Sumários
Wavefront metrology (class 3 of 3)
27 Maio 2026, 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 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.SRC. PDH stabilization
25 Maio 2026, 14:00 • José Manuel Rebordão
SRC –
Simplified model relating the SRC with the transfer function
Pound-Drever-Hall
stabilization technique: principles, error function
NEXT
CLASS
Optical
Detection architectures
Recycling cavities
22 Maio 2026, 09:00 • José Manuel Rebordão
Dual resonant MI. Carrier at the SYM port, +1
reflectivity. GW signal at the ASY port.
Power recycling concept.
Single arm, three mirrors and two coupled cavities,
maximization of the arms intracavity power. Field at the SYM port.
Power recycled MI, Small MI (SMI) defined with the BS.
Coupling three cavities, PRC, SMI and Arms. Output at the ASY port. Resonances
and anti-resonances.
Cavities’ poles analysis. Example of aLIGO.
Signal recycling concept and overview of tuning.
NEXT
CLASS
SRC.
Michelson interferometry (class 2 of 3)
20 Maio 2026, 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.
Wavefront metrology (class 2 of 3)
20 Maio 2026, 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 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.