Computational Holographic Imaging for 3D Holographic Projection

In this blog,we will see how amazingly we can use the computer hologram images for three dimensional projection.As we have seen in earlier post that the 3D hologram can be seen without using 3D glasses.So,How do they do it?

The concept is actually based on an illusionary technique called Peppers Ghost.John Henry Pepper was the one who attempted to popularize this effect.It was first used in Victorian Theaters  across  London in the 1860s.

In pepper's ghost there are two rooms, one room is visible to the audience which is the "main room  and the other one is hidden called as "blue room".A plate of glass is placed somewhere in the main room at an angle that reflects the view of the blue room towards the audience. Generally this is arranged with the blue room to one side of the stage, and the plate on the stage rotated around its vertical axis at 45 degrees.

This can be used to make objects appear to float in space. Isn't it interesting?

Similarly in  this , we first calculate the   computer-generated hologram (CGH) of the image we want to project. Then Different types of commercial spatial light modulators (SLMs) are used to load the CGH for projecting image. The CGH is calculated from the image using  the angular spectrum method or the Fresnel diffraction . In the Fresnel Diffraction the fast Fourier transform (FFT) is used for fast calculation of large data from the image.

Furthermore Shimobaba also proposed a method called as ARSS-Fresnel diffraction to calculate CGH, It is  nothing but a scaled Fresnel diffraction calculation that calculates diffraction at different sampling rates on a projected image and hologram .This type of CGH  produces  the zoom function of the projected image without using zoom lenses.

Due to this technique, we get a high resolution three dimensional images without the 3D glasses and projector screen being needed.We get the life like images and interactive display.

This is used in live stage shows, Advertising, Gaming, Education ,Training, Medical, Communication,Military and Space Applications.

       

3D Holographic projection is the new wave of technology that will change how we view things in new era.It will have tremendous effect on all fields of life. It has endless applications as far as the human mind can imagine.

Thank You!


-Shreya Uttarwar