各位大大，最近我在看一篇二區(qū)的
論文，題目是Grating_micro-dot_patterned_light_guide_plates_for_LED_backlights，Seung Ryong Park，2007。作者在里面提到，團(tuán)隊的
導(dǎo)光板設(shè)計理念是通過在導(dǎo)光板上表面刻正弦型
光柵，使得光以衍射-1級主級大出射，如圖所示。那么在作者所希望達(dá)到的出射情況（摘自原文）“when δi=0, all diffracted orders are located in the x-o-z plane as shown in Fig. 2(b). This grating diffraction geometry is referred to as classical “in-plane diffraction.” Under this condition with a sufficiently large incident inclination angle (typically larger than the critical angle), it is possible to make the forward diffracted zero-order vanescent and only the -1st diffracted order to be vertically (in the z-axis direction) out-coupled into air by suitable choice of the grating period”時，這個大于臨界角的入射角
光線竟然不會繼續(xù)在導(dǎo)光板內(nèi)全反射，而是發(fā)生了
衍射，這里我覺得矛盾[了。既然滿足全反射的條件卻不發(fā)生全反射，為什么呢？
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