| 摘要 |
An optical system for use in reproducing a secondary image simultaneously with the main image of a projector. The secondary image is beamed in a direction which is 180 DEG from the path of the beam of light from the projector causing the main image. The secondary image is caused by (a) a mirror arranged in the main beam path to intercept a component of the light, and by converging it to reduce the size of the secondary image and shorten the focal length of the image of the rays forming the secondary image, and (b) a second mirror in the reflected beam to direct the reflected beam onto a screen. Thus, the main beam can be utilized to project the main image to be viewed by a person whose eyes are being tested, while the eye examiner may sit facing the patient to adjust various lenses before his eyes and see the secondary image in front of him which is the same as that which the patient sees.
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