This work presents a combination of differential absorption technique and frequency domain optical coherence tomography for detection of glucose, which is an important analyte in medical diagnosis of diabetes. Differential absorption technique is used to detect glucose selectively in the presence of interfering species especially water and frequency domain optical coherence tomography (FDOCT) helps to obtain faster acquisition of depth information. Two broadband super-luminescent diode (SLED) sources with centre wavelengths 1586 nm (wavelength range of 1540 to 1640 nm) and 1312 nm (wavelength range of 1240 to 1380 nm) and a spectral width of ≈ 60 nm (FWHM) are used. Preliminary studies on absorption spectroscopy using various concentrations of aqueous glucose solution gave promising results to distinguish the absorption characteristics of glucose at two wavelengths 1310 nm (outside the absorption band of glucose) and 1625 nm (within the absorption band of glucose). In order to mimic the optical properties of biological skin tissue, 2% and 10% of 20% intralipid with various concentrations of glucose (0 to 4000 mg/dL) was prepared and used as sample. Using OCT technique, interference spectra were obtained using an optical spectrum analyzer with a resolution of 0.5 nm. Further processing of the interference spectra provided information on reflections from the surfaces of the cuvette containing the aqueous glucose sample. Due to the absorption of glucose in the wavelength range of 1540 nm to 1640 nm, a trend of reduction in the intensity of the back reflected light was observed with increase in the concentration of glucose.
This study aims at developing a non-invasive technique to evaluate periodontal loss of attachment in the oral cavity.
A method of imaging periodontal loss of attachment based on time-domain optical coherence tomography is proposed
and studied. Based on measurements, boundaries of gingival tissue and tooth were seen separated by ≈0.3 mm. Further
study is in progress to image the anatomical landmarks and evaluate the periodontal loss of attachment. The conventional
time domain OCT systems acquisition speed is limited by the speed of the mechanical scanning system. In order to
overcome this issue, a novel electro-optic based scanning system is proposed and demonstrated. Studies were performed
initially with lithium niobate and potassium titanyl phosphate crystals and the tuning range observed were low. In order
to increase the tuning range, a crystal with high electro-optic coefficient – potassium tantalite niobate was identified and
experiments were carried out to characterise the crystal and electro-optic based phase tuning is demonstrated.