Real-time Raman sensing without spectrometer

Min Ju Kim; Sungho Kim; Timothy K. Yang; Dinesh Kumar; Sung Chul Bae

doi:10.1117/12.2079278

11 March 2015 Real-time Raman sensing without spectrometer

Min Ju Kim, Sungho Kim, Timothy K. Yang, Dinesh Kumar, Sung Chul Bae

Proceedings Volume 9318, Optical Biopsy XIII: Toward Real-Time Spectroscopic Imaging and Diagnosis; 93180Z (2015) https://doi.org/10.1117/12.2079278
Event: SPIE BiOS, 2015, San Francisco, California, United States

Abstract

Raman spectroscopy has been a powerful tool in various fields of science and technology ranging from analytical chemistry to biomedical imaging. In spite of unique features, Raman spectroscopy has also some limitations. Among them are weak Raman signal compared to strong fluorescence and relatively complicated setup with expensive and bulky spectrometer. In order to increase the sensitivity of Raman technique, many clever attempts have been made and some of them were very successful including CARS, SRS, and so on. However, these still requires expensive and more complicated setup. In this work, we have attempted to build a real-time compact Raman sensor without spectrometer. Conventional spectrometer was replaced with a narrow-band optical filter and alternatively modulated two lasers with slightly different wavelengths. At one laser, Raman signal from a target molecule was transmitted through the optical filter. At the other laser, this signal was blocked by the optical filter and could not be detected by photon detector. The alternative modulation of two lasers will modulate the Raman signal from a target molecule at the same modulation frequency. This modulated weak Raman signal was amplified by a lock-in amplifier. The advantages of this setup include compactness, low cost, real-time monitoring, and so on. We have tested the sensitivity of this setup and we found that it doesn’t have enough sensitivity to detect single molecule-level, but it is still good enough to monitor the change of major chemical composition in the sample.

Citation Download Citation

Min Ju Kim, Sungho Kim, Timothy K. Yang, Dinesh Kumar, and Sung Chul Bae "Real-time Raman sensing without spectrometer", Proc. SPIE 9318, Optical Biopsy XIII: Toward Real-Time Spectroscopic Imaging and Diagnosis, 93180Z (11 March 2015); https://doi.org/10.1117/12.2079278

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