A periscope allows you to see something from a corner or a higher-than-normal vantage point. Although modern submarines and other high-tech vehicles often use a more complex system of prisms and lenses, the basic mirror periscope described below is easy to make at home and provides such a sharp image that it has been used on a large scale for military purposes by much of the 20th century.
Method 1 of 2: Making a Cardboard Periscope
Step 1. Find two small mirrors about the same size
You can use any flat mirror with a rectangular, round, or other shaped edge. They don't even have to be the same shape, but they should be small enough to fit in a milk carton.
You can find small mirrors at a craft store or online
Step 2. Cut off the tops of two clean milk cartons
Find two empty milk cartons, each at least a quart in size and wide enough to fit the mirrors. Cut and discard the triangular top of each and wash the interior thoroughly to get rid of odors.
- A long, sturdy cardboard tube may also work.
- You can still use a large, flat sheet of the same material: mark it using a stylus to divide it into four parts, then fold it up to form a box, securing with tape.
Step 3. Tape the two milk cartons together
Use strong tape, such as packing tape, to join the open ends of the milk cartons together to make a long carton. To secure better, try joining the inside of the boxes on one side and then tape all the outside sides together.
You can attach two tubes or two cardboard boxes in the same way to make a longer periscope. However, the larger the periscope, the smaller the image
Step 4. Cut a hole in one side big enough for a mirror
Place one of the mirrors on one of the vertical sides of the milk carton, about 6 mm from the edge. Trace the mirror with a pencil, then cut out the outline to make a hole.
- It may be easier to use a knife to make this cut, but only with adult supervision, as this object is very sharp.
- If you're using a cardboard tube instead of a milk carton, flatten it a little so you can trace the mirror.
Step 5. Insert a mirror facing the hole at a 45° angle
Use masking putty or double-sided tape to attach the contoured mirror to the inside side of the milk carton, in front of the cut hole. Adjust the mirror so that the entire surface can be seen when looking through the hole, but point it down towards the opposite end of the box at a 45° angle.
- To test the angle, measure the distance from the closest corner of the box to the bottom edge of the mirror, where it touches the side of the box. Then measure the distance from the same corner to the opposite end of the mirror, where it touches the top of the box. The two distances will be the same if the mirror is at 45º.
- Don't use glue yet as you may need to make adjustments to the mirror's position.
Step 6. Make a cut at the other end and facing the opposite direction
To find out where to cut, place the box facing you on the short side, with the first hole near the top. Rotate it so that the hole is on the opposite side. The second hole will be made at the bottom of the side that is now facing you. Trace the second mirror and cut as you did before.
Step 7. Insert the second mirror facing the first
Like the first mirror, this one should be visible through the hole and face the other end of the box at a 45º angle. In this position, one mirror will reflect light straight down through the periscope, and the second will reflect it directly through the hole and into your eye. You will see this reflected light as an image of what is in the opposite hole of the periscope.
Step 8. Look through a hole and adjust
Do you see a clear picture when looking through it? If it is blurry or you are only seeing the inside of the periscope, adjust the position of the mirrors. Once both are at 45° angles, you will be able to see through the periscope clearly.
Step 9. Secure the mirrors permanently
If the putty or tape isn't enough to hold them together, use glue. Once they are permanently fixed in position, you can use the periscope to spy on people or see over a crowd.
If the "eye" side of the periscope is getting too much light, making it difficult to see the reflection, glue a piece of black cardboard over the outer edges of the hole
Method 2 of 2: Making a Periscope with PVC Pipes
Step 1. Find one or two pieces of PVC pipe
Try to find something between 30 and 50 cm, but be aware that the longer the pipe, the smaller the image. You can also use two slightly different sized sections to fit one into the other. This will allow you to rotate the top of the periscope while using it to observe everything around you.
You can find PVC pipe at a hardware or home improvement store
Step 2. Add a small elbow to the ends
Place an elbow joint over each end of the pipe to make a periscope shape. Keep the two openings pointing in opposite directions if you want to look around corners or over obstacles.
Step 3. Find two mirrors that fit the pipe
They must be small enough to be inserted at one end. It may be easier to use circular mirrors, which are sold at craft stores or online.
Step 4. Insert a 45° mirror into one end
Use masking putty or strong double-sided tape to secure it to the inside corner of the elbow. Look through that elbow at the mirror you just put up. Adjust the mirror until you can see the base of the barrel at the opposite end, or remove the opposite elbow and adjust until you can see through the barrel.
Step 5. Insert the second mirror at the opposite end
Place it at the same angle so that the light reflected from the first goes through the pipe, hit the second and exits through the other opening.
Step 6. Secure the mirrors in place once the periscope is working
Adjust them until you can see through them clearly. When the image is clear, attach the mirrors more securely using several layers of packing tape or a specialized glue such as PVC adhesive or plastic epoxy.
- The bigger the mirrors, the more you will see.
- Use masking tape to seal the middle.
- You can make little mirrors using an old CD, but put on gloves and safety glasses to protect yourself from splinters and work under adult supervision. Heat the CD first with a blow dryer to make it less fragile, then mark it lightly and repeatedly with a stylus until you cut it into the shape you want.