数字聚焦压缩全息成像技术研究

Study on Numerical Focusing Compressive Holographic Imaging

同轴全息重建由于相位共轭波的干扰,会产生二阶噪声与孪生像噪声,从而影响重建质量和精度,而在全息重建中,获取最佳重建平面的相关全息聚焦距离参数也是全息成像领域的关键。为此,提出了一种基于压缩感知的聚焦重建算法,通过选取轴向方向内固定间隔的一系列重建图像,以压缩感知的全变分正则化约束重建不同深度的图像,根据图像灰度变化或绝对梯度算子等聚焦度量指标计算并构建数字全息重建图像的聚焦曲线,确定最佳聚焦位置。所述算法抑制了重建噪声,提升了物体轴向的重建精度,实现了聚焦位置周围更宽范围的高分辨率图像重建。

In holographic reconstruction,the two-order and twin image noise produced by the phase-conjugate wave arising from the symmetry of the complex field,will affect the accuracy and the image quality of the reconstructed image.The acquisition of the holographic focus distance parameter for judging the best focal plane of object is also the key to holographic imaging.In this work,a numerical focusing imaging algorithm based on compressive sensing is proposed.By choosing a stack of reconstructed images in the axial direction with fixed interval,every image is processed by the total variation regularization.These images are used to calculate and construct the focus curve of the digital holography according to the focus metrics such as the tamura coefficient and the absolute gradient operator.Then the best focus plane is evaluated.The proposed method suppresses the noise of in-line digital reconstruction,improves the axial accuracy of reconstructing,and realizes a larger range of high-resolution imaging around the focus plane.