In-Vivo functional optical-resolution photoacoustic microscopy with stimulated Raman scattering fiber-laser source

Abstract

Abstract:In this paper a multi-wavelength optical-resolution photoacoustic microscopy (OR-PAM) system using stimulated Raman scattering is demonstrated for both phantom and in vivo imaging. A 1-ns pulse width ytterbium-doped fiber laser is coupled into a single-mode polarization maintaining fiber. Discrete Raman-shifted wavelength peaks extending to nearly 800 nm are generated with pulse energies sufficient for OR-PAM imaging. Bandpass filters are used to select imaging wavelengths. A dualmirror galvanometer system was used to scan the focused outputs across samples of carbon fiber networks, 200μm dye-filled tubes, and Swiss Webster mouse ears. Photoacoustic signals were collected in transmission mode and used to create maximum amplitude projection C-scan images. Double dye experiments and in vivo oxygen saturation estimation confirmed functional imaging potential.

Multiparametric photoacoustic microscopy of the mouse brain with 300-kHz A-line rate

“…Thus, the expanded beam is reflected by a polarizing beam splitter (PBS; PBS121, Thorlabs) and then coupled through a microscope objective (M-10X, Newport) into a 5-m-long polarization-maintaining singlemode fiber (PM-SMF; F-SPA, Newport) for stimulated Raman scattering-based wavelength conversion. 7,8 To maximize the conversion efficiency, the orientation of the PM-SMF is carefully adjusted to align its principal axis with the polarization of the incident light. 9 The output of the PM-SMF is collimated by a collimator (CFC-11X-A, Thorlabs) and purified by a bandpass filter (FB560-10, Thorlabs) to isolate the 558-nm component.…”

Single all-fiber-based nanosecond-pulsed supercontinuum source for multispectral photoacoustic microscopy and optical coherence tomography

“…Compared to dye lasers and OPOs, SC sources are more stable and less bulky; they also exhibit a fast-tuning potential and offer a broader wavelength range [7]. SC sources also provide a much more uniform output spectrum and, thus, wider wavelength selection than stimulated Raman scattering lasers, whose major energy is distributed on a series of fixed individual peaks [8]. Besides PAM applications, SC sources also demonstrate gratifying performance in OCT systems [9].…”

Development of a Fiber Laser with Independently Adjustable Properties for Optical Resolution Photoacoustic Microscopy

“…For lasers utilizing SRS, major energy is distributed on a series of fixed individual wavelength peaks that result from nonlinear interaction between incoming photons through the fiber and the molecules in the fiber itself, thus offers a limited wavelength tunability46. Koeplinger et al 41.…”

“…determined oxygen saturation of hemoglobin and hemoglobin concentration via the same laser source. Whensoever the applications by coupling the output of Q-switched Nd:YAG microchip to PCF are considered, energy per band is reported to be lower in supercontinuum case than SRS, which may be a drawback for many applications46. In order to achieve wider tunability in the wavelength with high energy per band, Shu et al 39.…”

“…The repetition frequencies of solid-state lasers are limited up to several kHz; but recently, fiber lasers with high repetition rates emerge as an alternative excitation source for PAM. Through their high repetition rate, near real and real time imaging can be achieved46525354. It has already been reported that in comparison to conventional systems with solid state lasers, the ones with fiber lasers are at least two orders of magnitude faster without compromising lateral resolution5255.…”