10 research outputs found
Measurement of Vibrating Tympanic Membrane in an In Vivo Mouse Model Using Doppler Optical Coherence Tomography
No full textOptical coherence tomography (OCT) has a micro-resolution with a penetration depth of about 2 mm and field of view of about 10 mm. This makes OCT well suited for analyzing the anatomical and internal structural assessment of the middle ear. To study the vibratory motion of the tympanic membrane (TM) and its internal structure, we developed a phase-resolved Doppler OCT system using Kasai’s autocorrelation algorithm. Doppler optical coherence tomography is a powerful imaging tool which can offer the micro-vibratory measurement of the tympanic membrane and obtain the micrometer-resolved cross-sectional images of the sample in real-time. To observe the relative vibratory motion of individual sections (malleus, thick regions, and the thin regions of the tympanic membrane) of the tympanic membrane in respect to auditory signals, we designed an experimental study for measuring the difference in Doppler phase shift for frequencies varying from 1 to 8 kHz which were given as external stimuli to the middle ear of a small animal model. Malleus is the very first interconnecting region between the TM and cochlea. In our proposed study, we observed that the maximum change in Doppler phase shift was seen for the 4 kHz acoustic stimulus in the malleus, the thick regions, and in the thin regions of the tympanic membrane. In particular, the vibration signals were higher in the malleus in comparison to the tympanic membrane
Functional assessment of moisture influenced cadaveric tympanic membrane using phase shift‐resolved optical Doppler vibrography
No full textUltrahigh-Speed Spectral-Domain Optical Coherence Tomography up to 1-MHz A-Scan Rate Using Space-Time-Division Multiplexing
No full textThe primary optimization of the imaging speed of optical coherence tomography (OCT) has been keenly studied. In order to overcome the major speed limitation of spectral-domain OCT (SD-OCT), we developed an ultrahigh-speed SD-OCT system, with an A-scan rate of up to 1 MHz, using the method of space-time-division multiplexing (STDM). Multicameras comprising a single spectrometer were implemented in the developed ultrahigh-speed STDM method to eliminate the dead time of operation, whereas STDM was simultaneously employed to enable wide-range scanning measurements at a high speed. By successfully integrating the developed STDM method with GPU parallel processing, 8 vol/s for an image range of 250 x 250 x 2048 pixels (9 x 4.5 x 5 mm) was achieved, with an adjustable volume rate according to the required scanning speed and range. The examined STDM-OCT results of the customized optical thin film confirmed its feasibility for various fields that require rapid and wide-field scanning
OCT for non-destructive examination of the internal biological structures of mosquito specimen
No full textOptical Interferometric Fringe Pattern-Incorporated Spectrum Calibration Technique for Enhanced Sensitivity of Spectral Domain Optical Coherence Tomography
No full textDepth-visualizing sensitivity can be degraded due to imperfect optical alignment and non-equidistant distribution of optical signals in the pixel array, which requires a measurement of the re-sampling process. To enhance this depth-visualizing sensitivity, reference and sample arm-channeled spectra corresponding to different depths using mirrors were obtained to calibrate the spectrum sampling prior to Fourier transformation. During the process, eight interferogram patterns corresponding to point spread function (PSF) signals at eight optical path length differences were acquired. To calibrate the spectrum, generated intensity points of the original interferogram were re-indexed towards a maximum intensity range, and these interferogram re-indexing points were employed to generate a new lookup table. The entire software-based process consists of eight consecutive steps. Experimental results revealed that the proposed method can achieve images with a high depth-visualizing sensitivity. Furthermore, the results validate the proposed method as a rapidly performable spectral calibration technique, and the real-time images acquired using our technique confirm the simplicity and applicability of the method to existing optical coherence tomography (OCT) systems. The sensitivity roll-off prior to the spectral calibration was measured as 28 dB and it was halved after the calibration process
In Situ Characterization of Micro-Vibration in Natural Latex Membrane Resembling Tympanic Membrane Functionally Using Optical Doppler Tomography
No full textNon-invasive characterization of micro-vibrations in the tympanic membrane (TM) excited by external sound waves is considered as a promising and essential diagnosis in modern otolaryngology. To verify the possibility of measuring and discriminating the vibrating pattern of TM, here we describe a micro-vibration measurement method of latex membrane resembling the TM. The measurements are obtained with an externally generated audio stimuli of 2.0, 2.2, 2.8, 3.1 and 3.2 kHz, and their respective vibrations based tomographic, volumetric and quantitative evaluations were acquired using optical Doppler tomography (ODT). The micro oscillations and structural changes which occurred due to diverse frequencies are measured with sufficient accuracy using a highly sensitive ODT system implied phase subtraction method. The obtained results demonstrated the capability of measuring and analyzing the complex varying micro-vibration of the membrane according to implied sound frequency
Clinical utility of intraoperative assessment for tympanomastoidectomy using an intrasurgical optical coherence tomography microscope (Conference Presentation)
No full textVision-Inspection-Synchronized Dual Optical Coherence Tomography for High-Resolution Real-Time Multidimensional Defect Tracking in Optical Thin Film Industry
No full textLarge-scale product inspection is an important aspect in thin film industry to identify defects with a high precision. Although vision line scan camera (VLSC)-based inspection has been frequently implemented, it is limited to surface inspections. Therefore, to overcome the conventional drawbacks, there is a need to extend inspection capabilities to internal structures. Considering that VLSC systems have access to rich information, such as color and texture, high-resolution real-time multimodal optical synchronization between VLSC and dual spectral domain optical coherence tomography (SD-OCT) systems was developed with a laboratory customized in-built automated defect-tracking algorithm for optical thin films (OTFs). Distinguishable differences in the color and texture of the bezel area were precisely determined by the VLSC. Detailed OCT assessments were conducted to verify the detection of previously unobtainable border regions and micrometer-range sub-surface defects. To enhance the accuracy of the method, VLSC images were aided for the precise surface defect identification using OCT and the image acquisition, signal processing, image analysis, and classification of both techniques were simultaneously processed in real-time for industrial applicability. The results demonstrate that the proposed method is capable of detecting and enumerating total number of defects in OTF samples with exceptional resolution and in a cost-effective manner facilitating wide area inspection for OTF samples
Non-Invasive Optical Coherence Tomography Data-Based Quantitative Algorithm for the Assessment of Residual Adhesive on Bracket-Removed Dental Surface
No full textThe aim of this study was to quantitatively assess the residual adhesive on orthodontic ceramic bracket-removed dental surface. In orthodontic process, ceramic bracket was repeated debonding physically, then the adhesive remained on the dental surface. The residual adhesive caused a lack of adhesive strength between dental and ceramic bracket. Since commonly used adhesive in orthodontics is translucent, residual adhesive is hard to be detected with conventional microscopes. Therefore, 1310 nm center wavelength swept-source OCT system based on laboratory customized image processing algorithm was used for the precise detection of residual adhesive on tooth surface. The algorithm separates residual adhesive from dental surface by comparing the height of adjacent B-scan images, while providing color-scaled images emphasizing the thickness information of residual adhesive. Finally, the acquired results were compared with microscopic and adhesive remnant index scoring gold standards, while the comparison confirmed the potential merits and the improvements of the proposed method over gold standards
OCT for non-destructive examination of the internal biological structures of mosquito specimen
Get PDFThe Study of mosquitoes and their behavioral analysis are of crucial importance to control the alarmingly increasing mosquito-borne diseases. Conventional imaging techniques use either dissection, exogenous contrast agents. Non-destructive imaging techniques, like x-ray and microcomputed tomography uses ionizing radiations. Hence, a non-destructive and real-time imaging technique which can obtain high resolution images to study the anatomical features of mosquito specimen can greatly aid researchers for mosquito studies. In this study, the three-dimensional imaging capabilities of optical coherence tomography (OCT) for structural analysis of Anopheles sinensis mosquitoes has been demonstrated. The anatomical features of An. sinensis head, thorax, and abdomen regions along with internal morphological structures like foregut, midgut, and hindgut were studied using OCT imaging. Two-dimensional (2D) and three-dimensional (3D) OCT images along with histology images were helpful for the anatomical analysis of the mosquito specimens. From the concurred results and by exhibiting this as an initial study, the applicability of OCT in future entomological researches related to mosquitoes and changes in its anatomical structure is demonstrated
