Anritsu MS9740B - Precautions at Measurement

Chapter 2 Before Use
2-14
2.7 Precautions at Measurement
CAUTION
Never input an optical signal with a level that exceeds the
maximum input level of the analyzer. Input of an over-level
signal runs the risk of damaging the optical parts and level
error will increase due to degraded level linearity.
Effect of Optical Fiber on Measurement Results
The following optical fibers can be used with MS9740B:
● Single-mode fiber (SM) (core diameter of 5 to 9.5 µm)
● Multimode fiber (GI) (core diameter of 50 µm)
When using SM fiber, press
F1 Measure Mode
and set
f5 MM Mode
to Off.
When using GI fiber, press
F1 Measure Mode
and set
f5 MM Mode
to On.
The performance is limited as follows, depending on the fiber used.
(1) Limitations on wavelength resolution
The MS9740B wavelength resolution accuracy meets the
specifications using SM fiber with a core diameter of 9.5 µm or less.
If a fiber with a core diameter of more than 9.5 µm is used, the
specified resolution accuracy may not be met.
(2) Limitations on measurement level
There are limitations depending on the Numerical Aperture (NA) of
the optical input fiber.
The MS9740B has a built-in monochromater.
When connecting an SM optical fiber with an NA larger than 9.5/125
µm, not all the light radiated from the fiber is captured by the
MS9740B, causing connection loss equivalent to the lost amount of
light. As a result, the measured level is smaller than the true level.
The NA of multimode fiber is about 0.2 to 0.35 larger than the NA of
SM fiber, causing error when measuring level using multimode fiber.