22 February 2011 Wavelength agile photoacoustic microscopy with a photonic crystal fiber supercontinuum source
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Spectroscopic photoacoustic microscopy (PAM) requires a pulsed nanosecond laser with tunable wavelength, but such lasers are expensive and have poor wavelength switching speed. We are developing a rapidly tunable system based on a high repetition rate supercontinuum source. A supercontinuum is produced by propagating 0.6 ns duration pulses from an 7.5 kHz Q-switched Nd:YAG microchip laser through 7 meters of photonic crystal fiber (PCF). Wavelength selection is achieved with a rapidly tunable prism-based monochromator, where an actuator-controlled mask selects the desired wavelength band. Ten different wavelength bands (570 to 930 nm) are acquired in less than 1 second for each image pixel. Each wavelength has a bandwidth of 40 nm. The PAM system employs optical focusing of the excitation beam and detection with a 25 MHz spherically focused f/3 transducer. Multiwavelength imaging is tested on phantoms with different color inks. The inks were correctly identified by processing the multiwavelength images with a linear discriminant analysis. A major advantage of our tunable source is the high repetition rate and rapid access to widely separated wavelengths. These promising results suggest the potential of our wavelength agile source for spectroscopic photoacoustic microscopy.
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Mengyang Liu, Mengyang Liu, Takashi Buma, Takashi Buma, } "Wavelength agile photoacoustic microscopy with a photonic crystal fiber supercontinuum source", Proc. SPIE 7899, Photons Plus Ultrasound: Imaging and Sensing 2011, 789944 (22 February 2011); doi: 10.1117/12.875875; https://doi.org/10.1117/12.875875

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