Aluminum surface defect detection method based on a lightweight YOLOv4 network.

Deep learning is currently being used to automate surface defect detection in aluminum. The common target detection models based on neural networks often have a large number of parameters and a slow detection speed, which is not conducive to real-time detection. Therefore, this paper proposes a lightweight aluminum surface defect detection model, M2-BL-YOLOv4, based on the YOLOv4 algorithm.

Assessing the biomechanical properties of the porcine crystalline lens as a function of intraocular pressure with optical coherence elastography.

In this study, we investigated the relationship between the biomechanical properties of the crystalline lens and intraocular pressure (IOP) using a confocal acoustic radiation force (ARF) and phase-sensitive optical coherence elastography (OCE) system. ARF induced a small displacement at the apex of porcine lenses at various artificially controlled IOPs. Maximum displacement, relaxation rate, and Young's modulus were utilized to assess the stiffness of the crystalline lens.

Can We Improve Vaginal Tissue Healing Using Customized Devices: 3D Printing and Biomechanical Changes in Vaginal Tissue.

Background: Determining biomechanical changes in vaginal tissue with tissue stretch is critical for understanding the role of mechanotransduction on vaginal tissue healing. Noncontact dynamic optical coherence elastography (OCE) can quantify biomechanical changes in vaginal tissues noninvasively. Improved vaginal tissue healing will reduce postoperative complications from vaginal surgery.

Quantifying the effects of hydration on corneal stiffness with noncontact optical coherence elastography.

Purpose: To quantify the effects of the hydration state on the Young's modulus of the cornea.

Setting: Biomedical Optics Laboratory, University of Houston, Houston, Texas, USA.

Design: Experimental study.

Quantitative Assessment of Thin-Layer Tissue Viscoelastic Properties Using Ultrasonic Micro-Elastography With Lamb Wave Model.

Characterizing the viscoelastic properties of thin-layer tissues with micro-level thickness has long remained challenging. Recently, several micro-elastography techniques have been developed to improve the spatial resolution. However, most of these techniques have not considered the medium boundary conditions when evaluating the viscoelastic properties of thin-layer tissues such as arteries and corneas; this might lead to estimation bias or errors.

Nanobomb optical coherence elastography.

Wave-based optical elastography is rapidly emerging as a powerful technique for quantifying tissue biomechanical properties due to its noninvasive nature and high displacement sensitivity. However, current approaches are limited in their ability to produce high-frequency waves and highly localized mechanical stress. In this Letter, we demonstrate that the rapid liquid-to-gas phase transition of dye-loaded perfluorocarbon nanodroplets ("nanobombs") initiated by a pulsed laser can produce highly localized, high-frequency, and broadband elastic waves.

Ultra-fast line-field low coherence holographic elastography using spatial phase shifting.

Optical coherence elastography (OCE) is an emerging technique for quantifying tissue biomechanical properties. Generally, OCE relies on point-by-point scanning. However, long acquisition times make point-by-point scanning unfeasible for clinical use.

Applanation optical coherence elastography: noncontact measurement of intraocular pressure, corneal biomechanical properties, and corneal geometry with a single instrument.

Current clinical tools provide critical information about ocular health such as intraocular pressure (IOP). However, they lack the ability to quantify tissue material properties, which are potent markers for ocular tissue health and integrity. We describe a single instrument to measure the eye-globe IOP, quantify corneal biomechanical properties, and measure corneal geometry with a technique termed applanation optical coherence elastography (Appl-OCE).

Assessing the effects of riboflavin/UV-A crosslinking on porcine corneal mechanical anisotropy with optical coherence elastography.

In this work we utilize optical coherence elastography (OCE) to assess the effects of UV-A/riboflavin corneal collagen crosslinking (CXL) on the mechanical anisotropy of porcine corneas at various intraocular pressures (IOP). There was a distinct meridian of increased Young's modulus in all samples, and the mechanical anisotropy increased as a function of IOP and also after CXL. The presented noncontact OCE technique was able to quantify the Young's modulus and elastic anisotropy of the cornea and their changes as a function of IOP and CXL, opening new avenues of research for evaluating the effects of CXL on corneal biomechanical properties.

Optical coherence elastography for evaluating customized riboflavin/UV-A corneal collagen crosslinking.

UV-induced collagen cross-linking is a promising treatment for keratoconus that stiffens corneal tissue and prevents further degeneration. Since keratoconus is generally localized, the efficacy of collagen cross-linking (CXL) treatments could be improved by stiffening only the weakened parts of the cornea. Here, we demonstrate that optical coherence elastography (OCE) can spatially resolve transverse variations in corneal stiffness.

Optical coherence elastography assessment of corneal viscoelasticity with a modified Rayleigh-Lamb wave model.

The biomechanical properties of the cornea play a critical role in forming vision. Diseases such as keratoconus can structurally degenerate the cornea causing a pathological loss in visual acuity. UV-A/riboflavin corneal collagen crosslinking (CXL) is a clinically available treatment to stiffen the cornea and restore its healthy shape and function.

Quantifying tissue viscoelasticity using optical coherence elastography and the Rayleigh wave model.

This study demonstrates the feasibility of using the Rayleigh wave model (RWM) in combination with optical coherence elastography (OCE) technique to assess the viscoelasticity of soft tissues. Dispersion curves calculated from the spectral decomposition of OCE-measured air-pulse induced elastic waves were used to quantify the viscoelasticity of samples using the RWM. Validation studies were first conducted on 10% gelatin phantoms with different concentrations of oil.

Lorentz force optical coherence elastography.

Quantifying tissue biomechanical properties can assist in detection of abnormalities and monitoring disease progression and/or response to a therapy. Optical coherence elastography (OCE) has emerged as a promising technique for noninvasively characterizing tissue biomechanical properties. Several mechanical loading techniques have been proposed to induce static or transient deformations in tissues, but each has its own areas of applications and limitations.

Noncontact Elastic Wave Imaging Optical Coherence Elastography for Evaluating Changes in Corneal Elasticity Due to Crosslinking.

The mechanical properties of tissues can provide valuable information about tissue integrity and health and can assist in detecting and monitoring the progression of diseases such as keratoconus. Optical coherence elastography (OCE) is a rapidly emerging technique, which can assess localized mechanical contrast in tissues with micrometer spatial resolution. In this work we present a noncontact method of optical coherence elastography to evaluate the changes in the mechanical properties of the cornea after UV-induced collagen cross-linking.

Investigating Elastic Anisotropy of the Porcine Cornea as a Function of Intraocular Pressure With Optical Coherence Elastography.

Purpose: To evaluate the elastic anisotropy of porcine corneas at different intraocular pressures (IOPs) using a noncontact optical coherence elastography (OCE) technique.

Methods: A focused air-pulse induced low amplitude (≤ 10 µm) elastic waves in fresh porcine corneas (n = 7) in situ in the whole eye globe configuration. A home-built phase-stabilized swept source optical coherence elastography (PhS-SSOCE) system imaged the elastic wave propagation at different stepped radial directions.

Evaluating the Effects of Riboflavin/UV-A and Rose-Bengal/Green Light Cross-Linking of the Rabbit Cornea by Noncontact Optical Coherence Elastography.

Purpose: The purpose of this study was to use noncontact optical coherence elastography (OCE) to evaluate and compare changes in biomechanical properties that occurred in rabbit cornea in situ after corneal collagen cross-linking by either of two techniques: ultraviolet-A (UV-A)/riboflavin or rose-Bengal/green light.

Methods: Low-amplitude (≤10 μm) elastic waves were induced in mature rabbit corneas by a focused air pulse. Elastic wave propagation was imaged by a phase-stabilized swept source OCE (PhS-SSOCE) system.

Classifying murine glomerulonephritis using optical coherence tomography and optical coherence elastography.

Acute glomerulonephritis caused by antiglomerular basement membrane marked by high mortality. The primary reason for this is delayed diagnosis via blood examination, urine analysis, tissue biopsy, or ultrasound and X-ray computed tomography imaging. Blood, urine, and tissue-based diagnoses can be time consuming, while ultrasound and CT imaging have relatively low spatial resolution, with reduced sensitivity.

Analysis of the effects of curvature and thickness on elastic wave velocity in cornea-like structures by finite element modeling and optical coherence elastography.

Wave models that have been used to extract the biomechanical properties of the cornea from the propagation of an elastic wave are based on an assumption of thin-plate geometry. However, this assumption does not account for the effects of corneal curvature and thickness. This study conducts finite element (FE) simulations on four types of cornea-like structures as well as optical coherence elastography (OCE) experiments on contact lenses and tissue-mimicking phantoms to investigate the effects of curvature and thickness on the group velocity of an elastic wave.

Quantitative methods for reconstructing tissue biomechanical properties in optical coherence elastography: a comparison study.

We present a systematic analysis of the accuracy of five different methods for extracting the biomechanical properties of soft samples using optical coherence elastography (OCE). OCE is an emerging noninvasive technique, which allows assessment of biomechanical properties of tissues with micrometer spatial resolution. However, in order to accurately extract biomechanical properties from OCE measurements, application of a proper mechanical model is required.

Quantitative assessment of corneal viscoelasticity using optical coherence elastography and a modified Rayleigh-Lamb equation.

We demonstrate the use of a modified Rayleigh–Lamb frequency equation in conjunction with noncontact optical coherence elastography to quantify the viscoelastic properties of the cornea. Phase velocities of air-pulse-induced elastic waves were extracted by spectral analysis and used for calculating the Young’s moduli of the samples using the Rayleigh–Lamb frequency equation (RLFE). Validation experiments were performed on 2% agar phantoms (n ¼ 3) and then applied to porcine corneas (n ¼ 3) in situ.

Assessing age-related changes in the biomechanical properties of rabbit lens using a coaligned ultrasound and optical coherence elastography system.

Purpose: To evaluate the capability of a novel, coaligned focused ultrasound and phase-sensitive optical coherence elastography (US-OCE) system to assess age-related changes in biomechanical properties of the crystalline lens in situ.

Methods: Low-amplitude elastic deformations in young and mature rabbit lenses were measured by an US-OCE system consisting of a spectral-domain optical coherence tomography (OCT) system coaligned with a focused ultrasound system used to produce a transient force on the lens surface. Uniaxial compressional tests were used to validate the OCE data.

Differentiating untreated and cross-linked porcine corneas of the same measured stiffness with optical coherence elastography.

Structurally degenerative diseases, such as keratoconus, can significantly alter the stiffness of the cornea, directly affecting the quality of vision. Ultraviolet-induced collagen cross-linking (CXL) effectively increases corneal stiffness and is applied clinically to treat keratoconus. However, measured corneal stiffness is also influenced by intraocular pressure (IOP).

Air puff induced corneal vibrations: theoretical simulations and clinical observations.

Purpose: To investigate air puff induced corneal vibrations and their relationship to the intraocular pressure (IOP), viscoelasticity, mass, and elasticity of the cornea based on theoretical simulations and preliminary clinical observations.

Methods: To simulate the corneal movement during air puff deformation, a kinematic viscoelastic corneal model was developed involving the factors of corneal mass, damping coefficient, elasticity, and IOP. Different parameter values were taken to investigate how factors would affect the corneal movements.

Corneal hysteresis with intraocular pressure of a wide range: a test on porcine eyes.

Purpose: To investigate the relationship between corneal hysteresis (CH) and intraocular pressure (IOP) using porcine eyes in the low to high IOP ranges.

Methods: In vitro porcine eyes were used to investigate the relationship of CH and IOP. IOP was altered by changing the height of a drip stand within the dynamic range of 60 mm Hg.

Biomechanical and refractive behaviors of keratoconic cornea based on three-dimensional anisotropic hyperelastic models.

Purpose: To investigate the biomechanical and refractive behaviors of normal and keratoconic corneas based on three-dimensional anisotropic hyperelastic corneal models with two layers.

Methods: Based on an anisotropic hyperelastic formula, the finite element method was employed to develop normal and keratoconic corneal models in which the fiber orientations and the biomechanical differences between corneal layers were taken into account. The displacements for normal and keratoconic corneal models were studied, as well as changes in corneal refractive power with intraocular pressure (IOP).