An optical image retrieval method, which makes optical input devices work on
media, which method generates a light and projects it in a vertical direction.
The light is directed to a light-splitter and transmitted to an image contacting
surface under a transparent medium. Optical image signals retrieved on the image
contacting surface are reflected to the light-splitter, and then an optical axis
of the image signals is reflected to a lens by the light-splitter once or more.
Finally, the lens will focus the image signals onto an image detecting element.