Cape Naturaliste Lighthouse

We’d never been inside a light house before , they have always been locked ,so it was rather exciting to have a tour up and around and see the view from the very top out to the headland.

Cape Naturaliste is a headland in the south western region of Western Australia at the western edge of the Geographe Bay. It is the northernmost point of the Leeuwin-Naturaliste Ridge, which was named after the cape. The Leeuwin-Naturaliste National Park, the Cape Naturaliste Lighthouse and the Cape to Cape hiking track were also named after this location.

Cape Naturaliste Lighthouse -
Cape Naturaliste, in the south west of Western Australia, is the site of a lighthouse which was activated in 1904. It was automated in 1978, but remained manned by a lighthouse keeper until 1996.

It is a 20-metre-high (66 ft) cylindrical tower built of limestone that still uses its original first order Fresnel lens made by Chance Brothers. The light characteristic is ""Fl. (2) 10 s", a group of two flashes every ten seconds, the focal plane is at 123 metres (404 ft) above sea level. Another precious lens optic is displayed there, the second order Fresnel lens of the Jarman Island Light, as well as the original Great Sandy Islands beacon. Both items were originally used on the Pilbara coast further north.

The lighthouse is constructed of limestone quarried from nearby Bunker Bay, which was also known as the Quarries.This lighthouse is part of a network of aids to navigation around the Australian coastline managed by the
Australian Maritime Safety Authority for the safety of shipping.

This lighthouse was established in 1904.
Range: 25 Nautical Miles
Power Source: Mains Powered
Height ol Structure: 19 Metres
Elevation of light. 123 Metres

If your interested -
How does a Fresnel Lens Work?
The inventor of the Fresnel lens was a French physicist Augustin-Jean Fresnel, 178% - 1827.
The basic concept of the dioptric lens was proposed earlier by Georges-Louis Lecere.
However, it was Fresnel who independently reinvented and significantly improved the design in 1821, specifically for use in lighthouses.
Fresnel lenses focus nearly 98% of the rays produced by a central light source into a bright beam of concentrated light, this light can be visible from more than 20 miles out to sea. A Fresnel lens creates a beam of light using glass prisms set in a metal frame. These prisms change the direction the light travels in, so all light exits the lens in the same direction to a focused point. The prisms do this by refracting (or bending) and reflecting the light.
Refraction is the scientific word used to describe how light is bend as it enters or exits a dense transparent material or medium, such as glass, at an angle other than 90°.
Reflection occurs when light bounces off the surface of smooth, shiny material like metal, glass or water. Reflection can occur on both the interior and exterior surface of the transparent object. The reflection of a mountain range on the surface of a crystal clear alpine lake and the reflection of a fish on the underside of a lakes surface are both great examples of external and internal reflection in action.
Fresnel lenses often use three types of prisms to focus light: dioptric prisms, catadioptric prisms and convex prisms.
- Dioptric prisms are the workhorses of the Fresnel lens. Each prism acts like a tiny lens, bending light rays inward to a focal point. By carefully arranging numerous dioptric prisms of different shapes and sizes, the lens can effectively collect and concentrate light over a wide area.
- Catadioptric prisms combine refraction (bending light) with the reflection (bouncing light). They typically have a mirrored surface on one side that reflects light rays onto the dioptric prisms, further improving the efficiency of light collection and focusing.
- Convex prisms have a rounded surface that acts like a convectional convex lens, further focusing the light rays that have already been bent by the dioptric and catadioptric prisms. They are often used in the final stage of focusing to achieve a pinpoint beam or sharp image.
Many light houses are still equipped with their historic Fresnel lenses; however, some lighthouses have had their original optic removed and new modern day electric beacons have been installed in their place. Although introduced more that 200 years ago during the industrial revolution, Fresnel lens technology is still widely used to this day. Today you can find this technology in the headlights of your car, surgical lasers and even in spacecrafts.もっと詳しく