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Revision 9 as of 2010-06-13 02:43:04
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Editor: RanaAdhikari
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The reference cavity was locked using a 21.5 MHz signal from a rack mounted board (FSS REF - Crystal Frequency Reference [http://www.ligo.caltech.edu/docs/D/D980353-C.pdf]). That turned out to have many problems and we removed it completely from the system circa 2008 with a fixed 21.5 MHz OCXO from Wenzel and an RF Amplifier (see [http://nodus.ligo.caltech.edu:8080/40m/986 elog]). The reference cavity was locked using a 21.5 MHz signal from a rack mounted board (FSS REF - Crystal Frequency Reference http://www.ligo.caltech.edu/docs/D/D980353-C.pdf). That turned out to have many problems and we removed it completely from the system circa 2008 with a fixed 21.5 MHz OCXO from Wenzel and an RF Amplifier (see [http://nodus.ligo.caltech.edu:8080/40m/986 elog]).
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|| Mirror T || 300 ppm ||
|| Mirror RoC || 1 m?
||
|| Cavity Length || 0.245 m ? ||
|| Cavity Finesse || ||
|| Cavity g-factor || ||
|| Cavity FSR || ||
|| Mirror T_HR || 300 +/- 30 ppm ||
|| Mirror R_AR || < 500 ppm ||
|| Mirror RoC || 500 mm
||
|| Cavity Length || 8" (203.2 mm) ||
|| Cavity Finesse || 10000 ||
|| Cavity g-factor (g1*g2) || 0.352 ||
|| Cavity waist || 0.218 mm
||
|| Cavity FSR || 737.7 MHz ||
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Some FEA of the LIGO/40m reference cavity using COMSOL:
[[/FEA]]
Some FEA of the LIGO/40m reference cavity using COMSOL: [[/FEA]]
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See also [[Frequency Stabilization Servo]].  See also [[Frequency Stabilization Servo]].

The reference cavity was locked using a 21.5 MHz signal from a rack mounted board (FSS REF - Crystal Frequency Reference http://www.ligo.caltech.edu/docs/D/D980353-C.pdf). That turned out to have many problems and we removed it completely from the system circa 2008 with a fixed 21.5 MHz OCXO from Wenzel and an RF Amplifier (see [http://nodus.ligo.caltech.edu:8080/40m/986 elog]).

We got the design parameters for the reference cavity from [http://www.ligo.caltech.edu/docs/D/D980670-00.pdf D980670]

Spacer Material

Fused Silica (Corning?)

Mirror Material

Fused Silica

Mirror T_HR

300 +/- 30 ppm

Mirror R_AR

< 500 ppm

Mirror RoC

500 mm

Cavity Length

8" (203.2 mm)

Cavity Finesse

10000

Cavity g-factor (g1*g2)

0.352

Cavity waist

0.218 mm

Cavity FSR

737.7 MHz

Cavity pole

Some FEA of the LIGO/40m reference cavity using COMSOL: /FEA


Reference_Cavity (last edited 2012-01-03 23:02:39 by localhost)