Both disease and treatment of the cornea alter its microstructural and biomechanical properties. Previous work showed that dynamic light scattering (DLS) reflects changes in the cornea with respect to crosslinking treatment and post-surgical healing in vivo. However, due to the complex structure of the corneal stroma, the exact mechanisms which give rise to the DLS signal are unclear. This work attempts to determine the cause of DLS in the cornea by comparing the scattering signal under different conditions. The conclusions drawn from these studies inform the use of OCT-based dynamic light scattering measurements for corneal assessment.

Esophageal cancer is one of the most common types of cancer. Surgical treatment is associated with high morbidity and mortality due to the high incidence of anastomotic leakage (AL). Hypoperfusion of the gastric conduit plays an important role in developing AL. Per-operative perfusion quantification methods are currently lacking. The laparoscopic Laser Speckle Contrast Imaging device PerfusiX-Imaging could be a promising alternative to the surgical eye and ICG, showing real-time imminent perfusion differences.

Real-time assessment of liver optical properties can play a critical role in evaluating liver perfusion and oxygen delivery immediately post a liver transplant and the extent of tissue damage during thermal tumor ablation. Diffuse reflectance spectroscopy in the visible wavelength range (vis-DRS) is a powerful tool for measuring tissue absorption and scattering properties but is challenging to be used on highly absorptive liver tissue. We demonstrated that, with proper design, vis-DRS can be used to reliably quantify liver tissue optical properties, hemoglobin contents, and oxygen saturation, in both ex vivo and in vivo settings.

In the present study, for the first time, spectral-domain optical coherence tomography (SD-OCT) and optical coherence elastography (OCE) have been used in a combinatorial manner to characterise the corneal limbal architecture and biomechanical properties. 11 cadaveric corneas were obtained from a UK tissue bank. The architecture and effect of donor age on the limbal Palisades of were quantified using SD-OCT. OCE was used to determine the Young’s modulus of the epithelium and POV regions. The regional stiffness differences were observed, with ageing effect. Hence a correlation of structural and biomechanical properties within the limbal niche was demonstrated.

We present a practical laser speckle imaging device for skin cancer detection based on a 980 nm source and black silicon camera technology, with superior penetration depth and contrast. By operating at 980 nm we obtain deeper perfusion contrast and are immune to differences in skin pigmentation. The use of a black silicon camera ensures a high quantum efficiency without significantly increasing the cost and complexity of the device. We will show the effectiveness of the device in imaging different skin lesions and discuss the system specifications (wavelength, power, exposure time, frame rate, and processing algorithm) that led to the optimal contrast.

Although tissue water monitoring is necessary for diagnostics of diseases and cosmetic applications, at present there is no technique for accurate, noninvasive, high-resolution measurement of water content in skin and other tissues. We proposed optoacoustic monitoring of water in tissues and performed in vitro and in vivo studies using high-resolution optoacoustic, ultrasound, and optical scattering systems. The NIR spectral range was used to generate optoacoustic signals from epidermis, dermis, and subcutaneous tissues. Our results suggest that the optoacoustic technique can be used for accurate water monitoring by providing simultaneously both structural and molecular information from tissues with high resolution.

In order to realise the clinical potential of Brillouin scattering-based techniques, it is critical to develop an endoscopic probe for measuring elasticity in future in-vivo environments. We have developed a phonon probe which actively injects high amplitude GHz strain pulses into specimens and have demonstrated proof of concept this technique can be used for high resolution 3D imaging. In this talk we show that this new technology is highly applicable to the 3D elasticity imaging of biological tissue from the single-cell scale to multi-cellular organisms and provides a future pathway for the clinical application of in-vivo Brillouin spectroscopy of tissue.

We developed De-scattering with Excitation Patterning or "DEEP,” an extension of the work of Dholakia group. DEEP allows high throughput depth selective wide-field multiphoton imaging in tissues without suffering from blurring due to the scattering of emission photons. We are exploring extensions of this approach along several directions including to simultaneously reconstruct 3D volumes and to combine lifetime imaging to increase information content. In both cases, the extension to a higher dimensional measurement space allows better utilization of the inherent sparsity in many samples allowing for even higher efficiency.

Cells in vivo exist in a 3D porous network of proteins that lend structural support while permitting cellular attachment and migration. Characterization of pore size and microstructural network dynamics is imperative to the biophysical study of cell-ECM interactions and for tissue-engineering applications. We implemented Laser Speckle Microrheology at sub-MHz frequencies to measure mean square displacement (MSD) and its log-log derivative (α) of particles embedded in purified fibrin clots. The power law behavior of the time-dependent MSD provides a measure of pore sizes spanning different particle-to-pore size ratios, relevant for advancing our understanding of cell-ECM interactions.

Quantum optical approaches to biological measurement could enable unprecedented sensitivity, specificity, and resolution with minimal sample perturbation. Additionally, quantum optics provides new “knobs to turn” in imaging and spectroscopy that are not approachable with classical means. One such example is through entangled photons, in which groups of photons have properties that are intrinsically and inseparably linked. In this presentation, I will provide an introduction to entangled light applications, our experimental work in two-photon absorption with entangled light, and our experimental work establishing that even post-traversal through micrometers and millimeters of biological tissue/media, time-energy entangled light can maintain this unique linkage.

We show that the estimation of cerebral blood flow (CBF) measured with diffuse correlation spectroscopy using a 3-layer model of the head is strongly influenced by errors in assumed values of numerous parameters, including brain optical properties, layer thickness, and head curvature, which are often not known/measured in the clinical setting. However, these parameters (with the exception of layer thickness) have negligible influence on relative changes in CBF (rCBF). Brief pressure modulation can be used to optimize thickness and improve accuracy of rCBF. These findings suggest that the 3-layer model is superior approach to monitor trends in CBF with DCS.

Current work considers theoretical evaluation of two Monte Carlo (MC) based techniques which were previously developed indecently and extensively utilized inhouse for simulation of polarized light propagation in tissue-like scattering media. Both techniques are based on the tracking of the transformations of the Stokes vectors along the ray propagation direction. We performed numerical comparison and assessed the capabilities of each technique with regard to handling the classical polarization phenomena for a variety of configurations of turbid media/detecting settings. Finally, the accuracy of each technique has been evaluated by comparing the results of simulations with phantom experiments and known analytical solutions. The techniques have been incorporated into the online, open access computational resource allowing the researchers to use, validate and test out solutions.

In recent years, with the development and progress of society, the demand for non-destructive testing in the fields of safety testing, biomedicine, cultural heritage, and material science is becoming more and more urgent. Now, conventional testing methods such as radiographic testing, ultrasonic testing and infrared testing gradually fail to meet people's needs. Terahertz wave, with its low photon energy and high penetration to many non-metallic and non-polar materials, can be used in nondestructive testing, filling the vacancy in the field of nondestructive testing. In this paper, we study the terahertz nondestructive testing technology in depth. Firstly, we conduct experiments on terahertz tomographic imaging, and use point-by-point scanning method to image the samples composed of rubber and resin, which can realize two-dimensional and three-dimensional images of the samples. Secondly, we design a set of terahertz nondestructive detectors, including terahertz transceiver module, data acquisition module, imaging system. The terahertz transceiver module adopts the large-bandwidth frequency modulated continuous wave and, based on the superheterodyne detection structure, converts the echo signal down frequency into the intermediate frequency signal we need. The intermediate frequency signal then realizes the three-dimensional reconstruction of the sample through the data acquisition module and the imaging system. The dynamic range of the system is large, the action distance can reach about 1m, and the range resolution and directional resolution can reach millimeter level, which will fill the vacancy in the field of nondestructive testing and lay a solid foundation for the following quantum terahertz detection.