The Fresnel Lens and How the Lighthouse Worked

One of the most remarkable features of Point Cabrillo Lighthouse is its original third-order Fresnel lens. The station’s official site says the lighthouse still contains the original Chance Brothers third-order Fresnel lens, while Wikipedia notes that the lens was made by Chance Brothers in England and remains a defining part of the station’s identity.

The lens system is one reason Point Cabrillo stands out among California lighthouses. Fresnel lenses use carefully arranged glass prisms to focus and magnify light into a strong beam visible far offshore. The beam rotates once every 40 seconds, producing a flash every 10 seconds. The station’s original illumination was later updated as lighthouse technology improved.

Electricity reached the station in 1935, replacing the older kerosene-and-clockwork setup with an electric light and motor. That same year, an air diaphone supertyfone fog signal was installed, an important detail for a lighthouse serving one of the foggiest stretches of the Northern California coast.

From Coast Guard Control to Mid-Century Damage

In 1939, the United States Coast Guard took over the Lighthouse Service, placing Point Cabrillo under Coast Guard administration. The lighthouse remained part of the active coastal navigation system, but the station’s history in the mid-20th century also shows how vulnerable even sturdy coastal structures can be.

In February 1960, a storm sent waves high enough to crest above the light, flooding the building with mud and causing major damage, though the lens itself survived. There remains historic debate over what caused these waves (seismic event or Pacific storm). One thing that wasn’t debated, the lighthouse staff saw a wave engulf the building as they fled for higher grounds.

During the Cold War, the site even took on an unexpected secondary role when it was used in training exercises to simulate a Soviet radar base. It is one of those unusual historical footnotes that makes the place feel more layered than the average California lighthouse.

Automation, Decline, and Restoration

Point Cabrillo was automated in 1973. After that, the original lens was covered and a more modern rotating beacon was mounted on a metal stand west of the lantern room. Like many historic lighthouses in the United States, the station then faced a period where its original structures were no longer central to operations in the same way they had once been.

The turnaround began in the late 1980s. In 1988, the California Coastal Conservancy started acquiring the land around the station. In 1991, Point Cabrillo Light Station was added to the National Register of Historic Places as part of the Light Stations of California MPS. California State Parks did not immediately take over because of budget limitations, so the property was managed for years by a nonprofit organization before the larger restoration took shape.

Beginning in 1996, a major restoration aimed to return the station to the appearance it would have had in the 1930s after electrification. In 1999, the original third-order Fresnel lens was reinstalled after being upgraded to modern standards. The restored lighthouse reopened to the public in 2001, and California State Parks purchased the light station in 2002. The restoration later received the Governor’s Historic Preservation Award in 2007.

Today, California State Parks describes the site as a fully restored lighthouse with three original lightkeepers’ houses and outbuildings, while the Point Cabrillo Lightkeepers Association continues to play a major role in preservation, interpretation, public access, and lodging. That is a big reason Point Cabrillo feels like a complete historic place instead of just a surviving tower.