Borescope

The gradient lens combines the best of both worlds as it provides the glare protection of a darker lens with the visual clarity of a lighter lens by blocking more light across the top portion of the lens than in the viewing area. The name is short for gradient index.

Gradient lenses are mostly used to focus and collimate light within a variety of fiber optic components. Here is how they operate. Light is focused through a precisely controlled radial variation of the lens material’s index of refraction from the optical axis to the edge of the lens. This allows a gradient lens with flat or angle polished surfaces to collimate light emitted from an optical fiber or to focus an incident beam into an optical fiber.

The main advantage of gradient lenses compared to classical lenses is that the optical surfaces of gradient lenses are flat. The flatter the surface, the better the quality of the joint between lens and, for example, optical fiber. Or in other words, gradient lenses are the better type of lens for a flexible borescope. Keep that in mind when buying a borescope.

Gradient lenses find application in a wide variety of products that require either passive or active electrical components, such as wavelength division multiplexers (WDM), optical switches, and attenuators. In active components, GRIN lenses are used in fiber-to-detector and laser-to-fiber coupling. GRIN lenses are well suited to coupling the output of diode lasers into optical fibers because they can achieve aberration correction without complex multi-element systems or aspheric lenses; and because real images can be formed at the lens surface. In the field of fiber coupling or in creating beam patterns, GRIN lenses are an economical, special alternative to conventional lenses.

When estimating which of the available GRIN lenses is the most suitable one for a given application, the buyer must consider the effective focal length, lens diameter, radius of the curvature, and the thickness of the edge and the center. Focal length is defined as the distance from the lens to the point of focus when the lens is focused on infinity. It determines the angle of view, which directly effects how much the subject will be magnified for a given photographic position. The diameter can also be regarded as the height. The center thickness of gradient lenses is simply the thickness of the lens at its center, as the name suggests.

The most widely used method for producing gradient lenses is ion exchange.

Upper Endoscopy | Borescope Lens | Camera Lens | Gradient Lens | Optical Lens | Rod Lens |