Photoinject is a term that is most commonly used in physics and optics, referring to the process of generating an electron beam using the power of light. Synonyms for photoinject include photoemission, photoelectric effect, and photoelectron generation. These terms all describe the underlying process of using light to excite electrons in a material, causing them to be released and forming a beam that can be used for applications such as particle accelerators and electron microscopy. Other related terms include photoionization, which refers to the production of positively charged ions by excitation with light, and photoconductivity, which describes the increase in electrical conductivity that occurs when light is absorbed by certain materials.