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How to Make Reflecting Telescopes for Physics

It is not that difficult to make your own telescope for a physics project. A reflecting telescope is also called a Newtonian telescope because Isaac Newton first constructed one in 1668. Two mirrors are used to capture and reflect the image, which is then viewed through an adjustable eyepiece with a magnifying glass.

The benefits of a reflecting telescope are mirrors that are more economical than lenses for the same power of magnification. A problem with this kind of telescope is its size because it can be bulky to transport. Its size is also a benefit though, because the large opening contributes to a quality image.

Things You'll Need

6-inch concave mirror with known focal length
Yardstick or measuring tape
6-inch diameter cardboard tube, about 50 inches long
Glue
1-inch square regular mirror
2 smaller cardboard tubes, one that fits inside the other
Sharp craft knife
Magnifying glass without a handle
Double sided tape
Flat narrow wood piece, about 1 inch x 8 inches

Instructions

- 1
  Fit the concave mirror, facing inward, into the very end of the 6-inch tube and secure with glue and let dry. This mirror will close one end of the tube.
  
  Measure from the other end of the tube to the focal length of the concave mirror, and subtract 4 inches. Mark this location on the tube.
- 2
  Measure the diameter of the larger of the pair of small cardboard tubes. Cut this size circle at the mark on the 6-inch wide tube.
  
  Glue the magnifying lens into the very end of the smallest tube so that the end is closed off by it.
- 3
  Imagine the hole you cut in the large tube is at 12 o'clock, and cut 2 slits in the tube where 3 and 9 o'clock would be, to fit the wooden piece. Make the slits at a 45 degree angle from the concave mirror at the other end of the tube, and the hole you just cut.
  
  Fit the wooden piece across the tube and stick the small flat mirror to it with the double stick tape to secure it. The mirror needs to be centered on the wooden piece across its back.
- 4
  Fit the small cardboard tube with the magnifying glass inside the larger of the pair and put into the cut hole. This is the ocular piece. You should be able to slide the inside tube to focus the image collected by the mirrors. Secure the outside tube to the large tube with glue.

Astronomy