The two bundles are introduced into the body through veins and arteries and are threaded toward the organ to be examined.
A bundle of light from a high intensity source is focused into one bundle and sent to the organ to be examined.
The light reflected from a small region of the organ is collected by each of the fibers in the other bundle.
Here the light is focused into an image which can be viewed by eye or displayed on an electronic screen.
The illuminating bundle surrounds the light-collecting bundle.
Miniature video cameras attached to the endoscopies form images of the internal organs for display on TV monitors.
The use of fiber-optic devices has been greatly expanded by attaching to the endoscope remotely controlled miniature instruments to perform surgical operations.
Measurement of pressure in arteries, bladder, and uterus using optical sensors and laser surgery where powerful laser light is directed through one of the bundles to the tissue which is destroyed is one of the more recent applications of fiber optics.
A point source of light that is not in focus produces a disk image.
The data presented in the text can be used to calculate the focusing power of the eye.
The angu lar resolution of the eye can be calculated using the dimensions of the reduced eye.