基于相位编码的联合菲涅耳变换相关器

Joint Fresnel Transform Correlator Based on Phase Encoding

使用纯相位空间光调制器编码线性相位掩模,实现了联合菲涅耳变换相关器。单色平面波照明下,通过线性相位掩模对参考图像和目标图像进行调制。在菲涅耳衍射场中心重合的平面上,由CCD记录得到参考图像与目标图像的联合菲涅耳变换功率分布(JFTPD)。将联合菲涅耳变换功率分布输入光学傅里叶逆变换系统,经光学傅里叶逆变换后在输出面上得到相关点。数值模拟和实验结果表明,相关器输出尖锐的相关峰,且相关峰值对参考图像与目标图像的相对位置比较敏感;当参考图像与目标图像间距分别改变-30pixel和+40pixel时,相关峰值分别下降至23%和48%。

The joint Fresnel transform correlator is achieved by using a phase-only spatial light modulator to encode linear phase mask. Under the illumination of monochromatic plane wave, the reference image and the target image are modulated by the linear phase mask. In the plane where Fresnei diffraction field centers are superimposed, the joint Fresnel transform power distribution （JFTPD） of the reference image and the target image can be recorded with a CCD camera. The JFTPD is input to the optical Fourier inverse transform system, and the correlation spots can be obtained in the output plane after Fourier inverse transform. The results of numerical simulations and experiments show that the correlator can output sharp correlation peaks, and the correlation peak values are sensitive to the relative position of the reference image and the target image. When the distance between the reference image and the target image changes by -30 pixel and ＋40 pixel, the correlation peak value decreases to 23% and 48% respectively.