Figure 4.
Developments in PAE instrumentation. (A) A side-viewing photoacoustic endoscope with 3.8 mm diameter (i, ii) that uses a conventional single-crystal transducer (LiNbO3, 36 MHz) and achieves circumferential scanning with a rotating mirror that reflects ultrasound waves and laser pulses. Representative images from rabbit esophagi with Cartesian and cylindrical coordinate systems (iii) are shown in (iv) and (v) 58. (B) A photograph (i) and schematic (ii) of a side-viewing endoscope (4.5 mm diameter) that uses an optically transparent, micro-ring resonator transducer. 103. (C) A schematic of a forward-viewing endoscope with 3.2 mm diameter that uses an optically transparent Fabry-Pérot ultrasound sensor attached to the distal end of the device. A magnified view of the distal end (i) shows individual fiber-optic cores beneath the Fabry-Pérot sensor which is revealed in (iii): it is made from two dielectric mirror coatings that sandwich a Parylene C polymer spacer (15 µm) 60.