（1）確(que)定(ding)下(xia)偏(pian)(pian)(pian)光(guang)鏡(jing)(jing)（起偏(pian)(pian)(pian)振(zhen)鏡(jing)(jing)）的(de)振(zhen)動(dong)(dong)方(fang)向(xiang)：將上(shang)偏(pian)(pian)(pian)光(guang)鏡(jing)(jing)（檢偏(pian)(pian)(pian)振(zhen)鏡(jing)(jing)）自鏡(jing)(jing)中推出，只用(yong)下(xia)偏(pian)(pian)(pian)光(guang)鏡(jing)(jing)觀察工作臺上(shang)。轉動(dong)(dong)工作臺，當黑云母(mu)解(jie)理縫與下(xia)偏(pian)(pian)(pian)光(guang)鏡(jing)(jing)的(de)振(zhen)動(dong)(dong)方(fang)向(xiang)平(ping)行時(shi)對黑云母(mu)吸(xi)收性(xing)(xing)*強，此(ci)時(shi)呈(cheng)現(xian)深棕色；當解(jie)理縫與起偏(pian)(pian)(pian)振(zhen)鏡(jing)(jing)的(de)振(zhen)動(dong)(dong)方(fang)向(xiang)垂直時(shi)，黑云母(mu)吸(xi)收性(xing)(xing)微弱(ruo)，此(ci)時(shi)晶(jing)體呈(cheng)現(xian)淡黃色，據此(ci)就能確(que)定(ding)起偏(pian)(pian)(pian)振(zhen)鏡(jing)(jing)的(de)振(zhen)動(dong)(dong)方(fang)向(xiang)。

（2）調(diao)整下(xia)(xia)偏(pian)光(guang)鏡的振動方向(xiang)(xiang)與目鏡分(fen)劃(hua)板十(shi)字(zi)線橫絲平(ping)行(xing)：將(jiang)黑云母解理縫與目鏡分(fen)劃(hua)板十(shi)字(zi)線橫絲平(ping)行(xing)，轉動下(xia)(xia)偏(pian)光(guang)鏡至黑云母呈現深棕色位置，此時下(xia)(xia)偏(pian)光(guang)鏡的振動方向(xiang)(xiang)平(ping)行(xing)橫絲，其刻(ke)線應(ying)對準0°或(huo)180°。

（3）確定上偏(pian)(pian)光(guang)鏡(jing)（檢偏(pian)(pian)振(zhen)鏡(jing)）與下(xia)偏(pian)(pian)光(guang)鏡(jing)（起偏(pian)(pian)振(zhen)鏡(jing)）的振(zhen)動方(fang)向正交(jiao)：將(jiang)黑(hei)云母切(qie)片取出，推入(ru)上偏(pian)(pian)光(guang)鏡(jing)，如果視域呈黑(hei)暗，則(ze)上、下(xia)偏(pian)(pian)光(guang)鏡(jing)振(zhen)動方(fang)向正交(jiao)；否(fou)則(ze)轉動上偏(pian)(pian)光(guang)鏡(jing)直(zhi)至視域*黑(hei)暗。