Sumários
Optical detection architectures
16 Maio 2025, 09:00 • José Manuel Rebordão
Optical detection: heterodyne, homodyne and DC-Readout (homodyne
balanced). Mains similarities and differences. Application to different LIGO’s
and impact on architectural functions. Mathematical treatment of heterodyne
detection.
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Recycling
cavities.
Michelson interferometry (class 1 of 3)
14 Maio 2025, 17:00 • Bachar Wehbe
Setup
of a Michelson Interferometer (MI), using amplitude splitting, and analysis of
the generated interferograms in several configurations.
Usage of cube beam splitters and polarisation optics to control laser beam
polarization.
Assessment
of how the MI can be used to measure relative displacements of one of the
mirrors, using a piezo electric stage actuator to move one of the mirrors.
Analysis
of several polarization optical elements (polarizers, polarizing beam splitters
and wave plates) using a polarimeter (an instruments that measure the
polarisation state of light).
Acquisition of interferograms using a CMOS 2D camera for post processing.
Michelson interferometry (class 1 of 3)
14 Maio 2025, 15:00 • Alexandre Pereira Cabral
Setup
of a Michelson Interferometer (MI), using amplitude splitting, and analysis of
the generated interferograms in several configurations.
Usage of cube beam splitters and polarisation optics to control laser beam
polarization.
Assessment of how the MI can be used to measure relative displacements of one of the mirrors, using a piezo electric stage actuator to move one of the mirrors.
Analysis of several polarization optical elements (polarizers, polarizing beam splitters and wave plates) using a polarimeter (an instruments that measure the polarisation state of light).
Assembly of a homodyne quadrature detection configuration to achieve higher resolution compared to the previous simple homodyne detection.Acquisition of interferograms using a CMOS 2D camera for post processing.
Frequency behaviour. The PDH technique for frequency locking. Gaussian waves (review)
12 Maio 2025, 14:00 • José Manuel Rebordão
Temporal
response of LIGO, modelling the GW disturbance on the end mirrors. Poles.
Bandwidth and tunability.
Pound-Drever-Hall control
technique for frequency stabilization.
Gaussian
waves: review; high order Hermite and Laguerre modes. Gouy phase term and its operational
importance for mode cleaning cavities. Particular relevance of LG33, in view of
LIGO Voyager specifications and use of Si for test masses.
Phase
matching between beams and cavities: concept and effects of lenses &
mirrors to transform laser beams into actual cavity modes. Examples.
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CLASS
Detection
architectures. Recycling cavities.
Analysis of Fabry-Perot cavities using matrix methods
9 Maio 2025, 09:00 • José Manuel Rebordão
Layer media – matrix methods, Transfer and scattering
matrices, examples.
Analysis of MI and Fabry-Perot cavities with matrix
methods.
Common and differential signals, dark fringe
configuration, again.
Intracavity and reflected fields from a FP cavity.
Resonance and anti-resonance conditions. Cavity gain.
Operational point of cavities, enabling maximum
phase sensitivity.
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CLASS
Frequence
response of a FP cavity in a MI arm.
Power
Recycling. Double FP cavities. Signal recycling.