反射式同轴非相干数字全息显微成像系统研究

Study on In-Line Incoherent Digital Holographic Microscopy in Reflection Configuration

当前，数字全息显微主要采用相干性好的激光作为光源，对设备及环境条件要求较高，且会在全息图中引人大量的散斑噪声和寄生干涉条纹。基于非相干光照明下的数字全息可以很好地解决以上问题。采用非相干光作为光源，空间光调制器和CCD组成非相干干涉仪作为全息记录模块，从波动光学角度分析了该模块的记录及再现原理，给出了系统的点扩展函数、横向放大率和再现距离。采用该模块结合物镜搭建了反射式同轴非相干数字全息显微成像系统。利用该系统对分辨率板成像，获得与传统宽场光学显微镜相当的空间分辨率。对300～500μm单颗粒金刚钻进行全息拍摄，在不同平面实现了数字聚焦。结果表明，该系统可以快速获取微小物体的三维空间信息，在医学检测、材料分析等领域具有广阔的应用前景。

Currently, the digital holographic microscopy mainly uses a laser with good coherence as the light source, it needs high equipment and environmental condition, and a large amount of speckle noise and parasitic interference fringes can be introduced in the hologram. The digital holography based on incoherent light is a good way to solve those problems. The incoherent light is used as light source, and the spatial light modulator as well as the CCD composes the incoherent interference for recording holograms. The recording and reconstructed principles of the module are analyzed from the angle of wave optics and the point spread function, the axial magnification and the reconstruction distance of the system are given. Combined with the microscope objective, the system of in-line incoherent digital holographic microscopy in reflection configuration is established. Using this system to experiment on resolution imaging, a high spatial resolution as good as the traditional wide-field Optical microscopy is obtained. The holograms of one diamond whose size is between 300 ~m and 500 μm are captured and digital focused in different planes. The results show that the proposed system can obtain three-dimensional spatial information of small objects simply and rapidly. It has limitless applications in medical tests, material analysis and other fields.