Research Express@NCKU - Articles Digest

Research Express@NCKU - Articles Digesttheir clinical applications. We modified our optical design for backward mechanism and used Cr:forsterite laser as the light source. A pair of galvano mirror was used to control the X-Y scanning of thefiled. A pair of PMT was used to pick up the photon signal. For long time in vivo observation of theanimal model, we have integrated anesthesia and body temperature control to keep vital signs inphysiological range during imaging acquisition process (figure 1).Figure 1. Schematic illustration of the higher harmonic generation imagingacquisition system (http://www.opticsinfobase.org/abstract.cfm?&uri=oe-14-13-6178).Molecules with repetitive structures usually exhibit strong second harmonics optical property. Theseinclude many biomolecules such as cytoskeleton, collagen, elastin, etc. It is conceivable that harmonicgeneration imaging could well be applied for molecular topographic imaging for biomolecules in thetissue. In addition, although THG nonlinearity exists in all bio-materials, the Gouy phase shift effectsubstantially limits THG to be observed in the vicinity of interfaces where the first order or third ordersusceptibility discontinues. Therefore, THG is generally regarded as a morphological imaging for cellularstructures such as special domains in cellular membrane, nucleus, etc. The following figure presents aseries of tomographic in vivo imaging for normal oral mucosa (left) versus oral cancer lesions (right) in alive hamster by harmonic generation optical system (Figure 2). The blue channel in the images camefrom third harmonics signals and mostly distributed in the intercellular junction of normal oral mucosalepithelium. The green fibrous structure was collected from the second harmonic signals from collagenfibers in the dermis. The image quality provided more detailed information for the orientation, density,and distribution of the fibers compared to traditional H&E stain in pathological sections. On the onehand, collagen could only be visualized in deeper tissue and usually intermingled with cancerous cells incancer lesions. Prominent nucleoli and peri-nuclear granular structures could be clearly identified in the2 of 6