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IM AQ6373-01EN
Preparing for Measurement
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App
Index
3.7 Important Points During Measurement
Types of Optical Fibers
In addition to single mode optical fibers with core diameters of 5 to 9.5 μm, and
multimode (GI) optical fibers with core diameters of 50 and 62.5 μm, the instrument can
use large core size optical fibers of up to 800 mm. Functions may be limited or restricted
depending on which type of optical fiber is used. The table below shows which of the
typical types of fiber may be used and the limitations on their use.
Limitations on Wavelength Resolution
The maximum wavelength resolution for the instrument is 0.01 nm, which is only
obtainable when using a single-mode optical fiber with a core diameter of 9.5 μm or less,
and when measuring within a measurement wavelength range of 400 to 700 nm.
As shown in Table, the maximum wavelength resolution decreases when outside of this
measurement wavelength range or when optical fibers with thicker core diameters are
used.
Setting a resolution value finer than those shown in the table below will simply result in
an inaccurate measurement level without improving resolution.
Optical fibers with a thick core diameter are especially useful for inputting spatial light for
measurement, but they have poor resolution.
Choose the best type of optical fiber for your particular application.
Note that the instrument is designed for input through optical fiber only. It will not work
with inputs that do not pass through optical fiber, such as direct input of a gas laser
beam to the optical input connector, or bonding an LED to the optical input connector. It
is important to note that optical spectrum measurements taken through such inputs are
completely unreliable.
For spatial light measurements, input the spatial light to the optical fiber and from the
optical fiber to the instrument. A variety of adapters are available for this purpose.
Summary of usable optical fiber types and usage limitations
Optical Fiber
Obtained Wavelength Absolute Level
CORE SIZE
Type Core Diameter (in
µ
m) Resolution (in nm)
Accuracy
Setting
SM 5
0.02
OK*
SMALL
SM 9.5
0.02
NG
SMALL
GI 50
0.05
NG
SMALL
GI 62.5
0.05
NG
SMALL
SI 50
0.05
NG
SMALL
SI 80
0.10
NG
SMALL
SI 100
0.20
NG
SMALL
SI 200
0.50
NG
LARGE
SI 400
1.00
NG
LARGE
SI 800
2.00
NG
LARGE
* Calibrated at 850 nm.