An optical device that helps to project the image on the surface known as the projection screen is known to be the projector or an image projector. Using a shining light through the small transparent lens most of the projectors create the images. By using laser some of the new projectors project the image. Instead of using the extensional projection screen, a virtual retinal display helps to project the image straightly on the retina. Nowadays we are using the common type of projector named video projector. Slide projectors and overhead projectors are replaced with video projectors which are known to be digital replacements. In the projector led is used in the lens of the projector. Throughout the 1990s and early 2000s, digital video projectors replaced the earlier type of projectors. Whatever the replacement arrives, still at some places the old analog projectors are used. The replaced projectors are known to be the new type projectors and they are handheld and it can be carried over anywhere. The handheld projectors use lasers or LEDs to the projection of an image. If there is too much ambitious light it is very hard to see the projection. Nowadays the movie theatres use the digital cinema video projector. Usually, the movie projectors are used in movie theatres.
History of the projector:
In the earliest days, the projection of the image is given with the original shadowgraphy which is provided on the date of prehistory. Shadow play is not considered to be the projection device but it is known to be the first step for the invention of the projectors. Shadow puppetry is known to be the refined form of the shadow play in Asia that the shadow puppetry is most commonly known for the long history in various places such as Malaysia, Thailand, Indonesia, China, Cambodia, Nepal, and India. These are considered to be the prehistory to 1100 CE. Probably there exist various types of projections like shadow play. But their nature is not clear to be practical. In the camera obscura, which is common in Latin known as the darkroom that the projector shares the history with the camera. The camera obscura is known to be the natural optical phenomena. This explains the projection of the image through a small hole in the box and then the image is reflected on the other side of the box. Han Chinese philosopher Mozi has described this oldest known record about the natural optical phenomenon of camera obscura. The description of Han Chinese philosopher Mozi is that the camera obscura image is reversed because the light travels in a straight line. Around the year 1550, the lens is used in the opening wall or in the closed dark room to project the image. In the latter half of the 17th century, the introduction of the magic lantern is split with the shared history of the camera and projection. In the form of tents and boxes, the camera obscura aids as a most live drawing aid. In the first decade of the 19th century, the process of camera obscura is adopted as a photographic camera. In the Castlegrande in Bellinzona, the ancient camera obscura effect is caused by balistrarias.