What’s Hologram?
The recording of the optical amplitude and optical phase data with the form of interference fringes is called hologram. The technology of making the recorded image (hologram) is called holography. Holography can record and reproduce the three-dimensional spatial data on the two-dimensional plane. This is what we call the ultimate three-dimensional display method. The hologram is applied to the various fields, such as display, measurement and processing with its unique characteristics.
Methods of making and reproducing hologram and its application examples
Method of making hologram
When we simultaneously irradiate object beam and reference beam on the sensitized medium, interference occurs between the two beams. It will form interference fringe on the recording medium which produce hologram.
Hologram consists from very narrow stripes and records enormous three-dimensional data.
We don’t know what is recorded from just observing the hologram itself.
Followings are the examples of reproducing holograms and its applications.
Reproducing hologram and its application example 1 (Holographic display)
We can reproduce the object beam equivalent to the beam at recording by reproducing the recorded hologram using the same reference beam at recording.
Namely we can observe three-dimensional object by observing hologram from the position 1.
What we applied to this method is 3D-display.
Reproducing hologram and its application example 2 (Holography microscope and holographic memory)
The Phase-conjugated light can be occurred at the exactly opposite direction of the object beam at recording when we reproduce the recorded hologram using the same reference beam from the exactly opposite side of its recording direction.
We can retrieve three-dimensional data in parallel by placing sensor at the position 2.
What we applied to this method is holographic memory and holography microscope
Reproducing hologram and its application example 3 (Processing: optical correlator)
The correlation signal of the reference beam can be occurred by reproducing the recorded hologram using the same object beam of its recording.
For example, when it is reproduced by the object beam of the slightly different shape three-dimensional object, the correlation signal of the reference beam will slightly weaken.
When it is reproduced by the object beam of the completely different shapes three-dimensional object, the correlation signal of the reference beam will not occur.
We can obtain the correlation value of three-dimensional object by placing the sensor at the position 3.
What we applied to this method is Optical correlator
Holograpy in the future
As mentioned above, we can record three-dimensional data in parallel and reproduce the data using holography. It is expected that the realization of hologram as the super-high-capacity and the super-fast input and output medium in the future.
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