LIGO Document T060035-x0

Orientation of Quadrant Diode for Wave Front Sensing

Document #:
Document type:
T - Technical notes
In current LIGO I interferometers, quadrant diodes for wave front sensors (WFS)
are oriented in such a way that the lines (i.e. gaps) between the segments forms “X”
instead of “+” pattern. The segment 1 and 3 are used for YAW degree of freedom,
while the segment 2 and 4 are used for PIT. Though at a first glance it looks as if there
are no fundamental difference between “X” and “+” configuration, “X” is more prone
to the crosstalk between YAW and PIT. There are other things, like DC centering
annoyances for human operators. All in all, there’s no reason to prefer “X” to “+”,
and there are some reasons to hate “X”. We should not use “X” configuration for future
LIGO interferometers
Files in Document:
  • PDF (T060035-00.pdf, 296.9 kB)
Notes and Changes:

Migrated document information from the old DCC:
- Full document number: LIGO-T060035-00-D
- Author(s): K. Kawabe
- Document date: 2006-04-04
- Document received date: 2006-05-01
- Document entry date: 2006-05-01
Referenced by:

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