We present a high-resolution microscope capable of imaging buried structures through optically opaque materials with micrometer transverse resolution and a nanometer-scale depth sensitivity. The ability to image through such materials is made possible by the use of laser ultrasonic techniques, where an ultrafast laser pulse launches acoustic waves inside an opaque layer and subsequent acoustic echoes from buried interfaces are detected optically by a time-delayed probe pulse. We show that the high frequency of the generated ultrasound waves enables imaging with a transverse resolution only limited by the optical detection system. We present the imaging system and signal analysis and demonstrate its imaging capability on complex microstructured objects through 200 nm thick metal layers and gratings through 500 nm thickness. Furthermore, we characterize the obtained imaging performance, achieving a diffraction-limited transverse resolution of 1.2 μm and a depth sensitivity better than 10 nm.

High-resolution microscopy through optically opaque media using ultrafast photoacoustics / Antoncecchi, Alessandro; Zhang, Hao; Edward, Stephen; Verrina, Vanessa; Planken, Paul C. M.; Stefan Witte, And. - In: OPTICS EXPRESS. - ISSN 1094-4087. - 28:23(2020), pp. 33937-33947. [10.1364/OE.405875]

High-resolution microscopy through optically opaque media using ultrafast photoacoustics

Vanessa Verrina;
2020

Abstract

We present a high-resolution microscope capable of imaging buried structures through optically opaque materials with micrometer transverse resolution and a nanometer-scale depth sensitivity. The ability to image through such materials is made possible by the use of laser ultrasonic techniques, where an ultrafast laser pulse launches acoustic waves inside an opaque layer and subsequent acoustic echoes from buried interfaces are detected optically by a time-delayed probe pulse. We show that the high frequency of the generated ultrasound waves enables imaging with a transverse resolution only limited by the optical detection system. We present the imaging system and signal analysis and demonstrate its imaging capability on complex microstructured objects through 200 nm thick metal layers and gratings through 500 nm thickness. Furthermore, we characterize the obtained imaging performance, achieving a diffraction-limited transverse resolution of 1.2 μm and a depth sensitivity better than 10 nm.
2020
acoustic waves; acoustic phenomena; photoacoustic effects; metrology ultrasound
01 Pubblicazione su rivista::01a Articolo in rivista
High-resolution microscopy through optically opaque media using ultrafast photoacoustics / Antoncecchi, Alessandro; Zhang, Hao; Edward, Stephen; Verrina, Vanessa; Planken, Paul C. M.; Stefan Witte, And. - In: OPTICS EXPRESS. - ISSN 1094-4087. - 28:23(2020), pp. 33937-33947. [10.1364/OE.405875]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1557592
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