The existing design of the reflection-mode OR-PAM mainly falls into four categories. First, an optical-acoustic combiner can be used to redirect the ultrasonic waves.3 However, the optical-acoustic combiner is too big to fit into the typically very small working distance of a large-NA objective. Moreover, under high-spatial-resolution conditions, it is difficult to precisely correct the optical distortion introduced by the acoustic lens and the 45 deg split between prisms. Second, a thin piece of glass can be used as the optical-acoustic splitter.4 But for a large-NA objective, even low refractive index glass (Magnesium Fluoride) will introduce noticeable distortion to the optical focusing. Third, a ring-shaped-focused ultrasonic transducer can be used to detect the ultrasonic waves.5 To fabricate such a transducer, a flat active-surface is created and then deformed into a spherical shape for acoustic focusing, so the acoustic NA is limited to . If the optical objective has a 0.5 NA, it is impossible to make a central hole in the transducer that is big enough for the light to pass through. Finally, it is possible to place a commercially available focused transducer off axis.6 However, with a large optical NA, the NA of the transducer is very limited and so is the detection sensitivity. Another issue with this design is the degradation of the axial resolution (e.g., two times degradation with 60° off axis). Therefore, we need a new design for the submicron-resolution PAM.