1.聲光可調諧濾波器的原理

濾波器的本質就是諧振電路，可調諧表示濾波器的諧振點可調。
聲光可調諧濾波器(Acousto-opticTunableFilter，AOTF)的原理是根據聲光衍射原理制成的分光器件，它由晶體和鍵合在其上的換能器構成，換能器將高頻的RF驅動電信號（一般約為幾十兆赫至二百兆赫之間）轉換為在晶體內的超聲波振動，超聲波產生了空間周期性的調制，其作用像衍射光柵。
當(dang)入射(she)光(guang)(guang)照射(she)到此(ci)(ci)光(guang)(guang)柵(zha)后將(jiang)產(chan)生布(bu)喇格衍(yan)射(she)，其衍(yan)射(she)光(guang)(guang) 的(de)波長(chang)(chang)與高頻驅動(dong)電信(xin)號的(de)頻率有著一一對應的(de)關系。因此(ci)(ci)，只要改變RF驅動(dong)信(xin)號的(de)頻率，即(ji)可改變衍(yan)射(she)光(guang)(guang)的(de)波長(chang)(chang)，進而(er)達到了分(fen)光(guang)(guang)的(de)目的(de)。

2.聲光可調諧濾波器的理論基礎

聲光可調諧光濾波器( acousto-optic tunable optical filters, AOT F) 的物理基礎是基于光彈性效應, 即通過聲光材料傳輸的聲波或超聲波信號產生隨聲波幅度周期性變化的應力, 使該材料的分子結構產生局部的密集和疏松, 相當于使折射率產生周期性的變化, 其結果是聲波產生了可以對光束衍射的光柵。
AOTF所應(ying)(ying)用(yong)的(de)(de)基(ji)本原理有(you)(you)逆壓電效(xiao)應(ying)(ying)、聲(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)光(guang)(guang)效(xiao)應(ying)(ying)、聲(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)光(guang)(guang)衍(yan)(yan)射(she)(she)(she)(she)、布(bu)(bu)拉(la)(la)格(ge)(Bragg)衍(yan)(yan)射(she)(she)(she)(she)。逆壓電效(xiao)應(ying)(ying)是(shi)指對晶(jing)體(ti)(ti)施加交變(bian)(bian)電場(chang)引起晶(jing)體(ti)(ti)機械變(bian)(bian)形(xing)的(de)(de)現(xian)(xian)象。聲(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)光(guang)(guang)效(xiao)應(ying)(ying)是(shi)光(guang)(guang)通過聲(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)波(bo)(bo)(bo)擾(rao)動的(de)(de)介(jie)質(zhi)時(shi)(shi)發(fa)(fa)生(sheng)(sheng)散(san)射(she)(she)(she)(she)或(huo)衍(yan)(yan)射(she)(she)(she)(she)的(de)(de)現(xian)(xian)象。當(dang)超(chao)(chao)聲(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)波(bo)(bo)(bo)進入(ru)(ru)到晶(jing)體(ti)(ti)中(zhong)時(shi)(shi)，聲(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)光(guang)(guang)晶(jing)體(ti)(ti)的(de)(de)光(guang)(guang)學性(xing)質(zhi)會(hui)受(shou)到超(chao)(chao)聲(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)波(bo)(bo)(bo)的(de)(de)作用(yong)而(er)改變(bian)(bian)，使(shi)聲(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)光(guang)(guang)晶(jing)體(ti)(ti)的(de)(de)折射(she)(she)(she)(she)率發(fa)(fa)生(sheng)(sheng)變(bian)(bian)化(hua)，而(er)折射(she)(she)(she)(she)率的(de)(de)變(bian)(bian)化(hua)與超(chao)(chao)聲(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)波(bo)(bo)(bo)的(de)(de)強(qiang)度(du)有(you)(you)關，因(yin)(yin)此會(hui)形(xing)成隨超(chao)(chao)聲(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)波(bo)(bo)(bo)強(qiang)度(du)不同變(bian)(bian)化(hua)的(de)(de)分布(bu)(bu)， 整個聲(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)光(guang)(guang)晶(jing)體(ti)(ti)就(jiu)類(lei)似一個位(wei)(wei)相(xiang)(xiang)光(guang)(guang)柵(zha)，這種現(xian)(xian)象被稱為(wei)聲(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)光(guang)(guang)效(xiao)應(ying)(ying)。若同時(shi)(shi)有(you)(you)光(guang)(guang)傳(chuan)過介(jie)質(zhi)，光(guang)(guang)將(jiang)被相(xiang)(xiang)位(wei)(wei)光(guang)(guang)柵(zha)所衍(yan)(yan)射(she)(she)(she)(she)，稱為(wei)聲(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)光(guang)(guang)衍(yan)(yan)射(she)(she)(she)(she)。布(bu)(bu)拉(la)(la)格(ge)衍(yan)(yan)射(she)(she)(she)(she)對方向(xiang)和波(bo)(bo)(bo)長有(you)(you)選(xuan)擇性(xing)，當(dang)超(chao)(chao)聲(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)波(bo)(bo)(bo)頻(pin)率af較高(gao)，光(guang)(guang)波(bo)(bo)(bo)入(ru)(ru)射(she)(she)(she)(she)的(de)(de)方向(xiang)與超(chao)(chao)聲(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)波(bo)(bo)(bo)波(bo)(bo)(bo)面(mian)(mian)一定(ding)角度(du)，且聲(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)光(guang)(guang)相(xiang)(xiang)互作用(yong)的(de)(de)長度(du) L較長，當(dang)有(you)(you)光(guang)(guang)波(bo)(bo)(bo)入(ru)(ru)射(she)(she)(she)(she)到介(jie)質(zhi)中(zhong)時(shi)(shi)，光(guang)(guang)波(bo)(bo)(bo)會(hui)和多個超(chao)(chao)聲(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)波(bo)(bo)(bo)波(bo)(bo)(bo)面(mian)(mian)發(fa)(fa)生(sheng)(sheng)相(xiang)(xiang)互的(de)(de)作用(yong)，因(yin)(yin)此聲(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)光(guang)(guang)介(jie)質(zhi)產生(sheng)(sheng)周期性(xing)結構是(shi)相(xiang)(xiang)位(wei)(wei)與體(ti)(ti)位(wei)(wei)光(guang)(guang)柵(zha)性(xing)質(zhi)的(de)(de)結合。入(ru)(ru)射(she)(she)(she)(she)光(guang)(guang)進入(ru)(ru)該聲(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)光(guang)(guang)介(jie)質(zhi)時(shi)(shi)，受(shou)到相(xiang)(xiang)位(wei)(wei)影響(xiang)和振幅(fu)影響(xiang)。當(dang)入(ru)(ru)射(she)(she)(she)(she)光(guang)(guang)波(bo)(bo)(bo)的(de)(de)入(ru)(ru)射(she)(she)(she)(she)角滿足一定(ding)的(de)(de)條(tiao)件(jian)的(de)(de)情況下，各級(ji)衍(yan)(yan)射(she)(she)(she)(she)光(guang)(guang)在介(jie)質(zhi)中(zhong)會(hui)相(xiang)(xiang)互干涉，相(xiang)(xiang)互抵消，只存在 0 級(ji)和+1 級(ji)（或(huo)-1 級(ji)）的(de)(de)衍(yan)(yan)射(she)(she)(she)(she)光(guang)(guang)，這種現(xian)(xian)象就(jiu)是(shi)布(bu)(bu)拉(la)(la)格(ge)衍(yan)(yan)射(she)(she)(she)(she)。

結論

聲光(guang)(guang)可調諧(xie)濾波(bo)器(qi)是一(yi)種電調諧(xie)濾波(bo)器(qi)，具(ju)(ju)有很(hen)(hen)(hen)寬的(de)(de)(de)光(guang)(guang)譜(pu)通(tong)帶，很(hen)(hen)(hen)高的(de)(de)(de)電調諧(xie)速率以及(ji)很(hen)(hen)(hen)好的(de)(de)(de)光(guang)(guang)譜(pu)分辨率，同(tong)時(shi)聲光(guang)(guang)可調諧(xie)濾波(bo)器(qi)在非臨(lin)界相(xiang)位匹配時(shi)具(ju)(ju)有較大的(de)(de)(de)視場角，不(bu)需要(yao)進行(xing)(xing)光(guang)(guang)譜(pu)掃描就能對較大視場進行(xing)(xing)光(guang)(guang)譜(pu)分析，因此(ci)可以用于光(guang)(guang)譜(pu)成(cheng)像系統，并且與系統光(guang)(guang)柵(zha)成(cheng)像光(guang)(guang)譜(pu)儀相(xiang)比具(ju)(ju)有結構簡單(dan)、體積小、易于電腦程(cheng)序控(kong)制等優(you)點，具(ju)(ju)有很(hen)(hen)(hen)好的(de)(de)(de)微(wei)型化的(de)(de)(de)前景。

（來源(yuan)：網站，版(ban)權歸原作者）