Label-free cell imaging based on multi-wavelength lensless digital holography

Abstract

Without any staining or labeling process, label-free cell imaging has less damage to cells and is suitable for longitudinal observation of cell behaviors. The lensless digital holographic microscopy, which directly uses photoelectric sensor chip to collect holographic images, has the advantages of low cost, non-invasive, large field of view and high resolution, and has been widely used in label-free cell imaging. However, when the classical angular spectrum method is used to recover the complex optical field in lensless digital holography, the twin image shows up and has a serious impact on image quality. To improve the quality of the reconstruction, a multi-wavelength lensless digital holography method is used for cell imaging in this paper. During numerical reconstruction, autofocus is performed firstly, and then the object light field is restored by the multi-wavelength phase retrieval (MWPR) iteration method combined with the compressive sensing (CS) strategy. The experiment results show that the reconstruction method based on multi-wavelength illumination combined with compressive sensing can effectively eliminate the influence of twin image and improve the reconstruction quality. Compared with the reconstruction results of single wavelength hologram, our method can not only obtain highresolution labeled cell images with large field of view, but also obtain high-quality non-labeled cell video, which can be used as an effective technique for cell imaging and dynamic continuous observation in the future.