Active Rotation Alignment - THORLABS Vytran GPX4000LZ User Manual

GPX4000LZ Glass Processor
\
To begin the process, select the Alignment menu then select "Enable PM Alignment". Select "PM," and the PM
alignment window will be displayed. This window consists of 4 parameters for both the left and the right fiber. Enter
the fiber cladding diameter, fiber type and the two PM geometry parameters as indicated in the below table. These
values must be entered for both fibers; if the values are the same for both fibers, then check the "same" window. If
the operator does not know the exact characteristics, it is possible to directly measure them on screen. Please note
that the P1 and P2 values are measured in pixels unless they are expressing an ID or OD ratio. An OD Ratio"
represents the fraction of the fiber diameter which will be used to calculate the fiber end angle. It is the fraction of
the fiber diameter that contains the PM Structure. Where an ID Ratio is specified, the PM structure is contained in
the area between the ID ratio and OD ratio.
Normally after the "Lens Left" process, a sequence such as, "Auto Exposure", "End View Focus", "Auto Exposure",
"End View Alignment", would be inserted to align the fiber. If the operator is not satisfied with the alignment, the
process can be stopped and the fibers can be manually aligned.
Fiber Type
Generic
Panda
Elliptical Core
Bow Tie
Symmetry Algorithm

5.14.6 Active Rotation Alignment

The active rotation alignment method can be used for elliptical-core fiber (PM or PZ), panda-style PM fiber, bow-tie
style PM fiber, or a hybrid splice between any of these. These polarization-maintaining fibers are aligned rotationally
and in the XY-axes, just as in the End View Alignment algorithm.
The active rotation alignment method uses a polarization analyzer to precisely align the fibers rotationally. A light
source is connected to the end of one of the fibers and the polarization analyzer is connected to the other. The
analyzer contains a polarizer which is set to absorb any light in a perpendicular orientation relative to the main axis
of the fibers' elliptical cores. The analyzer will measure the optical power produced by the system consisting of the
fibers and the polarizer. The alignment routine will align the fibers until this power reading is minimized.
Rev I, September 15, 2021
Figure 30 PM alignment settings
Parameter 1 (P1)
OD Ratio
Core Center to Stress Rod
Center, (Pixels).
Core Center to edge of
ellipse, Minor diameter
(Pixels).
OD Ratio
ID Ratio
Chapter 5: Operation
Parameter 2 (P2)
N/A
Stress Rod Diameter
(Pixels)
Core Center to edge of ellipse,
Major diameter (Pixels).
N/A
OD Ratio
Page 47