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Chapter 6. Calibration
3. Couple light into the
MWM
, preferably with plenty of power (a few
microwatts) exiting from the fibre endface (at the
MWM
end).
4. Run the
mogwave
program, and rotate the diffractive optical element
(see below) until a spectral peak is seen. On Rev 2 devices, the
indicator line on the diffractive element holder should point towards
the fibre such that the surface of the diffractive element is exposed
to the light.
To find the peak as the element is rotated, it can be helpful to use
the Focus or Ctrl-Focus feature to see a large area of the sensor.
5. Firmly retighten the screws holding the optical element in place and
replace covers.
6. Calibrate as above.
6.5 New fibre
The wavemeter relies on the precise location of the fibre core. Some fibre
patchcords (e.g. Diamond Fibre Optics) have highly repeatable fibre core
locations, but most require some correction. Also changing between PC
and APC terminations requires correction. The corrections are determined
by taking a full sensor image and finding the appropriate diffraction spots.
Ensure light is diffracted onto the sensor. Acquire a Full Image, with
exposure time of 10 ms or longer. You may need to run
mogwave
as
Administrator
to save the image file in the
MOGL
abs folder. Open the
fullimageYYMMDD_hhmmss.tiff
file, normally saved in the folder in which
mogwave
is installed, with an image viewer (e.g.
IrfanView
or
ImageJ
).
You should see one bright spot, and may also see one or two additional
secondary spots depending on which generation of wavemeter you have
(contact
MOGL abs if unsure). Find the x,y location of the main spot; for
example, in
IrfanView
, click on the spot, and while holding the mouse
button down, at the top left of the
IrfanView
window you will see the x,y
location.
The location should be programmed into the device. Using
telnet
or the