Detectors for Visible/IR Interferometry

Rafael Millan-Gabet (Smithsonian Astrophysical Observatory)

Abstract:

The science detector is the last surface that precious interfering photons encounter in an optical interferometer. Their interaction with the detector allows us to count them, or generates analog signals which are subsequently amplified and digitized. The ideal detector has arbitrarily fast response time, perfect quantum efficiency at all wavelengths, and introduce zero noise. Real detectors have none of those characteristics, and as such ultimately limit the sensitivity of the interferometer. Moreover, competing technologies and trade-offs -- in terms of wavelength response, noise performance, format, ease of use, and cost -- must often be considered when designing the detection system that will be used with a given beam combination method. I will review basic considerations of signal-to-noise ratio in the measurement of interferometric observables, and present the advantages and limitations of existing detectors for visible and infrared wavelengths. I will end with a discussion of next-generation technologies which appear particularly well suited to the needs of many-element optical interferometry.

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A note on the use of Summer School material.

Suggested Reading:

• Detection of Light, from the ultraviolet to the submillimeter, G. H. Rieke, (Cambridge University Press: 1994).

Astronomy techniques:

• Part II of ``Star Formation and Techniques in Infrared and mm-wave Astronomy'', Lecture Notes in Physics 431, T. P. Ray and S.V.W. Beckwith (Eds), Springer-Verlag 1994

Infrared optical design:

• Optical Design Fundamentals for Infrared Systems, Max J. Riedl, Tutorial texts in optical engineering vol. TT 20, SPIE press 1995

Instrument building practicalities, the only book of its kind:

• Building Scientific Apparatus. A Practial Guide to Design and Construction, Second edition, John H. Moore et al. (Addison-Wesley: 1989).

Electronics, the Bible:

• The Art of Electronics, second edition, P. Horowitz and W. Hill, (Cambridge University Press: 1989). Note: rumor has it a third edition is in the works ... might want to wait before purchasing!

Visibility estimation and SNR issues:

• Chapters 4 and 7 of Principles of Long Baseline Stellar Interferometry, Peter R. Lawson (Ed), Course Notes from the 1999 Michelson Summer School