Question #108

Dang, it's time once again to try another three images of Otto. You had better tell me if you are getting tired of Otto; I can think of at least a dozen more optical setups, and I am sure that there are even more! If you have not yet done an Otto set, click to go to Question 97, Question 99, Question 102, or Question 105, the previous Otto exercises. Shown in the drawing below is the face of Otto, the object for the optics exercises to follow. By clicking your mouse here you may view or print out the array of possible image faces that Otto might create when he positions himself at the appropriate place relative to the optical component under consideration. Again your job is to determine the characteristics of the image and answer questions about it. You may use any available technique, such as ray tracing, calculation, experience, looking it up in a textbook, or even building your own experiment.

You are to determine the following image characteristics:

• 1. the orientation and the relative size and shape of the image, by selecting from among the 28 examples given in the page linked above.
• 2. the location from where you must look to see the image.

Other details that you might want to ascertain include:

• 1. the location of the image.
• 2. the magnification.
• 3. whether the image is real or virtual.

The three optical elements for this week are:

• 1. A three-mirror corner reflector: Otto will stand at short distance in front of the corner of the three orthogonal mirrors, so that an observer at the corner would see Otto's face as in the photograph above.
• 2. A parabolic concave mirror: Otto will stand at a distance of twice the focal length in front of a spherically symmetric concave mirror, so that an observer at the mirror would see Otto's face as in the photograph above.
• 3. A vertically focusing cylindrical convex lens: Otto will stand at a distance equal to one-half of the focal length from a vertically focusing cylindrical convex lens, oriented like a horizontal log in front of Otto. He again faces the lens so that an observer at the lens would see Otto's face as in the photograph above.

Our answers will include the information above as well as a photograph of the image with the object for comparison.

Click here for Answer #108 after March 18, 2002.

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