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GENERAL INFORMATION ON USAGE AND MAINTENANCE
OPERATION PRINCIPLE
The patient's eye is illuminated by near infrared light, which is emitted by the fundus illumination optical
system (IR LED and xenon lamp
(Note 1)
). The fundus observation/photography optical system forms an
image on the image pick-up element (fundus observation camera), and the image can be observed on
the control panel.
The system works as follows: when operating the buttons which are displayed on the control panel by
the software, the photography light, which is emitted by the fundus illumination optical system, illumi-
nates the patient's eye. The image, which is received by the image pick-up element (fundus photogra-
phy camera) built in the fundus observation/photography optical system, is recorded as an electronic
fundus image
(Note 2)
. You can also set "digital zoom" that extracts and saves the center of the photo-
graphed image (equivalent to angle of view of 30°) through software.
(Note 1)
The anterior segment/fundus tomogram is obtained by using the optical interference phenomenon.
Near infrared light, which is emitted by the super luminescence diode (SLD), is separated by the fiber
coupler. One portion of the separated light is guided to the prism and is reflected by it, before returning
to the fiber coupler. The other portion of light is guided into the eye and is reflected by the cornea/fun-
dus tissues, before returning to the fiber coupler. When the two reflected portions of lights join and
overlap, a low interference wave with differing amplitude is generated. This wave is separated by the
diffraction grating and is then converted into the electric signal by the line CCD. This signal is then pro-
cessed to observe, photograph and record the anterior segment/fundus tomogram.
Using the sensor built in the auto alignment optical system (anterior segment observation LED and
camera), the auto alignment function detects the positions of the pupil and instrument. Then, the
instrument is moved to a position applicable to photography.
There are two auto focus functions, "Split auto focus function" and "OCT auto focus function". The
user should select and use one of them. The split auto focus function detects the reflected image of
the split lines projected to fundus. Then, the lens in the observation/photography optical system is
moved to a proper position by the auto focus mechanism to adjust focus correctly. In the case of the
OCT auto focus function, the lens in the observation/photography optical system is moved to a proper
position by the auto focus mechanism in order to get the optimum image quality level (coefficient calcu-
lated by S/N ratio) of the observed fundus tomogram. So focus is adjusted correctly.
By continuously photographing, recording and processing the fundus/anterior segment tomogram,
analysis such as three dimensional display, fundus image display or quantitative measurement is con-
ducted.
(Note 1) The instrument without the fundus photography function is excluded.
(Note 2) The instrument without the fundus photography function records the observed image as "still image"
and "electronic fundus image". It cannot emit the photography light and record an electronic image with
the fundus photography camera.
Fiber coupler
SLD
Patient’s eye
Line CCD
Prism
Diffraction grating