KTN-based high-speed axial and lateral scanning technique for an optical coherence tomography system and application to dental imaging.
TL;DR: A high-speed 840 nm based polarization-sensitive time domain optical coherence tomography (PSOCT) technique is proposed and demonstrated based on the quadratic electro-optic property of potassium tantalate niobate (KTN) crystals, which provides an automated high- speed two-dimensional scanning of samples of interest.
Abstract: A high-speed 840 nm based polarization-sensitive time domain optical coherence tomography (PSOCT) technique is proposed and demonstrated based on the quadratic electro-optic property of potassium tantalate niobate (KTN) crystals. A longitudinal (axial) scanning depth of ≈10 μm is obtained for an applied AC voltage of 600 V, at 1000 Hz and temperature maintained around 40°C. The OCT system with the KTN-based electro-optic delay line combined with a linear actuation is extended to image an early dental demineralization. For enhanced contrast by the elimination of the strong surface reflection from the sample and high-speed imaging, the quadratic electro-optically tunable PSOCT technique is proposed and demonstrated. Further, a lateral scanning range of 490 μm is also demonstrated by controlling the KTN temperature at 35°C for an applied voltage of 600 V on the tooth sample. This KTN-based quadratic electro-optic delay line combined with lateral scan approach provides an automated high-speed two-dimensional scanning of samples of interest.
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2 citations
15 Feb 2021
TL;DR: In this paper, an enhanced c-axis potassium tantalate niobate (KTN) based electro-optic (EO) deflector by compensating the performance degradation using a thermal gradient was proposed.
Abstract: In this paper, we propose an enhanced c-axis potassium tantalate niobate (KTN) based electro-optic (EO) deflector by compensating the performance degradation using a thermal gradient. The naturally existing composition gradient in KTN crystals prevents KTN deflectors from working at its maximum functionality at all locations along the propagation path. To overcome this fundamental limitation, we propose a KTN deflector with a temperature gradient to ensure all locations of KTN to work at the temperature having its highest permittivity. Our experimental data shows the KTN deflector with temperature gradient has near three times higher deflection angle than that of the case under uniform temperature.
2 citations
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TL;DR: A study of in-house built optical coherence tomography (OCT) system with a wavelength of 840 nm for imaging of dental caries, progress in demineralisation and cavity restoration is presented.
12 citations
TL;DR: In this paper, an improved fiber-stretcher-based scanning delay line in terms of both the scanning speed and the delay range was demonstrated in a dental OCT setup, and the results confirmed its feasibility into practical applications.
Abstract: We demonstrate an improved fiber-stretcher-based scanning delay line in terms of both the scanning speed and the delay range. Such a module is essential to optical coherence tomography (OCT) applications. An 18-mm delay range at 2-kHz scanning frequency is achieved and verified in a dental OCT setup. Repeatability and reliability of the new design are further evaluated through multiple trials within days. The results confirm its feasibility into practical applications.
7 citations
06 Nov 2014
TL;DR: A novel electro-optic tuning system is proposed in order to improve scanning speed and to perform noiseless imaging, and KTN based hybrid scanning for dental caries imaging is also planned.
Abstract: A conventional optical coherence tomography (OCT) system was set up in-house to image early dental caries, identify gap formation in the bonding interface for restoration and secondary caries. Two-dimensional images of tooth samples was obtained and dental defect were identified. A novel electro-optic tuning system is proposed in order to improve scanning speed and to perform noiseless imaging. Preliminary studies were conducted with two crystals namely, LiNbO3 (Lithium Niobate) and KTP (Potassium Titanyl Phosphate) using a SLED source for OCT system and the simulated and experimental results were found to be qualitatively similar. The tuning range for LiNbO3 and KTP was found to be in the order of few micrometers whereas KTN (Potassium Tantalate Niobate) using the quadratic electro-optic effect is expected to show scanning range of tens of micrometers. KTN based hybrid scanning for dental caries imaging is also planned.
6 citations
TL;DR: In this article, a KTa1−x Nb x O3 (KTN) deflector was used to achieve a full deflection angle of 95.8 mrad with a scanning frequency of 350 kHz.
Abstract: A scanning frequency of 350 kHz is demonstrated with a full deflection angle of 95.8 mrad using a KTa1−x Nb x O3 (KTN) deflector. To suppress degradation of the deflection angle, the KTN chip is directly glued to metal block electrodes with conductive paste, and the temperature of the deflector is controlled so that the capacitance of the KTN chip remains constant.
6 citations
TL;DR: In this article, a polarisation independent optical beam scanner that uses electro-optic KTa 1-x Nb x O 3 (KTN) crystals has been demonstrated, where the polarisation dependence was compensated for by using a pair of KTN beam scanners and a half-waveplate without any degradation in the performance of either KTN.
Abstract: A polarisation-independent optical beam scanner that uses electro-optic KTa 1-x Nb x O 3 (KTN) crystals has been demonstrated. The polarisation dependence was compensated for by using a pair of KTN beam scanners and a half-waveplate without any degradation in the performance of either KTN beam scanner. This compensation is the result of a combination of electro-optic effects consisting of Kerr effects and elasto-optic effects via the electrostrictive and elastic strains in KTN crystals.
3 citations