Carol Mayo Jenkins, a veteran TV, stage and film actress who retired last year after 22 years as an artist in residence in UT’s Theatre Department, spoke at the ceremony about the significance of ghost lights to theater people.

Fresnel acknowledged the British lenses and Buffon's invention in a memoir read on 29 July 1822 and printed in the same year.[25] The date of that memoir may be the source of the claim that Fresnel's lighthouse advocacy began two years later than Brewster's;[14] but the text makes it clear that Fresnel's involvement began no later than 1819.[26]

The largest Fresnel lenses are called hyperradiant (or hyper-radial). One such lens was on hand when it was decided to build and outfit the Makapuu Point Light in Hawaii. Rather than order a new lens, the huge optic construction, 3.7 metres (12 ft) tall and with over a thousand prisms, was used there.[61]

In some lenses, the curved surfaces are replaced with flat surfaces, with a different angle in each section. Such a lens can be regarded as an array of prisms arranged in a circular fashion with steeper prisms on the edges and a flat or slightly convex center. In the first (and largest) Fresnel lenses, each section was actually a separate prism. 'Single-piece' Fresnel lenses were later produced, being used for automobile headlamps, brake, parking, and turn signal lenses, and so on. In modern times, computer-controlled milling equipment (CNC) or 3-D printers might be used to manufacture more complex lenses.[citation needed]

I hate that I missed this event. I was house photographer for both the CBT and the Carousel Theatre for about 16 years. I think the first show I photographed was Bus Stop with David Keith, Melissa Gilbert and others. That was about 1986. Started with the 1986-1987 Season and ended with Babel in the 2003-2004 Season. Photographed a few productions after then, Tommy and Man of La Mancha. About 100 productions. Hundreds of memories!

“Together, actor and audience, create memories,” she noted. “Memories to take home. There is magic in those memories. Inside these walls, people have cried, laughed, been engaged — and been enraged!”

Mimi: I didn’t realize you had that much of a connection to the Carousel! I can tell it was a special place for a long time by the strong emotions it elicits among folks today.

A “ghost light” in the theater world is a single incandescent light that remains lit when the theater is unoccupied and would otherwise be completely dark. It is usually placed center stage on a portable stand.

In the same year he designed the first fixed lens—for spreading light evenly around the horizon while minimizing waste above or below.[11] Ideally the curved refracting surfaces would be segments of toroids about a common vertical axis, so that the dioptric panel would look like a cylindrical drum. If this was supplemented by reflecting (catoptric) rings above and below the refracting (dioptric) parts, the entire apparatus would look like a beehive.[38] The second Fresnel lens to enter service was indeed a fixed lens, of third order, installed at Dunkirk by 1 February 1825.[39] However, due to the difficulty of fabricating large toroidal prisms, this apparatus had a 16-sided polygonal plan.[40]

Fresnel lightexample

From left, Liz Stowers, who is spearheading the fundraising campaign, Steve Drevik, and Michelle Geller, interim assistant vice chancellor of advancement for the UT  Foundation.

From left, Jan Simek, Wayne and Sylvia Davis. Simek has been both acting chancellor and interim president of UT. Davis is chancellor emeritus and dean emeritus of the Tickle College of Engineering.

A first-order lens has a focal length of 920 mm (36+1⁄4 in) and stands about 2.59 m (8 ft 6 in) high, and 1.8 m (6 ft) wide. The smallest (sixth) order has a focal length of 150 mm (6 in) and a height of 433 mm (17+1⁄16 in).[58][59][60]

The practical use of a ghost light is for safety. It enables one to navigate the theater to find the lighting control console and to avoid accidents such as falling into the orchestra pit or tripping over cords or pieces of the set that might remain on the stage.

As lighthouses proliferated, they became harder to distinguish from each other, leading to the use of colored filters, which wasted light. In 1884, John Hopkinson eliminated the need for filters by inventing the "group-flashing" lens, in which the dioptric and/or the catadioptric panels were split so as to give multiple flashes—allowing lighthouses to be identified not only by frequency of flashes, but also by multiplicity of flashes. Double-flashing lenses were installed at Tampico (Mexico) and Little Basses (Sri Lanka) in 1875, and a triple-flashing lens at Casquets Lighthouse (Channel Islands) in 1876.[52] The example shown (right) is the double-flashing lens of the Point Arena Light, which was in service from 1908 to 1977.[53]

The French Commission des Phares [FR] (Commission of Lighthouses) was established by Napoleon in 1811, and placed under the authority of French physicist Augustin-Jean Fresnel's employer, the Corps of Bridges and Roads. As the members of the commission were otherwise occupied, it achieved little in its early years.[15] However, on 21 June 1819—three months after winning the physics Grand Prix of the Academy of Sciences for his celebrated memoir on diffraction—Fresnel was "temporarily" seconded to the commission on the recommendation of François Arago (a member since 1813), to review possible improvements in lighthouse illumination.[11][16]

The development of hyper-radial lenses was driven in part by the need for larger light sources, such as gas lights with multiple jets, which required a longer focal length for a given beam-width, hence a larger lens to collect a given fraction of the generated light. The first hyper-radial lens was built for the Stevensons in 1885 by F. Barbier & Cie of France, and tested at South Foreland Lighthouse with various light sources. Chance Brothers (Hopkinson's employers) then began constructing hyper-radials, installing their first at Bishop Rock Lighthouse in 1887.[54] In the same year, Barbier installed a hyper-radial at Tory Island. But only about 30 hyper-radials went into service[55] before the development of more compact bright lamps rendered such large optics unnecessary (see Hyperradiant Fresnel lens).

My love of the imagination of theater began by attending plays at Carousel as an elementary school student. Later, a favorite performance , “Cat on a Hot Tin Roof.” More recently, “People Where They Are.” Directing, acting, and set design in the round are a challenge, always done so well. Summer or winter, sweet memories.

I loved my time at The Carousel Theatre first taking Saturday acting lessons there as a teenager, then as an actress in several productions of The Children’s Carousel Theatre program. The experience led me to pursue my degree in Theatre at UT where much of my study was done right there in The Carousel! I always loved the dark , cozy ambiance of the wooden domed structure whose sliding paneled walls could instantly transform it to an open air theatre venue. It was pure magic for me!

Fresnel's next lens was a rotating apparatus with eight "bull's-eye" panels, made in annular arcs by Saint-Gobain,[12] giving eight rotating beams—to be seen by mariners as a periodic flash. Above and behind each main panel was a smaller, sloping bull's-eye panel of trapezoidal outline with trapezoidal elements.[27] This refracted the light to a sloping plane mirror, which then reflected it horizontally, 7 degrees ahead of the main beam, increasing the duration of the flash.[28] Below the main panels were 128 small mirrors arranged in four rings, stacked like the slats of a louver or Venetian blind. Each ring, shaped like a frustum of a cone, reflected the light to the horizon, giving a fainter steady light between the flashes. The official test, conducted on the unfinished Arc de Triomphe on 20 August 1822, was witnessed by the Commission—and by Louis XVIII and his entourage—from 32 kilometres (20 mi) away. The apparatus was stored at Bordeaux for the winter, and then reassembled at Cordouan Lighthouse under Fresnel's supervision—in part by Fresnel's own hands. On 25 July 1823, the world's first lighthouse Fresnel lens was lit.[29] As expected, the light was visible to the horizon, more than 32 kilometres (20 mi) out.[30]

In 1748, Georges-Louis Leclerc, Comte de Buffon was the first to replace a convex lens with a series of concentric annular prisms, ground as steps in a single piece of glass,[2]to reduce weight and absorption. In 1790[8] (although secondary sources give the date as 1773[9]: 609  or 1788[10]), the Marquis de Condorcet suggested that it would be easier to make the annular sections separately and assemble them on a frame; but even that was impractical at the time.[11][12] These designs were intended not for lighthouses,[2] but for burning glasses.[9]: 609  David Brewster, however, proposed a system similar to Condorcet's in 1811,[2][10][13] and by 1820 was advocating its use in British lighthouses.[14]

Clarence Brown Managing Director Tom Cervone recounted the history of the Carousel Theatre, which was built in 1951. At that time, patrons had to use the bathroom in nearby fraternity houses!

The Fresnel lens reduces the amount of material required compared to a conventional lens by dividing the lens into a set of concentric annular sections. An ideal Fresnel lens would have an infinite number of sections. In each section, the overall thickness is decreased compared to an equivalent simple lens. This effectively divides the continuous surface of a standard lens into a set of surfaces of the same curvature, with stepwise discontinuities between them.

By the end of August 1819, unaware of the Buffon-Condorcet-Brewster proposal,[11][13] Fresnel made his first presentation to the commission,[17] recommending what he called lentilles à échelons ('lenses by steps') to replace the reflectors then in use, which reflected only about half of the incident light.[18] Another report by Fresnel, dated 29 August 1819 (Fresnel, 1866–70, vol. 3, pp. 15–21), concerns tests on reflectors, and does not mention stepped lenses except in an unrelated sketch on the last page of the manuscript. The minutes of the meetings of the Commission go back only to 1824, when Fresnel himself took over as Secretary.[19] Thus the exact date on which Fresnel formally recommended lentilles à échelons is unknown.[citation needed] Much to Fresnel's embarrassment, one of the assembled commissioners, Jacques Charles, recalled Buffon's suggestion.[20] However, whereas Buffon's version was biconvex and in one piece,[21] Fresnel's was plano-convex and made of multiple prisms for easier construction.

Fresnel designed six sizes of lighthouse lenses, divided into four orders based on their size and focal length.[58] The 3rd and 4th orders were sub-divided into "large" and "small". In modern use, the orders are classified as first through sixth order. An intermediate size between third and fourth order was added later, as well as sizes above first order and below sixth.

The first stage of the development of lighthouse lenses after the death of Augustin Fresnel consisted in the implementation of his designs. This was driven in part by his younger brother Léonor—who, like Augustin, was trained as a civil engineer but, unlike Augustin, had a strong aptitude for management. Léonor entered the service of the Lighthouse Commission in 1825, and went on to succeed Augustin as Secretary.[46]

The day before the test of the Cordouan lens in Paris, a committee of the Academy of Sciences reported on Fresnel's memoir and supplements on double refraction—which, although less well known to modern readers than his earlier work on diffraction, struck a more decisive blow for the wave theory of light.[31] Between the test and the reassembly at Cordouan, Fresnel submitted his papers on photoelasticity (16 September 1822), elliptical and circular polarization and optical rotation (9 December), and partial reflection and total internal reflection (7 January 1823),[32] essentially completing his reconstruction of physical optics on the transverse wave hypothesis. Shortly after the Cordouan lens was lit, Fresnel started coughing up blood.[33]

Fresnel lenses of different focal lengths (one collimator, and one collector) are used in commercial and DIY projection. The collimator lens has the lower focal length and is placed closer to the light source, and the collector lens, which focuses the light into the triplet lens, is placed after the projection image (an active matrix LCD panel in LCD projectors). Fresnel lenses are also used as collimators in overhead projectors.

All of us at Fountain City Elementary School loved our field trips to the Carousel. I do hope such programs continue for local children. Goodnight, Ghost!

Plowman drew applause when she said, “At a time when other universities are moving away from supporting arts and humanities, the University of Tennessee-Knoxville is doubling down! From launching the new College of Music to investing in academic hubs like the Humanities Center, to, of course, building this new performance space.”

Virtual reality headsets, such as the Meta Quest 2 and the HTC Vive Pro use Fresnel lenses,[71] as they allow a thinner and lighter form factor than regular lenses.[72] Newer devices, such as the Meta Quest Pro, have switched to a pancake lens design[73] due to its smaller form factor and less chromatic aberration than Fresnel lenses.[74]

Fresnel lightfunction

As a junior or maybe senior in Central High School I worked on props at the Carousel. I also lit OEDIIPUS REX there as an adult. It is a theater that will always mean so much to me. I will miss it.

Since plastic Fresnel lenses can be made larger than glass lenses, as well as being much cheaper and lighter, they are used to concentrate sunlight for heating in solar cookers, in solar forges, and in solar collectors used to heat water for domestic use. They can also be used to generate steam or to power a Stirling engine.

As we headed next door to the Clarence Brown Theatre for a reception, I took a picture of the outside of the Carousel Theatre. That’s Carol Mayo Jenkins, in the photo second from left, and Dale Dickey, center.

In late 1825,[43] to reduce the loss of light in the reflecting elements, Fresnel proposed to replace each mirror with a catadioptric prism, through which the light would travel by refraction through the first surface, then total internal reflection off the second surface, then refraction through the third surface.[44] The result was the lighthouse lens as we now know it. In 1826 he assembled a small model for use on the Canal Saint-Martin,[45] but he did not live to see a full-sized version: he died on 14 July 1827, at the age of 39.

Fresnel lighteffect

Likewise, another famous Knoxville actor, Dale Dickey, nearly lost it as she spoke. “The people who work in theater are both rank sentimentalists, and often more than a little superstitious,” she said. “We fall in love with the buildings in which we work.”

Fresnellights theatre

We are told that unique aspects of the old Carousel will be incorporated into the new design. I hope everyone will visit and see for themselves. I know I can’t wait to see it.

Fresnel lenses are usually made of glass or plastic; their size varies from large (old historical lighthouses, meter size) to medium (book-reading aids, OHP viewgraph projectors) to small (TLR/SLR camera screens, micro-optics). In many cases they are very thin and flat, almost flexible, with thicknesses in the 1 to 5 mm (1⁄32 to 3⁄16 in) range.[citation needed]

Canon and Nikon have used Fresnel lenses to reduce the size of telephoto lenses. Photographic lenses that include Fresnel elements can be much shorter than corresponding conventional lens design. Nikon calls the technology Phase Fresnel.[75][76] The Polaroid SX-70 camera used a Fresnel reflector as part of its viewing system. View and large format cameras can utilize a Fresnel lens in conjunction with the ground glass, to increase the perceived brightness of the image projected by a lens onto the ground glass, thus aiding in adjusting focus and composition.

With an official budget of 500 francs, Fresnel approached three manufacturers. The third, François Soleil, found a way to remove defects by reheating and remolding the glass. Arago assisted Fresnel with the design of a modified Argand lamp with concentric wicks (a concept that Fresnel attributed to Count Rumford[22]), and accidentally discovered that fish glue was heat-resistant, making it suitable for use in the lens. The prototype, finished in March 1820, had a square lens panel 55 cm on a side, containing 97 polygonal (not annular) prisms—and so impressed the Commission that Fresnel was asked for a full eight-panel version. This model, completed a year later in spite of insufficient funding, had panels 76 cm square. In a public spectacle on the evening of 13 April 1821, it was demonstrated by comparison with the most recent reflectors, which it suddenly rendered obsolete.[23]

Fresnel LightBulb

Another automobile application of a Fresnel lens is a rear view enhancer, as the wide view angle of a lens attached to the rear window permits examining the scene behind a vehicle, particularly a tall or bluff-tailed one, more effectively than a rear-view mirror alone. Fresnel lenses have been used on rangefinding equipment and projected map display screens.[70]

Also in 1825, Fresnel unveiled the Carte des Phares ('lighthouse map'), calling for a system of 51 lighthouses plus smaller harbor lights, in a hierarchy of lens sizes called "orders" (the first being the largest), with different characteristics to facilitate recognition: a constant light (from a fixed lens), one flash per minute (from a rotating lens with eight panels), and two per minute (16 panels).[42]

Brings back memories of early ’60s. The Carousel Theater was a roundTent. In the summer the sides were rolled up and tied and in the winter it was very cold, but as always the show must go on! I was a volunteer hostess for the plays. Fabulous, I got to see the plays for free. Fond memories, Kathy Brennan

Fresnel lightLED

Soon after this demonstration, Fresnel published the idea that light, including apparently unpolarized light, consists exclusively of transverse waves, and went on to consider the implications for double refraction and partial reflection.[24]

Fresnel lenses are used as simple hand-held magnifiers. They are also used to correct several visual disorders, including ocular-motility disorders such as strabismus.[68] Fresnel lenses have been used to increase the visual size of CRT displays in pocket televisions, notably the Sinclair TV80. They are also used in traffic lights.

Jenny Boyd, who performed at the Carousel Theatre as an undergraduate in a production of “Brigadoon!” caused many in the crowd to dab at their eyes when she spoke directly to the theater building itself.

Other speakers included Ken Martin, Clarence Brown Theatre artistic director; Tom  Cervone, its managing director; David Brian Alley, head of undergraduate studies in the Theatre Department; UT-Knoxville Chancellor Donde Plowman; UT President Randy Boyd; and, finally, Jenny Boyd, after whom the new Carousel Theatre will be named to honor the $5 million commitment the Boyd Foundation has made to the $20 million construction project budget.

Most modern Fresnel lenses consist only of refractive elements. Lighthouse lenses, however, tend to include both refracting and reflecting elements, the latter being outside the metal rings seen in the photographs. While the inner elements are sections of refractive lenses, the outer elements are reflecting prisms, each of which performs two refractions and one total internal reflection, avoiding the light loss that occurs in reflection from a silvered mirror.

John and Margie Nichols Gill with Tyvi Small, right, vice chancellor for access and engagement. Margie has been actively involved in the fundraising campaign.

Glass Fresnel lenses also are used in lighting instruments for theatre and motion pictures (see Fresnel lantern); such instruments are often called simply Fresnels. The entire instrument consists of a metal housing, a reflector, a lamp assembly, and a Fresnel lens. Many Fresnel instruments allow the lamp to be moved relative to the lens' focal point, to increase or decrease the size of the light beam. As a result, they are very flexible, and can often produce a beam as narrow as 7° or as wide as 70°.[66] The Fresnel lens produces a very soft-edged beam, so is often used as a wash light. A holder in front of the lens can hold a colored plastic film (gel) to tint the light or wire screens or frosted plastic to diffuse it. The Fresnel lens is useful in the making of motion pictures not only because of its ability to focus the beam brighter than a typical lens, but also because the light is a relatively consistent intensity across the entire width of the beam of light.

Fresnel lightpronunciation

“We theater people are a fanciful lot,” she said. “We attribute spiritual meaning to our ghost lights.” Jenkins said some think the lights ward off mischievous spirits, while others believe they light the way for the ghosts, who are believed to inhabit every theater. Some even say the lights provide opportunities for the ghosts to perform onstage when no one is watching, thus appeasing them and preventing them from cursing the theater.

Aircraft carriers and naval air stations typically use Fresnel lenses in their optical landing systems. The "meatball" light aids the pilot in maintaining proper glide slope for the landing. In the center are amber and red lights composed of Fresnel lenses. Although the lights are always on, the angle of the lens from the pilot's point of view determines the color and position of the visible light. If the lights appear above the green horizontal bar, the pilot is too high. If it is below, the pilot is too low, and if the lights are red, the pilot is very low.[67]

Multi-focal Fresnel lenses are also used as a part of retina identification cameras, where they provide multiple in- and out-of-focus images of a fixation target inside the camera. For virtually all users, at least one of the images will be in focus, thus allowing correct eye alignment.

Fresnel lens design allows a substantial reduction in thickness (and thus mass and volume of material) at the expense of reducing the imaging quality of the lens, which is why precise imaging applications such as photography usually still use larger conventional lenses.

Eric: I didn’t know you were the house photographer there — but I should have guessed! What a great experience that must have been!

This tugs at my heartstrings. My first performance at the Carousel was in 1964 in a production of “The Snow Queen.” I was 8. This was one of the three-shows-per-year schedule put on by the Children’s Theater program. It was a child actor’s dream – every show ran for two weeks, and they bused in all the 3rd-5th graders from the entire city school system to see them. Each show was double cast, and the actors got to miss school every other day for two weeks. I was in at least one children’s show every year until I was 15.

Perhaps the most widespread use of Fresnel lenses, for a time, occurred in automobile headlamps, where they can shape the roughly parallel beam from the parabolic reflector to meet requirements for dipped and main-beam patterns, often both in the same headlamp unit (such as the European H4 design). For reasons of economy, weight, and impact resistance, newer cars have dispensed with glass Fresnel lenses, using multifaceted reflectors with plain polycarbonate lenses. However, Fresnel lenses continue in wide use in automobile tail, marker, and reversing lights.

In May 1824,[13] Fresnel was promoted to Secretary of the Commission des Phares, becoming the first member of that body to draw a salary,[34] albeit in the concurrent role of Engineer-in-Chief.[35] Late that year, being increasingly ill, he curtailed his fundamental research and resigned his seasonal job as an examiner at the École Polytechnique, in order to save his remaining time and energy for his lighthouse work.[36][37]

I joked that Robert Redford had come to the ghost light ceremony! It actually was Kent Farris and his sweet wife, Susan. (They put up with me always making Robert Redford remarks!)

The first fixed lens to be constructed with toroidal prisms was a first-order apparatus designed by the Scottish engineer Alan Stevenson under the guidance of Léonor Fresnel, and fabricated by Isaac Cookson & Co. using French glass; it entered service at the Isle of May, Scotland, on 22 September 1836.[47] The first large catadioptric lenses were made in 1842 for the lighthouses at Gravelines and Île Vierge, France; these were fixed third-order lenses whose catadioptric rings (made in segments) were one metre in diameter. Stevenson's first-order Skerryvore lens, lit in 1844, was only partly catadioptric; it was similar to the Cordouan lens except that the lower slats were replaced by French-made catadioptric prisms, while mirrors were retained at the top. The first fully catadioptric first-order lens, installed at Pointe d'Ailly in 1852, also gave eight rotating beams plus a fixed light at the bottom; but its top section had eight catadioptric panels focusing the light about 4 degrees ahead of the main beams, in order to lengthen the flashes. The first fully catadioptric lens with purely revolving beams—also of first order—was installed at Saint-Clément-des-Baleines in 1854, and marked the completion of Augustin Fresnel's original Carte des Phares.[48]

A Fresnel lens (/ˈfreɪnɛl, -nəl/ FRAY-nel, -⁠nəl; /ˈfrɛnɛl, -əl/ FREN-el, -⁠əl; or /freɪˈnɛl/ fray-NEL[1]) is a type of composite compact lens which reduces the amount of material required compared to a conventional lens by dividing the lens into a set of concentric annular sections.

“Here’s to a job well done, our special friend,” she said. “We’ll see you soon, with your lights shining bright. Now, we need to turn off the Carousel ghost light for the last time to make way for a new beginning.”

The simpler dioptric (purely refractive) form of the lens was first proposed by Georges-Louis Leclerc, Comte de Buffon[2], and independently reinvented by the French physicist Augustin-Jean Fresnel (1788–1827) for use in lighthouses.[3][4] The catadioptric (combining refraction and reflection) form of the lens, entirely invented by Fresnel, has outer prismatic elements that use total internal reflection as well as refraction to capture more oblique light from the light source and add it to the beam, making it visible at greater distances.

David Alley first attended a show at the Carousel when he was 8 years old. The experience made a great impression on him. After becoming an actor, himself, he has performed in the facility in 15 productions.

James Timmins Chance modified Thomas Stevenson's all-glass holophotal design by arranging the double-reflecting prisms about a vertical axis. The prototype was shown at the 1862 International Exhibition in London. Later, to ease manufacturing, Chance divided the prisms into segments, and arranged them in a cylindrical form while retaining the property of reflecting light from a single point back to that point. Reflectors of this form, paradoxically called "dioptric mirrors", proved particularly useful for returning light from the landward side of the lamp to the seaward side.[51]

Fresnel Lightprice

High-quality glass Fresnel lenses were used in lighthouses, where they were considered state of the art in the late 19th and through the middle of the 20th centuries; most lighthouses have now retired glass Fresnel lenses from service and replaced them with much less expensive and more durable aerobeacons, which themselves often contain plastic Fresnel lenses.[citation needed] Lighthouse Fresnel lens systems typically include extra annular prismatic elements, arrayed in faceted domes above and below the central planar Fresnel, in order to catch all light emitted from the light source. The light path through these elements can include an internal reflection, rather than the simple refraction in the planar Fresnel element. These lenses conferred many practical benefits upon the designers, builders, and users of lighthouses and their illumination. Among other things, smaller lenses could fit into more compact spaces. Greater light transmission over longer distances, and varied patterns, made it possible to triangulate a position.[citation needed]

I am blessed to have been able to see plays while in grade school and later perform and work on productions in the Carousel. Many good memories that will never be erased from my mind. I can even still smell the dirt they hauled in for Tobacco Road’s set. Always a theatre experience like no other!

My childhood home was on Lilly Ave, only a block away from The Carousel Theatre. As a young girl totally enthralled by anything in the world of performance, theater and dance in particular, I would talk my sister into walking to the theater on summer nights and we would literally sneak under the heavy curtains that surrounded this theater in the round and watch the performances until it was getting dark, when we would then walk back home. I have many but these are some of the best and most cherished memories of being so very fortunate to have grown up in the U. T. area. Thank you for sharing this very sweet story.

Fresnel lenses can concentrate sunlight onto solar cells with a ratio of almost 500:1.[77] This allows the active solar-cell surface to be reduced, lowering cost and allowing the use of more efficient cells that would otherwise be too expensive.[78] In the early 21st century, Fresnel reflectors began to be used in concentrating solar power (CSP) plants to concentrate solar energy. One application was to preheat water at the coal-fired Liddell Power Station, in Hunter Valley Australia.

There are two main types of Fresnel lens: imaging and non-imaging. Imaging Fresnel lenses use segments with curved cross-sections and produce sharp images, while non-imaging lenses have segments with flat cross-sections, and do not produce sharp images.[63] As the number of segments increases, the two types of lens become more similar to each other. In the abstract case of an infinite number of segments, the difference between curved and flat segments disappears.

UT President Randy Boyd even got a little emotional when talking about his wife, Jenny. “She’s beautiful, smart, talented — and she has a PUB!” he exclaimed. (She is the proprietor of Boyd’s Jig and Reel in Knoxville’s Old City.)

The use of Fresnel lenses for image projection reduces image quality, so they tend to occur only where quality is not critical or where the bulk of a solid lens would be prohibitive. Cheap Fresnel lenses can be stamped or molded of transparent plastic and are used in overhead projectors and projection televisions.

Production of one-piece stepped dioptric lenses—roughly as envisaged by Buffon—became feasible in 1852, when John L. Gilliland of the Brooklyn Flint-Glass Company patented a method of making lenses from pressed and molded glass. The company made small bull's-eye lenses for use on railroads, steamboats, and docks;[56] such lenses were common in the United States by the 1870s.[13]: 488  In 1858 the company produced "a very small number of pressed flint-glass sixth-order lenses" for use in lighthouses—the first Fresnel lighthouse lenses made in America.[56] By the 1950s, the substitution of plastic for glass made it economic to use Fresnel lenses as condensers in overhead projectors.[57]

From left, Elizabeth Weatherly, Liz Stowers, Margie Nichols Gill, and Theresa Lee, the soon-to-retire dean of the College of Arts and Sciences. Weatherly is the new executive director of advancement for the College of Arts and Sciences.

In 1825 Fresnel extended his fixed-lens design by adding a rotating array outside the fixed array. Each panel of the rotating array was to refract part of the fixed light from a horizontal fan into a narrow beam.[11][41]

On Tuesday, in a touching ceremony, theater-lovers witnessed the switching off of the ghost light in the University of Tennessee’s 73-year-old Carousel Theatre for the last time. The building is about to be disassembled and taken away to make room for a brand new theater building — one that will have state of the art sound and lighting technology, space to hold receptions, and, perhaps most important of all, restrooms! Until now, patrons have had to go next door to the Clarence Brown Theatre to avail themselves of toilets.

Jenny Boyd, after whom the new 20,000-square-foot Carousel Theatre will be named, extinguishes the ghost light at the old theater building.

Thomas Stevenson (younger brother of Alan) went a step beyond Fresnel with his "holophotal" lens, which focused the light radiated by the lamp in nearly all directions, forward or backward, into a single beam.[49] The first version, described in 1849, consisted of a standard Fresnel bull's-eye lens, a paraboloidal reflector, and a rear hemispherical reflector (functionally equivalent to the Rogers mirror of 60 years earlier, except that it subtended a whole hemisphere). Light radiated into the forward hemisphere but missing the bull's-eye lens was deflected by the paraboloid into a parallel beam surrounding the bull's-eye lens, while light radiated into the backward hemisphere was reflected back through the lamp by the spherical reflector (as in Rogers' arrangement), to be collected by the forward components. The first unit was installed at North Harbour, Peterhead, in August 1849. Stevenson called this version a "catadioptric holophote", although each of its elements was either purely reflective or purely refractive. In the second version of the holophote concept, the bull's-eye lens and paraboloidal reflector were replaced by a catadioptric Fresnel lens—as conceived by Fresnel, but expanded to cover the whole forward hemisphere. The third version, which Stevenson confusingly called a "dioptric holophote", was more innovative: it retained the catadioptric Fresnel lens for the front hemisphere, but replaced the rear hemispherical reflector with a hemispherical array of annular prisms, each of which used two total internal reflections to turn light diverging from the center of the hemisphere back toward the center. The result was an all-glass holophote, with no losses from metallic reflections.[50]

I was in other shows there, too — from Macbeth in 1965 to The Physicists in 1980. I met my late first wife during that one; she was appearing next door at CBT in Mother Courage, and both casts were using the CBT green room.

Fresnel lenses have also been used in the field of popular entertainment. The British rock artist Peter Gabriel made use of them in his early solo live performances to magnify the size of his head, in contrast to the rest of his body, for dramatic and comic effect. In the Terry Gilliam film Brazil, plastic Fresnel screens appear ostensibly as magnifiers for the small CRT monitors used throughout the offices of the Ministry of Information. However, they occasionally appear between the actors and the camera, distorting the scale and composition of the scene to humorous effect. The Pixar movie Wall-E features a Fresnel lens in the scenes where the protagonist watches the musical Hello, Dolly! magnified on an iPod.

“I prefer to think of them as benevolent sentinels,” Jenkins said, “guarding this precious space, protecting all the work, the creativity, the passion that has been unleashed in these walls.” She barely held back tears while concluding her remarks.

Fresnel lenses are used in left-hand-drive European lorries entering the UK and Republic of Ireland (and vice versa, right-hand-drive Irish and British trucks entering mainland Europe) to overcome the blind spots caused by the driver operating the lorry while sitting on the wrong side of the cab relative to the side of the road the car is on. They attach to the passenger-side window.[69]

The first person to focus a lighthouse beam using a lens was apparently the London glass-cutter Thomas Rogers, who proposed the idea to Trinity House in 1788.[6] The first Rogers lenses, 53 cm in diameter and 14 cm thick at the center, were installed at the Old Lower Lighthouse at Portland Bill in 1789. Behind each lamp was a back-coated spherical glass mirror, which reflected rear radiation back through the lamp and into the lens. Further samples were installed at Howth Baily, North Foreland, and at least four other locations by 1804. But much of the light was wasted by absorption in the glass.[6][7]

The design allows the construction of lenses of large aperture and short focal length without the mass and volume of material that would be required by a lens of conventional design. A Fresnel lens can be made much thinner than a comparable conventional lens, in some cases taking the form of a flat sheet.