Adjustment_60SMF-LSA 20.05.2021 © Schäfter+Kirchhoff GmbH
Schäfter+Kirchhoff GmbH Kieler Str. 212 22525 Hamburg, Germany +49 40 85 39 97-0 info@sukhamburg.de www.sukhamburg.com
4
3. Adjusting the Focus Setting
Focus adjustment (adjustment of the coupling lens in z-direction) is a demanding task and should be
performed preferably using a collimating telescope.
The laser beam coupler is shipped pre-adjusted for the labeled wavelength
and, often, it is not necessary for the customer to readjust the coupling lens
position. This is why you can skip this step in most cases.
Notice:
A fine-adjustment of the focus setting of a laser beam coupler already installed and adjusted is described in
Chapter 10.
To check the collimation setting of the laser beam coupler, couple a radiation source of appropriate wavelength
into the fiber connected to the laser beam coupler. Direct the beam to a target about half a Rayleigh length z
R
away:
z
R
π
∙
∅
2
beam
=
2
λ
∙8
Here
λ
is the optical wavelength and Ø
beam
the collimated beam diameter (1/e
2
level).
Refer to the laser instruction manual for all instructions regarding laser
safety!
• Do not stare directly into the laser beam (which can cause permanent
damage to the eyes).
• Do not stare at the reflected beam from reflective objects.
• Do not point the laser beam to other individuals.
Caution!
When correctly collimated, the laser spot diameter on a target about z
R
/2 away must have approximately the
same diameter such as the beam directly behind the laser beam coupler. Additionally, make sure that there is
no focused spot between the laser beam coupler and the target at z
R
/2.
The lens position is adjusted by means of an eccentric key. The eccentric key type 60EX-4 is used for laser
beam couplers with focal lengths
≤
11 mm. For laser beam couplers with focal lengths
≥
12 mm please use the
eccentric key type 60EX-5.
For adjusting the lens position perform the following steps:
Figure 8:
Loosen the two grub screws fixing the
lens position by means of a screwdriver
type 9D-12.
