Development of an endoscope video camera with an optical gradient

• Grant number: 97/07514-5
• Support Opportunities: Research Grants - Innovative Research in Small Business - PIPE
• Duration: April 01, 1999 - September 30, 2002
• Field of knowledge: Engineering - Biomedical Engineering
• Principal Investigator: Cicero Livio Omegna de Souza Filho
• Grantee: Cicero Livio Omegna de Souza Filho
• Host Company: KOM Montagens e Comércio Ltda
• City: Campinas

Abstract

The present project proposes the development of an endoscope optimized for use as a video camera. The endoscope is an optical instrument that allows for the observation of locations with limited access. The instrument is composed of a metallic rod and in its interior are housed the image optics and a bundle of optical fibers for illumination. Its diameter varies from 1.8 to 12 mm. The endoscope that we propose to develop will be of the rigid type and we will make use of technology of graduated lenses (grin lenses). These lenses have a cylindrical form and possess a profile of refractive index that diminishes gradually from the axis to the cylinder. The use of the technology of grin lenses, as against conventional lenses, allows: the use of less lenses, as a consequence less loss through reflection and accumulated aberrations; greater precision in the positioning of the lenses preserving the optical axis of the system, since they possess cylindrical symmetry; and a smaller tube diameter, making the inspection of the cavity less invasive. Currently the video endoscope requires an additional optical system to link the image of the endoscope to the CCD camera. Considering the illumination side, the fiber optic cable is interrupted by a connector placed between the source and the endoscope, and this connection causes a loss in the order of 50 per cent. In the first phase of this project, we built four prototypes, three of them possessing optical gradient and one a microvideo-otoscope using conventional lenses. Innumerable gadgets and mechanical tools were made to assemble and test the produced instruments. Efforts in the mounting and development of a new light source integrated with the control unit of a micro camera were experimented with. A special type of fiber was designed and made up with a diameter of 40 microns. Using this fiber, beams for the illumination of the prototypes were constructed. (AU)