Specifically the high-intensity, long-range beam used by military, prisons, and old-style movie premieres — not an indoor stage spotlight (that's 聚光灯 jùguāngdēng). Reach: typically 10-20 km.
memory
Components stack: 探 (search/probe) + 照 (illuminate) + 灯 (lamp) = "probe-illuminate-lamp." The character order mirrors the function precisely.
