Three-dimensional scanning of the cornea by using a structured light module

Abstract

ABSTRACT:Corneal topography is a computerized diagnostic tool that creates a three-dimensional map of the surface of the cornea. Corneal topography provides tools needed to know the morphology, optics, power distribution and radii of the anterior surface of the cornea. This is of great help for multiple fields of optometry and ophthalmology: contact lens fitting, keratoconus detection and tracking and corneal ecstasies, detection of suspicious corneas in refractive surgery, etc. Although there are basically two types of corneal surveyors: specular reflection and elevation, many authors agree that the accuracy of these devices is affected by multiple factors, which obey both the mathematical process used and certain physiological variables. Three-dimensional (3D) scanning systems, consisting of devices based on a structured light module, are widely used to perform high-precision measurements in primarily industrial and medical applications. The present work is proposed to show the application of fringe projection technique in three-dimensional scanning of corneal surface.Key words: Three-dimensional scanning, corneal surface, optometry RESUMEN:La topografía corneal es una herramienta diagnóstica computarizada que crea un mapa tridimensional de la superficie de la córnea. La topografía corneal proporciona herramientas necesarias para conocer la morfología, la óptica, la distribución de la potencia y de los radios, de la superficie anterior de la córnea. Esto es de gran ayuda para múltiples campos de la optometría y la oftalmología: adaptación de lentes de contacto, detección y seguimiento de queratocono y ectasias corneales, detección de córneas sospechosas en cirugía refractiva, etc. Aunque existen básicamente dos tipos de topógrafos corneales: de reflexión especular y de elevación, muchos autores coinciden que la precisión de estos dispositivos es afectada por múltiples factores, que obedecen tanto al proceso matemático empleado como a ciertas variables fisiológicas. Los sistemas de digitalización tridimensional (3D), formados por dispositivos que se basan en un módulo de luz estructurada, son usados ampliamente para realizar mediciones de alta precisión en aplicaciones industriales y médicas principalmente. El presente trabajo se plantea con el objetivo de mostrar la aplicación de la técnica de proyección de franjas en la digitalización tridimensional de la superficie de la córnea.Palabras clave: Digitalización tridimensional, superficie de la córnea, optometría

Fringe Quality Map for Fringe Projection Profilometry in LabVIEW

“…The experimental setup consisted in two parts: a projection system and an observation system. The projection system used was an LED pattern projector (Optoengineering LTPRHP3W-W) [18] that contains a stripe pattern of 400 lines with line thickness 0.01 mm. An objective lens of 12-mm focal length was used to project the fringe pattern onto the object.…”

Camera-Projector Calibration Methods with Compensation of Geometric Distortions in Fringe Projection Profilometry: A Comparative Study

“…Three-dimensional (3D) scanning techniques based on fringe pattern projection and imaging have been extensively developed to meet the demands of many applications including, industrial inspection, computer-aided design, manufacturing, medical diagnosis, etc., [1]- [4]. The main advantages of these techniques include their non-contact nature, dense measurement, high speed, high automation degree and high accuracy [5], [6].…”