The Ten Minute Stereoscope

The Ten Minute Stereoscope Thomas G. Ferguson Using a ruler, fold up and crease all three dotted lines. Decorate the unprinted side of the stereoscope body with crayons, markers, paint, or stickers.

I. INTRODUCTION Viewing stereo images can be fun for all ages. However, these three-dimensional images can not be viewed like conventional images, and require a special viewer called a stereoscope. The following instructions detail how to make your own; for just a few dollars. You will need the following parts and tools. Most of these items may be found around the house. Parts • One flat plastic Fresnel magnifying lens. This is the critical part of our stereoscope, and is available in most pharmacies or department stores; in the eye-care isle. The lens specified in these instructions may be found at any local CVS pharmacy for around three dollars.1 If you can not find the one listed, you may substitute it with a similar Fresnel lens.2 • •

Fig. 1. Print this design on a piece of heavy card stock. Make sure the “Scale to paper size” setting is unchecked.

III. PREPARING THE LENS Place the lens with the rough side of the lens facing down on top of the template on page 4. Use a Sharpie, or marker, trace all three red lines.

One piece of 8 1/2 x 11 inch card stock. Scotch or Masking tape

Tools • Computer with printer • Ruler • Scissors • Sharpie or marker Optional • Crayons • Glue • Markers • Paint • Stickers

Fig. 2. Use the template on page 4 to cut the Fresnel lens to size.

Carefully cut along each of these lines. The plastic lens should cut easily with a sharp pair of scissors. Discard the end pieces, and save the two middle pieces for the next step.

II. THE STEREOSCOPE BODY Using a piece of card stock, print page 3; ensuring that the “Scale to paper size” setting is unchecked.3 The design, shown in figure 1, should measure exactly 10 inches wide by 7 ¾ inches high.

IV. FINAL ASSEMBLY With the rough side facing up, tape each half of the lens in place on the printed side of the stereoscope body. The center "bull's eye" of each half of the lens should be placed directly over a black “X.”

Carefully cut out the two red holes for the eyes, and one for the nose. Finally, cut out the red perimeter of the stereoscope body.

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Fold on the dotted lines, so the arrows A and B point toward each other, and form a box. Secure the stereoscope body with tape or glue.

You can find several stereo image galleries online, and even create your own.5 When printing stereo images, make sure the width of the image to set to 5 inches. If the image is larger, or smaller, it will not be possible to align both eyes properly on the image and perceive depth. VI. CONCLUSION This stereoscope can be a fun and cheap activity to introduce others to stereoscopy and optics. These instructions are meant to be just a starting point, and you should feel free to experiment with various arrangements of lenses, mirrors, and prisms. If you would like to learn more about the science and history behind stereoscopy, there are several resources located on the Internet.6

Img. 1. An assembled stereoscope. Notice how the arrows are pointed towards each other; to indicate when all sides are square

V. TESTING Print the sample image on page 5 to test your new stereoscope. Place the stereoscope on top of the image, and look through the holes. When viewed through the stereoscope, you should notice that parts of the image appear to jump out of the page.

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CVS SKU: 689163, UPC: 0 50428 14619 4, URL: http://www.cvs.com/CVSApp/catalog/shop_product_de tail.jsp?filterBy=&skuId=689163&productId=689163

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If you are using a lens from another source, you may need to experiment with lens placement, and distance from the image. Use these instructions as a guide for cutting the lens to size, and installing it in the stereoscope body. I measured the focal length of the Fresnel lens from CVS to be approximately TBD mm.

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For a professional look, you can print a design on one side of the card stock, and then proceed with printing page 3.

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Unfortunately, some people suffer from stereoblindness, and are unable to perceive depth by combining and comparing images from both eyes.

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If you would like to create your own stereo images, go to http://stereo.jpn.org/eng/stphmkr/index.html for more information and free software.

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To learn more about stereoscopy, please go to http://en.wikipedia.org/wiki/Stereoscopy.

Copyright 2009, Thomas G. Ferguson. Please send all suggestions and revisions to [email protected].

Img. 2. When using the stereoscope, you may need to move closer to, or farther away from, it in order to focus on the picture.

You may need to move closer to, or farther away from, the stereoscope in order to focus on the picture and perceive depth. If you have difficulty focusing on an image, you can make the stereoscope shorter by cutting away, or taller by adding to, the base.4

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