Optical-resolution photoacoustic microscopy (OR-PAM) is a novel imaging technology for visualizing optically absorbing superficial structures in vivo with lateral spatial resolution determined by optical focusing rather than acoustic detection. Since scanning of the illumination spot is required, OR-PAM imaging speed is limited by both scanning speed and laser pulse repetition rate. Unfortunately, lasers with high repetition rates and suitable pulse durations and energies are not widely available and can be cost-prohibitive and bulky. We are developing compact, passively Q-switched fiber and microchip laser sources for this application. The properties of these lasers are discussed, and pulse repetition rates up to 100 kHz are demonstrated. OR-PAM imaging was conducted using a previously developed photoacoustic probe, which enabled flexible scanning of the focused output of the lasers. Phantom studies demonstrate the ability to image with lateral spatial resolution of 7±2 µm with the microchip laser system and 15±5 µm with the fiber laser system. We believe that the high pulse repetition rates and the potentially compact and fiber-coupled nature of these lasers will prove important for clinical imaging applications where real-time imaging performance is essential.
Optical-resolution photoacoustic microscopy is a novel imaging technology for visualizing optically-absorbing
superficial structures in vivo with lateral spatial resolution determined by optical focusing rather than acoustic detection.
Since scanning of the illumination spot is required, the imaging speed is limited by the scanning speed and the laser
pulse repetition rate. Unfortunately, lasers with high-repetition rate and suitable pulse durations and energies are
difficult to find. We are developing compact laser sources for this application. Passively Q-switched fiber and microchip
lasers with pulse repetition rates up to 300 kHz are demonstrated. Using a diode-pumped microchip laser fiber-coupled
to a large mode-area Yb-doped fiber amplifier we obtained 60μJ
1-ns pulses at the frequency-doubled 532-nm
wavelength. The pulse-repetition rate was determined by the power of the microchip laser pump source at 808nm and
may exceed 10 kHz. Additionally, a passively Q-switched fiber laser utilizing a Yb-doped double-cladding fiber and an
external saturable absorber has shown to produce 250ns pulses at repetition rates of 100-300 KHz. A photoacoustic
probe enabling flexible scanning of the focused output of these lasers consisted of a 45-degree glass prism in an optical
index-matching fluid. Photoacoustic signals exiting the sample are deflected by the prism to an ultrasound transducer.
Phantom studies with a 7.5-micron carbon fiber demonstrate the ability to image with optical rather than acoustic
resolution. We believe that the high pulse-repetition rates and the potentially compact and fiber-coupled nature of these
lasers will prove important for clinical imaging applications where realtime imaging performance is essential.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.