An optical device used to project images onto a surface, similar to a slide projector but usually for level projection of transparencies or documents; also called 投影机 tóu​yǐng​jī or 投影器 tóu​yǐng​qì

A measuring instrument that applies the principles of light projection to inspect the shapes and sizes of complex workpieces, templates, or tools

An instrument used to transfer data from drawings or maps onto a compilation sheet using light reflection