Optical Domain Reflectometer

In communication fibers the light is guided
within a ‘glass tube’ of only a few micrometers.
Reducing fiber transmission losses by using
active fibers and finding the integrated optical
device are the big aims nowadays. To find out
sources of losses in the fiber which are induced
by manufacturing process or mechanical
stress Optical Time Domain Reflectometry
(OTDR) is used as an efficient method. Basically
this procedure couples a light signal into
the fiber and measures the occurrence of reflected
light blips. These blips will be produced
at stray centers at defects within the fiber core
or at fiber surfaces for example at fiber connectors.
This behavior is exploited within
OTDR and can be used to locate errors in fiber
links.
The goal of this educational kit is understanding
and training in this very important technique.
The students will be shown the principle
of operation of OTDR with the help of a complete
set-up shown in the figure below. The
measurement of the back scattered light and
the interpretation of the measured data are
explained and discussed. All needed mechanical,
optical and electronic components
are included. For the measurements a 100
MHz oscilloscope is necessary and can be ordered
as an option. Besides the OTDR many
other fiber related measurements and handling
like measurement of speed of light, behavior
of diode lasers or data transmission can
be carried out.
Educational Objectives
• Laser Diode Power Modes
• Optical Fiber
• Si PIN Photo Detector
• Fiber Handling and Preparation
• Coupling Light to Fiber
• Reflected Light Echoes
• Properties of Glass Fibers
• Speed of Light

1 Set of 4 flat rails with scale

2 Laser Diode in XY adjustment holder
3 Control electronics
4 Collimator for laser diode beam
5 Adjustable beam splitter on articulated connector
6 Imaging optics for start pulse detector
7 Detector for start pulse in holder
8 Quarter wave plate in rotation holder
9 5-axes adjustments holder with coupling optics
10 Fiber holder on linear stage
11 ~1000 m Optical glass fibers
12 Fiber holder on linear stage
13 Imaging optics for measurement pulse detector
14 Detector for measurement pulse in holder
15 Fiber cleaver and stripper
16 IR detector screen 0,8-1,2 μm
17 Set of 3 BNC cables
18 User manual
Measurements and Handling
• Measurements at the diode laser
• Coupling light into a fiber
• Measurement of fiber parameters
• Runtime of light in fibers
• Cutting and stripping of fibers
• Set-up and alignment of OTDR Systems

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