The book Telescopes; how to make them and use them by Page & Page (1966) provides a scientific discussion on the topic of telescopes in the era of the space exploration and scientific technological progress in the world of the twentieth century. Much of the issues in the book are relevant to my research question, namely: “what are the basic principles for telescope?”
Page & Page (1966) are too famous in the scientific circles of applied physics. Their academic degree and huge interest of making telescopes accessible to general public are proven through a long-term research provided at different universities of the United States. However, their basic place for making researches was at Wesleyan University as Professors of Astronomy and Geology respectively. The book is all about optical telescopes and their characteristics due to the forms and implementation of different lenses and mirrors. It points out the historical as well as scientific approaches toward investigating the structure and use of telescopes. Because Telescopes; how to make them and use them is full of authors’ personal sketches on the main problem, its academic applicability is clearly felt throughout the book.
The book is divided into 12 chapters which are linked sequentially in terms of their subject and related content. However, the most interesting chapter is the 12th responding to the kinds of different telescopes in pictures and in terms of some coverage. My analysis incorporates some features from all these chapters. However, in this paper I will investigate and further analyze Chapter 1: Basic Elements. I look at this chapter, as the introductory word to those who have recently started learning the structure of telescopes. Page & Page (1966, p. 15) admit the following statement: “In order to understand optical telescopes, one must first understand light, and how it is affected by mirrors and lenses – the subject of optics.”
The chapter itself is rather informative and full of different facts scoped out into four sections. These are as follows: 1) What is Light; 2) Notes on Basic Optics; 3) Refractor versus Reflector; 4) Principles of the Cassegrainian. To make it plain, authors use assistance of M. J. Julian and Earle B. Brown in composing these sections appropriately. These technical issues are vital to understand the way the authors explored and identified the main parts and principles in optical telescopes.
The overall discussion starts from the options prescribed to light and its spectral as well as photonic power. Moreover, the discussion and scientific terminology are supported by graphs and schemes on basic notes on optics (simple lenses, position of an observer, image formation by dint of mirrors, refractions, spherical and chromatic aberrations of lenses, off-axis image points) (Page & Page, 1966). This is why preliminary tailored information on optics in its basic definition makes it understandable for everyone who wants to get an idea of telescopes and their mechanisms.
The major focus is, therefore, on the form of lenses (spherical or flat), absence of thickness in simple lenses, reflection and refraction of a bundle of light and how it should be explained (Page & Page, 1966). Hence, the research gives elementary facts and their justifications through full-fledged explanatory data and visual aids as well. Positive and negative lenses are described to provide a reader with clearly-cut information on the optical tricks with light. Moreover, convex and concave mirrors are illuminated in their ability to focus a beam of light for an observer to distinctly see the object through pupils.
Three telescope systems are underlined in the chapter, namely: Newtonian, Gregorian, and Cassegrainian (Page & Page, 1966). This makes the main discussion more applied to the structural part of the issue of telescopic refractions and pivotal principles. The power of optical effects and their implementation within a telescope is considered owing to some laws and principles in Physics. Thereupon, the authors recommend paying attention to the law of refraction (n sin I = n’ sin I’) which maintains “how much the light is bent” (Page & Page, 1966, p. 24). This is one of the most significant and remarkable rules in the optics on the whole.
Page & Page (1966) promote also concise information on off-axis image points pointing out phenomena of distortion and coma and stigmatism. The principal (central) and peripheral rays are illuminated in their theoretical and practical differences. The next sub point of the chapter provides the principal features of a telescopic system. The question is about 10 basic features, namely: “definition; achromatism; magnifying power; light-gathering power; resolving power; size of image; flatness of field; versatility; economy and ease of construction; convenience of handling and upkeep” (Page & Page, 1966, p. 30). The last part is about the Cassegrainian telescopic system. It is chosen to demonstrate its perfection amid the rest two telescopic systems at the moment. All in all, the overall analysis of the chapter can be defined as quite convenient for a first-time reader. Thus, it makes more points for this book to be appreciated among students.
Page, T & Page, LW 1966, Telescopes; how to make them and use them, Macmillan, Portland, OR.
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