Victor C. Wong

Multimodal imaging system for dental caries detection

Dental caries is a disease in which minerals of the tooth are dissolved by surrounding bacterial plaques. A caries process present for some time may result in a caries lesion. However, if it is detected early enough, the dentist and dental professionals can implement measures to reverse and control caries. Several optical, nonionized methods have been investigated and used to detect dental caries in early stages. However, there is not a method that can singly detect the caries process with both high sensitivity and high specificity. In this paper, we present a multimodal imaging system that combines visible reflectance, fluorescence, and Optical Coherence Tomography (OCT) imaging. This imaging system is designed to obtain one or more two-dimensional images of the tooth (reflectance and fluorescence images) and a three-dimensional OCT image providing depth and size information of the caries. The combination of two- and three-dimensional images of the tooth has the potential for highly sensitive and specific detection of dental caries.

Optical design of a multimodal imaging system

A multimodal imaging system has been developed for tooth tissue imaging. This imaging system is designed to obtain one or more two-dimensional images of the tooth tissue, and those two-dimensional images are rendered with advanced algorithms to provide a high-contrast image. This system combines polarized reflectance imaging, fluorescence imaging, and optical coherence tomography (OCT) imaging. The imaging system design, as well as some experimental results, will be discussed in the presentation.

Effects of annealing on modal properties and second-harmonic generation in periodically poled LiTaO3 channel waveguides

We provide a systematic investigation of the effects of annealing on modal properties and second-harmonic generation in periodically domain-reversed LiTaO3 channel waveguides. Prism-coupling studies show complex spatial mode distributions and strong dependence of waveguide modal properties on index profiles. Second-harmonic measurements observe the recovery of the optical nonlinear coefficient by annealing. The optimum conversion efficiency is obtained in a very narrow window of annealing time. A considerably large shift in quasi-phase-matching wavelength is also documented. Measurement results are correlated with theoretical modeling.