Photoacoustic Remote Sensing (PARS) Microscopy

• Author / Creator

  Bell, Kevan

• Photoacoustic imaging systems have proven to be power tools for visualizing optical absorption contrast within highly turbid media such as biological tissues. They provide high chromophore specificity in vivo due to the dramatic optical absorption contrast which exists between biological targets. This allows for non-ionizing label-free visualization of a wide range of targets such as hemoglobin, melanin, DNA, RNA, lipids, and cytochrome to name a few. Moreover, these devices can utilize exogenous labelling to further extend contrast and functional imaging capabilities. However, conventional photoacoustic techniques require acoustic coupling to the sample to read out generated acoustic signals. This contact can be highly undesirable for a variety of imaging targets, particularly in situ. This motivated the created of a non-contact photoacoustic modality which is the focus of this dissertation. This novel modality which is known as photoacoustic remote sensing (PARS) microscopy, is a cellular-scale photoacoustic imaging technique which is capable of providing optical diffraction-limited resolutions while maintaining centimeter-scale working distance from the sample. Given that the approach is in its infancy, work here focuses on developing physical models which describe the underlying physical processes behind the non-contact detection. These models aim to describe the time-evolution of the PARS detection process for simple geometries known to be relevant to optics and photoacoustics. As well, new PARS-based embodiments are described which use these models to further extend system capabilities in terms of acquisition rates and axial resolution performance at deeper penetration depths in scattering tissue. Finally, experimental work into a second generation architecture for PARS is investigated which focuses on fiber tetherable optics, and real-time multiplex imaging. The capabilities of the PARS technique to operate within challenging biological samples makes it an exciting area of research which may provide an entire new field of imaging devices to the research and clinical fields.

• Subjects / Keywords

  • Remote Sensing
  • PARS
  • Biomedical Imaging
  • Photoacoustics

• Graduation date

  Fall 2019

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-akce-5r69

• License

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