Several people have asked me what is the use of these extremely long range flashlights. While furthering scientific research and personal learning is one of my goals, there are several real-world applications where this type of technology is used.
Architectural
Sometimes high intensity lights are used at the top of buildings as an architectural art piece. This beam of light is visible from many kilometres away and draws the attention of anyone looking up at the sky. One of the most well known examples of lighting used in architecture is the Luxor hotel, which has a several billion candlepower beam of light exiting from the top.
**Marine**  Searchlights are very commonly seen on boats. The light helps navigate at night where rocks, islands, or a dock may not be well illuminated. Having a beam that can penetrate thick fog and humidity often found at sea is important to avoid collisions and to be seen by other ships, similar to how headlights on a car serve as an indication to other drivers about where you are.
**Search and rescue**  A very common use for searchlights is exactly that, search and rescue. When a person is missing or a disaster happens, first responders such as helicopters, ships, or land vehicles need to use very bright and long distance lights during the night time. Searches can last many days, and it is important for these rescue services to work around the clock, including during night or storm conditions.
**Defence**  Military and other defence applications also have a use for high powered searchlights. Searchlights can be used to spot enemies and reduce their visibility at the same time, or to find well hidden objects of interest during the night.
**Entertainment**  Many different types of lights are used in the entertainment industry, one of the most common one being a ‘moving head’ light. Most commonly used in concerts and similar types of events, these lights can project an extremely bright and straight beam of light to create many unique visual effects.
**Inspection**  Certain types of maintenance and inspection jobs require working late hours or during the night, and a light which can easily illuminate objects at a far distance can help see. Not only that, but using a high intensity light at a closer distance can also give a much brighter spot, which can be useful in some cases.
**Monumental**  Similar to architectural lighting, searchlights are often used in “light monuments” consisting of extremely long vertical beams of light. These monuments, such as this one in iceland, are used to recognize and remember past events or people, and are a beautiful display of art that doesn’t have a very high cost.
**Surveillance**  Another application for searchlights is surveillance, especially in large expanses of land such as farms or prisons or any other area that needs to be occasionally searched at night. The search operation can be done at a safe and convenient distance at the searchlight without having to go very far to watch something. The use of binoculars is also very beneficial in this situation.
Finally, there is the undeniable bragging rights of holding the world record for the longest distance LED searchlight.