Takase Yuki, Shimizu Kazuki, Mochida Shogo, Inoue Tomoyoshi, Nishio Kenzo, Rajput Sudheesh K, Matoba Osamu, Xia Peng, Awatsuji Yasuhiro
Appl Opt. 2021 Feb 1;60(4):A179-A187. doi: 10.1364/AO.404140.
Sound field imaging techniques have been found very useful for acoustic designs. Building on this idea, innovative techniques are needed and presented in this paper, where we report on developed imaging of the sound field radiated from speakers by parallel phase-shifting digital holography. We adopted an ultrasonic wave radiated from a speaker for an object. The phase distribution of the light wave was modulated by the sound field radiated from the speaker. The modulated phase distribution was recorded in the form of multiplexed phase-shifted holograms at the frame rate of 100,000 fps. A 40,000 Hz sound field radiated from a speaker is used as an observation target. Our proposed method can implement the imaging of the sound field successfully. Also, in order to demonstrate the digital refocusing capability of digital holography, we set two speakers, whose difference in depth positions was 6.6 cm, as a long-depth object. We demonstrated the digital refocusing on the two speakers along with the capability of measuring the positions of the objects. Furthermore, we succeeded in imaging of 40,000 Hz and 41,000 Hz sound fields radiated from the two speakers. The presented experimental results showed that parallel phase-shifting digital holography is very useful and suitable for sound field imaging.
声场成像技术已被证明对声学设计非常有用。基于这一理念，本文提出了一些创新技术，我们报告了通过并行相移数字全息术对扬声器辐射的声场进行的成像研究。我们将扬声器辐射的超声波用作物体。光波的相位分布由扬声器辐射的声场调制。调制后的相位分布以多路复用相移全息图的形式以100000帧/秒的帧率记录。从扬声器辐射的40000Hz声场用作观察目标。我们提出的方法能够成功实现声场成像。此外，为了展示数字全息术的数字重聚焦能力，我们设置了两个深度位置相差6.6厘米的扬声器作为长深度物体。我们展示了对这两个扬声器的数字重聚焦以及测量物体位置的能力。此外，我们成功地对两个扬声器辐射的40000Hz和41000Hz声场进行了成像。所呈现的实验结果表明，并行相移数字全息术非常有用且适用于声场成像。
