Spectroscopy
Non-contact reflection-mode Spectroscopy
Optical absorption spectroscopy provides a powerful tool for material studies. As chromophores commonly provide unique optical absorption spectra, characterization of specific optical absorption properties is critical. One of our projects revolves around the development of a PARS®-based absorption spectrometer which can operate without any special preparation or contact with the sample. These aspects may allow for characterization of previously inaccessible targets such as large and opaque objects. As well, this approach may facilitate absorption spectroscopy across large distances or vacuum.
Further, OCT has the ability to resolve differences in order of micrometer as well as providing fast optical scanning. The fusion of both modalities can achieve high resolution imaging of individual depth-resolved structures along with the differentiation between fine layers. This dual-modal system is therefore helpful for studying tissue topography by determining its features’ name, position along with other parameters besides learning patterns within the tissue. Applications include breast cancer topographic visualization, choroidal thickness and topography and others.
Optical absorption spectroscopy provides a powerful tool for material studies. As chromophores commonly provide unique optical absorption spectra, characterization of specific optical absorption properties is critical. One of our projects revolves around the development of a PARS®-based absorption spectrometer which can operate without any special preparation or contact with the sample. These aspects may allow for characterization of previously inaccessible targets such as large and opaque objects. As well, this approach may facilitate absorption spectroscopy across large distances or vacuum.
Further, OCT has the ability to resolve differences in order of micrometer as well as providing fast optical scanning. The fusion of both modalities can achieve high resolution imaging of individual depth-resolved structures along with the differentiation between fine layers. This dual-modal system is therefore helpful for studying tissue topography by determining its features’ name, position along with other parameters besides learning patterns within the tissue. Applications include breast cancer topographic visualization, choroidal thickness and topography and others.
Kevan Bell and Parsin Haji Reza, "Non-contact reflection-mode optical absorption spectroscopy using photoacoustic remote sensing," Opt. Lett. 45, 3427-3430 (2020)
Several chromophore absorption sweeps. (a) Sweep of three dyes: blue, green, and red. (b) Comparison of a 50/50 mixture of the green and blue dyes along with sweeps of the pure samples. A plot of the unmixing error is inset. (c) PARS® spectrum of the paraffin surrounding biological tissue in an FFPE tissue block. (d) PARS® spectrum of a histone solution in UV. (e) PARS® spectrum of DNA solution in UV. (f) PARS® spectrum of cytochrome C in visible wavelengths. [https://doi.org/10.1364/OL.394637}
Outline of hyperspectral PARS® imaging with ROI tracking. (a) Set of images acquired on an unstained formalin-fixed paraffin-embedded human breast tissue slide. The same region is imaged consecutively while sweeping the excitation wavelength from 230 to 450 nm. (b) Shows the 250 nm frame from the set, and provides one example for nuclear regions and the surrounding tissue regions. (c) The means signal in these ROI are then plotted against wavelength. [https://doi.org/10.1364/OL.394637]