Title :
An Endoscope With 2 DOFs Steering of Coaxial Nd:YAG Laser Beam for Fetal Surgery
Author :
Yamanaka, Noriaki ; Yamashita, Hiromasa ; Masamune, Ken ; Chiba, Toshio ; Dohi, Takeyoshi
Author_Institution :
Dept. of Mechanoinformatics, Univ. of Tokyo, Tokyo, Japan
Abstract :
This paper reports a rigid endoscope that provides an endoscopic view and transmits a high-power infrared laser beam coaxially to arbitrary points in the view to photocoagulate body tissue, mainly for treatment of twin-to-twin transfusion syndrome. The endoscope system consists of a hot mirror for coaxial transmission of visible light and a neodymium-doped yttrium aluminum garnet laser beam, and an optical galvano scanner for steering the laser beam from the endoscope tip. The optical system of the endoscope is designed for high-power laser transmission, and achieves a small laser beam. The camera and galvano mirrors are calibrated to control the laser spot automatically by pointing a target on the endoscopic image. We evaluated the laser transmission efficiency, firing angle, positioning accuracy, and feasibility of photocoagulation by in vitro experiment. The laser transmission efficiency was 34%. However, the endoscope provided changeable firing angles of 24° in a horizontal direction and 22° in a vertical direction. Furthermore, the positioning accuracy was sufficiently high because the errors in both air and water were mostly smaller than the diameter of target vessels of 1 mm. As an in vitro experiment, we successfully coagulated rabbit´s mesenteric vessels by changing the firing angle.
Keywords :
beam steering; biological tissues; biomedical optical imaging; blood vessels; coagulation; endoscopes; infrared imaging; laser applications in medicine; laser beams; medical disorders; obstetrics; optical design techniques; optical scanners; surgery; YAG:Nd; body tissue photocoagulation; coaxial Nd:YAG laser beam; fetal surgery; high-power infrared laser beam; high-power laser transmission; hot mirror; laser beam firing angle; laser transmission efficiency; neodymium-doped yttrium aluminum garnet laser beam; optical galvano scanner; positioning accuracy; rabbit mesenteric vessels; rigid endoscope; twin-to-twin transfusion syndrome; Beam steering; Endoscopes; Laser applications; Optical imaging; Coaxial transmission; fetal surgery; laser beam steering; laser endoscope; wavelength separation;
Journal_Title :
Mechatronics, IEEE/ASME Transactions on
DOI :
10.1109/TMECH.2010.2078828