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How to Build a Reflective Telescope

The beauty of a reflective telescope is that mirrors are excellent at gathering light and reflecting it without the color distortions found in magnifying telescopes. Building a reflective telescope is a little more complicated than a simple, magnifying telescope that has no mirrors, but is still very easy to do, and is something you and your child could do at home using some very basic materials, most of which you probably already have laying around your house.

Things You'll Need

Large concave mirror
Measuring tape
Large tube
Scissors
Duct tape
Pencil
2 small tubes roughly 10 cm in length and 3 cm in diameter
Thin, flat sided rod
Small, flat mirror roughly 2 by 2 cm
Double sided tape
Small magnifying glass

Instructions

- 1
  Determine focal length of mirror. To do this, you will need to take the mirror outside and find an area where the sun is in front of you and you are facing a wall. Looking at the wall, take the mirror and raise it up until the mirror catches the sun's reflection. You will need to focus the mirror on the wall until the sun is a small dot on the wall. Measure the distance between the mirror and the wall. This is the focal length.
- 2
  Cut the large tube to size and attach a concave mirror to one end of the tube. The large tube should be at least as long as the focal length of the mirror. The tube should be wide enough for the concave mirror to fit. Attach the mirror so that it is facing inwards.
- 3
  Cut the ocular hole. Make a mark on the large tube 10 cm in from the focal length. Next, measure the diameter of the first small tube. Cut out a hole in the large tube that is the same diameter as the one in the first small tube.
- 4
  Insert the rod and add the mirror. To position the rod correctly, draw a line from the top of the hole on the large tube down at a 90-degree angle. Do the same on the other side of the tube. Now make two holes at the end of each line big enough for the rod to fit. Insert the rod through the two holes. To add the mirror, take some double sided tape and stick it to the back of the small mirror. Going through the ocular hole, attach small mirror to the rod so that the mirror forms a 45-degree angle with the diameter of the large tube.
- 5
  Attach magnifying glass to the second small tube. Cut down the entire length of this small tube, and wrap the sides tightly around the magnifying glass so they overlap. Tape the sides together.
- 6
  Insert the second small tube inside the first one. It should fit snugly, but also allow you to push the inner tube in and out of the outer one. This is your ocular piece.
- 7
  Insert the ocular piece into the ocular hole. When you look through the ocular piece, you will see images captured by the concave mirror and reflected by the flat mirror.

Astronomy