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Belay Glasses
Belay glasses are eyeglasses with Porro prism, prismatic lenses that are used by belaying, belayers in rock climbing to avoid the neck strain commonly associated with belaying. Belaying involves a person standing on a stable platform below a rock climber controlling the tension and friction of the climber's rope. Since this activity requires craning one's neck to look up at the climber, a common malady named "belayer's neck" can occur. The prismatic lenses of the belay glasses are arranged so as to bend light from above through total internal reflection into the observer's eye, allowing the belayer to observe the climber while maintaining a comfortable head/neck position. The design based on the eyeglasses frame provides for a split field of vision: * the central field through the lenses, providing a vertical view to the climber; * the peripheral field around the sides of the lenses, allowing the belayer to remain aware of their surroundings. The first belay glasses were invented ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eyeglasses
Glasses, also known as eyeglasses or spectacles, are vision eyewear, with lenses (clear or tinted) mounted in a frame that holds them in front of a person's eyes, typically utilizing a bridge over the nose and hinged arms (known as temples or temple pieces) that rest over the ears. Glasses are typically used for vision correction, such as with reading glasses and glasses used for nearsightedness; however, without the specialized lenses, they are sometimes used for cosmetic purposes. Safety glasses provide eye protection against flying debris for construction workers or lab technicians; these glasses may have protection for the sides of the eyes as well as in the lenses. Some types of safety glasses are used to protect against visible and near-visible light or radiation. Glasses are worn for eye protection in some sports, such as squash. Glasses wearers may use a strap to prevent the glasses from falling off. Wearers of glasses that are used only part of the time may have the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Porro Prism
In optics, a Porro prism, named for its inventor Ignazio Porro, is a type of ''reflection prism'' used in optical instruments to alter the orientation of an image. Description It consists of a block of material shaped like a right geometric prism with right-angled triangular end faces. In operation, light enters the large rectangular face of the prism, undergoes total internal reflection twice from the sloped faces, and exits again through the large rectangular face. When the light enters and therefore exits the glass at normal incidence, the prism is not dispersive. An image travelling through a Porro prism is rotated by 180° and exits in the opposite direction offset from its entry point. While a single Porro prism can be constructed to work as well as a roof prism, it is seldom used as such. Therefore, to reduce the cost of production for a Porro prism, the edge of the roof is usually left out. Sometimes only one small window as an entrance surface and one window as e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Belaying
Belaying is a variety of techniques climbers use to create friction within a climbing system, particularly on a climbing rope, so that a falling climber does not fall very far. A climbing partner typically applies tension at the other end of the rope whenever the climber is not moving, and removes the tension from the rope whenever the climber needs more rope to continue climbing. The term "belay" also means the place where the belayer is anchored; this is typically the ground or a ledge, but may be a ''hanging belay'', where the belayer themself is suspended from an anchor in the rock. How it works Belaying is a critical part of the climbing system. A correct belaying method lets the belayer hold the entire weight of the climber with relatively little force, and easily arrest even a long fall. In its simplest form, a belay consists of merely a rope that runs from a climber to another person (the belayer) who can stop the climber's fall. In the modern day, most climbers us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rock Climbing
Rock climbing is a sport in which participants climb up, across, or down natural rock formations. The goal is to reach the summit of a formation or the endpoint of a usually pre-defined route without falling. Rock climbing is a physically and mentally demanding sport, one that often tests a climber's strength, endurance, agility and balance along with mental control. Knowledge of proper climbing techniques and the use of specialized climbing equipment is crucial for the safe completion of routes. Because of the wide range and variety of rock formations around the world, rock climbing has been separated into several different styles and sub-disciplines, such as scrambling, bouldering, sport climbing, and trad (traditional) climbing another activity involving the scaling of hills and similar formations, differentiated by the rock climber's sustained use of hands to support their body weight as well as to provide balance. Rock climbing competitions have the objectives of either ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Belay Glasses Lens
Belaying is a variety of techniques climbers use to create friction within a climbing system, particularly on a climbing rope, so that a falling climber does not fall very far. A climbing partner typically applies tension at the other end of the rope whenever the climber is not moving, and removes the tension from the rope whenever the climber needs more rope to continue climbing. The term "belay" also means the place where the belayer is anchored; this is typically the ground or a ledge, but may be a ''hanging belay'', where the belayer themself is suspended from an anchor in the rock. How it works Belaying is a critical part of the climbing system. A correct belaying method lets the belayer hold the entire weight of the climber with relatively little force, and easily arrest even a long fall. In its simplest form, a belay consists of merely a rope that runs from a climber to another person (the belayer) who can stop the climber's fall. In the modern day, most climbers u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Total Internal Reflection
Total internal reflection (TIR) is the optical phenomenon in which waves arriving at the interface (boundary) from one medium to another (e.g., from water to air) are not refracted into the second ("external") medium, but completely reflected back into the first ("internal") medium. It occurs when the second medium has a higher wave speed (i.e., lower refractive index) than the first, and the waves are incident at a sufficiently oblique angle on the interface. For example, the water-to-air surface in a typical fish tank, when viewed obliquely from below, reflects the underwater scene like a mirror with no loss of brightness (Fig.1). TIR occurs not only with electromagnetic waves such as light and microwaves, but also with other types of waves, including sound and water waves. If the waves are capable of forming a narrow beam (Fig.2), the reflection tends to be described in terms of "rays" rather than waves; in a medium whose properties are independent of direction, such as air, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
