A Laser-induced Fluorescence Detection System Based On Upconversion Material

In recent decades, upconversion materials has been a hot point of scientific research. Due to its high sensitivity, good stability, difficult to bleach and many other advantages, it has been wildly used in biomedical imaging, drug screening and biological molecules quantitative analysis. Applications of upconversion materials base on the detection of its fluorescence intensity. Now reseachers usually use typical analytical instruments to detect upconversion fluorescence. There are very few instruments specially designed for upconversion materials.Considering characteristics of upconversion fluorescence materials, a new type of fluorescence detection system is established for upconversion materials based on photoelectric detection technology.Following works have been done to complete the fluorescence detection system:1. This thesis summarized radiation mechanism and characteristics of upconversion materials. Based on these characteristics that upconversion luminescence efficiency is low, a cube-corner retroreflector is used to collect more fluorescence from upconversion materials. An optic path contain cube-corner retroreflector is designed to collect fluorescence and a coaxial multicore fiber is used to accept fluorescence out from both sides of cube-corner retroreflector. This optic path can get more fluorescence so it improves the efficiency of detection of weak fluorescence.2. According to the basic theory of the photoelectric detection, a fluorescence detection system has been designed. The system choose silicon photomultiplier to convert the fluorescence signals into voltage values, and low-pass filter and amplifying circuit are used to convert the voltage to a stable voltage value.3. According to the analysis of each component of the detection system, appropriate components were selected to complete the system. Concrete experiment have been taken to verify this system.Accurate detection of upconversion fluorescence is an important step for specific applications of upconversion materials. This thesis demonstrated practical meaning for the wide use of upconversion materials on highly sensitive detection and imaging field.