The Optical Coupling of a Scintillation Chamber to an Image-Intensifying Tube

Several methods for coupling a fiber scintillation chamber to an image intensifying tube will be considered. A high-speed lens has been designed to image the ends of a curved fiber bundle on the curved cathode of an image intensifying tube. The lens covers a five-inch field at one-to-one magnification, and at a speed of f/1.5. The details of this lens design and its expected performance will be discussed. The results of a series of experiments on plastic scintillating fibers have been used to determine that the internal reflectivity is 0.993 and absorption constant is 0.015 cm-1 in the fiber. The data have then been used to compute the optical properties of fibers appropriate to a scintillation chamber system. Certain other optical properties of the components were estimated so that three possible optical coupling schemes could be compared in detail. They are; 1) the lens alone, 2) a glass fiber bundle alone, and 3) a combination of the lens and a glass fiber bundle. The lens alone is about half as efficient as either of the other two methods. The numerical aperture and probable transmission properties of each system will be outlined.