Many companies were involved in the development and refinement of the Fresnel lens.  Some supplied only the glass for the lenses, either in rough form, or both cast and polished.  Other companies assembled the glass elements and performed finish work on the lens elements.  Still other companies produced both the glass and the finished lenses.  This story will be divided into several parts, each discussing one or more of these companies and their contribution to the development of the Fresnel lens.

The Ring Floodlight Cam tacks on some additional features like activity zones and night vision (which Kuna and Toucan don't offer). Ring also promises to add Floodlight Cam support for IFTTT, Samsung SmartThings, Wink and even Apple HomeKit soon. (A Ring representative told me Floodlight Cam's are already outfitted with the Apple MFi chips needed for HomeKit, it's just a matter of activating them.)

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Some years ago Chad Kaiser of the US Lighthouse Society ran across a photograph of what was supposed to be the most powerful lighthouse in the world at 1 billion candlepower.  Yes, that is billion not million.  I became intrigued and started researching this light and its history.  This story will describe this very unusual lighthouse in France and how it came to be.  It is actually not a true lighthouse at all.  Instead it is an example of one of the earliest and most powerful Airway Beacons ever built.  But, first we need to understand a little more about air

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Netgear's Arlo was one of the first products to popularize modern, DIY outdoor home security. Since then, plenty of other manufacturers have followed suit with related devices like the Nest Cam Outdoor and the Canary Flex. Weatherproof security cameras integrated into outdoor lighting is one subcategory that has developed slowly, but is now becoming an industry trend.

The live feed was clear in day and night mode and it was easy to set motion and lighting schedules in the app. The main limitation of this device will likely be your Wi-Fi connection. Out here in the Kentucky countryside, the Wi-Fi is hit-and-miss.

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Ring's Floodlight Cam costs more than Kuna and Toucan, but less than Netatmo's Welcome. At the same time, the Floodlight Cam has 1080p HD video resolution compared to Kuna and Toucan's 720p HD. The Floodlight Cam's $3 per month cloud storage fee is also less than Kuna and Toucan's. The Welcome camera, on the other hand, has internal local storage so you don't have to worry about a monthly expense at all.

Below is a listing of the major changes in the Fresnel lens through time and in most cases who the creator of each change was.

Ring's $249 (£195, AU$330 converted) Floodlight Cam is a definite improvement over your typical outdoor security light. In addition to being equipped with two LEDs, this Wi-Fi device also comes with an integrated 1080p HD security camera. Sign up for motion alerts in the related Ring app, where you can also set activity zones, create schedules and control the built-in 110-decibel siren. Starting at $3 per month, you can view saved video history on a contract-free basis.

The German government etched symbols onto the prisms of their Fresnel Lenses. This is the story of those symbols. The German government marked most of their lenses with a government certification symbol. Before 1933 and the Nazi Reich, the symbols used were the German Imperial Eagle and a symbol that looked like a castle, which represented the German Seamarks Service. These marks were etched onto the lens glass to certify that the lens met the requirements for government usage.

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Fresnel lenses represent a unique aspect of U.S. Coast Guard history.  These artifacts are highly sought by a wide variety of museums and associations.  Due to their historic significance, fragility, high value and the U.S. Coast Guard’s policy to protect and preserve these artifacts, an additional set of conditions is placed upon prospective borrowing organizations.  Requirements for the care, security and display of Fresnel lenses are as follows:

There's clearly a lot of functionality packed into this thing, but I can't give it full marks for the following reasons:

The Floodlight Cam comes equipped with two 1,500-lumen LEDs, which are each roughly equivalent to a 100W incandescent bulb. That isn't incredibly bright, particularly if you install it high on your roofline like a typical floodlight. Of course, you can also install it lower so it doubles as a porch light.

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Once the Floodlight Cam's installed, download the app and add your local Wi-Fi info to get it online; this should take roughly 5 minutes.

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Now you're ready to opt-in to motion alerts, create activity zones and more. One important thing to note is that you have to create activity zones before you receive any motion alerts, even if you've already enabled motion alerts. Once I figured that out, everything worked well. I received prompt alerts tied to motion outside. You can adjust the sensitivity of the sensor, too, if you're getting too many notifications of your neighbor's cat.

While these limitations make Ring's clever floodlight-security camera hybrid slightly less recommendable, it's still well worth your consideration.

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The French Commission for Lighthouses was established on April 29, 1811.  In 1819, Arago who had become a member of the French Commission for Lighthouses in 1813, offered to make a systematic review of possible improvements in lighthouse illumination.  He requested that Claude Mathieu and Augustin Fresnel be assigned as his coworkers on the project.  His request was granted on June 21, 1819, and Augustin agreed to serve on the committee.

The first National Lighthouse Lens Survey was released in 2001 at the Sixth Maritime Heritage Conference in Wilmington, N.C. It listed more than 400 classical Fresnel lighthouse lenses in the United States, and two pre-Fresnel, Winslow Lewis lenses. The inventory was a compilation of databases researched by Mike Vogel of the Buffalo Lighthouse Association and the American Lighthouse Coordinating Committee, and by Al and Helen Gademsky of Ohio.

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Ring's $249 Floodlight Cam goes a long way toward helping you keep an eye on the perimeter of your home. At the same time, I really wish it offered free cloud storage as an entry-level option. I also wish Ring had introduced smart home integrations at launch rather than making us wait. Even so, you should consider adding Ring's LED floodlight and HD camera to your outdoor security setup. It's only going to get smarter with time.

Ring's Floodlight Cam is a fairly simple DIY installation, but it's a hardwired device. If you have any reservations about setting up a product that requires electrical wiring, hire someone to handle it for you. I enlisted one of CNET's technical gurus, Steve Conaway, to install the Floodlight Cam.

It took Steve about 30 minutes from start to finish, but we ran into an unexpected setback along the way. The width of the Floodlight Cam's baseplate didn't match up with the width of the standard-sized electrical box at the CNET Smart Home. So, we currently have just one screw holding up the whole thing. That workaround has worked surprisingly well for us during testing, but it wouldn't be ideal for a more long-term installation.

During testing, the area around the Floodlight Cam typically averaged 10 mbps for download speed and 1 mbps (or slightly less) for upload speed. The Ring app says anything above 1 mbps for download and upload is good, but this Ring support page says at least 2 mbps is best. Because of this, we experienced some lag times, pixelated video feeds and a two-way talk intercom that occasionally cut in and out.

Editors' note, Dec 14: You can find all of our coverage about Ring on this aggregation page, including our reporting about Ring's privacy and security policies. This commentary covers how we factor those issues into our product recommendations.

The English and Scottish lighthouse authorities wanted to produce all Fresnel lenses and other lighthouse equipment in their own country and persuaded the Cookson Glass Company to begin production of Fresnel lenses in 1834. Cookson brought in Leonor Fresnel, Augustin’s brother, as a consultant and produced Fresnel lenses from individual pieces and prisms as done by the French lens companies.  The first of these better designed Fresnel lenses, built by the Cookson Co., was installed in Scotland in 1835, in the Inchkeith lighthouse.

Most lighthouse enthusiasts think that the Fresnel lens was the first lens used in lighthouses.  However, that assumption is incorrect in that a number of lenses were proposed and put into use in the years before Augustin Fresnel designed his famous lens.  This story will give you information about these early attempts to use lenses to augment the power of lighthouse optics.