Where can I get lens to build stereoscope?

Hi, I am trying to make an art installation involving
6x6 cm stereographic transparencies. I am making my own stereo-viewers for this.
Does anyone know what type of lenses I need and where I could order them online? I need to get 10 pairs so the cheaper the better, but I dont know anything about the characteristics of the lenses i need, what they are called etc etc.
Any pointers would be really appreciated thanks
ross

 

What you need is a prism to do either cross eye or parallel viewing. The pictures show a cross eye viewer as the prisms bend the sight lines in. A parallel viewer would have the wide ends of the prisms on the outside.

The viewer uses two microscope slides that are cut in half with a glass cutter. This is the two sides of the prism. The other parts a just some plastic I had. Everything is glued together with rubber cement and is water proof. As shown the viewer does nothing but when filled with water it becomes two prisms.

You are using 6 cm slides so they are pretty small and if they are about 2.2 inches apart they need a different viewer. A one diopter lens has a focal length of one meter. A two diopter lens is ½ meter and so on. Just get the correct focal length for your viewing distance. You can get reading glasses at most any drug store and many other stores. Probably you should start with a 4 diopter reading glass. You will need to cut the glasses in half so the width can be adjusted. Each person will use a different width.