大功率单色LED的空间相干特性

基于van Cittert-Zernike定理,从理论上计算出大功率单色发光二极管(LED)辐出光,在空间中传输后的空间相干性分布。计算结果表明,自发辐射的LED光源其辐射光在空间中传输后,由非相干光变为部分相干光,且其空间相干性与LED芯片的结构有关。实验上采用双缝干涉对LED辐射光的空间相干性进行测量,由干涉条纹的可见度与两点间的相干度之间的关系得出,非相干LED光源的辐射光在传输后为部分相干光。而采用间隔可调的双缝干涉测量两点间的相干度后发现,LED的芯片发光区域决定了其辐射光在传输中的空间相干性分布。理论计算的空间相干性分布与实验测量结果基本吻合。

Spatial Coherence of High-Power Single-Color LED

Based on the van Cittert-Zernike theorem, we study the spatial coherence distribution of the light beam, which radiated from the high-power single-color light-emitting diodes (LED) after propagation theoretically. The theoretical calculations show that, the spectral coherence of the light beams which radiated from the non-coherent LED source changed into partially coherent after propagation. Moreover, the spatial coherence of the light beams is related to its chip architecture of the LED. By double-slit interference we measure the spatial coherence of the light beams experimentally. And the visibility of the interference fringes show that the light beams from the non-coherent LED source change into partially coherent after propagation. In addition, the measurement of the visibility by use of adjustable double-slit reveal that, the emitting area of the LED determines the spatial coherence of the light beams from LED source. The theoretical result of the spatial coherence is almost consistent with the experimental measurement.