基于菲涅耳微透镜的光学加速度传感器原理研究

目前航空业惯性导航系统中广泛采用的加速度传感器存在抗电磁干扰（EMI）和电磁冲击（EMP）能力差等缺陷，针对此提出了一种基于菲涅耳衍射微透镜的光学加速度传感器，它能够有效地解决上述问题。该传感器的传感原理是把一个反光膜平行地置于微透镜的后方，根据微透镜前方汇聚点处光强的变化来敏感加速度的大小。通过Fresnel-Kirchhoff衍射公式详细推导了传感器的光学原理，并且对光纤的偏移对光强的影响进行了计算机模拟分析。结果表明：光纤接收的光强对反光膜的位置具有纳米级的灵敏度，并且对光纤沿微透镜焦平面方向的偏移极其敏感，当此偏移超过2μm，光强就会下降至不足理想情况下的50%。验证性实验结果表明这种传感器的原理是正确的。

Principle of an optical acceleration sensor based on Fresnel microlens

At present,the acceleration sensor widely used in inertial navigation system of aviation industry can't offer effective immunity towards the electro magnetic interference (EMI) and electro magnetic pulse (EMP),so a novel optical acceleration sensor based on a Fresnel diffractive microlens is proposed,which can solve the problems mentioned above effectively. The sensing principle of the sensor is that a reflecting membrane is put behind the microlens in parallel,and the acceleration is calculated by measuring the variation of the light intensity at the converging point in front of the microlens. The optical principle of the sensor is discussed in details by using Fresnel-Kirchhoff diffractive formula. The effect of the optical fiber deviation on the light intensity is analyzed with the computer simulation. The results prove that the light intensity received by the optical fiber has visible changes even for the nanometer level changes of the position of the reflecting membrane and is highly sensitive to the deviation of optical fiber in the direction of the focal plane. The light intensity will drop off to less than 50% of ideal light intensity when the deviation exceeds 2 microns. Moreover,the principle of this sensor was proved to be correct by a demonstration experiment.