How does a hologram differ from a conventional photograph?
The correct answer and explanation is:
Correct Answer:
A hologram differs from a conventional photograph in that it records and displays three-dimensional (3D) information, while a photograph captures only two-dimensional (2D) images.
Explanation (300 words):
A conventional photograph is a two-dimensional representation of a scene. It captures the intensity of light reflected off objects and forms an image on a flat surface such as photo paper or a digital screen. While it may give the illusion of depth through perspective and shading, it does not actually contain depth information. As a result, when you look at a photograph from different angles, the image does not change — the viewpoint is fixed.
In contrast, a hologram is a physical structure that uses interference patterns of light to store information about the amplitude and phase of light waves reflected from an object. This allows it to reconstruct a full three-dimensional image of the object. When illuminated with a suitable light source (usually a laser), the hologram diffracts the light in such a way that the viewer perceives a 3D image that can change as they move around it — just like seeing a real object from different angles.
To create a hologram, laser light is typically split into two beams: a reference beam and an object beam. The object beam illuminates the subject, and the light reflected from the subject meets the reference beam on a recording medium (like holographic film), forming an interference pattern. This pattern encodes the 3D information.
Holography has many applications, including security (on credit cards and currency), data storage, art, and scientific visualization. Its ability to present depth and parallax makes it vastly different from traditional photography, which cannot replicate the full spatial experience of a three-dimensional object.
In summary, while a photograph captures a flat image of a scene, a hologram records and displays depth and perspective, giving the illusion of viewing a real object in 3D space.