[Non-permanents only] Imaging light fluence distribution in blood vessels with combined photoacoustic fluctuation imaging and Ultrasound Power Doppler / Shaping evanescent waves - Ivana Falco / Marc Grosjean

Ivana Falco (LIPhy)

Imaging light fluence distribution in blood vessels with combined Photoacoustic fluctuation imaging and Ultrasound Power Doppler

Numerous optical biomedical imaging or therapeutic modalities suffer from unknown light fluence distribution at depths. Photoacoustic (PA) imaging enables the imaging of blood vessels and probes the product between fluence and effective optical absorption, which depends on the size or density of blood vessels. In the case of unresolved structures, fluence and absorption cannot be decoupled using PA imaging alone.

Photoacoustic fluctuation (PAFI) and Ultrasound Power Doppler (UPD) imaging are both sensitive to blood vessels and share the same acquisition system.

Hence, we propose to combine these two modalities, after resolution compensation with a PSF filter, to directly image fluence maps within vascularized areas, including unresolved vessels.

We demonstrate 3D fluence imaging through simulations and experiments using a flow phantom.

 Marc GrosJean (LIPhy)

Shaping evanescent waves

Total internal reflection fluorescence (TIRF) microscopy is a well-known technique allowing to confine the light close to the surface of a glass substrate. This axial confinement is based on the generation of evanescent waves. In TIRF microscopy however, there is no control of the light intensity in the transverse plane. Here, we propose a method to create evanescent patterns, which uses a fast-switching digital micro-mirror device. This presentation may be a bit short. If we have time I would be pleased to present another topic. But I have not decided which one yet (bubbles, numpy array, masculine contraception or super-resolution microscopy).