The Basics
Opaque projectors are often called episcopes, epidioscopes, or epidiascopes. They projectors were common before overhead projectors became popular. An opaque projector functions by shining a bright source of light onto an object from above. Then numerous small mirrors, imaging lenses and prisms are used to cast the image onto a screen to be viewed.

Though used opaque projectors have many similarities to the more modern overhead projector they are not identical. For example, the opaque projector uses bulbs that are brighter and lenses that are larger to help them reflect the light onto a screen. Because of this, special attention should be paid to the material being projected with this machine. The large lens and intense bulb can easily damage objects with the heat they generate.

Their Uses
Beseler opaque projectors were commonly used in classrooms and offices to cast the images of book pages, documents, graphs, pictures, photographs, charts, and graphs. They made the images available for large audiences to view in the past

In addition, three dimensional objects can be projected using American optical opaque projectors. These objects can be insects, coins, leaves, keys and much more. In order to view these objects correctly they must be placed upside down on the projector, because the image will be inverted by the lens.

Also, in the beginning of the twentieth century opaque projectors were produced as a type of children’s toy for some time

Currently the opaque projector has been replaced in most offices and classrooms by overhead projectors or digital whiteboards. And they are no longer manufactured as children’s toys either. They are however, still used by large numbers of artists. Painters and drawers commonly use the projector as a means to enlarge objects and trace them on to a variety of materials.

Benefits
One of the main advantages of an opaque projector is that it displays information on a large screen for an audience to view. This eliminates the need to make a multitude of hard copy documents, and saves the time it would take to hand them out. This is good for the environment and is considered an effective way to present information. The presenter can use a pointer or a dry erase marker to highlight areas of interest or make additional notes on the subject material.

Another advantage of the opaque projector is its affordability. Because these machines have been replaced by more innovative devices you can often buy them inexpensively. While they might not be as easy to find as they were in years past, you should be able to find them a t discount prices.