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Astronomical Telescopes and Instruments


Admission requirements

The course requires knowledge of optics (geometrical optics, physical optics, interference, diffraction), Fourier transforms, astronomical observing techniques and computer programming. Students who have not followed the bachelor's course Astronomical Observing Techniques (AOT) must follow the AOT crash-course during the first week.


This course provides the fundamental understanding of how modern astronomical telescopes and optical instruments work and how they are designed; it is the cornerstone of the Astronomy and Instrumentation master's specialisation.

The first part of the course is focused on the fundamental physics that is relevant to understand the intricacies of modern optical instruments with a focus on the assumptions that are typically made. The second part applies this knowledge to optical components and optical design. The third part covers specific instrument categories that are typically found at astronomical observatories.

Students will write their own codes and use optical design software to apply their knowledge. Each student will present a specific instrument described in the literature to provide the class with insight into actual astronomical instruments.

The lectures and exercises cover the following topics:

  • Foundations of optics

  • Interference, diffraction and Fourier optics

  • Geometrical optics

  • Polarization

  • Thin films and coatings

  • Optical design

  • Telescopes

  • Imagers

  • Classical spectrographs

  • Advanced spectrographs

  • Interferometers

  • Polarimeters

Course objectives

Upon completion of this course, students will be able to design their own optical telescopes and instruments.

In particular, students will be able to:

  • Explain the fundamental optics principles used in modern astronomical instruments

  • Calculate the performance of simple optical systems

  • Design simple optical systems given certain specifications

  • Model the performance of thin-film coatings

  • Explain the respective advantages and disadvantages of different telescope designs

  • Model different telescope concepts

  • Explain the advantages and disadvantages of different imager and spectrograph designs

  • Simulate polarimeters for coherent and incoherent light

Soft skills

In this course, students will be trained in the following behaviour-oriented skills:

  • Problem solving (recognizing and analyzing problems, solution-oriented thinking)

  • Analytical skills (analytical thinking, abstraction, evidence)

  • Verbal communication (presenting, speaking, listening)

  • Critical thinking (asking questions, check assumptions)


See Astronomy master schedules

Mode of instruction

  • Lectures

  • Exercise classes

  • Practical classes

Assessment method

Retake exams will be oral. Homework assignments and presentation will still count for the final grade.


Blackboard will be used to communicate with students. To have access, you need an ULCN account. More information:

Reading list

Recommended but not mandatory:

  • Field Guide to Astronomical Instrumentation, by Keller, Navarro, Brandl, published by SPIE

  • Optics, by Eugene Hecht, published by Addison Wesley


Via uSis. More information about signing up for your classes can be found here. Exchange and Study Abroad students, please see the Prospective students website for information on how to apply.

Contact information

Lecturers: Prof.dr. C.U. Keller
Assistant: Alexander Bohn
Course website: Astronomical Telescopes and Instruments


Please note that this is a mandatory course for all master's students who follow the Astronomy and Instrumentation specialisation.