基于数字全息显微的海洋浮游生物三维形貌快速重建方法研究

Study of Rapidly Reconstruction Method of Marine Plankton 3D Profile Based on Digital Holographic Microscopy

针对海洋浮游生物实时探测中,三维形貌特征难以快速获取的问题,本文提出了一种海洋浮游生物三维形貌快速重建的方法。基于离轴菲涅尔数字全息显微系统,通过改进相位恢复方法预消除相位畸变,直接得到正确的相位信息,进而对浮游生物三维形貌重建。该方法不需要进行后期复杂的相位补偿计算,就可以对浮游生物三维形貌进行快速重建,有利于对动态、微小尺寸的浮游生物进行实时探测及分析。论文对青岛近海岸浮游生物桡足类和夜光虫进行了三维形貌重建,分辨率可达到3.5μm。实验结果为离轴菲涅尔数字全息显微系统用于海洋浮游生物原位、实时探测的可行性提供了依据。

Marine plankton detection is an important part of the Marine ecological research, in recent years, how can obtain real-time high-resolution, three-dimensional images of plankton, become a research hotspot in the field of Marine biological detection. Digital holographic microscopy is a modern measuring technology combined with digital holographiy and microscopic imaging technique, which own the advantages of digital holography such as large depth of field, real-time, and non-interference detection, is very suitable for the detection of marine plankton activities in different depth. In addition, the microscopic lens magnifies the tiny structure of the object to be tested and improved the imaging resolution. The biggest advantage is that the technology can get the amplitude and phase information at the same time, especially for the application of detecting of almost completely transparent objects such as biological section, cells in the body, plankton and so on, and can get the object’s 3D information through the quantitative measurement of the phase distribution.To solve the problem of rapidly capture of three-dimensional profile characteristics of marine plankton in real-time detection, this paper achieve rapid detection of three-dimensional profile of the plankton through digital holographic microscopy experimental system. First of all, based on the Fresnel optical path of off-axis digital holographic microscopy system, recording and reconstructing the hologram of plankton, then pointing to the phase distortion existed in the reconstructed image, this paper puts forward an improved phase recovery method, in order to eliminate the phase distortion. The advantage of this method is that directly to eliminate the phase distortion during the process of the hologram recording and reconstructing, get the correct phase distribution image. The method avoids the complicated phase distortion compensation calculation, which can rapidly reconstructing three-dimensional profile of plankton, and it is beneficial to real-time detection and analysis of the plankton of dynamic and small size.As a method of 3D microscopic imaging detection,the method which is proposed in this paper achieve in situ, real-time, three-dimensional, non-interference detection of marine plankton activities, and through the precise measuring phase distribution of plankton, its surface morphology of high-resolution, three-dimensional images. Experiment of different size of Qingdao offshore plankton copepods （0.5-1 mm） and noctiluca （100-500 μm） detection, microscopic structure and surface morphology of the detecting resolution can be achieved, and achieve the reconstruction of 3D surface topography. The experimental results for off-axis Fresnel digital holographic microscopy system applied in situ in Marine plankton, provide a basis for the feasibility of real-time detection, and the detection data is of great significance to set up 3D database of Marine plankton, realization of phytoplankton species group of automatic identification.