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| Recently, our lock acquisition scheme is: | The basic idea behind the process here (which differs from the approach of initial LIGO) is to first bring the interferometer under control (to 'lock' it) using signals which are naturally reasonably well diagonalized, and which have a large useful range. This initial lock point need not be at the operating point. The intial signals are: |
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| * TRX -> ETMX * TRY -> ETMY * REFL33_I -> PRC * REFL33_Q -> MICH |
* TRX -> ETMX * TRY -> ETMY * REFL33_I -> PRC * REFL33_Q -> MICH |
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These signals bring us to a point where there is effectively a large CARM offset, which means that both ARM cavities are detuned from resonance by the same amount, in the same direction. ---------- |
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| attachment:loc_control_sequence.png |
Overview
To lock the detuned RSE configuration (sort of like LIGO-I + signal recycling), all of the interferometer's length degrees of freedom (DOF) are brought under control from an uncontrolled state. Typically this results in resonating the laser field within the resonant cavities formed by the interferomter optics and gives us a configuration which is optimal for audio-frequency gravitational-wave sensitivity.
The basic idea behind the process here (which differs from the approach of initial LIGO) is to first bring the interferometer under control (to 'lock' it) using signals which are naturally reasonably well diagonalized, and which have a large useful range. This initial lock point need not be at the operating point. The intial signals are:
TRX -> ETMX
TRY -> ETMY
REFL33_I -> PRC
REFL33_Q -> MICH
REFL166_I -> SRC
These signals bring us to a point where there is effectively a large CARM offset, which means that both ARM cavities are detuned from resonance by the same amount, in the same direction.
Detuned RSE lock acquisition procedure
attachment:loc_control_sequence.png