noun
floodlight; floodlight projector
Technical term for a lighting device that projects a broad, intense beam, used in stadiums, construction sites, or outdoor events.
工事現場では夜間作業のために投光照明器が使われる。
Floodlights are used at construction sites for nighttime work.
スタジアムの投光照明器が一斉に点灯した。
The stadium floodlights came on all at once.
投光器 is a more common, shorter term for a floodlight or projector, while 投光照明器 explicitly includes the lighting (照明) aspect and sounds more technical.
Compound of 投光 (projecting light) + 照明 (illumination) + 器 (device). A straightforward technical coinage.