The UPNLT laser produces a "spot" about 150 mm x 75 mm at 500 metres, so a very small misalignment of the laser will cause the "spot" to miss the target and prevent communication.
Care is therefore necessary in the design of the UPNLT mounts so that the beam can be aligned without unnecessary difficulty, and so that the alignment is not easily disrupted. If the mounting is flexible, alignment will be difficult.
For ranges up to 450 metres the arrangement shown below is sufficient, although care and patience are necessary during beam alignment. For longer ranges (see "Extended Range Operation"), screw adjustment of beam direction is almost essential.
The wooden base should be secured to a window frame or other solid structure.
A UPNLT should not be in direct sunlight. The laser diode life will be reduced significantly if the sun heats the case. The photodiode should also be protected from direct sunlight.
If a UPNLT is mounted indoors on a window frame, a sheet of cardboard can be taped to the window, with small holes for the transmitted and received beams.
If mounted outdoors, protection from sun, rain and birds is necessary.