| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an electronic endoscope which can be easily focused on the surface of a subject and has a small-diameter distal end portion. <P>SOLUTION: A recess portion 26 and a distal end surface 27 are formed on a distal end portion 16a provided in the electronic endoscope. The distal end portion 16a includes a side-viewing observation optical system 47 and a front-viewing observation optical system 48. The side-viewing observation optical system 47 has a side-viewing observation lens 28, a prism 41, and a zoom lens 42. Light incident from the side-viewing observation lens 28 is reflected on the half-mirror 41a of the prism 41. The zoom lens 42 and a CCD 44 are positioned on the emitting surface 41b of the prism 41. In the side-viewing observation optical system 47, a focal distance is switched between normal observation and magnifying observation and vice versa. A predetermined distance L is set between the position of the surface of the side-viewing observation lens 28 and the position on an extension line of the outer circumferential surface 25 in a side-viewing direction S. In the magnifying observation using the side-viewing observation optical system 47, the distance L is set so that the best focal position BP can match the extension line of the outer circumferential surface 25. <P>COPYRIGHT: (C)2013,JPO&INPIT |
