Compound parabolic concentratorsolar collector

Edmund Scientific has provided items used in television shows such as House, MythBusters, 24, Modern Marvels, and motion pictures such as Star Trek, and the 1975 version of Escape to Witch Mountain. Wah Chang, the artist who designed and built several props in the 1960s for the Star Trek television show, used moiré patterns found in the Edmund Scientific Educator's and Designer's Moiré Kit for the texture used in the Starfleet communicator props.[6]

Edmund Scientific Corporation, based in Barrington, New Jersey, was founded in 1942 as a retailer of surplus optical parts like lenses. It later branched out into complete systems like telescopes and microscopes, and in the 1960s, a wide variety of science toys and kits. Through the 1970s and 80s they were best known for their mail order sales and associated catalogs, although they also maintained a retail presence at their factory store.

Parabolictroughconcentrator

Some sources claim that certain of the original polyhedral dice used in the Dungeons & Dragons role-playing game system were obtained from Edmund Scientific.[4]

As of 2009, online sales made up the bulk of Edmund Scientific's revenues. The company was still selling telescopes (including an updated version of their Astroscan Telescope), microscopes (mostly they have carried the Boreal brand, manufactured for their parent company Science Kit LLC), surplus optics, magnets, and Fresnel lenses. They continued to sell many of their old favorites along with new items such as the Impossiball and hand boilers as well as other science-themed toys, novelty items, gifts, and gadgets.[citation needed]

"Edmund is the best source we know of for low-cost scientific gadgetry (including math and optics gear). [In this category,] many of the items we found independently... turned up in the Edmund catalog, so we were obliged to recommend that in this area we've been precluded."[2]

As of 2017, Edmund Optics continued to offer brand-new stock optics, as well as offering custom and specialized optics to corporations and higher education institutions.[citation needed]

Compound parabolic concentratorPDF

Section 7.6. of this book covers the fundamental optical principles of CPC collectors and also considers particular cases of truncated collector. Some practical examples are also presented. Section 7.7. talks about the orientation of CPC collectors. While CPC technology does not require continuous tracking, proper orientation with respect to the sun position is crucial to maximize absorbed radiation. The theoretical material in this section is also supported by practical examples.

Edmund's catered to the 1960s generation by expanding and highlighting their line of projectors, color wheels, black lights, filters, and other optical devices which could be used by rock bands and in psychedelic light shows. Other items catering to the counterculture were eventually added to the catalog covering the fields of Biofeedback, ESP, Kirlian photography, Pyramid power, and alternative energy.[citation needed]

There are some other useful expressions that describe the design of CPC concentrators. The following equations relate the focal distance of the side parabola (f) to the acceptance angle, receiver size, and height of the collector (Duffie and Beckman, 2013):

Compound parabolic concentratorequation

In 1942, amateur photographer Norman W. Edmund (1916–2012[1]) found it hard to find lenses he needed for his hobby. He found that the military was happy to sell off less-than-perfect optics for next to nothing and began using these. Buying in bulk, he began to sell his own surplus through advertisements in photography magazines. It was so successful he founded "'Edmund Salvage Corporation'" in 1942. Working from a card table in his home, the company soon had so much stock that they had to rent space in more than 30 separate garages.[2]

The compound parabolic concentrators (CPC) are typical representatives of non-imaging concentrators, which are capable of collecting all available radiation - both beam and diffuse - and directing it to the receiver. These concentrators do not have such strict requirements for the incidence angle as the parabolic troughs have, which makes them attractive from the point of view of system simplicity and flexibility. Like parabolic and other shapes, CPC concentrators can be applied in both linear (troughs) and three-dimensional (parabolocylinder) versions. The same as in "pure" parabola case, troughs are most widespread and useful for this type of concentrator.

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In 2000 Edmund Scientific was purchased by Science Kit and Boreal Laboratories, a western New York based science supply company. Science Kit and Boreal Laboratories is part of a group of companies that provide science supplies to elementary, middle, and high schools, as well as colleges and universities. This group falls under the unofficial umbrella "VWR Education", and its constituent enterprises are owned by VWR International, a multi-national conglomerate with offices in India, China, Europe, Canada, and the United States. They are no longer affiliated with Edmund Optics Inc.[citation needed]

Parabolicdish collector diagram

In 2001, the Barrington, New Jersey, store closed after Edmund Scientific was acquired by Science Kit and Boreal Laboratories.[citation needed]

Following Sputnik, Edmund was able to capitalize on a growing national interest in science and astronomy. They expanded their business into a full line of telescopes and telescope kits as well as equipment, parts, and supplies for other scientific fields such as physics, optics, chemistry, microscopy, electronics, and meteorology. They continued to grow as a supplier to teachers and schools with demonstration devices and kits which covered most fields of science.

Norman W. Edmund retired in 1975 and left the company to his son, Robert. The company continued on as before into the 1980s, but the original business model began to wane. Robert split the company into Edmund Scientifics and Edmund Optics.[2] Edmund Scientifics marketed to consumers and specialized in science-themed toys, vaguely high-tech household gadgets, and "science gifts." Edmund Optics did not have a public showroom like Edmund Scientifics, although the two organizations shared the same building. The large back room of Edmund Scientifics still sold military surplus from World War II and other wars well into the 1980s and into the mid-1990s. Some of the items in the surplus room were from German and other non-American militaries. None of these items were in the mail-order catalogs. They also sold other surplus wares of interest to hobbyists, including specialized motors and other miscellaneous electronics, parts from toys, and other household items.[citation needed]

Authors: Mark Fedkin, John A. Dutton e-Education Institute, College of Earth and Mineral Sciences, Penn State University.

Compound parabolic concentratorwikipedia

In 1984, the company split into Edmund Scientific and Edmund Industrial Optics, the latter taking over their optical manufacturing. Later known simply as Edmund Optics, the commercial side of the company continued to expand and now has a multinational presence. In 2001, the two companies were purchased by Boreal Science, which was in turn purchased by VWR International. Many of the science toys and kits are currently offered by the online retailer Scientifics Direct.

In addition to optics, the company soon branched out into various kits and plans for optics-related systems like telescopes and microscopes. It soon changed its name to Edmund Scientific and made its name with ads in publications like Scientific American. Its advertisements caught the attention of hobbyists, amateur astronomers, high school students, and cash-strapped researchers.[1] The company also began publishing a series of pamphlets on telescopes in a do-it-yourself fashion that was popular in contemporary magazines like Popular Mechanics. These were later collected into book form in 1967, "All About Telescopes", which contained many plans for telescope systems that became a best seller and was republished repeatedly into the 1980s.[3]

Knowing that the geometric concentration ratio is the quotient of the aperture area to the receiver area (see Section 2.3), for a linear CPC concentrator, we can obtain the relationship between the concentration ratio and the acceptance angle:

CPC lens

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Book chapter: Duffie, J.A. Beckman, W., Solar Engineering of Thermal Processes, Chapter 7: Sections 7.6 and 7.7 - pp. 337-349. This book is available online through the PSU Library system and can also be accessed through e-reserves (via the Library Resources tab).

One large parabolic mirror with a second mirror sitting tangent to the parabolic axis with an end at mirror #1’s focus. The distance between the two upper ends of the parabolas is labeled aperture (2a) and the bottom two ends is labeled receiver. Dashed lines connect one top end to the opposite bottom end. The angle between their y intercept, y-axis and upper tip represents the acceptance half-angle.

The business continued in the post-war era and owned so much stock that when the Korean War started the military came to him for the optics needed to repair war-era systems. One official told him, "Gee, you have more optics than the Army!"[2] In 1948 they completed a new building and warehouse in Barrington and opened a retail store at the front. Among its displays was a complete periscope from a WWII Japanese submarine.[2] The core of the company in this era remained surplus lenses. These were single-element lenses, shipped in 2.5-by-4.25-inch (64 mm × 108 mm) coin envelopes, with the approximate diameter and focal length stenciled on them. Reflecting their salvage and surplus origins, available diameters and focal lengths did not fall into regular progressions.

Parabolicdish collector

Beginning in 2000, Edmund Optics offered a variety of experimental grade and stock clearance items via a print catalog and online under a separate business named Anchor Optics, but this operation ceased in 2016, and the current Anchor Optics web site now redirects to a page at Edmund Optics listing clearance items.[5]

The John A. Dutton Institute for Teaching and Learning Excellence is the learning design unit of the College of Earth and Mineral Sciences at The Pennsylvania State University.

The company became briefly famous in 1973 when Comet Kohoutek approached Earth and the company sold out of telescopes, a fact that made national news.[2] Neil deGrasse Tyson would later comment that "The Edmund Scientific catalog was a geek's paradise. At a time when no one had access to lasers, they had them for sale."[2]

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The geometry of a CPC collector is demonstrated in Figure 2.12. If we consider a CPC trough, this diagram represents its cross-section. Each side of the shape is a parabola, and each of the parabolas has its focus at the lower edge of the other parabola (e.g., F is the focus of the right-hand parabola in Figure 2.12). Each parabola axis is tilted relative to the axis of the CPC shape. One of its key parameters is acceptance half-angle ( θ c), which is the angle between the axis of the collector and the line connecting the focus of one of the parabolas with the opposite edge of the aperture. The collector is designed in such a way that each ray coming into the CPC aperture at an angle smaller that θ reaches the receiver; if this angle is greater than θ c , the ray will return (Figure 2.13). The relationship between the size of the aperture (2a), the size of the receiver (2a') and the acceptance half-angle is expressed through the following equation:

Among the company's best-known products were the Astroscan reflector telescope and their inexpensive bimetallic jumping disks.