Preface of English edition
Progress in
astronomy has been fueled by the construction of many modern astronomical telescopes.
Today, astronomical telescopes image cosmic sources not only across the entire
electromagnetic spectrum from 10-meter radio waves to 100 zeptometer (
) gamma rays, but
also through cosmic ray, dark matter, and gravitational waves. Electromagnetic
waves cover a wide range of energy density. However, the non-electromagnetic
waves or particles have an even more extreme range of energies. Some of these
particles have macroscopic energies almost a billion times those accelerated at
Fermilab and some of these have energies so tiny that they are almost beyond the detection limit.
In fact, real searches are still underway for dark matter particles and weak gravitational
radiation.
Over the last 400
years, the size, the wave or particle types, and the spectrum coverage of
telescopes have also increased substantially. Only in the past 15 years, the
total collecting area of optical telescopes around the world, with apertures as
large as 10 meters, has more than tripled. At radio wavelengths, collecting
area for a single telescopes is still dominated by the 300
Arecibo one
(roughly 70,000
) although a 500 one is under
construction in China and, for interferometers, by the VLA (roughly 
). ALMA, presently being constructed, will have
a collecting area of roughly 6000. In gravitational wave detection, LIGO has its
two very long laser interferometer arms, each 4
long. The
sensitivity reached by this instrument is as low as 
. For cosmic ray
detection, Pierre Auger Observatory has 30 fluorescence detectors, 1600 water
Cherenkov detector stations, and covers 6000
of earth surface. In
the search for dark matter, detectors are located 1400 underground and
under deep sea. Some of the detectors are working at an extremely low
temperature of 20-40 millikelvins. At the same time, plans are underway to
construct optical telescopes with diameters of 30 or even larger,
radio telescope arrays with a square kilometer aperture area, space telescopes
and interferometers with diameters up to 6.5, and extremely
sensitive gravitational wave and dark matter telescopes. Larger apertures and
greatly improved sensitivity mean more detecting power for fainter objects and even
increasing clarity of images. However, it is not just the size and accuracy of
a telescope that matters; the gain in efficiency that results from performing
many functions simultaneously and the ability to measure spectra and monitor
rapid variation are also important figures of merit.
Adaptive optics was pioneered by radio interferometers. A resolution of 50 milliarcseconds was routinely obtained by the VLA array. Long baseline interferometry at millimeter wavelengths, using the VLBA, can achieve a thousand times better angular resolution. In optical field, advances in adaptive optics (AO), such as those being made by the Gemini or Keck telescopes, hold promise to transform the next generation of large aperture, ground-based, optical telescopes by correcting for the time dependent distortion caused by the Earth’s atmosphere. These techniques achieve impressive angular resolution, routinely better than those achieved by the Hubble Space Telescope. In addition, advances in spectroscopic methods and instrumentation have increased the scientific reach of today’s telescopes immensely by improving spectral precision, efficiency, and multiplexing capability. In non-electromagnetic wave detections, extremely low temperature, vibration isolation, adaptive compensation of interference, and SQUID quantum detectors are widely used for improving the sensitivity and accuracy. All these are pushing the technologies to their limiting boundaries.
To write a book on these exciting achievements and techniques is a challenge for anyone. The author’s intention is to introduce the basic principles and techniques applied to all these astronomical telescopes, especially those relevant new technologies, in a step-by-step manner. The readers can immediately get into these exciting fields. These relevant technologies include active and adaptive optics, artificial guide star, speckle, Michelson, Fizeau, intensity, and amplitude interferometer, aperture synthesis, holographic surface measurement, infrared signal modulation, optical truss, broadband planar antenna, stealth design, laser interferometer, Cherenkov fluorescence detector, wide field of view retro-reflector, wide field of view telescope, x-ray imaging, and many more. The theories behind these technologies involve many advanced physics fields. Therefore, they are presented in a manner tempered by practical applications, sometimes at the sacrifice of rigor. Telescope components are discussed in relevant chapters. However, these design principles may be used to telescopes in other wavelengths or in wave-particle formats. The early version of this book was started as lecture notes for postgraduate students in 1986 in Nanjing, China. The notes had a wide circulation and in 2003, a Chinese edition of this book was published. The Chinese version was welcomed by the astronomical community, especially postgraduate students, engineers, and astronomers who are interested in the different types of telescopes and instruments in China. Translation of this book from Chinese to English has taken more than four years of hard work. The book is intended to target postgraduate students, engineers, and scientists in astronomy, optics, particle physics, instruments, and other related fields. During the preparation of this book, many experts and friends provided great help both in contents and in language. Without this help, the book translation project would not have succeeded.
The author
Dec 2008
Preface of Chinese edition
This monograph provides a systematic discussion of principles and design of various astronomical telescopes. Astronomical telescopes, which serve as the most important tools in exploration of the universe, are complex systems. The development of astronomical telescopes reflect the highest design achievements of their times. Reflecting upon the application and influence of modern technical achievement, this book introduces all relevant new technology as various astronomical telescopes are discussed. These techniques include not only those which are specialized for astronomy, telecommunication, aerospace, remote sensing, military, high energy physics, and atmospheric sciences, but also those which are widely used in industry and other fields. Specialized techniques within these include active and adaptive optics, artificial guide star, speckle and amplitude interferometer, holographic surface measurement, infrared signal modulation, optical truss, broadband planar antenna, stealth design and more. Widely used techniques include optical mirror manufacture, mirror supporting, air and hydraulic bearings, Stewart platform, encoder, system simulation, vibration control, homologous design, laser ranger, laser lateral positioning, wide field retro-reflector, carbon fiber reinforced composite, tilt meter, accelerometer, precision surface manufacture, x-ray imaging, lightning protection, three dimensional measurement, etc. This book discusses the effect of wind, temperature, and earthquake on telescope performances. Last, but perhaps not least, the foundation requirements and design for telescopes are also covered.
The writing of this book took 16 years. The author tested multiple versions of the book to explore the best way to explain complicated electromagnetic wave theory. The first draft of the book was used as a lecture notes for postgraduate students in astronomical instruments field. The notes expand as new information was gained through telescope design and research practice. The book includes all the author’s experience and knowledge. This book can be used not only by scientists, engineers, students of astronomy, communications, aerospace,