Development of a multiplex stimulated Raman microscope for spectral imaging through multi-channel lock-in detection

• Published in: Review of scientific instruments Vol. 84; no. 8; p. 083705
• Main Authors: Seto, Keisuke, Okuda, Yoshinao, Tokunaga, Eiji, Kobayashi, Takayoshi
• Format: Journal Article
• Language: English
• Published: United States 01.08.2013
• Subjects: Light; Microscopy - instrumentation; Optical Fibers; Spectrum Analysis, Raman
• ISSN: 1089-7623
• DOI: 10.1063/1.4818670

We report the development of a multiplex stimulated Raman microscope for spectral imaging through multi-channel lock-in detection with a single light source. A white pump beam is prepared with a piece of photonic crystal fiber (PCF). The system does not require the synchronization of plural light sources or the scanning of their wavelengths, and thus a jitter-free pair of pump and Stokes beams is obtained, and a high degree of temporal synchronization is attained in the spectra. The multi-channel lock-in detection (extended to 128 channels) enables the observation of pseudo-continuous stimulated Raman spectra, demonstrating the strong ability of qualitative analysis to identify various types of C-H stretching modes such as the symmetric and asymmetric modes of the methylene∕methyl and aromatic groups. Images of a mixed film of polystyrene and polymethylmethacrylate are presented to demonstrate the system's spectral imaging ability. The spatial distribution of these materials is successfully captured through one-time imaging, although the noise of the white light pump beam generated with the PCF limits the system's imaging speed.