Stereoscope

Stereoscope

The stereoscope is an optical gizmo that lets you comfortably cross your eyes slightly and fuse a pair of images into one three-dimensional view (actually, it optically de-converges your eyes for you with a pair of slightly angled lenses). You've probably seen one in the attic of an elderly relative, or in an antique store.

Image copyright by Christopher Fluke.
The Holmes Stereoscope
Image courtesy of Dr Christopher Fluke,
Swinburne University of Technology


The most familiar modern stereoscope is the View-Master, an evolute of the once much more famous Holmes stereoscope your great grandmother (and everyone she knew) had in her drawing room. The latter, interestingly enough, was named after its inventor, Oliver Wendell Holmes, who was a fan of the technology and an early American entrepreneur. Holmes, of course, is best known as the essayist-poet surgeon and Harvard professor who authored Old Ironsides, and other poems, novels, and humor.

The stereoscope is often mistakenly called a stereopticon (which was itself often called a "magic lantern"). The stereopticon was a projector, not a viewer, and did not produce 3-dimensional images.


Holmes card for viewing in a stereoscope. (Public domain)

Holmes stereoscope card
Photo origin unknown.
If you own the copyright, please contact me.

 

The Holmes stereoscope card (above) cannot be viewed by crossing your eyes (the images are in the wrong order, and require the lenses of the stereoscope to be seen by the correct eyes). If you have good convergence control, you may be able to see the 3D by looking "past" the image, allowing your eyes to diverge somewhat (the opposite of "cross-eyed") until you see three images; then allow your attention to settle on the middle one.

However, the following image (below) can be viewed cross-eyed. It takes some practice, but if you gently cross your eyes until you can see three images, and then allow your attention to settle on the middle one, you'll see it in full 3D.


Image copyright 2004 Allen Cobb. All rights reserved. Image copyright 2004 Allen Cobb. All rights reserved.
left image right image

Ringed planet image (above, and high resolution version below) copyright 2005 by Allen Cobb. All rights reserved.

To download a high resolution version of the stereo pair above, please click here and here.