Polarizing Beam Splitter Endoscope for Simultaneously Observing Front and Lateral View

Abstract

Fetal surgery sometimes requires multiple field-of-views (FOVs). The authors have developed an FOV extended endoscope for simultaneously observing front and lateral view with single lens system. A polarizing beam splitter (PBS) mounted at its distal end guides the rays from the two FOVs to relay lenses in orthogonal linear polarizations, and the other PBS mounted at its base separates them at eye lens systems. However, the images of the two views are superimposed because lenses rotate the direction of linear polarization. To solve the problem, the authors adopt a rectifier to cancel the rotation. Additional approaches consist of polarizing plates, image processing, and light source control. Polarizing plates improve the contrast of image by 13.8%. Light source control unit switches chip LEDs on and off. The cameras synchronized to LEDs get images alternately. Taken endoscopic movie with light source control was 30fps. By using these methods, clearer images are acquired.