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If single point measurements are carried out with the sensor head OFV-512,
one of the two fibers must be terminated with a reference head. The reference
head is marked with a red dot. Always mount the reference head to the refer-
ence fiber, also marked with a red dot.
As described in section 4.2.4, the intensity of the optical signal varies periodi-
cally with the stand-off distance. The adjustable reference head OFV-152 is
suitable for measurements which have to be carried out near a maximum of
visibility, but in which the stand-off distance of the fiber head can not be
changed e.g. using the fiber head OFV-130-3 or OFV-130-5.
Using the OFV-152, the distance between mirror and fiber can be varied over
a wide range. This is achieved by moving the retroprism in the reference
head. In addition the intensity of the signal can be optimized by collimating
the laser beam onto the retroprism with a lens. It is easy to access the lens
through a drilled hole in the reference head. The reference head OFV-152 is
shown in figure B.1.
Figure B.1: Side view and bottom view of the reference head OFV-152 (dimensions not specified are given in mm)
60
54
35
25
14
DIN74-Kf3
7
19
27
38
M61/4" - 20G
310.5
ø20
ø40
40