In this project, characteristic properties of photoacoustic imaging such as the "sparsity" of the photoacoustic signals are to be exploited, because the measured ultrasound signal is zero everywhere except where absorbing structures were excited in the light focus. With so-called L1 minimization, this additional information enables the reconstruction of images with less measurement effort and thus a much faster measurement. Furthermore, e.g. "prior knowledge" generated by simulation can be used for image reconstruction with neural networks trained with it. Preliminary work on these topics was done in a soon to be successfully completed FWF project together with Markus Haltmeier, Professor of Applied Mathematics in Innsbruck. The excitation of the photoacoustic signal will be done with ultraviolet (UV) light pulses - this will allow to visualize further structures like cell nuclei.

Finally, the detection of the ultrasound signal shall be done contactless optically, where RECENDT is one of the leading research organizations worldwide due to numerous laser-ultrasound projects. The functionality of this Compressed Photoacoustic Remote Sensing (COPARS) microscopy will be demonstrated on non-biological phantoms, such as structured multilayer polymer films, as well as on animal and human tissue samples (research partner Pathologie Feldkirch). The exploitation partner Prospective Instruments distributes devices and methods for imaging tissue sections with multiphoton microscopy. In this process, cell nuclei can only be made visible by staining the sections. In the future, the COPARS microscopy researched here should enable this to be done "label-free" without staining.