• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
  1. 1
  2. 2
  3. 3
  4. 4
  5. 5
  6. 6
  7. 7
  8. 8
  9. 9
  10. 10
  11. 11

Telescopes - research into types and properties of telescopes

Extracts from this document...


Telescopes are instruments that magnify distant objects. Astronomers use telescopes to study the planets, stars, and other floating bodies. In most telescopes a lens or mirror is used to form an image of an object. The image may be viewed through an eyepiece or recorded on photographic film or by electronic devices. Telescopes produce images of objects too far away to be seen by the unaided human eye. The Dutch optician Hans Lippershey designed the first telescope in 1608, when he mounted two glass lenses in a narrow tube. Within a year the Italian astronomer Galileo built a similar device and became the first person to use a telescope to study the sky.

Optical Telescopes

Optical Telescopes use a lens or mirror to collect and focus light waves. There are three main types of optical telescopes.

Refracting telescope

Refracting telescopes also known as refractors have a large lens called an objective lens at one end of a long, narrow tube. The lens is convex on both sides so that the middle of the lens is thicker than the edges. The glass slows the light rays as they pass through the lens.

...read more.


Astronomers generally prefer reflecting telescopes to refracting telescopes. The weight of a large lens can cause it to bend and become distorted. But a large heavy mirror can be supported from behind. As a result mirrors can be made much larger than lenses, and therefore can gather more light. In addition, parabolic mirrors are useful because they can collect infra red and some ultra-violet rays’ as well as visible light. Reflector telescopes also do not suffer from chromatic aberration, as all the wavelengths will reflect off the mirror in the same way. Also only one side of the reflector telescope needs to be made perfect as the light is reflecting off the objective.

However it is easy to get the optics out of alignment. Often a secondary mirror is used to redirect the light into an eyepiece. This secondary mirror produces diffraction effects, making bright objects appear to have spikes.

Isaac Newton designed one of the first reflectors in 1668 to avoid chromatic aberration caused by lenses. In his design, Newton used a small, flat mirror to reflect light from the primary mirror to an eyepiece at the side of the telescope tube.

...read more.


Modern Developments in Telescopes

Several Breakthroughs in mirror designs have enabled astronomers to make large mirrors that do not bend or become distorted under their own weight.

One new design is the segmented mirror, used in the Keck telescope (completed in 1992) on the island of Hawaii. The Kecks light-gathering mirror consists of 36 hexagonal mirrors mounted close together. The mirrors form a reflecting surface 10 metres in diameter.  

In conclusion I personally believe that reflecting telescopes would be the best option to invest in. As refracting telescopes suffer from Chromatic aberration, and Catadioptric telescopes due to their more complex design cost a fair deal more then reflecting telescopes.  Catadioptiric telescopes also lose some light due to the secondary mirror obstruction. Which intern can result in a less visible image.

...read more.

This student written piece of work is one of many that can be found in our AS and A Level Microscopes & Lenses section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Microscopes & Lenses essays

  1. My experiments focus is to obtain an accurate measurement for a specific lenss power.

    This is because they feature maximum, mean, and minimum lines which produce a more accurate result. To calculate the final value I added the four lens powers up and divided by 4. To work out the uncertainty I worked out the percentage uncertainties for each experiment result, found the average

  2. In this experiment I will be investigating the efficiency of a motor. I hope ...

    With a ruler I might decide to place, it directly parallel to the end of the bench, and blue - tack it firmly down. I could also use the setsquare to measure the middle of the lens so it is clear to see where I am measuring from.

  1. Refracting telescope.

    Suppose a ray of light is incident upon medium 2 from medium 1 at angle relative to the normal to the interface between the media. Then the angle that the transmitted ray makes to the normal is given by the following equation: This is Snell's law.

  2. Investigating the Positioning of Real Images formed by a Convex Lens.

    The independent variables I shall vary As v is the dependant variable, the independent variables I will have are, u and f. I would like to investigate how v depends on u and f, and I will several convex lenses of different of different focal lengths.

  1. Use of the material Zerodur in the KECK observatory telescope. The very low CTE ...

    The mirrors are moved by a complicated system of sensors that position the mirrors within 4nm (4 billionths of a metre) of each of the neighbouring segments2. Because such precision is required in order for the mirror to function at maximum capability, the materials that the primary mirror is made

  2. Proving the lens formula.

    and with the lens; I placed it in front of a window, and focussed the image on the paper. I then had a measurement of approximately 15 cm. This would help me greatly in my experiment, as it would indicate immediately any results way off the mark, considering the variables and errors.

  1. Relationship Between U and V For a Convex Lens

    Which would mean it would enable us to get a wider and clearer range of results. 'RED LENS CHOOSEN' ANALYSIS The fat lenses instantly weren't chosen because they produced images that were to small to measure, and could only be measured at large distances for v.

  2. Given a Tube Containing a Lens, Calculate The Focal Length of The Lens and ...

    -Find the minimum and maximum values for 'b' -Choose appropriate measurements for 'b' (i.e. divide gap by 6 to gain 7 distances) From this, I chose to use measurements of b from 0.01 to 0.07 enabling 7 values to be obtained -Move object to 1st value of 'b' -Focus image on screen and measure values of 'c' and magnification.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work