We demonstrate a flexible stand-alone, minimally invasive video-endomicroscope with an outer diameter of
1.6 mm and a length of the rigid tip of 6.7 mm that enables surgeons and biologists to image hardly accessible
regions in-vivo in epifluorescence mode. The 60 mg light device improves state-of-the-art objectives by a
double deflection approach using a side-fire fiber in combination with spherical microlenses, GRIN-lenses
with a specific adapted gradient index profile and an extremely miniaturized chip-on-the-tip camera to
achieve an excellent imaging quality. A high NA of 0.7 enables the observation of subcellular features within
the entire field of view with a diameter of 183 μm, assure a bright and high-contrast image and promise a
good overview during the intervention. Ex-vivo measurements of biological samples confirmed the
functionality of the probe.
Objective: Following tumour surgery in the head and neck region, skin flap transplants are usually required to cover the resection
area. The purpose of the development was to provide a simple and reliable means to assess whether the transplanted flap
is sufficiently perfused.
Methods: Fluorescence of intravenously injected Indocyanine green (ICG) was detected with a slightly modified 3-chip CCD
camera. Appropriately coated optical filters allow for excitation of ICG with NIR light and detection of NIR ICGfluorescence
with the blue channel of the camera. In addition, low intensities of white light can be transmitted to allow
for simultaneous display of a remission image in the green and red channels of the camera. Further processing was
performed with a LabVIEW program.
Results: A satisfactory white light image (red, green and blue display (RGB)) could be calculated from the remission images
recorded with the green and red channels of the camera via a look-up table. The look-up table was programmed to
provide an optimized blue intensity value for each combination of red and green values. This was generated using a
reference image. Implementation of image tracking and intensity measurements in regions of interest (ROIs) in the
images is useful to reliably monitor perfusion kinetics of flap and adjacent normal tissue.
Background:
High brightness light emitting diodes (LEDs) have become available that appear suitable to replace light sources
currently used for illumination through thin light guides, e.g. in endoscopy. We investigated the essential characteristics
of a series of commercial single LEDs relevant for direct coupling to a single optical multimode fiber.
Methods:
LED fiber coupling efficiency was assessed experimentally and theoretically by using a ray tracing software.
Results:
Surface emitting LEDs proved suitable to be coupled directly into plastic optical fibers (POFs). We have successfully
applied a 1 mm core POF-fiber (outer diameter 1.01 mm) in contact with a OSTAR LED (Osram Opto Semiconductors,
Regensburg, Germany) to achieve a coupling efficiency of 10-20%, which gave 42 mW, 23.7 mW and 27 mW for blue,
green and red LED respectively.
Ray tracing simulation revealed a considerable part of photons travelling "out of axis" in spirals along the core-clad
interface (non-meridional beams). They account for approximately 30% of the transmitted power.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.