投影系统中DMD衍射效率的研究北大核心CSCD

数字微镜阵列(DMD)作为空间调制元件常用于投影光学系统,入射光为长波红外时产生的衍射效应会影响进入系统的能量分布,该文主要讨论光源入射角度对衍射效应的影响,将DMD作为闪耀光栅模型,研究其在长波红外波段产生的衍射效应。从光程差的角度分析在主、副对角线分别处于“开态”情况下的衍射效应,发现衍射效应与入射角度有关;将DMD作为闪耀光栅模型,采用矢量衍射理论计算7.7μm~9.5μm波段下DMD处于“开态”下的衍射效率。计算结果表明:当TM偏振光以44°角照射时,1级衍射达到闪耀状态,衍射效率可达到70%。

Diffraction efficiency of digital micromirror device in projection system

The digital micromirror device (DMD) as spatial modulation component is often used in projection optical system, when the incident light is long wave infrared, the diffraction effect affects the energy distribution into the system. The effect of the light incident angle on diffraction effect was mainly discussed. As a blazed grating model, the DMD was used to study the diffraction effect produced in long wave infrared band. Firstly, from the angle of optical path difference, the diffraction effect when the main and counter diagonals were in the open state was analyzed, and the diffraction effect was related to the incident angle. Then, the DMD was used as a blazed grating model and the vector diffraction theory was used to calculate the diffraction efficiency of DMD in the open state at 7.7 μm~9.5 μm band. The results show that when TM polarized light irradiating at an angle of 44°, the first order diffraction reaches a blazed state, and the diffraction efficiency can reach to 70%.