Three-Dimensional Optical-Resolution Photoacoustic Microscopy - Biomedical Optical Imaging Technologies: Design and Applications - page 55

Chapter 2
Three-Dimensional Optical-Resolution
Photoacoustic Microscopy

Song Hu, Konstantin Maslov, and Lihong V. Wang

Three-dimensional optical-resolution photoacoustic microscopy (OR-PAM), an
emerging optical-acoustic hybrid technology capable of imaging optical absorption
contrasts with subcellular resolution and sensitivity, has been recognized as a
valuable complement to existing optical microscopy technologies. In this chapter,
we provide detailed discussion on the design and operation of OR-PAM, including
the principle, system design, system configuration, system alignment, experimental
procedures, laser safety, functional imaging scheme, recent technical advances, and
sample biomedical applications. Future directions of OR-PAM development are also
discussed at the end of this chapter.

2.1 Introduction

The past two decades have witnessed a dramatic growth in biomedical applications
of optical microscopy. Mainstream microscopy technologies—including, but not
limited to, confocal microscopy, multiphoton microscopy, and optical coherence
tomography (OCT)—have greatly benefited from advances in laser technology,
fluorescent labeling, scanning mechanisms, and image acquisition; however, all
these technologies rely on either optical scattering or fluorescent contrast and have
difficulty in sensing optical absorption properties of biological tissues [ 1 ].
Recently, the photoacoustic effect has been utilized for biomedical imaging of
tissue optical absorption, leading to a blooming technology—photoacoustic tomog-
raphy (PAT). In PAT, the object absorbs short-pulsed or intensity-modulated optical
irradiation, resulting in heating and further inducing high-frequency ultrasonic

S. Hu Lihong V. Wang ( )

Optical Imaging Laboratory, Department of Biomedical Engineering, Washington University
in St. Louis, St. Louis, MO 63130-4899, USA
e-mail: [e-mail]

K. Maslov