J. Eur. Opt. Society-Rapid Publ. 2025, 21, 9 Ó The Author( s), published by EDP Sciences, 2025 https:// doi. org / 10.1051 / jeos / 2025004 Available online at: https:// jeos. edpsciences. org
Journal of the European Optical Society-Rapid Publications
RESEARCH ARTICLE
Single-shot impulsive stimulated Brillouin microscopy by tailored ultrashort pulses
David Krause 1, 2, a,*, Leon Liebig 1, John Boehm 1, Nektarios Koukourakis 1, 2, a, and Juergen W. Czarske 1, 2, 3, 4
1 |
Laboratory of Measurement and Sensor System Technique, TU Dresden, Helmholtzstrasse 18, 01069 Dresden, Germany |
2 |
Competence Center for Biomedical Computational Laser Systems( BIOLAS), TU Dresden, 01069 Dresden, Germany |
3 |
Cluster of Excellence Physics of Life, TU Dresden, 01069 Dresden, Germany |
4 |
School of Science, Faculty Physics, TU Dresden, 01069 Dresden, Germany |
Received 19 November 2024 / Accepted 20 January 2025
Abstract. Brillouin microscopy has become an important tool for investigating the mechanical properties of tissue. The recently developed Impulsive Stimulated Brillouin Scattering( ISBS) promises a label-free, non-invasive measurements of viscoelastic properties of transparent samples and offers the potential for a high temporal resolution. However, the spatial resolution of ISBS is currently limited. Increasing the spatial resolution of ISBS leads to an increase in the energy density of the pump beams, which requires a balancing of the excitation parameters to stay below the phototoxic threshold. This paper focuses on the influences of different excitation parameters on the spatial, temporal, and spectral resolution and their optimal values. Combined with the adoption of a noise suppressing window function, a measurement rate of 20 ls / pixel in hydrogel is achieved, which is promising for fast 3D imaging. The presented advanced impulsive stimulated Brillouin microscopy can be applied for fast tissue elastography toward disease studies.
Keywords: Single-shot, Exponential window, Interface effects.
1 Introduction
The study of mechanical properties of biological material provides important insights into its biological function [ 1, 2 ] and can characterize the pathological states of tissue [ 3 ]. Consequently, mechanical mapping of tissue by medical imaging is a rapidly developing field that has emerged as a valuable tool in biomedical research and is already used in clinical practice as organ-level diagnostic assistance tool for various diseases such as prostate cancer [ 4, 5 ], liver fibrosis [ 6 ], and breast lesions [ 7 ]. Many techniques have been developed, such as ultrasound elastography [ 8 ] and atomic force microscopy( AFM) [ 9 ]. However, the acquisition of mechanical properties at sub-cellular resolution has long posed significant challenges, primarily due to the reliance of traditional techniques on direct physical contact or their insufficient cellular resolution. Optical elastography on the other hand offer various advantages over classical methods, being non-invasive, contactless, label-free, and can provide cellular or even sub-cellular resolution [ 3 ].
An emerging optical elastography technique is Brillouin Microscopy( BM) which is based on the interaction of light
a These authors contributed equally to this work * Corresponding author: david. krause @ tu-dresden. de
( photons) with an acoustic wave( phonons) [ 10 – 15 ] andhas become a highly appreciated technique for studying condensed matter systems [ 16 – 18 ]. The spontaneous BM( SpBM) offers high spatial resolution, but is based on the interaction of photons with spontaneous occurring thermal phonons leading to long integration times due to the low signal-to-noise ratio( SNR) and therefore making the application of SpBM in clinics difficult. Despite these challenges line measurements at acquisition times in the range of 100 – 200 ms, which effectively equates to 1 ms / pixel, have been accomplished [ 19, 20 ].
The active stimulation of phonons, instead of the resonant spontaneous scattering of thermally generated phonons, can lead to an efficiency that is orders of magnitude higher and thus to faster imaging. Stimulated Brillouin Scattering( SBS) utilizes two slightly detuned continuouswave( cw) lasers for phonon excitation( pump and probe technique) [ 21 – 25 ]. The higher SNR leads to lower integration times and measurements rates of 20 ms / pixel were achieved [ 23 ], however, the wavelength must be scanned to measure the entire spectrum, which outweighs the advantage of the lower integration times. Impulsive Stimulated Brillouin Scattering( ISBS) holds promise for achieving measurement rates in the MHz range, owing to the signal generation through the interaction of ultra-short laser pulses
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