Endoscopic Laser-Based 3D Imaging for Functional Voice Diagnostics

Abstract

Recently, we reported on the in vivo application of a miniaturized measuring device for 3D visualization of the superior vocal fold vibrations from high-speed recordings in combination with a laser projection unit (LPU). As a long-term vision for this proof of principle, we strive to integrate the further developed laserendoscopy as a diagnostic method in daily clinical routine. The new LPU mainly comprises a Nd:YAG laser source (532 nm/CW/2ω) and a diffractive optical element (DOE) generating a regular laser grid (31 × 31 laser points) that is projected on the vocal folds. By means of stereo triangulation, the 3D coordinates of the laser points are reconstructed from the endoscopic high-speed footage. The new design of the laserendoscope constitutes a compromise between robust image processing and laser safety regulations. The algorithms for calibration and analysis are now optimized with respect to their overall duration and the number of required interactions, which is objectively assessed using binary classifiers. The sensitivity and specificity of the calibration procedure are increased by 40.1% and 22.3%, which is statistically significant. The overall duration for the laser point detection is reduced by 41.9%. The suggested semi-automatic reconstruction software represents an important stepping-stone towards potential real time processing and a comprehensive, objective diagnostic tool of evidence-based medicine.

Impact of Subharmonic and Aperiodic Laryngeal Dynamics on the Phonatory Process Analyzed in Ex Vivo Rabbit Models

“…In recent years, the cameras have become smaller and faster and the spatial resolution has improved enormously. Particularly when used in the clinical diagnosis of dysphonia, the HSI technique is superior to stroboscopy [10] and it is impossible to imagine phonatory clinical research today without HSI [10][11][12][13][14][15][16]. As long as the frame rate of the camera reaches at least 4000 frames per second, the technique enables one to capture an accurate representation of the vibratory cycle of the vocal folds [17].…”

Laryngeal Image Processing of Vocal Folds Motion

“…Recently, laryngeal image processing of vocal folds motion have been used to visualize the 3D superior vocal fold vibrations from laryngeal recordings [23,24,[167][168][169]. The authors proved that healthy phonation does not depend on symmetric oscillation patterns since great asymmetric vertical dynamics were observed.…”

“…Current laryngeal image modalities include Laryngeal VS, Videokymography (VKG), High-Speed Digital Kymograghy (DKG) and Laryngeal HSV. However, there are new modalities that emerge for analyzing the vocal folds dynamics [22] and also devices for 3D visualization of the vibration of vocal folds superior margins [23][24][25][26]. This paper is focused on two laryngeal image modalities: VS and HSV.…”

Measurement and Analysis of the Stepwise Curved Surface of Diffractive Optical Elements by a Constant Speed Confocal Probe

“…The surface profile of the DOEs, which is responsible for the optical power of the element, is preserved, but the volume and weight of the DOEs are reduced and the optical system specifications are improved, which is a common means to achieve miniaturization of optical systems. Planar substrate DOEs are usually used to build the optical path, but the quality of the system will be lost, whilst aspherical-based DOEs are often used to correct spherical aberrations in special cases [2,3]. Especially in an infrared optical system, due to the limitations of the optional infrared material, the diversification of the surface design can not only correct the chromatic aberrations and improve the system performance, but also increase the design freedom.…”