| 摘要 |
The eye test machine (13) has a LED (16) passing monochromatic light through a test pattern (18) in a holder (17). Light from the pattern is reflected via two prisms (19) and through a first lens (22). The light is reflected via two prisms (24,25) through a second lens (21) to a semi reflecting beam-splitting prism. Light is reflected into the eye (A) and returns through the beam splitter to an optical system with lenses (36,37) and prisms (39-41) and a receiver (42) for determining the refractive index of the eye. The machine projects a real image of the test pattern onto the retina of the eye and examines the image to determine if it is in focus.
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