how to make a projector with a glass cup

 

A projector is a device to project an image onto a surface such as a wall or screen. The light beam can originate from various sources, including electronic light sensors or lamps, liquid crystal displays, cathode ray tubes (CRTs), plasma screens and light emitting diodes.

 

 

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A LCD will not produce an actual projection on the front of the glass cup but it will become translucent so that you can use your hand to illuminate the inside of the cup."

 

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Many people have tried this idea before without success. It's just not possible to make an object that reflects ultraviolet light back after you put it in front of the projector lens. Unfortunately I am not a physicist and can't explain why that is. The only thing I know for sure is that you can't do it, but you can see what happens when you try anyway.

 

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You should always use protective equipment on any projector lens when not looking through them (don't look at the lens in some cases). With the lens of a regular projector pointing towards you, your eyes will be only about a foot away from the lenses. 

 

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Unfortunately this causes much more visible danger than it does because it gets really hot really quickly. It could burn your eye into an eyeball. 

 

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This may also damage theprojection lens so don't try to do this with lenses built into projectors like most people do.

 

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What you want to do is take a cup that you can use your hand to hold without burning yourself. It should be clear, because the ultraviolet light will not be able to pass through glass that is not transparent.

 

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To make it work, put some glue on the inside and outside of the glass cup. You don't need much or it will overflow. 

 

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Then put the cup on a flat surface with the bottom of it just below or above your face and fully in front of the projector lens so that there are no obstructions between them. Try to hold things steady for long periods of time as you project (get a friend).

 

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The glue you put on the inside will reflect ultraviolet light towards the projector lens, and it will come back at least partially. 

 

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It will be dimmer than it went in, but it will still have the same basic shape. If you don't have a UV flashlight to test this with then there are a few alternatives:

 

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1) Shine a blacklight on the glass cup for about 30 seconds. Then try to project an image onto the inside of the glass cup by holding a white piece of paper about 2 inches from your face for about 30 seconds as you look into the cup.

 

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 You should see an image on both sides of your paper because it is being reflected from both sides at once.

 

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2) Turn off the lights where you are going to do this experiment. Hold the glass cup in front of a white piece of paper that is about 2 inches from your face, so that if you look through the glass at the paper it is about an inch away from your eyes. 

 

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Look into the bottom of the cup for about 1 minute and it should look like there is a ghost in there.

 

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I want to warn you all again before you try this experiment. If you don't handle all of these steps with extreme care, it could be very dangerous and damaging to repairable property.