)(du)為(wei)(wei)1.0℃～2.4℃。精密光(guang)電高(gao)溫(wen)(wen)(wen)計(ji)的結(jie)構參數和性能(neng)適合溫(wen)(wen)(wen)度(du)(du)精密測量(liang)并(bing)作(zuo)為(wei)(wei)溫(wen)(wen)(wen)標的傳(chuan)遞標準,也為(wei)(wei)高(gao)溫(wen)(wen)(wen)溫(wen)(wen)(wen)標采用多(duo)波長(chang)傳(chuan)遞方法(fa)及固定點分度(du)(du)等技(ji)術創造(zao)了條件。
按功能劃分(fen)(fen)高溫計在形(xing)式上分(fen)(fen)為(wei)兩部分(fen)(fen)。一部分(fen)(fen)為(wei)光學機械系(xi)統(tong)、光電(dian)轉(zhuan)換(huan)及微電(dian)流放大(da)器(qi),另一部分(fen)(fen)為(wei)由微控制器(qi)等組成的測量顯示儀表。
精(jing)密(mi)光(guang)(guang)(guang)電(dian)(dian)(dian)高溫(wen)計(ji)光(guang)(guang)(guang)學系(xi)(xi)統(tong)的(de)設計(ji),參考(kao)了復現ITS-90的(de)基準(zhun)光(guang)(guang)(guang)電(dian)(dian)(dian)溫(wen)度比較儀的(de)光(guang)(guang)(guang)學系(xi)(xi)統(tong)及國外(wai)同類儀器(qi)的(de)方案。高溫(wen)計(ji)光(guang)(guang)(guang)學系(xi)(xi)統(tong)布置：被(bei)測輻射(she)源經(jing)物鏡(jing)成像于(yu)視(shi)場光(guang)(guang)(guang)闌(lan),視(shi)場光(guang)(guang)(guang)闌(lan)中心(xin)為直(zhi)(zhi)徑0.2mm的(de)圓(yuan)孔(kong),周圍為鏡(jing)反(fan)射(she)面(mian),用(yong)于(yu)瞄(miao)準(zhun)。被(bei)測目標成像于(yu)圓(yuan)孔(kong)上,其輻射(she)經(jing)準(zhun)直(zhi)(zhi)鏡(jing)、限制(zhi)光(guang)(guang)(guang)闌(lan)、干(gan)涉(she)(she)濾光(guang)(guang)(guang)片(pian)、減弱(ruo)濾光(guang)(guang)(guang)片(pian)、準(zhun)直(zhi)(zhi)鏡(jing)后會聚(ju)到光(guang)(guang)(guang)電(dian)(dian)(dian)探(tan)測器(qi)上。限制(zhi)光(guang)(guang)(guang)闌(lan)決(jue)定高溫(wen)計(ji)的(de)孔(kong)徑比。可(ke)轉動的(de)干(gan)涉(she)(she)濾光(guang)(guang)(guang)片(pian)輪上有四個(ge)安(an)裝位置,可(ke)安(an)裝三片(pian)不同波(bo)長的(de)干(gan)涉(she)(she)濾光(guang)(guang)(guang)片(pian),使(shi)光(guang)(guang)(guang)束(shu)單色化,減弱(ruo)濾光(guang)(guang)(guang)片(pian)用(yong)于(yu)擴展測溫(wen)上限(使(shi)光(guang)(guang)(guang)電(dian)(dian)(dian)探(tan)測器(qi)工作于(yu)線性區(qu)域),為瞄(miao)準(zhun)系(xi)(xi)統(tong)的(de)反(fan)射(she)鏡(jing),為瞄(miao)準(zhun)物鏡(jing),為減光(guang)(guang)(guang)片(pian)(輪),為目鏡(jing)。
高溫計(ji)(ji)物鏡(jing)直徑(jing)為68mm,焦距140mm,最(zui)小(xiao)測(ce)(ce)量距離約(yue)(yue)0.4m,最(zui)小(xiao)測(ce)(ce)量靶面(mian)直徑(jing)小(xiao)于(yu)0.8mm,顯微(wei)物鏡(jing)和目鏡(jing)放(fang)大倍數(shu)為2×15。高溫計(ji)(ji)采(cai)用(yong)干(gan)涉(she)濾光(guang)片(pian)為單色器,其中心波(bo)長約(yue)(yue)為660nm,半(ban)寬帶約(yue)(yue)為10nm,長波(bo)截止至1200nm,830nm附近(jin)次峰透過率約(yue)(yue)為1×10-4；采(cai)用(yong)吸熱玻璃(li)可將次峰透過率降低1～2個數(shu)量級。根據需要(yao)可選用(yong)900nm或950nm的紅外干(gan)涉(she)濾光(guang)片(pian)。
雖然高溫(wen)計在(zai)小(xiao)目標(biao)和窄譜帶條(tiao)(tiao)件下(xia)測(ce)(ce)量(liang)(liang)難度(du)(du)增(zeng)加,但(dan)在(zai)測(ce)(ce)量(liang)(liang)靶(ba)直徑為(wei)0.75mm條(tiao)(tiao)件下(xia)使用時,測(ce)(ce)量(liang)(liang)靶(ba)的(de)形狀(zhuang)大小(xiao)、有效波長及光譜帶寬等(deng)參(can)數(shu)與國家(jia)基準的(de)相應參(can)數(shu)基本(ben)一致,避免(mian)了溫(wen)度(du)(du)基準至標(biao)準的(de)傳遞過(guo)程中因(yin)這些參(can)數(shu)不同(tong)引起的(de)系統誤差。
電流放大器通常有5～6個量程,其動態范圍滿足800℃～3200℃測溫范圍探測器光電流的測量要求。放大器的輸入失調電壓的變化將導致探測器光譜響應率的變化, 必須嚴格限制。由于測量信號微弱,對光電探測器及放大器采取了嚴格的屏蔽措施。帶有微處理(li)機的(de)測(ce)(ce)量(liang)(liang)顯(xian)(xian)示(shi)(shi)儀表的(de)組(zu)成部分：測(ce)(ce)量(liang)(liang)顯(xian)(xian)示(shi)(shi)儀表在(zai)微處理(li)器(qi)(qi)的(de)控制(zhi)下完成對(dui)微電(dian)(dian)流放(fang)大器(qi)(qi)的(de)控制(zhi)及(ji)對(dui)放(fang)大器(qi)(qi)輸出電(dian)(dian)壓的(de)AD轉換;按放(fang)大器(qi)(qi)相應量(liang)(liang)程(cheng)增益計算(suan)光電(dian)(dian)流,并根(gen)據普朗克定律計算(suan)并顯(xian)(xian)示(shi)(shi)溫(wen)度值(zhi)。可通過GPIB接口接收相應的(de)控制(zhi)命(ming)令或發送測(ce)(ce)量(liang)(liang)數(shu)據、儀器(qi)(qi)狀(zhuang)態、參數(shu)等。在(zai)800℃,高溫(wen)計的(de)分辨率優(you)于0.05℃,在(zai)900℃時分辨率優(you)于0.01℃。
根據(ju)普朗克定(ding)律測溫(wen)(wen)(wen)的(de)(de)(de)前(qian)提之一(yi)是(shi)準確(que)(que)確(que)(que)定(ding)精密光(guang)(guang)(guang)電高(gao)溫(wen)(wen)(wen)計(ji)的(de)(de)(de)有(you)(you)效(xiao)(xiao)(xiao)(xiao)波(bo)(bo)(bo)(bo)長。它是(shi)高(gao)溫(wen)(wen)(wen)計(ji)光(guang)(guang)(guang)學系統光(guang)(guang)(guang)譜(pu)透過(guo)率、光(guang)(guang)(guang)電探(tan)測器光(guang)(guang)(guang)譜(pu)響應及被測溫(wen)(wen)(wen)度(du)(du)的(de)(de)(de)函數。其(qi)數值主要取決(jue)于干涉濾(lv)(lv)(lv)光(guang)(guang)(guang)片(pian)的(de)(de)(de)光(guang)(guang)(guang)譜(pu)特性。干涉濾(lv)(lv)(lv)光(guang)(guang)(guang)片(pian)具有(you)(you)顯(xian)著的(de)(de)(de)不(bu)均勻(yun)性,必須(xu)采用(yong)原地(di)測量方(fang)法確(que)(que)定(ding)高(gao)溫(wen)(wen)(wen)計(ji)有(you)(you)效(xiao)(xiao)(xiao)(xiao)波(bo)(bo)(bo)(bo)長,以減(jian)(jian)小(xiao)有(you)(you)效(xiao)(xiao)(xiao)(xiao)波(bo)(bo)(bo)(bo)長的(de)(de)(de)不(bu)確(que)(que)定(ding)度(du)(du)。由于選用(yong)的(de)(de)(de)中心波(bo)(bo)(bo)(bo)長約為660nm的(de)(de)(de)干涉濾(lv)(lv)(lv)光(guang)(guang)(guang)片(pian)在(zai)(zai)(zai)830nm附近有(you)(you)次(ci)峰(feng),其(qi)峰(feng)值透過(guo)率為10-4數量級。該次(ci)峰(feng)將導(dao)致有(you)(you)效(xiao)(xiao)(xiao)(xiao)波(bo)(bo)(bo)(bo)長在(zai)(zai)(zai)較低溫(wen)(wen)(wen)度(du)(du)時隨溫(wen)(wen)(wen)度(du)(du)降低迅速增(zeng)大。為減(jian)(jian)小(xiao)次(ci)峰(feng)對(dui)有(you)(you)效(xiao)(xiao)(xiao)(xiao)波(bo)(bo)(bo)(bo)長的(de)(de)(de)影響,在(zai)(zai)(zai)干涉濾(lv)(lv)(lv)光(guang)(guang)(guang)片(pian)前(qian)加一(yi)吸熱(re)玻(bo)璃,使有(you)(you)效(xiao)(xiao)(xiao)(xiao)波(bo)(bo)(bo)(bo)長隨溫(wen)(wen)(wen)度(du)(du)變化顯(xian)著減(jian)(jian)小(xiao),同時也減(jian)(jian)小(xiao)了光(guang)(guang)(guang)電探(tan)測器光(guang)(guang)(guang)譜(pu)響應測量不(bu)確(que)(que)定(ding)度(du)(du)對(dui)有(you)(you)效(xiao)(xiao)(xiao)(xiao)波(bo)(bo)(bo)(bo)長不(bu)確(que)(que)定(ding)度(du)(du)的(de)(de)(de)影響。加吸熱(re)玻(bo)璃前(qian)后(hou)干涉濾(lv)(lv)(lv)光(guang)(guang)(guang)片(pian)的(de)(de)(de)光(guang)(guang)(guang)譜(pu)透過(guo)率及平均有(you)(you)效(xiao)(xiao)(xiao)(xiao)波(bo)(bo)(bo)(bo)長計(ji)算結果。加吸熱(re)玻(bo)璃后(hou)有(you)(you)效(xiao)(xiao)(xiao)(xiao)波(bo)(bo)(bo)(bo)長隨溫(wen)(wen)(wen)度(du)(du)的(de)(de)(de)變化顯(xian)著減(jian)(jian)小(xiao)。
用真空燈(deng)和充氣燈(deng)分(fen)度(du)(du)高溫計的分(fen)度(du)(du)重(zhong)復(fu)性,10天(tian)內分(fen)度(du)(du)6次。實驗時(shi)室(shi)溫控制在22℃±1℃內,燈(deng)座(zuo)溫度(du)(du)控制在21℃±0.3℃內。
由于光學系統(tong)雜散光及象差等(deng)因素的影響,高溫計測(ce)量(liang)(liang)溫度(du)一定的輻射(she)源(yuan)時,測(ce)量(liang)(liang)結果與被測(ce)源(yuan)形狀大小有關。高溫計在(zai)(zai)測(ce)量(liang)(liang)1000℃和2000℃的40mm面黑(hei)體時,SSE的影響分別(bie)為0.13℃和0.43℃。該(gai)特性表(biao)明,用鎢(wu)帶燈(deng)分度(du)該(gai)高溫計,在(zai)(zai)測(ce)量(liang)(liang)黑(hei)體爐時,若不做SSE修正也不致產生顯著的誤差。
測量(liang)距(ju)(ju)離不同時高(gao)溫計光學系統的透(tou)過(guo)率(lv)略(lve)有變化(hua)。用鎢(wu)帶燈和黑體爐測量(liang)了高(gao)溫計放大(da)器(qi)輸(shu)出(chu)受(shou)測量(liang)距(ju)(ju)離的影(ying)響(DE)。在近距(ju)(ju)離測量(liang)時要注意(yi)距(ju)(ju)離變化(hua)的影(ying)響。
精密(mi)光(guang)電(dian)(dian)(dian)(dian)高溫(wen)(wen)計在確(que)定(ding)(ding)(ding)(ding)(ding)(ding)其(qi)有(you)效(xiao)波長(chang)和(he)放(fang)大器各(ge)量程增益(yi)比(bi)后,僅(jin)需(xu)一個參考溫(wen)(wen)度(du)點分度(du),即可(ke)確(que)定(ding)(ding)(ding)(ding)(ding)(ding)其(qi)溫(wen)(wen)度(du)量值(忽略高溫(wen)(wen)計非線(xian)性(xing)的(de)影(ying)(ying)響(xiang)(xiang)(xiang))。作為(wei)(wei)溫(wen)(wen)標(biao)(biao)(biao)的(de)傳遞標(biao)(biao)(biao)準(zhun)(zhun)(zhun)(zhun)時(shi),為(wei)(wei)與現行檢定(ding)(ding)(ding)(ding)(ding)(ding)方法統一,800℃～2200℃暫用工作基準(zhun)(zhun)(zhun)(zhun)燈檢定(ding)(ding)(ding)(ding)(ding)(ding)(或(huo)檢驗)精密(mi)(標(biao)(biao)(biao)準(zhun)(zhun)(zhun)(zhun))光(guang)電(dian)(dian)(dian)(dian)高溫(wen)(wen)計。影(ying)(ying)響(xiang)(xiang)(xiang)其(qi)不(bu)(bu)確(que)定(ding)(ding)(ding)(ding)(ding)(ding)度(du)的(de)主要因(yin)素為(wei)(wei)以下6項(xiang):分度(du)重復性(xing)標(biao)(biao)(biao)準(zhun)(zhun)(zhun)(zhun)不(bu)(bu)確(que)定(ding)(ding)(ding)(ding)(ding)(ding)度(du);標(biao)(biao)(biao)準(zhun)(zhun)(zhun)(zhun)光(guang)電(dian)(dian)(dian)(dian)高溫(wen)(wen)計年穩定(ding)(ding)(ding)(ding)(ding)(ding)性(xing)的(de)標(biao)(biao)(biao)準(zhun)(zhun)(zhun)(zhun)不(bu)(bu)確(que)定(ding)(ding)(ding)(ding)(ding)(ding)度(du);工作基準(zhun)(zhun)(zhun)(zhun)燈的(de)合(he)成標(biao)(biao)(biao)準(zhun)(zhun)(zhun)(zhun)不(bu)(bu)確(que)定(ding)(ding)(ding)(ding)(ding)(ding)度(du);工作基準(zhun)(zhun)(zhun)(zhun)燈電(dian)(dian)(dian)(dian)測設備標(biao)(biao)(biao)準(zhun)(zhun)(zhun)(zhun)不(bu)(bu)確(que)定(ding)(ding)(ding)(ding)(ding)(ding)度(du)(含標(biao)(biao)(biao)準(zhun)(zhun)(zhun)(zhun)電(dian)(dian)(dian)(dian)阻、電(dian)(dian)(dian)(dian)壓測量儀(yi)表和(he)穩流電(dian)(dian)(dian)(dian)源紋波的(de)影(ying)(ying)響(xiang)(xiang)(xiang));有(you)效(xiao)波長(chang)的(de)標(biao)(biao)(biao)準(zhun)(zhun)(zhun)(zhun)不(bu)(bu)確(que)定(ding)(ding)(ding)(ding)(ding)(ding)度(du)(0.2nm)對(dui)鎢(wu)帶燈亮度(du)溫(wen)(wen)度(du)的(de)影(ying)(ying)響(xiang)(xiang)(xiang)u5;環境溫(wen)(wen)度(du)對(dui)標(biao)(biao)(biao)準(zhun)(zhun)(zhun)(zhun)光(guang)電(dian)(dian)(dian)(dian)高溫(wen)(wen)計影(ying)(ying)響(xiang)(xiang)(xiang)的(de)標(biao)(biao)(biao)準(zhun)(zhun)(zhun)(zhun)不(bu)(bu)確(que)定(ding)(ding)(ding)(ding)(ding)(ding)度(du)。
當采用(yong)固定點作為溫(wen)(wen)(wen)度參考點的分(fen)度方法(fa)時,參考點溫(wen)(wen)(wen)度不確定度對各(ge)溫(wen)(wen)(wen)度延伸點的影(ying)響都(dou)將(jiang)顯著減小。由于本精(jing)密光電高(gao)溫(wen)(wen)(wen)計在設計上完全具備(bei)用(yong)單(dan)點分(fen)度的技術(shu)特點,因此(ci)為將(jiang)來采用(yong)新分(fen)度方法(fa)傳遞溫(wen)(wen)(wen)標(biao)、減小測溫(wen)(wen)(wen)不確定度打下了(le)良好基礎。
精(jing)密光電高(gao)溫(wen)計的結構參數和性能不(bu)僅適用于溫(wen)度(du)精(jing)密測(ce)量(liang),而且(qie)可作為溫(wen)標的傳(chuan)遞標準(zhun)。該高(gao)溫(wen)計在小目(mu)標和窄譜(pu)帶的測(ce)量(liang)條件下,具有(you)(you)分辨(bian)率高(gao)、SSE小、自(zi)動化(hua)測(ce)量(liang)等特(te)點(dian)。采用原地(di)測(ce)量(liang)有(you)(you)效波(bo)長(chang)標定技術,測(ce)溫(wen)范圍為800℃～3200℃。在660nm波(bo)長(chang)下,900℃時溫(wen)度(du)分辨(bian)率為0.01℃,在800℃～2200℃溫(wen)度(du)范圍內,置信水平為0.99時,擴展不(bu)確定度(du)為1.0℃～2.4℃。
