Quantitative Phase Imaging System With Active Phase Stabilization Based On White Light Interferometry

Modern optical test and measurement is one of the key technology of precise and hyper-precise measurement and nano-detection. Optical interference technique is a main branch of modern optical test and measurement. It is an non-contact method with which has high sensitivity and precision. As one of the most popular technologies, phase measurement is more and more widely used recently.In this thesis, existing development of optical interference technique and phase measurement is introduced, based on which, a novel phase measurement interference technology and method was developed. System theory, technique and experiments were studied and excellent results were obtained.First chapter reviews the history of optical test and measurement. Typical interference measurement technologies and instruments are introduced. Combining the background of phase measurement technology, study object and aim are put forward.Chapter two introduces theory and method of the phase measurement interference technology. Phase modulation, universal algorithm of phase measurement, sampling condition, algorithm of phase extracting measurement and phase unwrapping, construction of sample surface are introduced. Three phase measurement methods are summarized. FOUR-BUCKET method is emphasized and introduced in detail because it is improved and applied in this paper. We use concrete example to explain the process of phase measurement, analyses results and errors and discuss eliminations of errors.In chapter three, we develop the new methods and technique of the phase measurement technology, including scheme, optical path, control circuit, sampling, phase extraction, phase unwrapping. On the basis of traditional phase extraction algorithm, we propose a new fast phase extraction and phase unwrapping algorithms. Chapter four reports the procedures of the system set-up. Characteristics of light source are analyzed. Optical path, phase-shifting technique, feed-back & phase-lock circuits are designed. Light source, detectors and receptors are chosen to achieve the whole system. Mirror experiment is used to calibrate the system.In chapter five we discuss the errors in the phase measurement and imaging system. Optimizations of performances of the system were established. The resolution and measurement range were studied.In chapter six, we used standard negative test chart, polystyrene balls, HeLa cells as samples respectively. Quantitative clear phase images were obtained. Experiments results show that this self-stabilized quantitative phase measurement and imaging system has high resolution, high stability and low noise. The advancement of this technique rests with quite short coherence length of thermal light source.In the last chapter, we summarized our work and results achieved in this thesis. As the system has the advantages in quantitative phase imaging, it will be applied in real-time observing and analyzing of the surface movement of cell.