在使用普通的光學影像測量儀檢(jian)(jian)(jian)測工(gong)件的(de)(de)過程中(zhong),行(xing)抖(dou)動(dong)(dong)是產(chan)生(sheng)(sheng)幾(ji)何(he)誤差(cha)的(de)(de)主要原因之一.由(you)于在(zai)圖像傳(chuan)感(gan)器與圖像采(cai)集(ji)(ji)卡之間缺乏發送頻率作參考,以至在(zai)時(shi)(shi)間同(tong)(tong)步(bu)上產(chan)生(sheng)(sheng)偏移.因此(ci)會(hui)產(chan)生(sheng)(sheng)行(xing)抖(dou)動(dong)(dong).CCD圖像傳(chuan)感(gan)器通常遵守(shou)照光導攝像管,攝像機標(biao)準(zhun)(zhun)而設計,輸出(chu)(chu)為具(ju)有(you)水(shui)平和垂直同(tong)(tong)步(bu)信號(hao)(hao)(hao)相加而形(xing)成(cheng)的(de)(de)復合(he)同(tong)(tong)步(bu)信號(hao)(hao)(hao). 在(zai)圖像采(cai)集(ji)(ji)卡中(zhong),同(tong)(tong)步(bu)信號(hao)(hao)(hao)被同(tong)(tong)步(bu)分離(li)器從復合(he)視頻信號(hao)(hao)(hao)中(zhong)分離(li)出(chu)(chu)來.鎖(suo)相環電路用(yong)于為圖像采(cai)集(ji)(ji)卡中(zhong)的(de)(de)A/D產(chan)生(sheng)(sheng)采(cai)集(ji)(ji)時(shi)(shi)鐘(zhong)頻率.像素時(shi)(shi)鐘(zhong)和分離(li)出(chu)(chu)來的(de)(de)水(shui)平垂直同(tong)(tong)步(bu)信號(hao)(hao)(hao)用(yong)于把(ba)據(ju)以符合(he)CCIR標(biao)準(zhun)(zhun)的(de)(de)固定(ding)頻率輸出(chu)(chu).對像元進行(xing)A/D轉換是在(zai)水(shui)平同(tong)(tong)步(bu)信號(hao)(hao)(hao)被檢(jian)(jian)(jian)測出(chu)(chu)后給定(ding)的(de)(de)時(shi)(shi)鐘(zhong)周期數(shu)上進行(xing)的(de)(de).起(qi)始(shi)周期檢(jian)(jian)(jian)測位置的(de)(de)任何(he)偏差(cha)都會(hui)產(chan)生(sheng)(sheng)行(xing)抖(dou)動(dong)(dong),其結果(guo)是在(zai)X方(fang)向(xiang)而不(bu)是在(zai)Y方(fang)向(xiang)產(chan)生(sheng)(sheng)誤差(cha).行(xing)抖(dou)動(dong)(dong)是隨機的(de)(de),許多(duo)圖像采(cai)集(ji)(ji)卡的(de)(de)行(xing)抖(dou)動(dong)(dong)誤差(cha)在(zai)1/4到1/8像素之間.
要消除行(xing)抖動(dong),需將(jiang)CCD成像(xiang)元件(jian)的(de)發送時鐘頻(pin)率作為圖像(xiang)采集卡中A/D的(de)采集時鐘頻(pin)率
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