condenser; light condenser
Technical term for an optical device that concentrates light, such as in microscopes or projectors.
I adjusted the microscope's condenser to get a brighter image.
Compound of 集 (しゅう, 'gather') + 光 (こう, 'light') + 器 (き, 'device'). The exact historical derivation is uncertain, but the spelling is conventionally associated with the meaning of a light-condensing device.