光學設計者在建構一個膠囊內視鏡的照明系統時，因為LED 的發光隨著角度而有不同，有其配光曲線，故其投光未必如預期能均勻分布在膠囊前的物面，使得感測器的成像品質降低，物面上有照明甚弱的暗處，或是光照過強的亮點，這個問題顯現在最後的影像上，會有極暗而無法辨別的區域與白色的亮點；針對這個問題，可以配合多顆LED 的排列位置與角度，而能夠改善投光，但此方法自由度有限，故考慮對前端透明的光學保護罩加以設計，不但能使投光效果大為改善，還能配合後方收光的鏡頭，亦可成為收光的透鏡之一，此乃一舉兩得之考量，本文主要對膠囊內視鏡的照明問題來進行研究，提出利用光學保護罩與LED相對距離、改變光學保護罩的曲率與形狀、LED 的排列與角度…等方法，可消除雜散光收入鏡頭，並改進原型膠囊的照明均勻度由0.12 提升至0.41，總能僅損失2%，並進而提出新的照明系統，可在彎曲目標物面0.71 的均勻度；改善照明系統可以間接提升成像的品質，輔助醫生對膠囊內視鏡攝影的活體影像資料下更正確的診斷。 Developing the illumination system in a capsule endoscope, it is difficult to obtain the uniform illumination on the observed object because the light intensity of LED is sensitive to package, driving current and projective angles, the LED light source location nearby imaging lenses and the strong total reflective from the dome will saturate the CMOS sensors. Those reasons induce the over blooming contrast and decrease imaging quality. The paper proposes a photometric model for analysis and design of LED illumination system in capsule endoscope. There are several key parameters resulting as illumination uniformity. Those include LED position of the imaging optical axis, LED numbers and arrangement, and the inner curvature of the dome. It can be improved by the following. Besides it makes the lighting more uniform in sample surface, the dome cooperate with camera lenses, to let the optical dome be one lens of camera lenses is possible. It is an idea to improve lighting intensity distribution and camera lenses, and design of illumination system is main goal in this research. It can lead to new design of illumination system in capsule endoscope. In this way, the uniformity of optimized original model is from 0.12 to 0.41, and the total intensity only loses 2%. Finally the uniformity of new design is 0.71 in curved sample surface. To improve illumination system can advance the imaging quality indirectly. It can help doctor to make a diagnosis and give treatment by vivo picture much correctly.
