Reflection-mode multifocal optical-resolution photoacoustic microscopy
Compared with single-focus optical-resolution photoacoustic microscopy (OR-PAM), multifocal OR-PAM utilizes both multifocal optical illumination and an ultrasonic array transducer, significantly increasing the imaging speed. A reflection-mode multifocal OR-PAM system based on a microlens array that provides multiple foci as well as an ultrasonic array transducer that receives the excited photoacoustic waves from all foci simultaneously is presented. Using a customized microprism to reflect the incident laser beam to the microlens array, the multiple optical foci are aligned confocally with the focal zone of the ultrasonic array transducer. Experiments show the reflection-mode multifocal OR-PAM is capable of imaging microvessels in vivo, and it can image a 6×5×2.5 mm^3 volume at 16 μm lateral resolution in ∼2.5 min, which was limited by the signal multiplexing ratio and laser pulse repetition rate.
Additional Information© 2013 SPIE. Paper 12771LR received Dec. 4, 2012; revised manuscript received Feb. 11, 2013; accepted for publication Feb. 12, 2013; published online Feb. 27, 2013. This work was sponsored in part by National Institutes of Health (NIH) Grants R01 EB000712, R01 EB008085, R01 CA134539, U54 CA136398, R01 CA157277, R01 CA159959, and DP1 EB016986 (NIH Director's Pioneer Award). L. V. Wang has a financial interest in Microphotoacoustics Inc., and Endra Inc., which, however, did not support this work. K. I. Maslov has a financial interest in Microphotoacoustics Inc., which did not support this work. The authors appreciate James Ballard's close reading of the manuscript. They also thank Liang Song, Lidai Wang, Junjie Yao, and Jun Xia for helpful discussions and experimental assistance.
Published - JBO_18_3_030501.pdf