Asymmetric acoustic beam shaping based on monolayer binary metasurfaces

AbstractNegative refraction of acoustic waves is demonstrated through underwater experiments conducted at ultrasonic frequencies on a 3D locally resonant acoustic metafluid made of soft porous silicone-rubber micro-beads suspended in a yield-stress fluid. By measuring the refracted angle of the acoustic beam transmitted through this metafluid shaped as a prism, we determine the acoustic index to water according to Snell’s law. These experimental data are then compared with an excellent agreement to calculations performed in the framework of Multiple Scattering Theory showing that the emergence of negative refraction depends on the volume fraction $$\Phi$$ Φ of the resonant micro-beads. For diluted metafluid ($$\Phi =3\%$$ Φ = 3 % ), only positive refraction occurs whereas negative refraction is demonstrated over a broad frequency band with concentrated metafluid ($$\Phi =17\%$$ Φ = 17 % ).

Download Full-text

Convolutional neural network as a tool for automatic alignment of electron optical beam shaping devices

Microscopy and Microanalysis ◽

10.1017/s143192762100324x ◽

2021 ◽

Vol 27 (S1) ◽

pp. 822-824

Author(s):

Enzo Rotunno ◽

Amir Tavabi ◽

Paolo Rosi ◽

Stefano Frabboni ◽

Peter Tiemeijer ◽

...

Keyword(s):

Neural Network ◽

Convolutional Neural Network ◽

Beam Shaping ◽

Optical Beam ◽

Automatic Alignment

Download Full-text

Holographic Display System to Suppress Speckle Noise Based on Beam Shaping

Photonics ◽

10.3390/photonics8060204 ◽

2021 ◽

Vol 8 (6) ◽

pp. 204

Author(s):

Di Wang ◽

Yi-Wei Zheng ◽

Nan-Nan Li ◽

Qiong-Hua Wang

Keyword(s):

Optical Element ◽

Speckle Noise ◽

Beam Shaping ◽

Diffractive Optical Element ◽

The Other ◽

Spatial Light Modulators ◽

Viewing Angle ◽

Display System ◽

Holographic Display ◽

Light Modulators

In this paper, a holographic system to suppress the speckle noise is proposed. Two spatial light modulators (SLMs) are used in the system, one of which is used for beam shaping, and the other is used for reproducing the image. By calculating the effective viewing angle of the reconstructed image, the effective hologram and the effective region of the SLM are calculated accordingly. Then, the size of the diffractive optical element (DOE) is calculated accordingly. The dynamic DOEs and effective hologram are loaded on the effective regions of the two SLMs, respectively, while the wasted areas of the two SLMs are performed with zero-padded operations. When the laser passes through the first SLM, the light can be modulated by the effective DOEs. When the modulated beam illuminates the second SLM which is loaded with the effective hologram, the image is reconstructed with better quality and lower speckle noise. Moreover, the calculation time of the hologram is reduced. Experiments indicate the validity of the proposed system.

Download Full-text

Anti-Reflection Nanostructures on Tempered Glass by Dynamic Beam Shaping

Micromachines ◽

10.3390/mi12030289 ◽

2021 ◽

Vol 12 (3) ◽

pp. 289

Author(s):

Petr Hauschwitz ◽

Jan Brajer ◽

Danijela Rostohar ◽

Jaromír Kopeček ◽

Tomáš Mocek ◽

...

Keyword(s):

Mobile Phones ◽

Thermal Damage ◽

Pulsed Laser ◽

Processing Parameters ◽

Beam Shaping ◽

Separation Distance ◽

Tempered Glass ◽

Fundamental Wavelength ◽

Speed Up ◽

Scanning Head

Reflectivity and surface topography of tempered glass were modified without any thermal damage to the surroundings by utilizing 1.7 ps ultrashort pulsed laser on its fundamental wavelength of 1030 nm. To speed up the fabrication, a dynamic beam shaping unit combined with a galvanometer scanning head was applied to divide the initial laser beam into a matrix of beamlets with adjustable beamlets number and separation distance. By tuning the laser and processing parameters, reflected intensity can be reduced up to 75% while maintaining 90% of transparency thus showing great potential for display functionalization of mobile phones or laptops.

Download Full-text