菲涅耳非相干相关全息相移技术

菲涅耳非相干相关全息术（Fresnel Incoherent Correlation Holography，FINCH）属于同轴全息系统，需要通过相移技术去除零级像和共轭像。通过对FINCH系统记录及再现过程的理论分析，根据系统点扩散函数推导出了n步相移数学计算公式，模拟仿真了相移步数n对FINCH系统成像质量的影响，并搭建了非相干光反射式数字全息记录系统，对模拟结果进行了实验验证。模拟仿真及实验结果表明:通过增加相移步数不能显著提高再现像质量；二步相移能够提高记录速度，通过去除原始图像和小波分解的方法可以抑制零级像，提高再现像质量；通过对三步相移每个相移全息图拍摄多次求平均值后得到的再现像与拍摄一次得到的再现像对比发现，随着拍摄次数的增加，得到的再现像质量越来越好，背景噪声大大减弱，再现像强度越来越大，为FINCH系统再现像质量的改善提供了新的思路和新的实验基础。

Fresnel incoherent correlation holography with phase-shifting technology

The Fresnel Incoherent Correlation Holography (FINCH) technology is an on-axis system, which needs phase-shifting technology to eliminate the conjugate image and the zero-order image. Based on the theory of FINCH imaging system, the formula of n-step phase-shifting method was derived, an experimental light path of incoherent light reflection digital holographic recording was constructed. The effect of n-step phase-shifting on the FINCH imaging system through simulation and experiment was studied. The results show that the quality of the reconstructed image cannot significantly improved by increasing phase-shifting steps; two-step phase-shifting can enhance recording speed, whose zero-order image can be suppressed by eliminating original image and wavelet decomposition. A comparison was made between the reconstructed images obtained separately by averaging hologram and hologram photographing once of three-step phase-shifting, and the result shows that the quality of the reconstructed image is getting better and better with the increase of the shots. Not only the background noise is greatly weakened, but also the intensity of the pixels becomes stronger and stronger, which provides a new way and new experimental basis to promote the development of the FINCH system.