Duration
15h Th, 5h Pr
Number of credits
| Master in space sciences (120 ECTS) | 2 crédits |
Lecturer
Language(s) of instruction
English language
Organisation and examination
Teaching in the second semester
Schedule
Units courses prerequisite and corequisite
Prerequisite or corequisite units are presented within each program
Learning unit contents
Atmospheric optics is the study of optical effects induced by the Earth atmosphere on light propagating from distant sources. Of particular concern to astronomers is atmospheric turbulence, which limits the performance of ground-based telescopes. The past two decades have seen remarkable progress in the capabilities and performance of adaptive optics (AO) systems. These opto-mechanical systems actively compensate for the blurring effect of the Earth's turbulent atmosphere. By sensing, and correcting, wavefront distortion introduced by atmospheric index-of-refraction variations, AO systems can produce images with resolution approaching the diffraction limit of the telescope at near-infrared wavelengths.
In this course, we detail the physical processes and fundamental relations of atmospheric optics that are most relevant to astronomy, and discuss the techniques used to characterize atmospheric turbulence. The fundamentals of AO are then introduced and the many types of wave front sensors and advanced AO systems that have been developed over the last 20 years are described. The principles of each are outlined, and the performance and limitations are examined. Aspects of photometric and astrometric measurements of AO-corrected images are considered, and a few notable applications of AO-assisted imaging are discussed (extrasolar planets, circumstellar disks, galactic center, active galactic nuclei, etc). The course concludes with a discussion on some of the challenges related to current and future AO systems, particularly those that will equip the next generation of large ground-based optical and infrared telescopes.
Learning outcomes of the learning unit
This course aims to give an overview of the properties of atmospheric turbulence, to show how it affects the quality of astronomical images, and to describe how it can be corrected for using adaptive optics techniques. At the end of the course, the student will be able to understand and describe the successive deformations of a wave front from its entrance in the Earth atmosphere down to its measurement at the focus of a telescope equipped with adaptive optics. The course will give sufficient knowledge bases to embark in more advanced projects related to state-of-the-art ground-based astronomical imaging.
Prerequisite knowledge and skills
This course requires a basic knowledge of geometrical and physical optics. This is the reason why the following course is considered as co-requisite: PHYS0048-3 (Coherent and incoherent optics, Instrumental optics I)
Planned learning activities and teaching methods
Theoretical part: lectures based on two main review articles (Roddier et al. 1981 on atmospheric turbulence, Hickson et al. 2016 on adaptive optics). A slideshow will be used and made available to the students.
Practical part: critical review of a recent research paper in the field of atmospheric or adaptive optics, 10-min presentation of a summary of that paper, and discussion.
Mode of delivery (face to face, distance learning, hybrid learning)
Face-to-face
Organisational adjustments related to the current health context
Depending on the health situation in Q2, the lectures could be organized online.
Recommended or required readings
The slideshow used during the lectures will be made available to the students, as well as the two review articles on which the lectures are based.
Further recommended reading: "Principles of adaptive optics, 3rd edition" (Robert K. Tyson, 2012, CRC Press).
Assessment methods and criteria
Below you will find information on the evaluation methods planned for in-person and remote exams as well as those planned for hybrid sessions. Depending on how the health crisis evolves, the chosen method will be communicated to you no later than one month before the start of the exam session.
The evaluation will be carried out during an oral examination that will comprise:
- the answer to a question on the theoretical lectures randomly drawn from a list of questions submitted to the students a few weeks in advance,
- the presentation of the research article proposed to the student and discussion.
Each part will count for 50% of the final grade.
Work placement(s)
Organizational remarks
Contacts
- Teacher: Dr Olivier Absil, F.R.S.-FNRS Research Associate (olivier.absil@uliege.be)
- Secretary: Ms Nicole Massin (N.Massin@uliege.be)