28-09-2017, 09:59 AM
An image projector or 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 illuminating a light through a small transparent lens, but newer types of projectors can project the image directly, using lasers. A virtual retina screen, or retina projector, is a projector that projects an image directly onto the retina instead of using an external projection screen.
The most common type of projector used today is called a video projector. Video projectors are digital replacements for earlier types of projectors such as slide projectors and overhead projectors. These earlier types of projectors were replaced for the most part by digital video projectors throughout the 1990s and early 2000s, but old analog projectors are still used in some places. The new types of projectors are portable projectors that use lasers or LEDs to project images. Their projections are difficult to see if there is too much ambient light.
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