To provide an imaging unit for an endoscope, with which desired observation performance is readily obtained by making the variance amount of an actual visibility angle, after assembly small, with reference to the visibility angle in terms of design, and to provide its assembly method.
In the imaging unit for the endoscope constituted of an objective optical system and an imaging element, assembling is carried out in the following procedure. (i) By moving the imaging element C in the optical axis direction of the objective optical system comprising G1 and G2 with respect to the objective optical system, focusing is performed for the objective optical system; and (ii) by moving a part G2 of the objective optical system in the optical axis direction of the objective optical system, at least one of surface distances satisfying 0.5<¾ΔFOV/f¾<5 is adjusted, to obtain the desired visibility angle. Here, ΔFOV is the variation (° ) of the visibility angle in changing the surface distance by 0.01 mm, and (f) is the composite focal distance (mm) of the entire system.
COPYRIGHT: (C)2006,JPO&NCIPI
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Ryukichi Abe
Hirukawa Masanobu
Norihiko Uchida
Hideo Sugai
Kenji Aoki
Akira Yonezawa