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.
Citations
More filters
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
More filters
TL;DR: The review provides a concise explanation of principles of operation of different optical coherence tomography methods and a comparative analysis of their advantages and disadvantages is presented in relation to specific applications.
Abstract: An optical coherence tomography (OCT) apparatus includes an optical source, an interferometer generating an object beam and a reference beam, a transverse scanner 11 for scanning an object with said object beam, and a processor for generating an OCT image from an OCT signal returned by said interferometer. At least the optical source, the interferometer, and the scanner are mounted on a common translation stage 30 displaceable towards and away from said object. The optical components mounted on the stage are configured to maintain a coherence gate C in approximate coincidence with the focus F during the displacement of the transition stage.
221 citations
TL;DR: In this article, the principles of operation of electro-optical or acousto-optic deflectors and AODs are described and the characteristics, properties and the (dis)advantages of EODs, when compared to mirror-based mechanical de-∆ectors, are discussed.
152 citations
TL;DR: In this article, the experimental and theoretical studies of an anomalous optical beam deflection phenomenon based on electrooptic effect and space-charge-controlled electrical conduction are described.
Abstract: This paper describes the experimental and theoretical studies of an anomalous optical beam deflection phenomenon based on electrooptic effect and space-charge-controlled electrical conduction. In the experiment, a large deflection angle of 250mrad (=14.3°) has been observed by applying ±250V to a 0.5‐mm-thick KTa1−xNbxO3 crystal with a short interaction length of 5.0mm. The crystal has a rectangular shape with uniform electrodes and there is no prism shape involved which is a common geometrical shape of crystal, electrode, or ferroelectric domain in the conventional electro-optic deflectors. The operating principle is investigated and it is found that the space-charge-controlled electrical conduction in the crystal plays an essential role in this deflection phenomenon. The electrical conduction is carried by electrons injected from the Ohmic contact of the electrode with the crystal. The injected electrons induce the space-charge effect and the electric field becomes nonuniform between the electrodes. The...
101 citations
TL;DR: The three most common profiles of scanning functions for galvanometer-based scanners (GSs): the sawtooth, triangular and sinusoidal functions are analyzed and certain rules of thumb are deduced to make the best out of the galvoscanner.
Abstract: We analyze the three most common profiles of scanning functions for galvanometer-based scanners (GSs): the sawtooth, triangular and sinusoidal functions. They are determined experimentally with regard to the scan parameters of the input signal (i.e., frequency and amplitude). We study the differences of the output function of the GS measured as the positional error of the oscillatory mirror from the ideal function given by the input signal of the device. The limits in achieving the different types of scanning functions in terms of duty cycle and linearity are determined experimentally for the possible range of scan parameters. Of particular importance are the preservation of an imposed duty cycle and profile for the sawtooth function, the quantification of the linearity for the sinusoidal function, and the effective duty cycle for the triangular, as well as for the other functions. The range of scan amplitudes for which the stability of the oscillatory regime of the galvo mirror is stable for different frequencies is also highlighted. While the use of the device in certain scanning regimes is studied, certain rules of thumb are deduced to make the best out of the galvoscanner. Finally, the three types of scanning functions are tested with a Fourier domain optical coherence tomography (FD OCT) setup and the conclusions of the study are demonstrated in an imaging application by correlating the determined limits of the scanning regimes with the requirements of OCT.
93 citations
TL;DR: A novel Fourier domain fast scanning optical delay line is proposed in which the walk-off is eliminated by only two passes through a diffraction grating, ideal for balanced optical coherence tomography configurations with recirculation of the reference beam.
Abstract: A novel Fourier domain fast scanning optical delay line is proposed in which the walk-off is eliminated by only two passes through a diffraction grating. Working in transmission, the novel delay line is ideal for balanced optical coherence tomography configurations with recirculation of the reference beam. We evaluate theoretically and experimentally its walk-off and dispersion compensation capabilities.
76 citations