Application Of KTN Electro-optic Crystal In 3D Imaging Laser Radar

Tantalum niobate crystal as a new multifunctional crystal material,has a significant two electrooptic effect,which has been used in light intensity modulation,rapid room,laser scanning and other beam control fields.This paper aims to use tantalum niobate crystal to solve the problem of field angle limitation in 3D imaging laser radar system.The main contents of this paper are as follows:First,the reasons for the field angle limitation of the 3D imaging laser radar system based on the electro-optic intensity modulation are analyzed.The geometric model of cone beam propagating in uniaxial crystal and biaxial crystal were established,respectively,and the conoscopic models of these two kinds of crystals are studied.The conoscopic system of two deuterium phosphate crystal used in 3D imaging laser radar system is established.This paper explain the facts that the limitation of the field of view is induced by the limited optical axis separation angle of two deuterium phosphate crystal.Second,the conoscopic interference system of tantalum niobate crystal used under the external electric field is investigated by simulation and experiment measurement.Further confirmed that the tantalum niobate crystal used in electro optic intensity modulation has a large field of view.At the same time,the phase difference and polarization state of the beam propagating in the crystal are analyzed on the basis of the transverse electro-optic effect of the uniaxial crystal.Found that the main reason leading to the tantalum niobate crystal has large field characteristics in electro optic intensity modulation is the isochromates' wide range variation with the applied electric field.Finally,the extinction ratio and the half wave voltage of tantalum niobate crystal in the electro-optic intensity modulation was measured.The main factors that restrict the extinction ratio and the change law of half wave voltage are analyzed.An electronically controlled birefringence of KTN was found during the experiment of electro-optical modulation.The principle of this kind of performance that one beam of light through the crystal separated into two beams of orthogonal polarization light is illustrated.The function relationship between voltage and deflection angle was showed,which can explain the experimental phenomenon in theory.Expand the application scenario of tantalum niobate crystal.