LABORATORY OF ASTROPHYSICS 1

Second cycle degree in ASTRONOMY

Campus: PADOVA

Language: English

Teaching period: First Semester

Lecturer: ROBERTO RAGAZZONI

Number of ECTS credits allocated: 6


Syllabus
Prerequisites: Fundamentals of Physic and Astronomy at the level of the Bachelor Degree in Astronomy.
Examination methods: Oral exam about the topics discussed in the lectures.
Course unit contents: 1) Basic principles of optics and image formation: Nature of light and geometrical nature of thin lenses and of conical sections. Concept of stigmatic and non stigmatic imaging. Optical copies and Lagrange invariant. Relevance of the position and size of the stop in an optical system and its effects on the overall property.
2) Two mirrors telescope: Schwarzschild, Cassegrain, Gregorian and Ritchey-Chretienne solutions. The problem of the background in astronomical imaging and in particular in the infrared. Definition of the thermal and non-thermal infrared portion of the spectra. Vignetting and field of view in Cassegrain telescopes. Difference between images formed by parabolic and spherical mirrors and the case of Arecibo-like design. Examples of telescopes and instrumentation employing the various concepts devised.
3) Adaptive and active optics. Basic definitions, Kolmogorov turbulence and isoplanatic angle, Fried’s parameter and Greenwood frequency. Deformable mirrors and wavefront sensors in open and closed loop operations. Tip-tilt four quadrants sensing and Poissonian nature of photons effect on them. High order aberrations and Hamilton, Zernike and Karhunen-Loeve modes. Shack-Hartman and pyramid wavefront sensors. Concept of multi-conjugated adaptive optics. Star and Layer Oriented approaches. Adaptive optics with multiple field of views.
4) Detectors: Charge Coupled Devices Detectors, principles of working and basic parameters. Quantum efficiency, charge transfer efficiency, read out noise. CCD principle of working and effects on the Poissonian apparent noise. Concept of the avalanche photo diodes and quenching.
5) Experiments in the optical laboratory: Poisson’s spot, turbulence simulation and speckle formations.
6) Observations at the Asiago Astronomical Observatory: Speckle interferometry.