A projector is an optical instrument that uses an optical element to magnify the contour of a workpiece and project it onto a screen. It can be used for profile measurement with transmitted light, or it can be used to measure the surface shape of the through hole and observe the surface of the part. The projector is especially suitable for measuring complex contours and small workpieces, such as clock parts, stamping parts, electronic components, prototypes, molds, threads, gears and forming tools. It has high inspection efficiency and is easy to use. It is widely used in measuring rooms and production workshops. The instrumentation and watch industry is particularly suitable. A projector, also known as a projector, is a device that can project images or video onto a screen. It can be connected to a computer, VCD, DVD, BD, game console, DV, etc. through different interfaces to play corresponding video signals. Projectors are currently widely used in homes, offices, schools and entertainment venues, depending on the way they work, there are different types of CRT, LCD, DLP.