Increasing speed of raman acquisition through Hadamard based multiplexing
Date of Issue2017
School of Chemical and Biomedical Engineering
Raman spectroscopy is a strong candidate for analysis of biological samples due to its possible label-free nature, high chemical specificity and excellent capability of cell classification but its major drawback is the long time required to acquire signals. Two applications are presented which focus on increasing the speed of Raman acquisition by utilizing the multiplexing capability of Hadamard transform. First application is related to Raman based flow cytometry and the results obtained and the algorithms developed in this project will help in reducing reading acquisition time and minimizing the error in readings by adjusting the parameters of laser and cell flow line. Hadamard transform, Raman spectroscopy and Raman based flow cytometry is first introduced. An algorithm developed for implementation of the Hadamard transform which fastens acquisition is then explained. Experiments performed to evaluate errors induced by major factors are discussed. Lastly, the results obtained from the video processing algorithms for determining the actual cell line parameters and flow speed of the sample are presented. Second application is on developing a Hadamard based optical chopper for a multi-channel imaging system. An algorithm for selecting a suitable rotor position is proposed and afterwards the criteria for choosing an efficient transform matrix are described. Then an error determining algorithm for the recovered channel readings is presented. Finally the mechanical design of the chopper and the main considerations for its structural stability are reported.