Проверьте, знаете ли Вы следующие слова и словосочетания, необходимые для понимания текста.
a ) Найдите в правой колонке русские эквиваленты:
1. to process 1. увеличение
2. to enhance 2. видеть, рассматривать
3. magnification 3. экран
4. to view 4. обрабатывать
5. screen 5. увеличивать, усиливать
Б) Найдите в правой колонке английские эквиваленты:
1. удлинение, протяжение 1. to relate
2. преобразовывать 2. extension
3. сетчатка (глаза) 3. to intersect
4. быть связанным, относиться 4. to transform
5. перекрывать, пересекаться 5. retina
OPTICAL INSTRUMENTS
An optical instruments either processes light waves to enhance an image for viewing, or analyzes light waves (or photons) to determine one of a number of characteristic properties.
The word optics is very useful in physics which is related to the reflection of light. The instruments which are used in optics are optical instruments. Thus, the optical instruments are the devices which are used in a various purposes like microscope, telescope, lens, magnifying lens, mirror, astronomical telescope, glass etc. All are used in a different manner like a telescope is used for looking small things bigger. The first optical instruments were telescopes used for magnification of distant images, and microscopes used for magnifying very tiny images. These instruments have been greatly improved and extended into other portions of the electromagnetic spectrum.
Similar microscopes are used in biology and medicine. Cameras are used by artists. By this we can guess that how much these instruments are useful. These are the best way to observe reality but how do they work? How do they make a small object bigger? How does a mirror form a clear image? What types of lenses are there?
Two Kinds of Optical Instruments. The optical image-forming instruments can be divided into two groups. The first group (projectors) forms real images of an object which is projected onto a screen or photographic plate. This kind of image can be viewed simultaneously by many observers. A motion picture film is a typical example, since everyone in the cinema can simultaneously take in the real image projected on the screen.
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The second group forms virtual images of an object. As a rule, only one observer can see this kind of image, though in the case of a magnifying glass several people can be looking through it at the same time. The virtual image itself is something nonexistent for it is not the rays but their extensions that intersect, and the latter are purely imaginary.
However, the image becomes a reality as soon as the observer's eye becomes a part of the optical system. The virtual image formed by an instrument is transformed by the eye into the real image projected on the eye's retina. It is no coincidence that optical instruments for a virtual image are sometimes called optical aids. They include magnifying glasses, spectacles, microscopes, and telescopes. Strictly speaking, the observer's eye must always be included in the optical system.
Проверьте, знаете ли Вы следующие слова и словосочетания для понимания текста.
a ) Найдите в правой колонке русские эквиваленты:
1. vision 1. испускать, излучать
2. to exaggerate 2. рассматривать, считать
3. to emit 3. зрение, восприятие
4. to differentiate 4. преувеличивать
5. to regard 5. различать, отличать
б) Найдите в правой колонке английские эквиваленты:
1. воспринимать 1. to assess
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2. оценить 2. to underestimate
3. мнимое изображение 3. to emphasize
4. подчеркивать 4. to perceive
5. недооценивать 5. virtual image
THE EYE
What is the role played by an eye in an optical experiment? Is there a dividing line between the science of vision and the science of light, and what may optics be considered to be after all?
These questions have always been important to scientists. In the early days of optics the role of the eye was definitely exaggerated, and optics was, in fact, a science of vision. It has to remembered that in those days the eye was believed to emit rays, and the expression “light of my eyes” was taken literally Much later people understood that the role of the eye was to receive the light coming from an object, and still later they began to differentiate between the science of vision and optics which was then regarded as the science of light. Today we are in a position to assess the role of the observer's eye in experimental physics. It is curious, however, that while once the role of the eye used to be exaggerated, we now tend to underestimate it. In any case, a few modern textbooks and teaching aids on physics emphasize the role of the observer's eye in perceiving virtual images. A brief account of how our ideas about the mechanism of vision and the role of the eye have changed with the time will be quite useful. Naturally, they developed as we acquired more knowledge of the structure of the eye. We should therefore get to know what modern ideas are about the anatomy of the human eye.
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