PSN-L Email List Message
Subject: Re: wonderful invention of R. V. Jones (phase detection)
From: Charles Patton charles.r.patton@........
Date: Wed, 27 Feb 2008 14:21:16 -0800
An additional technique that might be useful for this sensor is to
construct the detector ruling – make it of two sets of rulings, with a
90 degree offset (1/2 line offset between the sets -- i.e., 1/4 period
offset.) Then use two photodetectors, one for each set. This way you
can eliminate much of the gain variation due to temperature, etc.
Additionally the sine wave phase difference from the detectors will
allow the detection of which way the mirror is moving so you have a
sense of positive/negative, north/south, etc.
Charles R. Patton
Public Seismic Network Mailing List (PSN-L)
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