4.7 Calibration adjustment
19
0.1
1
10
All
an
de
vi
a�
on,
MHz
Averaging
�
me, s
10
1
10
2
10
3
10
4
10
5
10
6
10
0
Figure 4.6:
For longer times, the Allan deviation increases, in this case
showing a dip at around one day, related to variations in the lab temper-
ature.
variety of broadband effects.
The
FZW
does not include an internal
calibration source because the inherent stability of the
FZW
across
the
full
wavelength
range
is
better
than
the
accuracy
of
compact
references such as a neon lamp.
However, often the accuracy of a wavemeter is only critical around a
particular wavelength of interest, and it is desirable to improve the
calibration of the device around this wavelength, even though this
negatively impacts the absolute accuracy at other wavelengths.
To
calibrate
at
a
single
wavelength,
connect
a
reference
laser
of
stable wavelength to the
FZW
using a single-mode fibre.
The refer-
ence laser wavelength must be known to at the least the precision
required
from
calibration.
Then
access
the
recalibration
function
through
the
“Device”
menu
of
the
host
software
and
enter the known laser frequency in THz.
This calibration correc-
Summary of Contents for FSW4
Page 1: ...Fizeau Wavemeter and Fibre Switcher FZW600 FSM2 FSW4 FSW8 Firmware v0 9 5 mogfzw v1 4 5 ...
Page 36: ...30 Chapter 5 PID locking ...
Page 50: ...44 Appendix A Specifications ...
Page 60: ...54 Appendix C Command language ...
Page 62: ...56 Appendix D Errors and troubleshooting ...
Page 67: ...F Dimensions and PCB 83 120 146 32 9 30V PID TRIG FSW Figure F 1 FZW chassis dimensions 61 ...
Page 68: ...62 Appendix F Dimensions and PCB 146 33 37 120 18 Figure F 2 FSW fibre switch dimensions ...
Page 71: ......