We propose a simultaneous imaging technique of both sound propagations and spatial distribution of acoustic frequencies. We experimentally demonstrated the proposed technique for the acoustic waves of frequencies 39,500 and 40,500 Hz, which have close sound pressure. The sounds were recorded at the framerate of 100,000 fps by parallel phase-shifting digital holography. To obtain the distribution of the acoustic frequencies, the short-time Fourier transform analysis was applied. The simultaneous imaging was carried out by assigning the frequencies and the pixel values of the phase-difference images to the components of HSL color space. The images obtained by the proposed technique represent the frequencies with the hue in addition to the sound propagations with the luminance. We succeeded in imaging the spatiotemporal evolution of the spatial frequencies of the sounds.
Lithium-metal anodes are promising electrodes for fabricating high-capacity all-solid-state batteries; however, lithium dendrite growth during charging limits their applicability. One method to suppress lithium dendrite growth is to insert a carbon interlayer between the solid electrolyte and the lithium-metal anode. There are many potential approaches for inserting a carbon interlayer. The optimal conditions for suppressing lithium dendrite growth and ensuring uniform lithium deposition have not yet been established. This study employs X-ray computed tomography to investigate anode-less all-solid-state batteries. Pressurized xenon is used to examine how the carbon interlayer functions and how uniformly lithium is deposited after various carbon interlayer insertion processes. Uniform deposition is observed following simultaneous pressure bonding of the carbon interlayer and compression of the solid electrolyte.
We report the three-dimensional (3D) trajectory of a Volvox moving in water was recorded by parallel phase-shifting digital holographic microscope providing 10X magnification. The recording frame rate, the shutter speed, and the total recording time were 1000 fps, 0.25 ms, and 2.1 s, respectively. In the reconstructed phase image of the Volvox, the shape of the Volvox is regarded as a circle. The lateral coordinates of the Volvox were determined as the center of the circle. The depth coordinates of the Volvox were determined as the propagation distance where the edge of the Volvox in the reconstructed amplitude image was clearest while the propagation distance was varied. We successfully demonstrated the 3D tracking of curvedly moving Volvox.
A novel wavelength-division-multiplexing label scheme for an optical label switch is proposed which has several advantages such as high-spectral and high-network efficiency, the bit-by-bit separation of labels without any active devices, and the label with low power consumption. In this letter, we achieved label/payload separation using the packet synchronized trigger pulse generated by input packets, label pattern recognition, and high-speed switching of less than 1-ns switching time with error-free performance. The power penalty between the input and the switched payloads was about 1 dB, which resulted from the wavelength conversion.
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.
An all-optical bistable (AOB) resonator device composed of a 430-nm-thick liquid crystal (LC) layer embedded in two thin gold films (MLM) is reported in this paper. This device allows the use of the incident illumination at normal incidence, whereas the previous AOB devices based on twisted nematic (TN)-LC function only for illumination at oblique incidence. The fastest switching time was measured to be 1.8 ms, which is significantly faster than that of TN-LC. Because the MLM device operates free from electronic circuits, it is promising for two-dimensional optical data processing, random access optical memories, and spatial light modulators.
We report imaging of a sound field radiated from a sound source by parallel phase-shifting digital holography. We used a Nd:YVO4 laser emitting light with a wavelength of 532 nm as a light source and a polarization imaging camera to record holograms. The holograms were recorded 40000 Hz sound with 100000 frame per second. To adjust one wavelength of sound to the recordable area of the image sensor, we introduced a demagnification optical system in the path of the object beam. The phase difference images were calculated from the recorded holograms. Thus, we observed propagation of periodical phase distributions of sound and succeeded in sound field imaging.
