How Do Holographic Projectors Work?

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Before we jump into the topic of “Holographic Projectors,” let us first understand what a “Hologram” is. In contrast to the traditional two-dimensional photographs, a hologram is a three-dimensional image whose impression is created by recording interference patterns of a coherent light source (Light waves with the same frequency and phase characteristics). In this case, the light source is a laser.

A hologram is created by splitting a laser beam into two parts. The first part (the object beam) is directed at the object, and from the object, it gets scattered to the target photographic plate. The second part (the reference beam) is directed to a photographic plate capturing the object’s reflection. When both these beams strike the target plate, a hologram is created.

For more insights on hologram creation, please watch this video.

Holographic Projectors 

We all have seen the traditional projects back in school. Here the light source is passed through an image that partially blocks some light and creates shading and a projected picture. But the holographic projectors generate an impression of a three-dimensional image on a flat 2D surface using the principle of refraction of light. The light source is made to pass through an interference pattern recorded on a holographic plate and creates the observer’s 3D experience. 

There is no loss of light in this case and maximum efficiency. Another advantage is the smaller size and lesser heat generated in comparison to its traditional counterpart. 

Working Principle

Some of the most commonly used holographic projectors and their working principles are described below.

1. Spinning Mirror Projector

The core component for producing 3D holographic images is a spinning mirror. A high-velocity video projector directs the images towards a spinning platform on which a mirror is attached. As the mirror rotates at high velocity, the reflection happens in every direction. The viewer can view the image from different perspectives from various angles of observation. The final impression being a 3D image floating in the air. 

A single-colored image is formed for a light source of single light-frequency. If required, colored holographic images can be created using lights of varying frequencies. The final image is projected to a glass or synthetic screen. 

2. Holographic Nets

This technique requires a transparent LED surface capable of emitting multiple colors. The LEDs are pre-programmed using electronic processors to create 3D images that can give the impression of moving and rotating in thin air. LEDs blink so fast that they can not be detected using the human eye.

Advertising companies widely use this technique to create colorful 3D images/videos on large walls to attract viewers. The display can be either flat or curved, providing a visually immersive experience. The video below gives a beautiful demonstration of holographic nets.

3. Holographic Pyramids

The core component in this variant is the glass pyramid. The reflection of light at 45-degree angles from the pyramid’s various sides gives the impression of a 3D hologram within the pyramid. 

The viewers can observe different image perspectives when viewed from different angles, making it a truly immersive experience. If your smartphone supports holographic imaging, the same effect can be observed by placing a glass pyramid over the smartphone display.

4.  Holographic Smokescreen

Instead of the conventional projector screen, this technique uses artificially generated smoke to project the holographic image. The projection comes from behind the smoke and creates a spectral impression or rather a “Ghost-like image.” 

The final projection looks translucent, and the image is not as clear as in the case of a spinning mirror or holographic net technique. This category is often used in theatres for horror entertainment.

5. Interactive Holographic Projectors

Using the help of computer processing, you can make the holographic experience interactive. In this technique, the computer provides the images to the projector. When a viewer touches the screen, a tactile membrane attached to the screen sends back the computer’s electrical impulses instantaneously. The computer then generates the response signal to the projector. As a consequence, the holographic image gets modified according to the response.

The tactile membrane is the critical component that enables interactivity. It is based on capacitive technology to capture user-touch and generate apt response signals back to the master computer. The video below gives a sample demonstration for Interactive Holography.

Future of Holographic Projection

Professionals across industries are very excited about the potential of holograms and holographic projections. Its applicability ranges from education, research, life sciences, gaming and entertainment, robotics, manufacturing, and the list keeps growing. 

This science branch has grown leaps and bounds in achieving complete parallax (horizontal and vertical) and depth variance. These features allow multiple viewers to view the same holographic projections with a unique perspective at different observation points. 

We hope you found the different working principles of holographic projections exciting and fun. Please share your valuable thoughts and information on holographic technology by commenting below.