Multispectral photoacoustic microscopy uses a wavelength-dependent absorption difference as a contrast mechanism to image the target molecule. In this paper, we present a novel multispectral pulsed fiber laser source, which selectively alternates the excitation wavelengths between green and red colors based on the stimulated Raman scattering (SRS) effect for imaging. This laser has a high pulse repetition rate (PRR) of 300 kHz and high pulse energy of more than 200 nJ meeting the real-time requirements of optical-resolution photoacoustic microscopy imaging. By switching the polarization state of the pump light and optical paths of the pump light, the operating wavelengths of the light source can be selectively alternated at the same fast PRR for any two SRS peak wavelengths between 545 and 655 nm. At 545 nm excitation wavelength, molecular photoacoustic signals from both blood vessels and gold nanorods were obtained simultaneously. However, at 655 nm, the photoacoustic signals of gold nanorods were dominant because the absorption of light by the blood vessels decreased drastically in the spectral region over 600 nm. Thus the multispectral photoacoustic system designed using the novel laser source implemented here could simultaneously monitor the time-dependent fast movement of two molecules independently, having different wavelength-dependent absorption properties at a high repetition rate of 0.49 frames per second (fps).
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation grant funded by the Ministry of Education , Korea ( 2019H1A2A1077006 ), the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI) , funded by the Ministry of Health & Welfare , Korea ( HI18C2383 ), the Technology innovation program funded by the Ministry of Trade, Industry and Energy , Korea ( 10063364 , 20004196 ), the Development of Measurement Standards and Technology for Biomaterials and Medical Convergence funded by Korea Research Institute of Standards and Science , Korea ( KRISS-2020-GP2020-004 ), and the Creative Materials Discovery Program funded by the Ministry of Science and ICT , Korea ( 2018M3D1A1058814 ).
- Fiber laser
- Gold nanoparticle
- Molecular imaging
- Photoacoustic microscopy
- Stimulated Raman scattering
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Radiology Nuclear Medicine and imaging