Astronomical Telescopes
Astronomical telescopes are instruments used to observe celestial objects such as stars, planets, and galaxies. They gather and focus light, allowing astronomers to study distant objects and phenomena. There are different types of telescopes, including refracting telescopes that use lenses and reflecting telescopes that use mirrors, each with its own advantages and limitations.
4 Key excerpts on "Astronomical Telescopes"
eBook - ePub- Galen C. Duree(Author)
- 2011(Publication Date)
- For Dummies(Publisher)
...Telescopes come in two basic types: refracting (using lenses) and reflecting (using mirrors). I talk more about telescopes in Chapter 19. In this section, I examine the simple refracting telescope. In a refracting telescope, two lenses are placed such that their separation is slightly larger than the sum of their focal lengths. Check out the simple refracting telescope in Figure 13-5. Figure 13-5: A schematic of a refracting telescope. Like the compound microscope (see the preceding section), the refracting telescope has an objective and an eyepiece. Unlike the microscope setup, however, the telescope’s objective is typically a long-length focal positive lens. Because the objects are far away, the light rays coming from the object into the telescope are basically parallel. The objective focuses these rays at its focal point, which is just within the focal point of the eyepiece. The image formed by the objective is real, reduced, and inverted. Because the image falls within the eyepiece’s focal length, the eyepiece forms a virtual image that is enlarged and remains inverted relative to the original object. The magnification of a telescope is given by In this equation, MP is the magnification power of the telescope (the negative sign means that the image is inverted). D e is the dioptric power of the eyepiece. D o is the dioptric power of the objective. In some applications, such as using a telescope to look at animals walking on a distant hillside, the magnification power of the telescope is important. In other applications, however, it doesn’t make any difference. Stellar astronomy looks at distant objects, such as stars, that are so far away that reaching the level of magnification required to make their images look like anything other than dots is impossible...
eBook - ePub- Vadim Backman, Adam Wax, Hao F. Zhang(Authors)
- 2018(Publication Date)
- CRC Press(Publisher)
...2 Optics Components and Electronic Equipment The role optical instruments have played in the advent of the contemporary age is frequently underemphasized. While other modern marvels have taken the spotlight in recent years, the history of optics stakes a strong claim in the formation of the world we know. The telescope has been decisive in resolving the clash between geocentric and heliocentric conceptions, affirming the Copernican universe during Galileo’s time. The microscope broadened the horizons for biology and medicine, opening windows on an entire new world that was previously unobservable. The camera ushered forth a perspective on the world more vivid and more real than any painter’s brush could portray. Day to day, we find ourselves in continuous contact with optical instruments and their products. These optical instruments, along with their modern electronics, are the cornerstones to shape and observe the world we live in. To fathom the world of optics is to understand the fundamentals behind their operation. To explore the design and function of various sophisticated optical instruments is to comprehend the individual lenses, mirrors, and other optical devices that compose them. This chapter begins with an introduction to various commonplace optical devices at their simplest, namely lenses, mirrors, and objectives. While this section primarily relies on a diagrammatic description to suffice for illustrating fundamental physics concepts, several accompanying photographs of optics equipment are included for reference. In In addition to to manipulating the geometry and spatial organization of light, properties such as polarization and phase are tantamount to intensity and direction when describing optics. Introductions to waveplates and linear polarizers will offer descriptions of how such properties of light are controlled and adjusted. An important concept in optics deals with the transmission and efficient delivery of light...
eBook - ePub- Shen-En Qian(Author)
- 2020(Publication Date)
- CRC Press(Publisher)
...The inverse of this condition is that a design with well-controlled point-imaging but large geometric nonuniformity may have unacceptable spot sizes once the distortion is corrected. Response uniformity must be enforced at the beginning (Mouroulis et al. 2000). It is for this reason that designs with minimum aberrations but uncontrolled uniformity may not be good starting points for a final uniform design. Such may be the case if one starts from a design form for which the distortion is inherently large and difficult to correct. 5.3 Telescope Design An optical telescope focuses and collects light, mainly from the visible to shortwave infrared of the electromagnetic spectrum to create a magnified image for direct viewing or on the silt of a spectrometer to be dispersed spectrally. The capability of a telescope to gather light and show small details is dependent on the diameter (i.e., the aperture) of the telescope's primary mirror that gathers and focuses the light of the objective. The larger the aperture, the greater the ability of the telescope to gather and focus light, and the greater its ability to show small details in the FOV. Based on the method that is used to focus the image into the viewing device, a telescope falls into one of three classes: refracting telescopes, reflecting telescopes, or catadioptric telescopes. 5.3.1 Refracting Telescopes A refracting telescope uses lenses to gather and focus light. The refracting telescope gathers a greater amount of light into the lens than is possible to gather with the naked eye. This presents the observer with a brighter, clearer, and magnified image of the object being observed. This is accomplished by focusing the parallel light onto a focal point while the peripheral light is focused onto a focal plane. The refracting telescope was the first telescope to be invented and used since early 17th century. Hans Lippershey, a Dutch lens maker, invented a telescope and filed a patent in 1608...
eBook - ePubAn Illustrated History of Science
From Agriculture to Artificial Intelligence
- Mary Cruse(Author)
- 2019(Publication Date)
- Arcturus(Publisher)
...Chapter 5 Optics ‘[Optics] is the flower of the whole of philosophy and through it, and not without it, can the other sciences be known.’ – ROGER BACON, MEDIEVAL PHILOSOPHER AND SCIENTIST T he science of optics is concerned with both the behaviour of light and the study of sight. We can understand optics as being broadly divided into two main subdisciplines: physical and geometrical optics. Physical optics is concerned with the nature of light itself as a wave, while geometrical optics considers the behaviour of light as a beam and how that beam can be manipulated using our eyes, lenses or other instruments that affect light. Human beings have always had an important relationship with light. The symbolism of light as a power for good appears in many religious texts; and on a practical level, being able to exploit light has helped humans to become a dominant species. Our understanding of light has increased over the centuries, with scholars all over the world contributing to optical science. These days, optics is at the core of modern science; from the telescopes that we use to explore the universe to the microscopes that help us diagnose disease and develop drugs, an understanding of optics and optical instruments is crucial to scientific progress. There’s still plenty that we don’t understand – some optical phenomena intersect with the field of quantum mechanics – but the knowledge that we’ve built up over the centuries has helped to advance science in myriad ways. This is the story of how we got from the earliest theories of light and optical tools to where we are now, and how we came to understand and control one of the most powerful tools known to humankind. From subatomic particles to stars, optical instruments – such as this scanning tunnelling microscope (STM) – help us to peer deeper into the universe. The Roots of Optics Long before we knew anything about the physical properties of light, human beings were trying to manipulate it...
