HP 8167A, User Manual, Page: 41 / 262

2
Press 4 W A VELENGTH 5 and
NNNNNNNNNNNNNNNNNNNN
nm/GHz as necessary to get this display .
See \Changing the V alue of a P arameter" in Chapter 1 if you need details on
how to edit parameters .
Example T o set the wavelength to 1505.500nm (on an HP 8168E/F)
1. Press 4 W A VELENGTH 5
2.
Press
NNNNNNNNNNNNNNNNNNNN
nm/GHz , if necessary , until the display looks as shown
in Figure 2-2
3. Type in 1505.5 on the numeric keypad, and press 4 ENTER 5 .
Setting a Relative W avelength
Y ou use a relative wavelength for heterodyning, for example , when you are
measuring the linewidth of DFB (distributed feedback) lasers .
Y ou can set a relative wavelength if the display looks like this:
Figure 2-3. Setting a Relative W avelength
Press 4
W A VELENGTH
5 and
NNNNNNNNNNNNNNNNNNNN
nm/GHz as necessary to get to this display .
The output wavelength () is set from the base wavelength (
0
) and the
frequency oset (df). The formula for calculating the output wavelength is:
=
c
(
0
)d f + c
0
where c is the speed of light in a vacuum (2.998210
8
ms
-1
).
Y ou can edit only the value of df directly . See \Changing the V alue of a
P arameter" in Chapter 1 if you need details on how to edit parameters .
Changing the Base W avelength
If you want to change
0
,
1. set to the value to which you want to set the base wavelength (by
calculating df, or by setting the wavelength directly) and then
Setting Wavelength and P ower 2-3