Development of a track marker light

A beam-coded track marker light that facilitates precise navigation along a straight line is described. The track marker light was developed by the Naval Ship Research and Development Laboratory, Panama City, Florida, and was sponsored by the Naval Ship Systems Command under Sub-project SF 0110235, Task 2517-2 and Task 2509-12. The light developed produces high intensity color coded beams side-by-side that are separated by a very narrow transition zone. The transition zone subtends an angle that approaches the system diffraction limit of 2.35 arc seconds. When the light is directed toward the horizon, the transition zone provides a vertical reference line for navigation that is visible with the unaided eye at 3 miles in daylight and is visible to the horizon at night. An iodine-quartz lamp serves as the light source and it may be either a-c or battery powered. The assembly consists of the lamp, collection and projection optics, filters, and the housing. The unit is lightweight, inexpensive, and is small enough for portable application.