In recent decades, electrical sensors have been used as standard equipment for measuring physical and mechanical phenomena. Although they are ubiquitous in test and measurement, they are inherently flawed as electrified devices, such as losses during signal transmission, and are susceptible to electromagnetic noise. These defects can make the use of electrical sensors quite challenging or even completely unsuitable in some special applications. Fiber optic sensors are an excellent solution to these applications, using a beam instead of current and a standard fiber instead of copper as the transmission medium. Over the past two decades, the development of optoelectronics and the vast array of innovations in the fiber optic communications industry have dramatically reduced the price and quality of optical devices. By adjusting the economic scale of the optical device industry, fiber optic sensors and fiber optic instruments have been extended from laboratory test research to field applications, such as building structural health monitoring applications. From a basic point of view, the fiber optic sensor changes one or more properties of the transmitted light wave, such as intensity, phase, polarization state, and frequency, based on changes in the external environmental parameters being tested. The intrinsic (hybrid) fiber optic sensor uses only the fiber as the transmission medium between the device and the sensing element, while the intrinsic fiber sensor uses the fiber itself as the sensing element. At the heart of fiber-optic sensing technology is fiber – a thin glass wire that can travel at its center. The fiber is mainly composed of three parts: a core, a cladding, and a buffer coaTIng. The cladding is capable of reflecting stray light waves emitted from the core back into the core to ensure that the light wave has the lowest transmission loss in the core. This function is implemented by the fact that the refractive index of the core is higher than the refractive index of the cladding, so that total internal reflection occurs when light waves propagate from the core to the cladding. The outermost protective layer provides protection against external damage caused by external environment or external forces. It is also possible to use multiple layers of protection depending on the strength and protection procedure required. Figure 1. Cross-sectional view of a typical fiber Fiber Bragg Grating (FBS) Sensor Fiber Bragg Grating Sensors are the most widely used and widely used fiber optic sensors that change the wavelength of the reflected light waves based on changes in ambient temperature and/or strain. Fiber Bragg gratings use a holographic interferometry or phase mask method to expose a small piece of light-sensitive fiber under a light wave with a periodic distribution of light intensity. Thus, the optical refractive index of the optical fiber changes permanently depending on the intensity of the light wave it is irradiated. The periodic variation of the refractive index of light caused by this method is called a fiber Bragg grating. When a broad-spectrum beam is propagated to a fiber Bragg grating, each segment of the fiber after the refractive index is changed will only reflect a specific wavelength of light. This wavelength is called the Bragg wavelength, as in the following equation ( Shown in 1). This property allows the fiber Bragg grating to reflect only one wavelength of light, while other wavelengths of light are transmitted. In equation (1), λb is the Bragg wavelength, n is the effective refractive index of the core of the fiber, and Λ is the length of the interval between the gratings, called the grating period. Figure 2. How a fiber Bragg grating sensor works Since the Bragg wavelength is a function of the length of the interval between the gratings (Λ in equation (1)), the fiber Bragg grating can be produced with different Bragg wavelengths, so that different fiber Bragg gratings can be used to reflect specific wavelengths. Light waves. Figure 3. Perspective of a fiber Bragg grating Lightweight, Reusable Goggles, Indirect Vented (Splash proof)
Screened top and bottom ports circulate air
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Clear Vision with a Wide Flange and Latex-free
Vents reduce fogging for extended wear.
Fits over most prescription glasses.
1.Material:The parts the wearer touches are not made of materials that can cause skin irritation
2.Structure:Smooth surface, no burr, no acute Angle and other defects that may cause eye and face discomfort.
It has good air permeability.
Adjustable parts and structural parts are easy to adjust and replace.
3.Package:The products are properly packaged and are accompanied by product certificates and instructions
4.fixing band : The minimum width of the headband in contact with the wearer is 11.5mm. The headband is adjustable, soft and durable
5.The appearance quality of the lens: the surface of the lens is smooth and free from scratches, ripples, bubbles, impurities, and other obvious defects that may impair vision
6.Diopter: 0.04D
7.The difference between the prism degrees of the left and right eye lenses: 0.12
8.Visible light transmission ratio: colorless transparent lens 89.35
9.Impact resistance: qualified
10.Protection performance of chemical fog drops: there is no color spot on the test paper within the center of the lens
11.Irritant gas protection performance: there is no color spot on the test paper within the center of the lens