서강대학교

초록/요약

In this thesis, the two applications of heterodyne interferometer using double-pass arrangement in acousto-optic modulator (AOM) are introduced. First, the application of double-pass AOM interferometer on the displacement sensor is presented. The output intermediate frequency signal from the interferometer is processed by using I/Q demodulator and the output signal from I/Q demodulator is processed by using computer. In this experiment, the phase modulations caused by the small amplitude vibrations have been measured. The sensitivity of the phase measurement is limited by the resolution of 16 bit A/D converter used for processing the I/Q demodulator signal. Second, the application of double-pass AOM interferometer on the readout sensor for a biochemical fluidic channel is proposed. This application, the deionized (DI) water and ethylene glycol solution with different concentrations have been applied to reference and probe channels respectively. The phase difference between the probe and reference beam is measured at various concentrations of ethylene glycol solution. In this preliminary study, the resolution for measuring the concentration of ethylene glycol is better than 0.001% in weight which corresponds to 9.97x10-7 refractive index change.