Impact of the fiber cutting angle on fiber optic proximity sensors in endoscopy

Abstract

In current endoscopes, the estimation of the proximity to the surrounding tissue is based on the experience of the user. To provide precise proximity meassurement, a suitable sensor is needed. This paper presents a fiber optic proximity sensor that is inserted through the working channel of an endoscope. The impact of the fiber cutting angle at the distal end of the optical fiber is investigated. If the fiber is cut at a 3° angle to the optical axis, the measurement signal in axial direction can be increased by 126mV at the peak (measurement accuray 4.9 mV). A 45° fiber cutting angle allows radial measurement but with a weak measurement signal compared to an axial measurement. A distance between endoscope tip and intestine wall up to 15 mm can be measured. In conclusion, optical fibers can be used to insert a low-cost sensor through a working channel of an endoscope. By modifying the fiber cutting angle, an increased sensor signal can be obtained in the axial direction and a measurement in radial direction is possible.

Keywords

• endoscopy
• proximity
• sensor
• optical fiber
• fiber cutting angle
• optical measuring method
• intensity measurement