| dc.description.abstract | In this thesis, we present a two times zoom lens for a one mega pixel capsule endoscope camera. The zoom lens with three group employed in the capsule endoscope simply consisted of three piece of plastic aspherical lens and a piece of spherical lenses. The first group of zoom lens that has two piece of lenses. The second group and the third group of zoom lens has one piece of lenses.Capsule endoscopy is mainly used to observe small intestine.The radius of the small intestine is 12.5 mm so we set that object height is 12.5 mm, and proposes the object plane of intestine is a curved surface. The first order of zoom lens has a half field of view of 30o to 71.66o, a focal length range of 1.064 mm to 2.039 mm, a f-number of 2.8 to 3.5, total length of 11.6 mm, the maximum aperture of 6 mm.
We divided the zoom lens into six-segment analysis depend on magnification. The magnification of six-segment zoom system is -0.0845, -0.0984, -0.1150, -0.1317, -0.1482, and -0.1690, respectively. The f-number of
first zoom system and second zoom system is 2.8. The f-number of third zoom system and fourth zoom system is 3.2. The f-number of fifth zoom system and sixth zoom system is 3.5. The minimum MTF was 0.408 at 147 lp/mm in first zoom system. The maximum absolute value of the difference between the tangential direction MTF and the sagittal direction MTF is 0.078 in first zoom system.The maximum distortion is -14.89% in first zoom system. The minimum relative illumination is 71.8% in first zoom system. The maximum lateral color is 1.5μm in first zoom system. | en_US |