Development of a wide-angle view endoscope for first wall and divertor regions on JT-60SA

Kamiya, Kensaku; Itami, Kiyoshi; Enokuchi, Akito*

Design study of a wide-angle infrared IR thermography and visible observation diagnostics for JT-60SA are reported. In order to image a large section inside the vacuum vessel of both in poloidal and toroidal directions, the optical system of endoscope is being designed with a field of view of 80 degrees having the spatial resolution better than a few cm. The optics of the system can be divided into three parts. A mirror based optical head (two set of spherical mirrors plus two flat mirrors), creating an intermediate image, a Cassegrain telescope system, and individual lens based imaging optics adapted to the various detectors for IR and visible observations, with their optical light paths being separated by in-vacuum small mirror. It makes possible to provide a optical solution without a blind spot, i.e. no image detection area.