Transversally travelling ultrasound for light guiding deep into scattering media

Cherkashin, Maxim; Brenner, Carsten; Schmitz, Georg; Hofmann, Martin R.

doi:10.1038/s42005-020-00443-w

Cited by 13 publications

(6 citation statements)

References 63 publications

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“…However, acousto-optic modulation helps to overcome this limitation, allowing the delivery or collection of light without confinement to shallow depths of the turbid medium. Existing acousto-optic modulation techniques form virtual waveguides within tissues using standing waves, which require the object to be situated inside an ultrasonic device (19)(20)(21)(22). The constraints imposed by the physical structure of the device hinder its application in vivo.…”

Section: Introductionmentioning

confidence: 99%

Acoustic hologram–induced virtual in vivo enhanced waveguide (AH-VIEW)

Lin,

Li,

Wang

et al. 2024

Sci. Adv.

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Optical imaging and phototherapy in deep tissues face notable challenges due to light scattering. We use encoded acoustic holograms to generate three-dimensional acoustic fields within the target medium, enabling instantaneous and robust modulation of the volumetric refractive index, thereby noninvasively controlling the trajectory of light. Through this approach, we achieved a remarkable 24.3% increase in tissue heating rate in vitro photothermal effect tests on porcine skin. In vivo photoacoustic imaging of mouse brain vasculature exhibits an improved signal-to-noise ratio through the intact scalp and skull. These findings demonstrate that our strategy can effectively suppress light scattering in complex biological tissues by inducing low-angle scattering, achieving an effective depth reaching the millimeter scale. The versatility of this strategy extends its potential applications to neuroscience, lithography, and additive manufacturing.

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Section: Introductionmentioning

confidence: 99%

Acoustic hologram–induced virtual in vivo enhanced waveguide (AH-VIEW)

Lin,

Li,

Wang

et al. 2024

Sci. Adv.

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“…Since ultrasound in the proper frequency range can propagate deep with minimal attenuation in the medium, the virtual optical components can be realized within the target medium to manipulate the trajectory of light without implanting any physical devices to disturb the medium. We have shown that these linear virtual optical components can be formed in transparent as well as scattering media such as biological tissue 12 . In this method, the virtual optical component can be reconfigured by simply changing the pattern of ultrasound waves from outside the medium.…”

Section: Introductionmentioning

confidence: 98%

“…We have recently shown that ultrasound waves can be used to guide and pattern the trajectory of light by locally changing the refractive index of the medium. Using this technique, we have demonstrated the possibility of forming in situ virtual gradedindex (GRIN) waveguides, virtual relay lenses, and spatial light modulators non-invasively [12][13][14] . Since ultrasound in the proper frequency range can propagate deep with minimal attenuation in the medium, the virtual optical components can be realized within the target medium to manipulate the trajectory of light without implanting any physical devices to disturb the medium.…”

Section: Introductionmentioning

confidence: 99%

Overcoming the tradeoff between confinement and focal distance using virtual ultrasonic optical waveguides

Scopelliti¹,

Huang²,

Pediredla³

et al. 2020

Opt. Express

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Conventional optical lenses have been used to focus light from outside without disturbing the medium. The focused spot size is proportional to the focal distance in a conventional lens, resulting in a fundamental tradeoff between depth of penetration in the target medium and spatial resolution. We have shown that virtual ultrasonically sculpted graded-index (GRIN) optical waveguides can be formed in the target medium to guide and steer light without disturbing the medium. Here, we demonstrate that such virtual waveguides can relay and tune an externally focused beam of light through the medium without compromising the spot size, thus breaking the tradeoff between the depth of penetration and spatial resolution in conventional physical lenses. We show that the virtual GRIN waveguides can be formed in transparent as well as in turbid media to provide an unprecedented enhancement of spot size and contrast ratio of the confined beam of light. This method can be used to realize more complex optical systems of external physical lenses and in situ virtual waveguides to extend the reach and flexibility of optical methods.

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“…Virtual optical waveguides can be implemented using ultrasonic waves from phased arrays [1], transient ultrasonic waves [4], and laser-induced nonlinear acoustic waves [5]. These implementations can be useful in a variety of applications that require in situ light steering.…”

Section: Introductionmentioning

confidence: 99%

Optimized Virtual Optical Waveguides Enhance Light Throughput in Scattering Media

Pediredla

Scopelliti

Narasimhan

et al. 2021

Preprint

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Ultrasonically sculpted gradient-index optical waveguides make it possible to non-invasively steer and confine light inside scattering media. This confinement capability has applications in tissue and brain imaging, where virtual optical waveguides can be used on their own or cascaded with physical optical elements. The level of light confinement strongly depends on ultrasound parameters such as modulation pattern, frequency, and amplitude, as well as the material parameters of the scattering medium such as the refractive index, scattering coefficient, and phase function. We provide a characterization of these dependencies for a radially symmetric virtual optical waveguide. To this end, we develop a physically-accurate simulator, and use it to quantify how different ultrasound and material parameters affect light confinement. We explain our observations through a qualitative analysis of the behavior of multiply scattered light. We use the results of this analysis to demonstrate that, by properly designing ultrasound parameters, we can achieve a fourfold improvement in light confinement compared to previous virtual optical waveguide designs. We additionally show that virtual optical waveguides can achieve up to 50% light throughput enhancement compared to an ideal external lens, in a medium that mimics the scattering properties of human bladder, and at an optical thickness of one transport mean free path. Lastly, we show experimental results that corroborate the simulation predictions. In particular, we demonstrate for the first time that virtual optical waveguides effectively recycle scattered light in turbid media, and can achieve a 15% light throughput enhancement at five transport mean free paths.

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Transversally travelling ultrasound for light guiding deep into scattering media

Cited by 13 publications

References 63 publications

Acoustic hologram–induced virtual in vivo enhanced waveguide (AH-VIEW)

Acoustic hologram–induced virtual in vivo enhanced waveguide (AH-VIEW)

Overcoming the tradeoff between confinement and focal distance using virtual ultrasonic optical waveguides

Optimized Virtual Optical Waveguides Enhance Light Throughput in Scattering Media

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