Thomas Berer
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View article: Measurement of the attenuation of elastic waves at GHz frequencies using resonant thickness modes
Measurement of the attenuation of elastic waves at GHz frequencies using resonant thickness modes Open
We present an evaluation of attenuation of elastic waves in the GHz range, based on the decay of thickness-stretch resonances of plates. We measured the elastic response of micro-scale aluminum plates, using a laser-ultrasound technique. T…
View article: Resolution Limits in Photoacoustic Imaging Caused by Acoustic Attenuation
Resolution Limits in Photoacoustic Imaging Caused by Acoustic Attenuation Open
In conventional photoacoustic tomography, several effects contribute to the loss of resolution, such as the limited bandwidth and the finite size of the transducer, or the space-dependent speed of sound. They can all be compensated (in pri…
View article: Using zero-group-velocity lamb waves to determine thickness and bulk sound velocities of isotropic plates
Using zero-group-velocity lamb waves to determine thickness and bulk sound velocities of isotropic plates Open
We present an ultrasound method to simultaneously determine the thickness of a plate together with the longitudinal and shear elastic wave velocities of its material [1]. The method works without assumptions or a priori knowledge of the pl…
View article: Diffraction limited mid-infrared reflectance microspectroscopy with a supercontinuum laser
Diffraction limited mid-infrared reflectance microspectroscopy with a supercontinuum laser Open
Chemical mapping was demonstrated with a mid-infrared (MIR) microspectroscopy setup based on a supercontinuum source (SC) emitting in the spectral range from 1.55 to 4.5 µm and a MEMS-based Fabry-Pérot filter spectrometer. Diffraction limi…
View article: A linear state space model for photoacoustic imaging in an acoustic attenuating media
A linear state space model for photoacoustic imaging in an acoustic attenuating media Open
In photoacoustic imaging, ultrasound waves generated by a temperature rise after illumination of light absorbing structures are measured on the sample surface. These measurements are then used to reconstruct the optical absorption. We deve…
View article: Fluorescence quantum yield and excited state lifetime determination by phase sensitive photoacoustics: concept and theory
Fluorescence quantum yield and excited state lifetime determination by phase sensitive photoacoustics: concept and theory Open
In this Letter, we theoretically describe photoacoustic signal generation of molecules, for which triplet relaxation can be neglected, by considering the excited state lifetime, the fluorescence quantum yield, and the fast vibrational rela…
View article: Determination of thickness and bulk sound velocities of isotropic plates using zero-group-velocity Lamb waves
Determination of thickness and bulk sound velocities of isotropic plates using zero-group-velocity Lamb waves Open
We propose a method to simultaneously determine the thickness of an isotropic plate together with the longitudinal and shear elastic wave velocities of its material. The method requires knowledge of the frequencies of two zero-group-veloci…
View article: Photoacoustic microscopy of single cells employing an intensity-modulated diode laser
Photoacoustic microscopy of single cells employing an intensity-modulated diode laser Open
In this work, we employ frequency-domain photoacoustic microscopy to obtain photoacoustic images of labeled and unlabeled cells. The photoacoustic microscope is based on an intensity-modulated diode laser in combination with a focused piez…
View article: Blind structured illumination as excitation for super-resolution photothermal radiometry
Blind structured illumination as excitation for super-resolution photothermal radiometry Open
Using an infrared camera for radiometric imaging allows the contactless temperature measurement of multiple surface pixels simultaneously.From the measured surface data, a sub-surface structure, embedded inside a sample or tissue, can be r…
View article: All-optical photoacoustic projection imaging
All-optical photoacoustic projection imaging Open
We introduce all-optical photoacoustic projection imaging. An array of fiber-optic interferometers is used to measure photoacoustic signals. The obtained images represent the projection of the three-dimensional spatial light absorbance wit…
View article: Super-resolution thermographic imaging using blind structured illumination
Super-resolution thermographic imaging using blind structured illumination Open
Using an infrared camera for thermographic imaging allows the contactless temperature measurement of many surface pixels simultaneously. From the measured surface data, the structure below the surface, embedded inside a sample or tissue, c…
View article: Super-resolution photoacoustic microscopy using blind structured illumination
Super-resolution photoacoustic microscopy using blind structured illumination Open
We present a method for enhancing the spatial resolution of optical-absorption-based photoacoustic imaging through or within highly scattering media. The optical speckle pattern that emerges as light propagates through diffuse media provid…
View article: Compressed sensing and sparsity in photoacoustic tomography
Compressed sensing and sparsity in photoacoustic tomography Open
Increasing the imaging speed is a central aim in photoacoustic tomography. This issue is especially important in the case of sequential scanning approaches as applied for most existing optical detection schemes. In this work we address thi…
View article: Frequency domain photoacoustic and fluorescence microscopy
Frequency domain photoacoustic and fluorescence microscopy Open
We report on simultaneous frequency domain optical-resolution photoacoustic and fluorescence microscopy with sub-µm lateral resolution. With the help of a blood smear, we show that photoacoustic and fluorescence images provide complementar…
View article: Inverse characterization of plates using zero group velocity Lamb modes
Inverse characterization of plates using zero group velocity Lamb modes Open
In the presented work, the characterization of plates using zero group velocity Lamb modes is discussed. First, analytical expressions are shown for the determination of the k-ω location of the zero group velocity Lamb modes as a function …
View article: Multimodal noncontact photoacoustic and optical coherence tomography imaging using wavelength-division multiplexing
Multimodal noncontact photoacoustic and optical coherence tomography imaging using wavelength-division multiplexing Open
We present multimodal noncontact photoacoustic (PA) and optical coherence tomography (OCT) imaging. PA signals are acquired remotely on the surface of a specimen with a Mach-Zehnder interferometer. The interferometer is realized in a fiber…
View article: Dual Modality Noncontact Photoacoustic and Spectral Domain OCT Imaging
Dual Modality Noncontact Photoacoustic and Spectral Domain OCT Imaging Open
We developed a multimodal imaging system, combining noncontact photoacoustic imaging and optical coherence tomography (OCT). Photoacoustic signals are recorded without contact to the specimens’ surface by using an interferometric technique…
View article: A Novel Compressed Sensing Scheme for Photoacoustic Tomography
A Novel Compressed Sensing Scheme for Photoacoustic Tomography Open
Speeding up the data acquisition is one of the central aims to advance tomographic imaging. On the one hand, this reduces motion artifacts due to undesired movements, and on the other hand this decreases the examination time for the patien…
View article: Characterization of the Spatio-temporal Response of Optical Fiber Sensors to Incident Spherical Waves
Characterization of the Spatio-temporal Response of Optical Fiber Sensors to Incident Spherical Waves Open
A theoretical framework is presented for calculating the opto-acoustic response of optical fiber ultrasound sensors with several layers of coating. A harmonic point source generating a spherical wavefront with arbitrary position and freque…