Michelson interferometry (class 2 of 3)

30 Abril 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.

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Apagão eléctrico - aula anulada

28 Abril 2025, 14:00 • José Manuel Rebordão

Faculdade inoperacional

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Wavefront metrology (class 1 of 3)

16 Abril 2025, 17:00 • Bachar Wehbe

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. 

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Michelson interferometry (class 1 of 3)

16 Abril 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.

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JWST – subarrays Gravitational wave observatories

14 Abril 2025, 14:00 • José Manuel Rebordão

JWST – Subarrays and their utilization and implementation
 
GWO
Gravitational wave (GW) detectors: history, general architecture. Links with General relativity: GW polarization, frequency and strain.
General subsystems and function of GW detectors.
ET - example of most relevant specifications.
Interferometers: Michelson and Sagnac.
 
NEXT CLASS
Noise factor. Review of basic concepts: resonant cavities, gaussian waves, Finesse, effect of lenses on beams…

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