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a recording of a light field

A hologram is a recording of a light field, with a typical light field comprising a pattern of optical fringes generated by two beams of laser light.

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a three dimensional image made of light

A hologram is a three dimensional image made of light.

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a recording of an interference pattern

A hologram is a recording of an interference pattern.

a physical structure that diffracts light into an image

According to the Holocenter, the Center for the Holographic Arts, a hologram is: a physical structure that diffracts light into an image.

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a specially constructed image

A hologram is a specially constructed image which, when illuminated by a laser beam, seems eerily suspended in three-dimensional space.

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a 3-dimensional image created with lasers, which has the quality that even when divided into parts

A hologram is a 3-dimensional image created with lasers, which has the quality that even when divided into parts, the whole is still present.

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an interference pattern produced by a split coherent beam of light

A hologram is an interference pattern produced by a split coherent beam of light.

a 3D image formed from the interference patterns of a coherent light source

According to Merriam-Webster and Oxford English Dictionary, a hologram is a 3D image formed from the interference patterns of a coherent light source.

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created by a photographic projection of a recording of a light field rather than an image formed by some sort of lens

A hologram is an image created by a photographic projection of a recording of a light field rather than an image formed by some sort of lens.

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done photographically

A hologram is a recording of a light field done photographically.

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a three-dimensional (3D)image, which can be seen with a naked eye

A hologram is a three-dimensional (3D)image, which can be seen with a naked eye.

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a photographic recording of a three-dimensional image

A hologram is, in short, a photographic recording of a three-dimensional image.

a truly three-dimensional and free-standing image that does not simulate spatial depth or require a special viewing device

Unlike 3-D or virtual reality on a two-dimensional computer display, a hologram is a truly three-dimensional and free-standing image that does not simulate spatial depth or require a special viewing device.

a 3D image — you can observe from different angles produced when a single laser light is split into two separate beams

A hologram is a 3D image you can observe from different angles—produced when a single laser light is split into two separate beams.