What is aFresnel lensused for

What it does: A one-way shoe stretcher frees up space in the toe box, widening the shoe for a better fit. Insert spot-stretching plugs for additional stretching at pressure points. This will prevent your shoes from causing bunions, corns, and calluses. A one-way shoe stretcher will work on most flat shoes, including flats, sneakers, and bucks.

With the advent of the Argand burner, a reliable and steady illuminant, it became possible to develop effective optical apparatuses for increasing the intensity of the light. In the first equipment of this type, known as the catoptric system, paraboloidal reflectors concentrated the light into a beam. In 1777 William Hutchinson of Liverpool, England, produced the first practical mirrors for lighthouses, consisting of a large number of small facets of silvered glass set in a plaster cast molded to a paraboloid form. More generally, shaped metal reflectors were used, silvered or highly polished. These were prone, however, to rapid deterioration from heat and corrosion; the glass facet reflector, although not as efficient, lasted longer. The best metallic reflectors available in 1820 were constructed of heavily silvered copper in the proportion of 6 ounces (170 grams) of silver to 16 ounces (454 grams) of copper (compared with the 0.5 ounce [14 grams] of silver to 16 ounces of copper commonly used for plated tableware of the period). With such heavy plating, cleaning cloths were kept for subsequent recovery of the silver. These mirrors could increase the intensity of an Argand burner, nominally about five candlepower, almost 400 times.

Best for: Anyone dealing with nagging foot-related issues (bunions, corns, and hammertoes) and needing spot stretching in trouble areas.

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While a boot stretcher works on most boots, high heel boots require a high heel boot stretcher, and Western boots require a Western boot shoe stretcher.

Prior to Fresnel’s invention the best mirror systems could produce a light of about 20,000 candlepower with an Argand burner. The Fresnel lens system increased this to 80,000 candlepower, roughly equivalent to a modern automobile headlamp. With the pressure oil burner, intensities of up to 1,000,000 candlepower could be achieved. For a light of this order, the burner mantle would measure 4 inches (100 mm) in diameter. The rotating lens system would have four large Fresnel glass lens panels, 12 feet high, mounted about four feet from the burner on a revolving lens carriage. The lens carriage would probably weigh five tons, about half of it being the weight of the glass alone. The rotating turntable would float in a circular cast-iron trough containing mercury. With this virtually frictionless support bearing, the entire assembly could be smoothly rotated by weight-driven clockwork. If the illuminant was acetylene gas, the lens rotation could be driven by gas pressure.

What it does: A two-way shoe stretcher lengthens and widens the entire shoe. Insert spot-stretching plugs for trouble spots. A two-way shoe stretcher gets rid of the “too tight” feeling with new shoes, and reduces the break-in period.

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In 1821 Augustin Fresnel of France produced the first apparatus using the refracting properties of glass, now known as the dioptric system, or Fresnel lens. On a lens panel he surrounded a central bull’s-eye lens with a series of concentric glass prismatic rings. The panel collected light emitted by the lamp over a wide horizontal angle and also the light that would otherwise escape to the sky or to the sea, concentrating it into a narrow, horizontal pencil beam. With a number of lens panels rotating around the lamp, he was then able in 1824 to produce several revolving beams from a single light source, an improvement over the mirror that produces only a single beam. To collect more of the light wasted vertically, he added triangular prism sections above and below the main lens, which both refracted and reflected the light. By doing this he considerably steepened the angle of incidence at which rays shining up and down could be collected and made to emerge horizontally. Thus emerged the full Fresnel catadioptric system, the basis of all lighthouse lens systems today. To meet the requirement for a fixed all-around light, in 1836 English glassmaker William Cookson modified Fresnel’s principle by producing a cylindrical drum lens, which concentrated the light into an all-around fan beam. Although not as efficient as the rectangular panel, it provided a steady, all-around light. Small drum lenses, robust and compact, are widely used today for buoy and beacon work, eliminating the complication of a rotating mechanism; instead of revolving, their lights are flashed on and off by an electronic code unit.

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How does aFresnel lenswork

Maintaining the shape of your leather shoes requires you to pay attention to your footwear. This is especially true when you’re not wearing them. Keeping the leather hydrated with shoe...

Installations of this type entered common use, although many were converted to electric lamps with electric motor drives. Modern lens equipment of the same type is much smaller, perhaps 30 inches (75 cm) high, mounted on ball bearings and driven by an electric motor. Lens panels can be molded in transparent plastic, which is lighter and cheaper. Drum lenses are also molded in plastic. In addition, with modern techniques, high-quality mirrors can be produced easily and cheaply.

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Most of us are on our feet for the greater portion of the day, so when our shoes hurt, life can suck. But it doesn’t have to be that way. Shoe stretchers can widen and lengthen a shoe overnight, saving you the trouble of breaking in a new pair while alleviating pressure points. But which type of shoe stretcher should you use? That depends on the type of shoe you’d like to stretch and your pain relief needs.

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One of the greatest things about leather is seeing how it develops a patina over time. No two pieces are the same nor will they live the same life, which...

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What it does: Made of cast-iron steel, a ball and ring shoe stretcher is an effective way to loosen pressure points overnight. A cast-iron ball and ring shoe stretcher is an ideal complement to a one-way or two-way shoe stretcher, as this type of stretcher reaches areas other stretchers cannot.

Because high heels come in many different heel heights, our FootFitter High Heel Shoe Stretcher is available in two sizes: one for 1” – 3” heels, and one for 3” – 6” heels.

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Remember: No matter which shoe stretcher you use, a stretcher work best on natural materials like leather and suede. Manmade materials like polyurethane and vinyl don’t have as much give, and tend to revert back to their original shape over time. If you own shoes comprised of manmade materials, this just means you’ll have to re-stretch the shoes again later on.

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Maintaining the shape of your leather shoes requires you to pay attention to your footwear. This is especially true when you’re not wearing them. Keeping the leather hydrated with shoe...

What it does: A vamp and instep raiser stretches the vamp (the top of part of a shoe that covers the instep and toes), alleviating pressure on the instep of your foot.

What it does: A boot stretcher loosens the toe area, while spot-stretching plugs give you additional pain relief at trouble spots. A boot stretcher reduces the break-in period, preventing pain and blisters.

Wearing your leathers shoes on a daily basis leads to inevitable creases. As much as we’d like to keep our shoes in pristine condition, they’re eventually going to show some...

Although the mirror could effectively concentrate the light into an intense beam, it was necessary to rotate it to make it visible from any direction. This produced the now familiar revolving lighthouse beam, with the light appearing as a series of flashes. Mariners were not favourably disposed to these early flashing lights, contending that a fixed steady light was essential for a satisfactory bearing. However, the greatly increased intensity and the advantage of using a pattern of flashes to identify the light gradually overcame their objections. The first revolving-beam lighthouse was at Carlsten, near Marstrand, Sweden, in 1781.

What it does: A high heel shoe stretcher widens the toe box so there’s less pressure on your toes and the balls of your feet. Use spot-stretching plugs for targeted relief from bunions, calluses, and corns.