Koheras HARMONIK
Fiber Coupler Installation Guide
Item# 800-634-01

General overview
Item list

Using four attachment bolts and washers, the fiber coupler
flange adapter is bolted onto the front panel of theHARMONIK module. An iris diaphragm is used to coarselyalign the adapter with the output beam. Coarse alignmentis achieved by using a power meter to measure thetransmitted 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 theflange adapter and then finely adjusted.

1 Koheras HARMONIK
2 aeroGUIDE Power cable
3 Flange adapter
4 Four M2x6 hex screws with washers
5 Fiber coupler for second harmonic and/or fundamental
outputTools required
1 Adjustable iris diaphragm2 50HD-15 hex screw driver
3 9D-12 screw driver
4 Eccentric key
5 Power meter

Installation environment
It is important that the installation environment is clean andfree from dust or other contaminants. Further, the output
windows should be free from any dust particles before
installation of the fiber couplers.

Removal of protection caps

Safety precautions

To prevent contamination, the fiber couplers come withdust protection caps. Remove the caps before continuing
the installation.

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 beaware of the laser operations and the danger involved.

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 withyour 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 withthe 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.

1Koheras HARMONIK Fiber Coupler Installation Guide
Revision 1.0 01-2022 W-10456

Koheras HARMONIK
Fiber Coupler Installation Guide

Step 1: Mount the optical flange adapter
a Turn off laser power.
b Insert the four M2x6 mounting screws with washers through theholes in the flange of the adapter.
c Make sure the adapters are orientated with the fundamental/SHG
output as shown with respect to the radially arranged pin screws.
d Slightly tighten the mounting screws using a 50HD-15 hex key ordriver.

“pin screws”

Step 2: Align the adapter
a Insert the iris diaphragm into the flange adapter.
b Minimize the iris diaphragm aperture.
c Set the laser to the lowest-possible power and turn it on.
d Measure the transmitted output power using a suitable power
meter.
e Maximize the transmitted power by laterally moving the flangeadapter.
f Tighten the four mounting screws while taking care not to movethe flange adapter from the maximum power position.
g Remove the iris diaphragm.
h Measure the free space output power for a later comparison to thefiber coupled power to calculate the coupling efficiency.

Step 3: Mount the fiber couplera Insert the fiber coupler into the adapter flange.
b Make sure the fiber coupler has the same orientation as depictedin the figure on the right. The flat surface has to be aligned
horizontally - perpendicular to the laser output polarization.
c Tighten the three tapered pin screws to fix the fiber coupler in theadapter flange.

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Fiber Coupler Installation Guide

Step 4: Connect the external DC power supplya Insert the fiber into the fiber coupler’s receptacle. The fiberconnector has a thin notch mark indicating its orientation.
b Make 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.
c Gently tighten the grub screw to fix the fiber ferrule in thereceptacle.
d Connect the fiber’s output end to a power meter.

a“fiber connectornut”“3 o’clock”

b“grub screw”
c3Koheras HARMONIK
Fiber Coupler Installation GuideStep 5: Adjust the coarse tilt
a Loosen the three tilt locking screws.
b Turn the tilt adjustment screws in sequence over a wide range inboth directions while observing the power meter.
c If there is no measurable light coupled into the fiber while turning
the adjustment screws, perform steps “d” to “f”, otherwise go tostep “g”.
d Loosen the two grub screws holding the collimator lens.
e Insert the eccentric key and rotate it until the collimator lens isclosest to the fiber end. This orientation is where the white
indicator on the eccentric key points towards the fiber end as thewhite arrow shows. From this position, rotating in either direction
moves the lens away from the fiber end.
f As was done in step “b”, turn the tilt adjustment screws insequence until the signal is found on the power meter.
g Optimize the tilt adjustment for maximum power coupled into thefiber.

a“tilt locking screws”“tilt adjustment screws”b“tilt locking screws”“grub screws”
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Fiber Coupler Installation Guide

Step 6: Adjust the focus“grub screws”
ca While monitoring the power meter, rotate the eccentric key until
the maximum signal is attained.
b Iteratively repeat steps “5g” (tilt optimization) and “6a” (focusoptimization) until the maximum signal cannot be increased
further.
c Tighten the two grub screws holding the collimator lens.

Step 7: Adjust the fine tilta Once more, check if you can enhance coupling efficiency by using
the three tilt adjustment screws.
b Finally, lock the tilt adjustment by tightening the three tilt locking
screws. Besides their locking function, the tilt locking screws canalso adjust the fine tilt.
c While tightening the first two tilt locking screws, the power metersignal typically drops significantly. However, when tightening thethird screw, the maximum signal should recover.

“tilt locking screws”

Step 8: Final checka While observing the fiber output power, gently press against thecladding stripper of the fiber from the side.
b When pressing against the cladding stripper in different directions,the signal normally drops.
c Release the cladding, the signal should recover to its maximum
value.
d In 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 thefiber output power decreases symmetrically in each pushdirection.
“cladding”

5Koheras HARMONIK
Fiber Coupler Installation Guide

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