Refractive Index Detetion Of The Ultra Small Volume Based On Micro Interferometric Backscatter

Environmental monitoring and rapid measurement of bio-pharmaceutical composition is a hot topic in modern times. In many universities and research institutes, this research has become a focus of the study subjects. There is a huge investment in environmental monitoring of the scientific researches among a lot of nations and relevant institutes.In physics and practical applications, refractive index has a important role. In practice, the refractive index has a very huge range of applications. Of course, the accurate measurement of the refractive index is a great important for our daily life and study. Refractive index detection, which is used in chemical and biochemical analysis, is a common technique. Rapid monitoring and refractive detection of ultra small volume samples are in great demand. It can be seen in two major areas of environmental monitoring and care disease detection. This demand covers a huge range of applications, such as drinking water and food quality. So far, several detection techniques have been used to measure change in refractive index of small amounts of analyte, and they are all on the basis of interferometry, waveguiding effect and forward scattering. However, they have their own drawbacks even though some of them produce excellent detection limits. Forward scattering methods are well-suited for working with nanoliter probe volumes, but they use a single pass optical train and are limited in resolution. The waveguiding methods have obvious small probe volumes, but they require long lengths of the waveguide to be interrogated. In large volume flow cells and detection limits, these results are poorer than the methods of interference and scatter. To solve the problems, a late-model common refractive index detector based on backscatter interferometry, which is called the microinterferometric backscatter detector (MIBD), has been developed in our lab.Microinterferometric backscatter detector (MIBD) is one of analytical methods, and it relies on the observation that coherent light impinging on a cylindrically shaped object produces a highly modulated interference pattern. MIBD analyzes reflections from a capillary tube filled with a liquid which is aimed for refractive index measurement. Bornhop is the first person who used and described this technique. In his study, MIBD was capable of measuring changes in refractive index of liquids on the order of 10-8 RIU.However, it is still a significant challenge for highly precise and mini-ature detectors to measure ultra small volume samples. This paper will present a flexible method to record the interference fringes which are caused by backscatter with a new linear CCD; furthermore, it will get the information of refractive index by tracking the displacement of fringes with FFT analysis. With this approach, we have been able to obtain detection limits of 2.44×10-7 RIU. corresponding to 1.37×10-6 g/mL...