NKT Photonics Koheras HARMONIK User manual

Koheras HARMONIK
Fiber Coupler Installation Guide
Item# 800-634-01
1
General overview
Warning: Koheras HARMONIK lasers are Class 4 lasers. Before any operation is attempted, ensure the procedures and notices
within this Installation Guide and the hazard labels on the product are read, noted, and adhered to. In addition, make sure to follow
all safety recommendations listed in the Koheras HARMONIK Safety, Handling and Regulatory Information document shipped with
your laser. If in doubt, consult your laser safety officer.
Warning: Do not install the fiber coupler with the laser powered on. Ensure power to the laser is removed before proceeding with
the installation.
Warning: Use of controls or adjustments or performance of procedures other than those specified herein and in the document
Koheras HARMONIK Product Guide may result in hazardous radiation exposure.
Using four attachment bolts and washers, the fiber coupler
flange adapter is bolted onto the front panel of the
HARMONIK module. An iris diaphragm is used to coarsely
align the adapter with the output beam. Coarse alignment
is achieved by using a power meter to measure the
transmitted power and then maximize it by laterally shifting
the adapter. This ensures the adapter is accurately
centered on the output beam. Once the coarse alignment
is completed, the fiber coupler is inserted and fixed to the
flange adapter and then finely adjusted.
Installation environment
It is important that the installation environment is clean and
free from dust or other contaminants. Further, the output
windows should be free from any dust particles before
installation of the fiber couplers.
Safety precautions
Align both the fundamental and second harmonic laser
apertures using an appropriate beam dump. To further
prevent damage and accidental exposure to personnel,
ensure the beam path is safely contained and known.
All nearby personnel must wear suitable clothing and be
aware of the laser operations and the danger involved.
Item list
1Koheras HARMONIK
2aeroGUIDE Power cable
3Flange adapter
4Four M2x6 hex screws with washers
5Fiber coupler for second harmonic and/or fundamental
output
Tools required
1Adjustable iris diaphragm
250HD-15 hex screw driver
39D-12 screw driver
4Eccentric key
5Power meter
Removal of protection caps
To prevent contamination, the fiber couplers come with
dust protection caps. Remove the caps before continuing
the installation.
Koheras HARMONIK Fiber Coupler Installation Guide
Revision 1.0 01-2022 W-10456

Koheras HARMONIK
Fiber Coupler Installation Guide
2
Step 1: Mount the optical flange adapter
aTurn off laser power.
bInsert the four M2x6 mounting screws with washers through the
holes in the flange of the adapter.
cMake sure the adapters are orientated with the fundamental/SHG
output as shown with respect to the radially arranged pin screws.
dSlightly tighten the mounting screws using a 50HD-15 hex key or
driver.
Step 2: Align the adapter
aInsert the iris diaphragm into the flange adapter.
bMinimize the iris diaphragm aperture.
cSet the laser to the lowest-possible power and turn it on.
dMeasure the transmitted output power using a suitable power
meter.
eMaximize the transmitted power by laterally moving the flange
adapter.
fTighten the four mounting screws while taking care not to move
the flange adapter from the maximum power position.
gRemove the iris diaphragm.
hMeasure the free space output power for a later comparison to the
fiber coupled power to calculate the coupling efficiency.
Step 3: Mount the fiber coupler
aInsert the fiber coupler into the adapter flange.
bMake sure the fiber coupler has the same orientation as depicted
in the figure on the right. The flat surface has to be aligned
horizontally - perpendicular to the laser output polarization.
cTighten the three tapered pin screws to fix the fiber coupler in the
adapter flange.
“pin screws”
e

Koheras HARMONIK
Fiber Coupler Installation Guide
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Step 4: Connect the external DC power supply
aInsert the fiber into the fiber coupler’s receptacle. The fiber
connector has a thin notch mark indicating its orientation.
bMake sure the orientation of the fiber cable is as depicted.
Orientate the thin notch mark to exactly the “3 o’clock” position,
before tightening the fiber connector nut.
cGently tighten the grub screw to fix the fiber ferrule in the
receptacle.
dConnect the fiber’s output end to a power meter.
a
b
“3 o’clock”
“fiber connector
nut”
c
“grub screw”

Koheras HARMONIK
Fiber Coupler Installation Guide
4
Step 5: Adjust the coarse tilt
aLoosen the three tilt locking screws.
bTurn the tilt adjustment screws in sequence over a wide range in
both directions while observing the power meter.
cIf there is no measurable light coupled into the fiber while turning
the adjustment screws, perform steps “d” to “f”, otherwise go to
step “g”.
dLoosen the two grub screws holding the collimator lens.
eInsert the eccentric key and rotate it until the collimator lens is
closest to the fiber end. This orientation is where the white
indicator on the eccentric key points towards the fiber end as the
white arrow shows. From this position, rotating in either direction
moves the lens away from the fiber end.
fAs was done in step “b”, turn the tilt adjustment screws in
sequence until the signal is found on the power meter.
gOptimize the tilt adjustment for maximum power coupled into the
fiber.
a
b
d
e
“grub screws”
“tilt adjustment screws”
“tilt locking screws”
“tilt locking screws”

Koheras HARMONIK
Fiber Coupler Installation Guide
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Step 6: Adjust the focus
aWhile monitoring the power meter, rotate the eccentric key until
the maximum signal is attained.
bIteratively repeat steps “5g” (tilt optimization) and “6a” (focus
optimization) until the maximum signal cannot be increased
further.
cTighten the two grub screws holding the collimator lens.
Step 7: Adjust the fine tilt
aOnce more, check if you can enhance coupling efficiency by using
the three tilt adjustment screws.
bFinally, lock the tilt adjustment by tightening the three tilt locking
screws. Besides their locking function, the tilt locking screws can
also adjust the fine tilt.
cWhile tightening the first two tilt locking screws, the power meter
signal typically drops significantly. However, when tightening the
third screw, the maximum signal should recover.
Step 8: Final check
aWhile observing the fiber output power, gently press against the
cladding stripper of the fiber from the side.
bWhen pressing against the cladding stripper in different directions,
the signal normally drops.
cRelease the cladding, the signal should recover to its maximum
value.
dIn case the signal increases while pressing against the connector
in a specific direction, the adjustment is not at its optimum. The
corresponding locking screw has to be fine tuned further, until the
fiber output power decreases symmetrically in each push
direction.
c
“grub screws”
“tilt locking screws”
“cladding”

Koheras HARMONIK
Fiber Coupler Installation Guide
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Support
Web https://www.nktphotonics.com/lasers-fibers/
support/technical-support-and-customer-service/
Shipping Address NKT Photonics A/S
Blokken 84
3460 Birkerød
Denmark