Optimal optical design of aspheric ultrasonic probe for photoacoustic microscopy
As a new non-destructive imaging technology in the field of biomedicine, photoacoustic imaging technology combines the advantages of pure optical and pure acoustic imaging with good spatial resolution, high sensitivity, and strong penetrating power. In the photoacoustic microscopy imaging system, the acousto-optic coupling prism is a component for optical transmission and ultrasonic detection. It is usually composed of an irregular prism and a spherical concave acoustic lens at the bottom. Because the spherical acoustic lens has a poor focusing effect on the ultrasonic beam, the accuracy of ultrasonic detection is low. In order to solve this problem, we propose an optimization method to eliminate the influence of acoustic lens on the beam transmission. A collimating lens is added to the acousto-optic coupling prism with an aspheric acoustic lens at the bottom of the system. In this paper, Zemax optimizes the curvature coefficient and thickness of the collimating lens to eliminate the deteriorating effect of the aspheric acoustic lens on the beam transmission, and evaluates the optimization effect by analyzing the spot and MTF image. The simulation results show that the collimating lens can eliminate the influence of the aspheric acoustic lens on the beam transmission, so that the optical focus and the acoustic focus can be kept coaxial and confocal, and the detection efficiency of the photoacoustic signal can be improved. This work has theoretical guiding significance for the study of photoacoustic microscopy imaging with large depth of field.
Nanchang Univ. (China)