Use of the capsule endoscope to inspect the digestive system, and in particular the intestine, for pathological change has recently been a great breakthrough in medical engineering. Some problems, however, need to be overcome. The field of view is not wide enough, and the image quality is not good enough. These drawbacks cause unclear and ambiguous digestive disease examinations by medical professionals. In order to solve these problems, the paper proposes a novel design for miniature lenses with a wide-angle field of view and good imaging quality. The lenses employed in the capsule endoscope would consist of a plastic aspheric lens and a glass lens, in a capsule 9.8 mm (W) ×9.8 mm (L) ×10.7 mm (H), associated with white LED light sources and a 256×256 CMOS array sensor of 10-μm pixel size. Experimental results prove that the lens field of view can be made as large as 86 deg, and the modulation transfer function for field of view 0 deg can be made 78.2% at 50-lpmm spatial frequency and 53.3% at 100 lpmm. Tolerance analysis shows that our design is feasible for manufacture, and consistent with the finished prototype.
- Wide-angle lenses
- Wireless capsule endoscope