Joseph Connelly

Scholar: Joseph Connelly

Joseph Connelly

Major: Electrical Engineering

Faculty Mentor: Dr. Xiaoshan Zhu

Research Topic: Analysis and Implementation of a Lock-In Amplifier Based Optical System for the Magnitude Measurement of Mimicked Molecules through Electromagnetic Radiation Absorption

Abstract: A comprehensive analysis of an optical sensor system using a Lock-In amplifier will be examined, including the complete description of the fundamental principles behind its operation. The discussion on Lock-In amplifiers will help facilitate an understanding as to how it is possible for an optical signal buried in noise to be extracted using the phase sensitive detection of the Lock-In. On the basis of the discussion, a mimicked electromagnetic radiation detection experiment was conducted; with the use of an ultra-sensitive Lock-In Amplifier I was able to detect the transmittance of the sample material (ND filters) down to as low as 0.001% transmittance. Detection intensities at even such low transmittance levels provided relatively high system accuracies of approximately 80.27%. This optical sensor system offers the possibility or providing a simple means of molecular identification and measurement in a cheap, discrete, package. With additional resources such as optical fiber waveguides, the system could have been manipulated to measure the magnitude of physical substances within 25~100 ppb using fluorescence chemistries.

Earned Baccalaureate Degree: spring 2011