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Image-Guided Surgery

Virtual Fear

Bypass Genes

Cyber Surgery

Nerves of Steel

Viewer Challenge
in the classroom


Imagine if a surgeon could be transported in cyberspace to the battlefield or an accident site. This scenario is becoming a reality, thanks to telepresence surgery. In this system, precision robotic arms are suspended over the area where a patient undergoes surgery. The arms are linked to a remote doctor site, where the surgeon manipulates surgical instruments electronically connected to the robot control mechanism. Join Frontiers on this fascinating journey to the operating room of the future.

Curriculum Links
Background Information: Remote-Controlled Surgery
Activity 1: Seeing in 3D
Activity 2: Capture Your Own Three Dimensions!
Find Out More





motor skills


polarized filters


sensor devices


As you see on Frontiers, telepresence surgery is truly remarkable. Two precision robot arms equipped with surgical tools are suspended over the area where a patient undergoes surgery. Electronic links connect the technology to a remote doctor site, which can be anywhere from several yards to several hundred miles away.

At the remote site, the surgeon puts on polarized glasses and peers into a video monitor - experiencing a totally realistic view of the surgical field. To move the robot arm, the surgeon manipulates real surgical tools attached to the robot control mechanism. As the surgeon probes, cuts and sutures in thin air, it feels as if he or she were actually performing surgery. And in the case of microsurgery, the surgeon's motions can be scaled down, so that all movements are reduced by a factor of ten - minimizing the effects of shaking.


In telepresence surgery, surgeons do not watch the patient directly during surgery, but rely on technology to send them visual images as they perform the operation.

Two cameras focus on the subject and send their images to a controller that interweaves the frames: right, left, right and so on. This combined signal is then sent to a regular monitor. A television monitor is flat and does not have depth, but with a few technical tricks, an image can be produced that appears in 3D.

While watching the monitor, surgeons wear polarized glasses that allow each eye to receive a slightly different image, producing a three-dimensional effect. (Surgeons in the brain tumor story, also in this episode, wear another kind of polarized glasses, but with shutter-like lenses connected to the TV.) The brain takes the images from two different fields and creates depth.

Similarly, our brains use cues to construct a 3D image of what we see. Humans and other higher primates have what is called stereoscopic vision. The eyes face forward and are set apart, so each eye perceives a slightly different view. The brain processes the visual information and reconstructs it to provide a 3D perspective.

In this activity, you'll construct a viewer that will produce a three-dimensional effect.


  • foam core or poster board
  • modeling knife, scissors
  • hot glue and glue gun
  • 2 identical magnifying lenses (inexpensive plastic ones work great)
  • tape
  • image pairs*
  • camera (ACTIVITY 2)

    * You can make your own image pairs (stereophotos) in ACTIVITY 2. Stereophotos are available over the Internet, as well. Or, look in antique stores for old stereoscope cards with two images on them.

These activities demonstrate the phenomenon of generating three-dimensionality using left and right eye images. You will be making a simple version of a stereoscope.


  1. Photocopy the viewer templates and enlarge/reduce the pattern until it is the right fit for your eyes. Then copy the templates onto form core or poster board. Cut out the sections with scissors or a modeling knife.

  2. Assemble the sections; secure with glue or tape.

  3. Tape a magnifying lens over each of the eye holes. (Attach the tape only to the handles of the lenses.)

  4. Hold the image pair directly in front of the viewer. Look at the image pairs. After a few seconds, your eyes will adjust and a 3D image should appear.

  5. If the viewer does not give you a 3D view, you may need to adjust the front end of the viewer so that it is closer to the image. Depending on the size and strength of the magnifying lenses, and the quality and size of the stereophotos, you will need to make adjustments to the viewer.


All you need is a camera to make your own 3D images. If you have a Polaroid camera, you can develop your image pairs right away.


  • Identify a subject. The visual elements of the scene should be still and have depth to their appearance.

  • Set up your camera on a fixed and stable support (tripods work best). Take a picture!

  • Approximate the distance between your two pupils (about 4 cm).

  • Carefully, move your camera to the left by the distance identified in step 3. This is the only move you should make; the camera's height, tilt, angle, subject, etc., MUST remain the same. Take a second picture.

  • Place the developed photos side by side. Use your 3D viewer to observe the depth embedded in these images.


  1. How do you think an image pair would look if you exchanged the right and left eye views?

  2. What type of camera system might capture stereo images of a moving subject?

  3. Why do you need stereoscopic vision to see "Magic Eye" pictures (stereograms)? To see 3D pictures printed in red and blue?

  4. What might be some evolutionary advantages of stereoscopic vision?


  1. The depth would be reversed.

  2. Side-by-side cameras that snapped their photos at the same time.

  3. The brain uses stereoscopic vision to decode the right- and left-eye views placed in a pattern of repetitive side-by-side strips. 3D pictures (stereoprints) are composed of a right-eye and a left-eye view imposed on top of each other; red-and-blue glasses are needed to enable the eyes to send two slightly different images to the brain, which synthesizes the visual information.

  4. Better ability to use tools, find prey, assess surroundings using sense of sight.


  • Stereograms have now become wildly popular, thanks to computer software that can be used to create them. Look for Stereogram and Super Stereogram (Cadence Books, 1994), two books that explain the phenomenon and include dozens of colorful and fun examples.

  • You'll find dozens of sites on the World Wide Web. Try searching for "stereogram" or "stereoscope."


Scientific American Frontiers
Fall 1990 to Spring 2000
Sponsored by GTE Corporation,
now a part of Verizon Communications Inc.