How to create a "Pepper's ghost" optical illusion | Hey Ray

Since we are in spooky season, let's use some old-fashioned science to create a ghostly effect.

The effect is called "Pepper's ghost," named after the man who popularized it, John Pepper. The Corning Museum of Glass says the effect first appeared on stage in 1862, and it is still used today by amusement parks, scare houses and even other industries.

So, what is a Pepper's ghost?

Simply, it is an optical illusion. The University of Arizona Wyant College of Optical Sciences says when light from a bright object reaches a strategically angled, transparent material, a portion of the light will reflect, causing an observer looking at the side of that angled material to see a virtual image, an object that appears to float.  

This illusion is old, but still effective, and it is pretty simple to make.

In a theatrical setting, you get a large pane of glass or plastic that is tilted at a 45-degree angle and situated between the audience and the stage. A secret area or room is just out of view of the audience. In that area, a brightly lit object or actor is reflected by the glass, making it look like a ghost to the audience.

Since most of us don't have stages and secret rooms, we will create this with a cell phone or tablet.

Now, this will be a much smaller-sized ghost, but you can scale this up if you want. For this, we will use a jar or glass, a small piece of thin plastic, and a phone or tablet. Cut the plastic so that you can situate it in the jar or glass at a 45-degree angle. It is easiest to figure out the cuts with a piece of paper as a template, then use that to cut the plastic. Now your jar is set. 

Now, you need a video or image to project. Here is a YouTube Playlist with videos you can use. If you prefer, you can also make your own image or video. Just make sure your actor or model is brightly lit with a black or very dark background.   

Set your glass or jar on the phone or tablet, and now you have a ghostly effect.   

There are professional applications for a Pepper's Ghost. The effect is how teleprompters work, which is quite cool to see, even though meteorologists don't use teleprompters.