光(guang)波根(gen)據振(zhen)動的(de)特點，可分為自(zi)(zi)然(ran)光(guang)與偏光(guang)。自(zi)(zi)然(ran)光(guang)的(de)振(zhen)動特點是在垂直光(guang)波傳導軸上具(ju)有(you)許多(duo)振(zhen)動面，各(ge)平面上振(zhen)動的(de)振(zhen)幅相同，其頻率也相同；自(zi)(zi)然(ran)光(guang)經過反射、折射、雙折射及吸(xi)收等作用(yong)，可以成為只在一(yi)個方(fang)向上振(zhen)動的(de)光(guang)波，這(zhe)種光(guang)波則稱為“偏光(guang)”或“偏振(zhen)光(guang)”。

偏(pian)光的產生及其作用：

偏光顯(xian)微鏡(jing)很重要的部件是偏光裝置：起偏器和檢偏器。過去兩者均為尼科爾棱鏡組成，它是由天然的方解石制作而成，但由于受到晶體體積較大的限制，難以取得較大面積的偏振，近來偏光(guang)顯微鏡則采用人造偏振鏡來代替尼科爾梭鏡。人造偏振鏡是以硫酸喹啉的晶體制作而成，呈綠橄欖色。當普通光通過它后，就能獲得只在一直線上振動的直線偏振光。 偏光顯(xian)微鏡(jing)有兩(liang)個(ge)偏(pian)(pian)(pian)(pian)(pian)振(zhen)鏡(jing)(jing)(jing)(jing)，一個(ge)裝(zhuang)置在(zai)光(guang)源(yuan)與(yu)被(bei)檢(jian)物體之(zhi)間(jian)的(de)(de)(de)(de)叫“起(qi)偏(pian)(pian)(pian)(pian)(pian)鏡(jing)(jing)(jing)(jing)”；另(ling)一個(ge)裝(zhuang)置在(zai)物鏡(jing)(jing)(jing)(jing)與(yu)目鏡(jing)(jing)(jing)(jing)之(zhi)間(jian)的(de)(de)(de)(de)叫“檢(jian)偏(pian)(pian)(pian)(pian)(pian)鏡(jing)(jing)(jing)(jing)”，有手柄伸手鏡(jing)(jing)(jing)(jing)筒(tong)或中間(jian)附件外方以(yi)便操作，其上有旋(xuan)轉(zhuan)角的(de)(de)(de)(de)刻度(du)(du)。 偏(pian)(pian)(pian)(pian)(pian)光(guang)顯微鏡(jing)(jing)(jing)(jing)從光(guang)源(yuan)射(she)出的(de)(de)(de)(de)光(guang)線通(tong)過兩(liang)個(ge)偏(pian)(pian)(pian)(pian)(pian)振(zhen)鏡(jing)(jing)(jing)(jing)時，如果(guo)起(qi)偏(pian)(pian)(pian)(pian)(pian)鏡(jing)(jing)(jing)(jing)與(yu)檢(jian)偏(pian)(pian)(pian)(pian)(pian)鏡(jing)(jing)(jing)(jing)的(de)(de)(de)(de)振(zhen)動方向(xiang)互相平(ping)(ping)行(xing)，即處(chu)(chu)于(yu)“平(ping)(ping)行(xing)檢(jian)偏(pian)(pian)(pian)(pian)(pian)立(li)”的(de)(de)(de)(de)情況(kuang)(kuang)下，則視場很為明亮(liang)。反之(zhi)，若兩(liang)者互相垂直(zhi)，即處(chu)(chu)于(yu)“正交(jiao)校偏(pian)(pian)(pian)(pian)(pian)位”的(de)(de)(de)(de)情況(kuang)(kuang)下，則視場完(wan)全(quan)(quan)黑暗，如果(guo)兩(liang)者傾斜，則視場表明出中等程(cheng)度(du)(du)的(de)(de)(de)(de)亮(liang)度(du)(du)。由(you)此可(ke)知，起(qi)偏(pian)(pian)(pian)(pian)(pian)鏡(jing)(jing)(jing)(jing)所(suo)形成的(de)(de)(de)(de)直(zhi)線偏(pian)(pian)(pian)(pian)(pian)振(zhen)光(guang)，如其振(zhen)動方向(xiang)與(yu)檢(jian)偏(pian)(pian)(pian)(pian)(pian)鏡(jing)(jing)(jing)(jing)的(de)(de)(de)(de)振(zhen)動方向(xiang)平(ping)(ping)行(xing)，則能(neng)完(wan)全(quan)(quan)通(tong)過；如果(guo)偏(pian)(pian)(pian)(pian)(pian)斜，則只以(yi)通(tong)過一部分；如若垂直(zhi)，則完(wan)全(quan)(quan)不能(neng)通(tong)過。因此，在(zai)采用偏(pian)(pian)(pian)(pian)(pian)光(guang)顯微鏡(jing)(jing)(jing)(jing)檢(jian)測時，原則上要使起(qi)偏(pian)(pian)(pian)(pian)(pian)鏡(jing)(jing)(jing)(jing)與(yu)檢(jian)偏(pian)(pian)(pian)(pian)(pian)鏡(jing)(jing)(jing)(jing)處(chu)(chu)于(yu)正交(jiao)檢(jian)偏(pian)(pian)(pian)(pian)(pian)位的(de)(de)(de)(de)狀態下進行(xing)。