| Digital holography is a new imaging method with high resolution,real time and non-contact.Microfluidic chip is an experimental reaction device for microfluidic test.The channel size in the chip is tens to hundreds of microns,which has the advantages of small sample consumption and controllable flow rate.Biochemical reaction of living cells is a focus research topic in biomedical filed.Most biological cells are either transparent or translucent,which is referred as to phase-type objects.In the thesis,the method for imaging living cells with non-staining and non-invasive by digital holography is investigated to achieve real-time digital holographic imaging of living onion cells and to characterize internal tissue.Firstly,in this thesis,the measurement method for refractive index of liquid solution in microfluidic chip by digital holographic microscopy is studied.The digital holographic measurement for refractive index of salt solution and sucrose solution with different concentrations are completed.The salt solutions with mass concentration ratio of 26.47% and 0% injected into a Y-type microfluidic chip are used as target samples in the experiment.Digital holograms of the microfluidic chip filled with abovementioned solutions are recorded in video by using a pre-amplified digital holographic system.After phase reconstruction,the curves of phase change with the salt solutions of concentrations 26.47% and 0% are obtained.The experimental results showed that the phase value of 26.47% salt solution is higher than that of 0%.Further,the phase subtractive measurement method of refraction index of microfluidic solution is presented,and the refractive indexes of microfluidic solutions with different concentrations are measured.In the experiment,the holograms with respect to salt solutions and sucrose solutions with mass ratios of 0%,5%,10%,and 20% injected into the microfluidic chip are recorded,respectively.Then,by using the phase subtractive method and according to their reconstructed phase distribution of these solutions,the fitting curves of refractive indexes versus the concentrations of the salt solutions and sucrose solutions are obtained,respectively.The relative error of measured refractive index values is 0.007 in this digital holographic imaging system.Secondly,real-time digital holographic imaging for living onion cells is studied.A pre-amplification digital holographic microscopy imaging system is designed for microscopic imaging of the biochemical reaction process of living onion cells in realtime.In the experiments,the digital holograms of onion's living epidermal cells are recorded with a CCD camera in video,and their phase images are reconstructed.In the first group of phase images,the onion's cell nucleus itself turning motion and the development of internal tissues are exhibited,and accordingly,the curves of the area and phase of cell nuclei and cytoplasm versus time during the biochemical reaction process are given.In the second group of phase images,the distribution and change process of endoplasmic reticulum in living cells are shown by extracting phase information.In the third group of phase images,the plasmolysis phenomenon happened in living onion cells is displayed by real-time playing the phase images.In addition,the curves of the phases respective to the cytoplasm and nucleus versus time during the plasmolysis process are obtained,which characterize the change of the internal tissue in onion's living epidermal cells.In summary,the pre-amplification digital holographic microscopy imaging system and reconstruction algorithm are illustrated.The measurement of refractive indexes of microfluidic solutions of the different concentrations by using digital holographic phase reconstruction is achieved.The characterizations for microfluidic concentrations and for onion's living cells are given.The digital holographic imaging for depicting onion's living epidermal cells and their biochemical reaction process are implemented. |
