Early Lighthouse Illumination Parabolic Reflector



Early Lighthouse Illumination Parabolic Reflector & Collector's Wood Case
Vintage Arc Lamp Ship's Signal Light Reflector

Date of it's manufacture and use is unknown. The only markings found on this reflector are on the back along the edge. Appear as: 8.L.2556

Very unique item. The reflector is substantial and completely intact. There are noticeable blemishes present however it's contrast of silvered reflective inner surface material still shines bright. The back of the reflector appears to be made of a black cast iron material. Small dents and scratches are present however it is the opinion that they are minimal in comparison to it's overall size and appearance. The storage case is made of wood. The brass metal hinges are in place and working well. Within the case there are four raised wood shelves covered in brown felt that the reflector sits on. The small metal hook latches that secure the case lid are present however the case does not close completely tight which hinders their purpose. Pictures 10&11 provide review.

Research finds that this could have been used as a sophisticated lighthouse illumination reflector, such as those designed by Robert Stevenson and installed at the Bell Rock Lighthouse in 1811.

From Wikipedia, free encyclopedia: A parabolic reflector (or dish or mirror) is a reflective device used to collect or project energy such as light, sound, or radio waves. Its shape is that of a circular paraboloid, that is, the surface generated by a parabola revolving around its axis. The parabolic reflector transforms an incoming plane wave traveling along the axis into a spherical wave converging toward the focus. Conversely, a spherical wave generated by a point source placed in the focus is transformed into a plane wave propagating as a collimated beam along the axis. Parabolic reflectors are used to collect energy from a distant source (for example sound waves or incoming star light) and bring it to a common focal point,[1] thus correcting spherical aberration found in simpler spherical reflectors. Since the principles of reflection are reversible, parabolic reflectors can also be used to project energy of a source at its focus outward in a parallel beam,[2] used in devices such as spotlights and car headlights.

Theory: The parabolic reflector functions due to the geometric properties of the paraboloidal shape: if the angle of incidence to the inner surface of the collector equals the angle of reflection, then any incoming ray that is parallel to the axis of the dish will be reflected to a central point, or "focus". Because many types of energy can be reflected in this way, parabolic reflectors can be used to collect and concentrate energy entering the reflector at a particular angle. Similarly, energy radiating from the "focus" to the dish can be transmitted outward in a beam that is parallel to the axis of the dish. In contrast with spherical reflectors, which suffer from a spherical aberration that becomes stronger as the ratio of the beam diameter to the focal distance becomes larger, the parabolic reflectors can be made to accommodate beams of any width. However, if the incoming beam makes a non-zero angle with the axis (or if the emitting point source is not placed in the focus), parabolic reflectors suffer from an aberration called coma. This is primarily of interest in telescopes because most other applications do not require sharp resolution off the axis of the parabola.

Applications: The most common modern applications of the parabolic reflector are in satellite dishes, reflecting telescopes, radio telescopes, parabolic microphones, and many lighting devices such as spotlights, car headlights, PAR cans and LED housings. The Olympic Flame has been lit using a parabolic reflector concentrating sunlight. Parabolic mirrors are one of many shapes for a burning-glass. A parabolic reflector pointing upward can be formed by rotating a reflective liquid, like mercury, around a vertical axis. This makes the liquid mirror telescope possible.

A unique find and addition to a nautical decor or maritime museum. For the Artist, this may be one of those rare items you could incorporate into your work where reflection of light is desired.

Approximate Measurents:

Overall case 14"x14"x4"
Reflector 12" in diameter with a center hole approx. 4" in diameter
Depth is approx. 2"
Reflector weighs in at approx. 8 lbs and in storage case...weighs approx. 7.2 lbs





Purchase Information

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