小角度衍射噪声光栅滤波方法研究

针对因衍射等原因引起的小角度差光噪声信号,探讨了利用闪耀光栅的2级闪耀,实现角度差放大,提高空间低通滤波器适应性的滤波新方法。理论分析和模拟仿真表明,对于小于5°的角度差,可实现3倍以上放大。放大所需闪耀光栅的频率与入射单色波长成反比,波长越长,所需光栅频率越低。与正的斜入射角相比,负斜入射角度差的放大倍数更大。当负斜入射角超过一定值时,会因为全反射角的限制而导致斜入射2级闪耀不存在,只保留了有效信号的2级闪耀,滤波效果更好。

Research of grating filtering for diffractive small-angle noise

A new filtering method for small-angle-diffraction noise is put forward. The angle difference between effective signal and the noise is enlarged by the 2nd order diffraction of blazed gratings. The adaptability of the spatial low-pass filter is improved. Through theoretical analysis and simulation, it is found that the small-angle difference can be enlarged more than three times. The needed frequency of the blazed grating is in inverse ratio of the incident wavelength. The longer the wavelength, the lower the grating frequency is. Comparing with the positive inclined incident angle, the enlarging times of the negative one is bigger. When the value of the negative angle is bigger than a threshold, the 2nd order blazed diffraction will disappear for total reflection. And only the 2nd order blazed diffraction of the effective signal is reserved. The effect of the grating filtering is better.