Download Optical and infrared astronomical telescopes and instruments (L16)

Optical and infrared astronomical telescopes and instruments
(L16)
Ian Parry
Astronomy is an observational science. Our understanding of the universe beyond the Earth
comes mostly from interpreting the electromagnetic radiation we see coming from the sky. This
course is about the equipment and techniques that we use to collect and measure the optical
and near infra-red component of this radiation (approximately 0.3 to 5 microns in wavelength).
The material presented will give the student a thorough understanding of how telescopes and
their instruments actually work. An important aim of the course is to quantify how well they
work leading to an understanding of what defines the state-of-the-art and what its limitations
are.
Specific topics will be selected from the following list;
1. Introduction: Effects of the Earths atmosphere, transparency, seeing, refraction, dispersion, basic definition of magnitudes.
2. Positional astronomy and coordinate systems: Sidereal time, right ascension, declination,
hour angle, aberration of starlight, spherical trigonometry, great circles, small circles,
spherical triangles, cosine and sine rules, tangent plane.
3. Optics: geometrical optics, lens-makers equation, principle planes, focal length, f-number,
aberrations, paraxial approximation, ray-tracing, image planes, pupil planes, conjugate
planes, simple lens design, achromatic lenses, the Petzval lens, methods of designing complex optical systems, tendue, physical optics, quantum optics, Fourier treatment of wave
propagation.
4. Telescopes. Refractors, reflectors, parabolic reflectors, Ritchey-Chretien telescopes, 3mirror anastigmats, the Schmidt telescope, ground-based telescopes, telescope mounts,
space-based telescopes.
5. Detectors: photo-electrons, useful semiconductor types, readout architectures, image intensifiers, linearity, dynamic range, quantum efficiency, pixel-to-pixel variations, readout
noise, dark-current, sensitivity to cosmic rays, defects, charge transfer, artefacts.
6. Adaptive Optics: wavefront sensors, deformable mirrors, control algorithms, Kolmogorov
turbulence, Zernike polynomials.
7. Imagers: eyepieces, the eye, magnification, collimators, cameras, detector matching, image
scale, field of view, filters, magnitude systems. Fabry Perot interferometers, polarimetry.
8. Coronagraphs: Fourier modelling, speckles, occulters, lyot-stop, apodization,
9. Spectrographs: Dispersive spectrometers (long-slit, multi-slit, multi-fibre, echelle, integral
field), disperser types, grating equation, spectro-polarimetry, Fourier-transform spectrometers.
10. Interferometers:, Stellar interferometry: Fizeau-Stephan interferometer, Michelson stellar
interferometer, closure-phase, non-redundant masks.
11. Signal-to-noise ratio: exposure time, Poisson noise, systematic errors, beam-switching,
cryogenics.
12. Future projects: E-ELT, LSST, JWST, HDST.
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Pre-requisites
This course is self-contained.
Literature
1. Roy, A.E., & Clarke, D., Astronomy Principles and Practice, 4th ed., Institute of Physics,
2003.
2. Kitchin, C.R.: Astrophysical Techniques, 4th ed., Institute of Physics, 2003.
3. Smart, W.M., Spherical Astronomy, 6th ed., Cambridge University Press, 1977.
4. Saha S. K., Diffraction-limited imaging with large and moderate telescopes, World Scientific, New Jersey, 2007.
5. Born & Wolf, Principles of Optics, 7th ed., Cambridge University Press, 2002
6. Optics : E.Hecht
7. Speckle Phenomenon in Optics : J.W.Goodman
8. Astronomical Optics : D.J.Shroeder
9. Astronomical Techniques : W.A.Hiltner
10. Optical Detectors for Astronomy : J.W.Beletic & P.DAmico
Additional support
Three examples sheets will be provided and three associated examples classes will be given.
There will be a one-hour revision class in the Easter Term.
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