Keratron™
Installation and operating manual
OPTIKON 2000
Cod. 161501EN
5-3
2014-04-23
Rev.0
Figure 5-2 : retro-mire working principle
To establish when the eye is at the ideal distance from the cone, the Keratron™
Onda uses an advanced version of the
EPCS
(
Eye Position Control System
)
electronic circuit adopted in the other topographs produced by Optikon 2000 S.p.A.
The eye's apex is intercepted by photocells when this is at a
range
around the
distance pre-set by the optical head. An indicator on the monitor and a sound alert
the operator when the eye is too near or far away, and permit capturing of the
images at the correct distance only.
The adoption of a double pair of photocells on the outside of the optical head in the
Keratron™, enables selection between the near distance, for the maximum
peripheral coverage, and that 3mm further away, to reduce invasiveness. These
choices can be made during the topographical acquisition by the
touch-screen
(e.g.
buttons 3 and 4 in
Errore. L'origine riferimento non è stata trovata.
).
The cone is backlit by a LED matrix with two wavelengths: the yellow-amber
(λ=590nm) to capture the topographical images and the infra-red (λ=940nm), the
same as the retro-mire, for the tracing of the pupil margin in scotopic conditions.
Behind this matrix is the fixture LED, focused a long distance away and a video
camera.
This video camera monitors and captures images of the eye in the two phases.
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Topography
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