Original Instructions Lumedica OQ LabScope 1.2 | Page 21 of 26
Reference arm pathlength and power control
The reference arm consists of a fiber optic section and a free space section. Within the free space
section there is a collimating lens, a focusing lens and a mirror.
Pathlength adjustment –
the pathlength of the reference arm can be adjusted by unscrewing the locking
ring and screwing in or out the assembly consisting of the focusing lens and mirror. Once the pathlength
is adjusted, the locking ring can be tightened down to hold the pathlength in place.
Power adjustment
– the power returned by the reference arm is set by the spacing between the focusing
lens and the mirror at the far end of the reference arm tube. If the distance from the lens to the mirror
is very close to the focal length of the lens, then a large amount of power will be reflected back to the
interferometer. If the mirror is closer to the lens than the focal length, less light will be coupled back into
the interferometer. By adjusting the spacing between the lens and mirror, the reference arm power can
be controlled with reasonable precision.
To make an adjustment, unscrew the locking ring closest to the end of the reference arm. Then screw
the tip with the mirror farther away from the lens for more light or closer to the lens for less light. Once
the power level is adjusted, tighten down the locking ring.
Note that adjusting the power level also adjusts the pathlength. After adjusting power, it may be
necessary to adjust pathlength as well.
Hardware – inside the scanner
There are no user adjustable or serviceable parts inside the scanner.
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