Research On Real-time Measure System Based On Digital Holography To Observe The Solution Concentration Change

Concentration of the solution is the key reference which reflects its related physical and chemical reactions, providing ways of observing, analyzing and controlling, so detecting concentration of solution is becoming more and more intention-getting nowadays in fields of biology, chemistry, material, medicine and so on. In the field of biology, solution concentration which reflects the character of the organism can help to observe, analyze and know the state of the organism; in medicine, detecting the concentration of the solution in human body can help to diagnose and cure; in beer industry, concentration of beer is one of the most important reference, which can enhance the quality, promote the efficiency and decrease the consume; in electrochemistry, the concentration change of the solution in electrochemical reactions helps to judge which period and state the reaction is and how the reaction proceeds.Based on analysis and summarization of measuring concentration change of the solution in electrochemical reaction by digital holography, a method aimed at processing holographic video is proposed to solve the time-consuming problem caused by former method which can only process the holographs discretely. The new method also provides a video which dynamically displays the concentration change of the solution in the form of phasic difference of object wave, making observing and analyzing much more convenient.In video processing, first, a method based on histogram and morphology is proposed to locate the cut-off frequency and realize auto-filtering. As the computer vision way is utilized, complicated mathematic calculation is avoided. Second, on the platform of SIMULINK, combined with powerful mathematic calculating and figure displaying function in MATLAB, a video processing and displaying system is established.In the process of auto-filtering, ringing which is the inhered property of ideal filtering is analyzed and Gaussian function is used to smooth the truncation of ideal filter to avoid the error caused by ringing. Mean while, Gaussian filtering provides a weigh function to counteract the error introduced by locating cut-off frequency in computer vision way.In addition, locating the interface of electrode and solution is discussed. Based on summarizing all kinds of edge detecting algorithms, multi-scale property of wavelet transform is analyzed and a method based on wavelet transform is proposed. It is proved that the new method can approximately locate the solid-liquid interface.