A projector or image projector is an optical device that projects an image (or moving images) onto a surface, commonly a projection screen. Most projectors create an image by shining a light through a small transparent lens, but some newer types of projectors can project the image directly, by using lasers. A virtual retinal display, or retinal projector, is a projector that projects an image directly on the retina instead of using an external projection screen.

The Eidoloscope was an early type of movie projector that was developed in the late 19th century. It was invented by Charles Francis Jenkins, an American inventor who was also one of the pioneers of early cinema.

The Eidoloscope was a simple projector that used a light source, a lens, and a film strip to project moving images onto a screen. The film strip was made up of a series of photographic images, which were mounted on a strip of flexible material.

When the film strip was passed through the Eidoloscope, a bright light was shone through the images, and the lens magnified and projected the images onto a screen. The result was a moving image that was viewable by an audience.

The Eidoloscope was an important development in the early history of cinema, as it allowed for the projection of moving images on a larger scale than had previously been possible. However, the technology was limited in several ways. The images were often blurry and low quality, and the projection was accompanied by a loud noise from the mechanical parts of the projector.

Despite these limitations, the Eidoloscope paved the way for further developments in movie projection technology, and helped to establish cinema as a popular form of entertainment around the world. Today, it is remembered as an important piece of cinema history and a symbol of the early pioneers of cinema technology.