Holography uses the wave behavior of light to record and recreate three-dimensional images. Unlike an ordinary photograph, a hologram stores an interference pattern that preserves information about the light scattered from an object. This lesson explains how holograms are recorded, how they produce images, and why lasers and holography are useful.
The word hologram means “entire picture.” A hologram can present a three-dimensional image whose appearance changes with the viewing angle: different parts of the object shift in relative position as the viewer moves, much as they would when looking directly at the object.
All flashcards
What is holography?
Holography is the recording and reconstruction of images using light-wave interference. It can reproduce three-dimensional perspectives rather than only a conventional flat image.
What are the object beam and reference beam?
The object beam illuminates the object, and scattered light from the object reaches the film. The reference beam travels directly to the film, where it interferes with the scattered light.
How does a hologram recreate an image?
When illuminated, its recorded pattern diffracts light in directions that recreate wave patterns similar to those originally scattered from the object. Viewing these waves from different positions reveals different perspectives.
How do transmission and reflection holograms differ?
A transmission hologram is viewed using light passing through it. A reflection hologram is viewed using light reflected from it and is commonly used in white-light security features.
Why did lasers make holography more practical?
Laser light is coherent and nearly single-wavelength, making it possible to record clear, pronounced interference patterns needed for holography.
Quiz questions
What does holography use to record information about an object?Answer: An interference pattern formed where object and reference light waves meet.
What is the role of the reference beam during hologram recording?Answer: It reaches the film directly and interferes with light scattered from the object.
Why is coherent laser light useful for making holograms?Answer: Its stable phase relationship supports a clear, recordable interference pattern.
Why can a holographic image appear to change as a viewer moves?Answer: The recorded pattern sends reconstructed light in different directions, revealing changing perspectives.
A security hologram viewed in white light has rainbow-colored edges. What best explains this appearance?Answer: Different wavelengths diffract at slightly different angles, producing separated colors.
Based on University Physics Volume 3 by Samuel J. Ling, Jeff Sanny, William Moebs (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.