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
References
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TL;DR: CP-OCT imaging using a beam splitter based design can examine the subsurface interface of dental composites in human subjects and is shown to have the ability to assess interfacial degradation such as early secondary caries prior to cavitation.
72 citations
TL;DR: In this paper, a beam scanning model that is applicable to electrooptic materials with electron traps was proposed, which can achieve both high-speed operation and wide-angle scanning, because the operating speed is limited not by the electron mobility but by the frequency limit of the electro-optic effect of the materials.
Abstract: We propose a new beam scanning model that is applicable to electrooptic materials with electron traps. With this model, we can achieve both high-speed operation and wide-angle scanning, because the operating speed is limited not by the electron mobility but by the frequency limit of the electrooptic effect of the materials. The voltage dependence of the scanning angle at 100 kHz using a KTa1-xNbxO3 crystal is consistent with the property predicted by the proposed model.
65 citations
TL;DR: It is demonstrated that PS-OCT can be used to non-destructively measure changes in lesion structure and severity upon exposure to an acidic remineralization model and that automated algorithms can been used to assess the lesion severity even with the presence of a weakly reflective surface zone.
50 citations
TL;DR: This study demonstrates that PS-OCT can automatically measure the changes in artificial enamel lesion structure and severity upon exposure to remineralization solutions.
Abstract: Accurate measurement of the highly mineralized transparent surface layer that forms on caries lesions is important for diagnosis of the lesion activity because chemical intervention can slow or reverse the caries process via remineralization. Previous in-vitro and in-vivo studies have demonstrated that polarization-sensitive optical coherence tomography (PS-OCT) can nondestructively image the subsurface lesion structure and the highly mineralized transparent surface zone of caries lesions. The purpose of this study was to develop an approach to automatically process 3-dimensional PS-OCT images and to accurately assess the remineralization process in simulated enamel lesions. Artificial enamel lesions were prepared on twenty bovine enamel blocks using two models to produce varying degree of demineralization and remineralization. The thickness of the transparent surface layer and the integrated reflectivity of the subsurface lesion were measured using PS-OCT. The automated transparent surface layer detection algorithm was able to successfully detect the transparent surface layers with high sensitivity ( = 0.92) and high specificity ( = 0.97). The estimated thickness of the transparent surface layer showed a strong correlation with polarized light microscopy (PLM) measurements of all regions (R2 = 0.90). The integrated reflectivity, ΔR, and the integrated mineral loss, ΔZ, showed a moderate correlation (R2 = 0.32). This study demonstrates that PS-OCT can automatically measure the changes in artificial enamel lesion structure and severity upon exposure to remineralization solutions.
50 citations
TL;DR: 2D images of the lesion depth and the integrated reflectivity can be used to accurately represent the severity of early lesions and are well suited for visualization of early demineralization.
Abstract: Several studies have demonstrated the potential of cross-polarization optical coherence tomography (CP-OCT) to quantify the severity of early caries lesions (tooth decay) on tooth surfaces. The purpose of this study is to show that 2D images of the lesion depth and the integrated reflectivity can be used to accurately represent the severity of early lesions. Simulated early lesions of varying severity were produced on tooth samples using simulated lesion models. Methods were developed to convert the 3D CP-OCT images of the samples to 2D images of the lesion depth and lesion integrated reflectivity. Calculated lesion depths from OCT were compared with lesion depths measured from histological sections examined using polarized light microscopy. The 2D images of the lesion depth and integrated reflectivity are well suited for visualization of early demineralization.
48 citations