Matthias Rutsch

Bosch

Arrays of ultrasonic sensors are capable of 3D imaging in air and an affordable supplement to other sensing modalities, such as radar, lidar, and camera, i.e. in heterogeneous sensing systems. However, manufacturing tolerances of air-coupled ultrasonic sensors may lead to amplitude and phase deviations. Together with artifacts from imperfect knowle...

We employ intense ultrasound fields in ambient air, enabling light control in extreme parameter ranges. We acousto-optically modulate 1030 nm ultrashort pulses with 20 GW peak power efficiently ( > 50%), paving the way toward novel gas-based light control methods.

Ultrasonic mixing is a well‐established method to disperse and mix substances. However, the effects of ultrasound on dispersed soft particles as well as on their adsorption kinetics at interfaces remain unexplored. Ultrasound not only accelerates the movement of particles via acoustic streaming, but recent research indicates that it can also manipu...

Control over the intensity, shape, direction and phase of coherent light is essential in numerous fields, from gravitational wave astronomy, quantum metrology and ultrafast sciences to semiconductor fabrication. Modern photonics, however, can involve parameter regimes where the wavelength or high optical powers involved restrict control due to abso...

Sparse array designs are a promising approach to improve the beam pattern and imaging quality, especially for applications, where hardware resources are severely limited. In particular, spiral sunflower arrays become increasingly popular due to their excellent point-spread-function (PSF) characteristics and their simple, deterministic and scalable...

Control over intensity, shape, direction, and phase of coherent light is essential in numerous fields, reaching from gravitational wave astronomy over quantum metrology and ultrafast sciences to semi-conductor fabrication. Modern laser optics, however, frequently demands parameter regimes where either the wavelength or the optical power restricts c...

As a novel stimulus, we use high-frequency ultrasonic waves to provide the required energy for breaking hydrogen bonds between Poly(N-isopropylacrylamide) (PNIPAM) and water molecules while the solution temperature is maintained below the volume phase transition temperature (VPTT = 32 °C). Ultrasonic waves propagate through the solution and their e...

A rotating view of the CAD-Data of the Experimental Setup in "Multipath Flow Metering of High-Velocity Gas Using Ultrasonic Phased-Arrays"

Sparse spiral phased arrays are advantageous for many emerging air-coupled ultrasonic applications, since grating lobes are prevented without being constrained to the half-wavelength element spacing requirement of well-known dense arrays. As a result, the limitation on the maximum transducer diameter is omitted and the aperture can be enlarged for...

In this work we combine a multipath ultrasonic gas flow meter (UFM) with an ultrasonic air-coupled phased-array. This allows complementing the advantages of a multipath UFM, i.e. higher accuracy and more robustness to irregular flow, with the extended velocity measuring range due to sound drift compensation via a phased-array. We created a 3D-print...

Waveguides allow grating lobe free beamforming for air-coupled ultrasonic phased-arrays by reducing the effective inter-element spacing to half wavelength. Since the sound waves propagate through the waveguide ducts, additional time delays are introduced. In this work, we present analytical, numerical, and experimental methods to estimate these tim...

Ferroelectrets are typical cellular polymer foams that exhibit high flexibility and an excellent matching to air. Recently, biodegradable cellular polylactic acid (PLA) ferroelectrets have been introduced, exhibiting a large longitudinal piezoelectric coefficient. In this work, we present a combination of a PLA film and a printed PLA backplate usin...

Ultrasound propagation in liquids is highly influenced by its attenuation due to viscous damping. The dissipated energy will be partially absorbed by the liquid due to its dynamic viscosity as well as its bulk viscosity. The former results in the generation of a flow that is called acoustic streaming, and the latter is associated with the vibration...

Air-coupled ultrasonic sonar systems are a valuable complement to lidar sensors for safe navigation of autonomous vehicles, especially in environments with optically transparent and reflective surfaces. Consequently, sonar systems based on phased arrays and beamforming are a promising compact solution, providing precise and unambiguous 3D localizat...

Spiral-shaped phased arrays are widely used for sound source localization and are trending in other fields, e.g. 3D medical ultrasound imaging. The non-uniform element geometry allows grating lobe free beamforming without an inter-element spacing of half wavelength. We demonstrate the 3D imaging capabilities of an air-coupled ultrasonic 40-kHz phas...

Schlieren photography is widely used for visualiza-tion of acoustic or shock waves, e.g. in ballistics and aerodynamics. Due to the low molar refractivity of air the visualization of acoustic waves requires sensitive equipment or high sound pressure levels. We present a Schlieren system utilized in a non-destructive test setup, that is capable to v...

We present an air-coupled ultrasonic imaging system based on a 40 kHz 8×8 phased-array for three-dimensional real-time localization of multiple objects in the far-field. By attaching a waveguide to the array, the effective inter-element spacing is reduced to half wavelength. This enables grating lobe free transmit and receive beamforming with a uni...

We present a simulation of an ultrasonic transducer element with piezoelectric and electrostatic transduction combined and with two bending plates. It combines the high SPL of a piezoelectric transducer with the tunable resonance frequency of a CMUT due to spring softening effect. In this work, we compare two state-of-the-art transducers with our a...

We present a three-dimensional far-field imaging method using an air-coupled 40 kHz 8×8 ultrasound phased-array. A waveguide is attached to the array which reduces the aperture to 35 mm×35 mm and the inter-element spacing to λ /2 for grating lobe free beamforming. Using transmit beamforming, a pulse echo detection is performed sequentially for each...

We introduce an ultrasonic one-dimensional (1D) air-coupled phased array transducer, operating at 40 kHz without any grating lobes. It is well known, that this achievement is only possible when each transducer element is small enough for an element pitch that is equal to or less than half of the wavelength, i.e. ≤ 4.3 mm for 40 kHz operation freque...

We present an efficient numerical method to analyze the diffraction loss of an ultrasonic air-coupled phased array transducer to an arbitrary located receiving aperture. The objective is the efficient calculation of diffraction loss for applications in which such an array is excited with arbitrary input signals on all channels for different beam st...

We present a versatile ultrasonic one-dimensional (1D) air-coupled phased array transducer with a focus on its receive performance. In addition to its beam steering capability in transmit mode, it can be used to listen to ultrasonic waves at 40 kHz and below. We fulfill the half-wavelength criteria for the element spacing by introducing an addition...