This crate provides Holo Gain for AUTD.
HoloGain produces multiple focal points.
S. Inoue et al, "Active Touch Perception Produced by Airborne Ultrasonic Haptic Hologram," Proc. 2015 IEEE World Haptics Conference, pp.362-367, Northwestern University, Evanston, II, USA, June 22–26, 2015.
Shun Suzuki, 2020