Dual view capsule endoscopic lens design.

A dual view capsule endoscopic (DVCE) lens is proposed with front view and back view functions. This is a hybrid lens with a catadioptric mirror and an aspherical surface to support both view functions. The field of view (FOV) for the front view function is 90 degrees. The FOV for the back view function is 260 to 290 degrees. The TV distortion for the front view and back view function is under 30% and 25%. The corner relative illuminations for the two view functions are above 0.53. The Modulation Transfer Function (MTF) performance at the Nyquist Frequency for the two view functions can be kept above 0.35, even under tolerance they can remain above 0.2. Moreover, the telecentric conditions at the image plane of the DVCE system can support constant magnification through focusing. This condition can reduce the measurement error by slightly defocusing of the lens. Thus, the two view functions can offer physicians a wide viewing angle to deal with lesions over the fold.