page_title: Signal lamp
hierarchical_section_title: Signal lamp
caption_attribution_description: English: USS Mason (DE-529). Signalman Second Class Julius Holmes receives Signal lamp instruction from SM1c Ernest V. Alderman (left), during training for Mason's crew at the Norfolk Naval Training Station, Virginia, 3 January 1944. Original caption: “Photo # 80-G-214545 USS Mason crewman receives signal lamp trainig”
context_page_description: A signal lamp is a visual signaling device for optical communication, typically using Morse code. Modern signal lamps are focused lamps which can produce a pulse of light. In large versions, this pulse is achieved by opening and closing shutters mounted in front of the lamp, either via a manually operated pressure switch, or, in later versions, automatically. With hand held lamps, a concave mirror is tilted by a trigger to focus the light into pulses. The lamps were usually equipped with some form of optical sight, and were most commonly used on naval vessels and in airport control towers. In manual signaling, a signalman would aim the light at the recipient ship and turn a lever, opening and closing the shutter over the lamp, to emit flashes of light to spell out text messages in Morse code. On the recipient ship, a signalman would observe the blinking light, often with binoculars, and translate the code into text.
context_section_description: A signal lamp (sometimes called an Aldis lamp, after Arthur Cyril Webb Aldis, who invented a widely used design, or a Morse lamp) is a visual signaling device for optical communication, typically using Morse code.  Modern signal lamps are focused lamps which can produce a pulse of light.  In large versions, this pulse is achieved by opening and closing shutters mounted in front of the lamp, either via a manually operated pressure switch, or, in later versions, automatically.  With hand held lamps, a concave mirror is tilted by a trigger to focus the light into pulses.  The lamps were usually equipped with some form of optical sight, and were most commonly used on naval vessels and in airport control towers (using color signals for stop or clearance).  In manual signaling, a signalman would aim the light at the recipient ship and turn a lever, opening and closing the shutter over the lamp, to emit flashes of light to spell out text messages in Morse code. On the recipient ship, a signalman would observe the blinking light, often with binoculars, and translate the code into text.
caption: Signal lamp training during World War II
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