IMPROVEMENT OF RIGID MEDICAL ENDOSCOPES

Abstract

Background. Endoscopes with a rigid relay optical system have several advantages over flexible endoscopes and therefore are widely used in medicine. The problem remains the predisposition of these endoscopes to the destruction of that part of the optical system, which is assembled from rigid rod glass lenses. The cause of the damage can be small (up to one degree) bends of the metal tube in the process of using the endoscope. Failure of the optical part of the endoscope during surgery can have serious negative consequences for the patient. Objective. The aim of the article is to improve the optical relay part of a rigid endoscope, aimed at a significant reduction of its destruction due to the bends of the tube. Methods. To eliminate the damage, the relay part of the optical system is proposed to be assembled from short rod lenses with spherical ends, which allow for flexible articulation of these lenses. It is proposed to place a special heat-resistant immersion in the gaps between the spherical ends of the lenses, which ensures the passage of light from one lens to another with virtually no loss of luminous flux. It is shown that the proposed improvement allows to bend the tube at an angle of up to 10 degrees without breakage of rod lenses, which is unprecedented for rigid endoscopes. It is confirmed that the introduction of an additional aberration compensator of two meniscus lenses located between one pair of adjacent rod lenses into the optical system provides high image quality across the entire field of view, superior to the image quality of the prototype. At the same time, the distribution of relative illumination in the image plane formed by the improved optical system remains almost unchanged. Results. Providing greater flexibility of the rigid endoscope increases its competitive ability. Further improvement of the optical system of rigid endoscopes will create the conditions for the introduction of new minimally invasive surgical techniques that will simplify, reduce the cost and make endosurgical procedures minimally traumatic.