Sumários
Signal Recycling Cavity. Tunability. Radiation pressure. Model cleaning
6 Maio 2024, 14:00 • José Manuel Rebordão
Signal Recycling Cavity: descriptions, analysis, poles. Temporal operating
mode of LIGO. Tunability, control of the pole position through the length of
the SRC; gain.
Radiation pressure
– overview of physics and effects. Brief analysis of different suspension systems
in aLIGO and ET.
Non-Planar
Ring Oscillators (NPRO) - overview
Mode cleaning
how it works; Gouy phase
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Frequency behaviour. The Power Recycling Cavity
3 Maio 2024, 09:00 • José Manuel Rebordão
Temporal
response of LIGO, modelling the GW disturbance on the end mirrors. Poles.
Bandwidth and tunability.
Brief
overview of the LIGO laser system.
The
Power Recycling Cavity (PRC): functions, implementation using a composite FP
cavity with 3 mirrors.
Concatenation
of 2 FP cavities; reflectance and transmittance. Resonance and anti-resonant
conditions.
PRC
gain and operational conditions
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Signal Recycling cavity (SRC)Fabry-Perot cavities
29 Abril 2024, 14:00 • José Manuel Rebordão
Analysis
of general 2 mirror FP cavities, reflection and transmittance, power cavity
gain.
Increased sensitivity due to the huge phase amplification of the reflected wave at resonances.
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CLASS
Reviews. Scattering matrix
26 Abril 2024, 09:00 • José Manuel Rebordão
Reviews: Fabry-Perot interferometer, gaussian waves, ressonant cavities.
Wavefront metrology (class 3 in 3)
24 Abril 2024, 15:00 • Alexandre Pereira Cabral
A Shack-Hartmann wavefront sensor was built based on an array of lenses that divide / sample the incoming wavefront into small sub-apertures, focusing independently the light from each lens in a 2D sensor that captures the focal plane pattern. This pattern was processed in order to obtain the position of each focus point from each individual lens.
An incident plane wave was created using a spatial filter and a collimated lens to produce a grid of equidistant focal points, the reference position, while several distorted waves (corresponding to a point source from an optical fibre in controlled positions) result in an uneven distribution of points that were referenced to the ideal plan wave situation in order to determine with the sensor the position of the fibre tip, using the Shack-Hartman sensor to measure an unknown wavefront based of the focus shifts from the calibration.