Dec 15, 2020 — If the extension cord is miswired, replace an end. If the receptacle in the wall is miswired, that needs to be corrected both electrically and ...

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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:

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What's the Difference Between Interlaced and Progressive Scan. You must have noticed that a video resolution is followed by a letter "i" or "p", such as 1080i ...

by H Kakeya · 2012 · Cited by 33 — Integral imaging with fine fly-eye lens is often called a 3D display based on light-ray reproduction. When the interval between the display panel and the fly- ...

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• Residential – bathroom / shower enclosures, partitions • Commercial – conference rooms, office doors/partitions, reception • Retail – changing rooms, projection displays • Healthcare: ICU Doors, Nurseries, ERs, ORs, clinic partitions • Hospitality – bathroom /shower enclosures, partitions • Banking – ballistic teller lines, transaction windows, safe deposit rooms

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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One of our previous posts discussed the increased use of sliding glass doors in office layouts.  It was noted that the use of glass as office fronts increases natural light and energy efficiency.  The increased use of glass however can contribute to decreased privacy.  One solution type that can bring the best of both worlds is Switchable Privacy Glass like the Dash Door PrivacyVue™ line.

Privacy Glass is a laminated glass. The laminated material within is Liquid Crystal Privacy Film, which responds to an electrical current.

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Laminated Switchable Privacy Glass is opaque / translucent when the switch is in the off position and clear when electric current is applied to each lite of glass

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Two sheets of glass are laminated over the PDLC film. The components are assembled under high pressure and temperature to form a single unit.

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When an electric current is applied, the liquid crystal molecules line up, the incidental light passes through, and the privacy glass becomes clear.

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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.

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.

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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.

When the power is off the liquid crystal molecules are randomly oriented and will scatter incidental light. This renders the Switchable Privacy Glass panel opaque.

One of our previous posts discussed the increased use of sliding glass doors in office layouts.  It was noted that the use of glass as office fronts increases natural light and energy efficiency.  The increased use of glass however can contribute to decreased privacy.  One solution type that can bring the best of both worlds is Switchable Privacy Glass like the Dash Door PrivacyVue™ line. This technology will switch the glass from transparent to an opaque translucent state with the simple flip of a switch, tap of an app, or wave of a hand.  The technology makes available a dynamic space that can be both private and open. Uses of switchable privacy glass include: • Residential – bathroom / shower enclosures, partitions • Commercial – conference rooms, office doors/partitions, reception • Retail – changing rooms, projection displays • Healthcare: ICU Doors, Nurseries, ERs, ORs, clinic partitions • Hospitality – bathroom /shower enclosures, partitions • Banking – ballistic teller lines, transaction windows, safe deposit rooms   Glass “OFF” – Opaque Glass “ON” – Transparent The Principal When the power is off the liquid crystal molecules are randomly oriented and will scatter incidental light. This renders the Switchable Privacy Glass panel opaque. When an electric current is applied, the liquid crystal molecules line up, the incidental light passes through, and the privacy glass becomes clear. Privacy Glass is a laminated glass. The laminated material within is Liquid Crystal Privacy Film, which responds to an electrical current. When electricity is applied to the film via the wiring, the liquid crystals align and the glass instantly becomes clear.  When the power is turned off, the liquid crystals return to their normal scattered positions rendering the glass an opaque translucent.   Technology PDLC (Polymer Dispersed Liquid Crystal) is a medium whose light scattering power is adjustable through applying an electric field. In their natural (uncharged) state, the PDLC droplets randomly align. PDLC Film consists of a polymer matrix of liquid crystals enclosed by electrically conductive Indium Tin Oxide-coated PET film. The resulting PDLC Film has wiring attached to a conductive copper strip (busbar) along the film’s edge.  In a low voltage platform, this wiring is connected to a step-down transformer through which power is supplied for the “on” (clear) state.  In their natural (uncharged) state, the PDLC droplets randomly align, thus creating the an opaque translucent condition. Two sheets of glass are laminated over the PDLC film. The components are assembled under high pressure and temperature to form a single unit. The ordinary refractive index of these liquid crystals does not match that of the polymer, and the incident light is thus scattered, resulting in a translucent state. When an electric field is applied across the material, the PDLC droplets re-orient, and subsequently the extraordinary refractive index of the liquid crystal matches that of the polymer. Therefore, the incident light can pass through, resulting in a transparent state.   Laminated Switchable Privacy Glass is opaque / translucent when the switch is in the off position and clear when electric current is applied to each lite of glass

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.

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.

PDLC (Polymer Dispersed Liquid Crystal) is a medium whose light scattering power is adjustable through applying an electric field. In their natural (uncharged) state, the PDLC droplets randomly align.

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Its 93/4" x 113/4 plastic lens provides 3X magnification of a standard 8" x 11" page without requiring you to adjust or reposition your reading material or the ...

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PDLC Film consists of a polymer matrix of liquid crystals enclosed by electrically conductive Indium Tin Oxide-coated PET film. The resulting PDLC Film has wiring attached to a conductive copper strip (busbar) along the film’s edge.  In a low voltage platform, this wiring is connected to a step-down transformer through which power is supplied for the “on” (clear) state.  In their natural (uncharged) state, the PDLC droplets randomly align, thus creating the an opaque translucent condition.

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When electricity is applied to the film via the wiring, the liquid crystals align and the glass instantly becomes clear.  When the power is turned off, the liquid crystals return to their normal scattered positions rendering the glass an opaque translucent.

by Z Mohammed · 2000 · Cited by 34 — For the reading task, contrast reserve is defined as the ratio of the letter contrast of the printed letters, to the reader's contrast threshold.

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Laminated Switchable Privacy Glass is opaque / translucent when the switch is in the off position and clear when electric current is applied to each lite of glass

This technology will switch the glass from transparent to an opaque translucent state with the simple flip of a switch, tap of an app, or wave of a hand.  The technology makes available a dynamic space that can be both private and open.

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.

The ordinary refractive index of these liquid crystals does not match that of the polymer, and the incident light is thus scattered, resulting in a translucent state. When an electric field is applied across the material, the PDLC droplets re-orient, and subsequently the extraordinary refractive index of the liquid crystal matches that of the polymer. Therefore, the incident light can pass through, resulting in a transparent state.

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.