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  2. Passive infrared sensor - Wikipedia

    en.wikipedia.org/wiki/Passive_infrared_sensor

    A passive infrared sensor ( PIR sensor) is an electronic sensor that measures infrared (IR) light radiating from objects in its field of view. They are most often used in PIR-based motion detectors. PIR sensors are commonly used in security alarms and automatic lighting applications. PIR sensors detect general movement, but do not give ...

  3. Fresnel lens - Wikipedia

    en.wikipedia.org/wiki/Fresnel_lens

    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.

  4. Fresnel equations - Wikipedia

    en.wikipedia.org/wiki/Fresnel_equations

    Fresnel equations. Partial transmission and reflection of a pulse travelling from a low to a high refractive index medium. At near-grazing incidence, media interfaces appear mirror-like especially due to reflection of the s polarization, despite being poor reflectors at normal incidence. Polarized sunglasses block the s polarization, greatly ...

  5. Microlens - Wikipedia

    en.wikipedia.org/wiki/Microlens

    Microlens. A microlens is a small lens, generally with a diameter less than a millimetre (mm) and often as small as 10 micrometres (μm). The small sizes of the lenses means that a simple design can give good optical quality but sometimes unwanted effects arise due to optical diffraction at the small features. A typical microlens may be a ...

  6. Optical landing system - Wikipedia

    en.wikipedia.org/wiki/Optical_landing_system

    The improved fresnel lens optical landing system, IFLOLS, uses a fiber optic "source" light, projected through lenses to present a sharper, crisper light. This has enabled pilots to begin to fly "the ball" further away from the ship making the transition from instrument flight to visual flight smoother.

  7. Fresnel number - Wikipedia

    en.wikipedia.org/wiki/Fresnel_number

    The Fresnel number is a useful concept in physical optics. The Fresnel number establishes a coarse criterion to define the near and far field approximations. Essentially, if Fresnel number is small – less than roughly 1 – the beam is said to be in the far field. If Fresnel number is larger than 1, the beam is said to be near field.

  8. New Presque Isle Light - Wikipedia

    en.wikipedia.org/wiki/New_Presque_Isle_Light

    Even with the reflectors, the lens still could not produce nearly as much light as the Fresnel lens system. Furthermore, it was difficult to clean and maintain, resulting in constant repair, adjustment, and other maintenance. Clearly, the Fresnel lens system was the optimum choice for the Lighthouse Service and for the Presque Isle Harbor ...

  9. Montauk Point Light - Wikipedia

    en.wikipedia.org/wiki/Montauk_Point_Light

    Montauk Light was the first lighthouse in New York State, and is the fourth-oldest active lighthouse in the United States. The tower is 110 feet 6 inches (33.68 metres) high. The current light is a 3 1 ⁄ 2 order bivalve (clamshell) Fresnel lens.

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