Fresnel magnifier is an ultra-thin magnifier. Made of transparent plexiglass (of course more materials can be used). The minimum thickness of a Fresnel magnifier made of PVC can be between 0.4mm and 0.90mm.
Unlike
ordinary magnifiers, its surface is covered with tiny stripes, and its vortex
stripes contain many convex lenses (Ring shape for short), so that the light
passing through it bends to produce a diffraction phenomenon, thereby forming
an enlarged image.
Fresnel
lenses are characterized by higher brightness than ordinary lenses, a flat
surface, and a large radiating area. Generally, the diameter of the ordinary
meniscus lens is very limited, and Fresnel has played a very good role in the
field of magnifying glass, achieving an effect that cannot be achieved by
ordinary lenses.
And
the Fresnel magnifier
made now has a thickness of only 0.4mm, and it is portable. In fact, the main
function is to reduce the weight and volume of ordinary plexiglass and glass
magnifier made by traditional magnifiers.
Compared
with traditional lenses, Fresnel lenses have the advantages of large area,
light weight, low price, lightness and portability, etc. Therefore, they are
characterized by a short focal length, less material consumption and weight smaller
volume. Its surface is composed of a series of zigzag grooves, and the central
part is an oval arc.
Each
groove has a different angle from the adjacent groove. However, the light is
concentrated in one place, to form the central focus, which is the focus of the
lens. Each groove can be regarded as an independent small lens, which adjusts
the light into parallel light or focused light. This lens also eliminates some
spherical aberrations
The light
enters from one side, passes through the Fresnel lens and comes out on the
other side to focus into a point or exit in parallel light. The focus is on the
other side of the light and is finitely conjugated.
This type
of lens is usually designed as a collimator lens (such as a Fresnel lens for
projection and a magnifying glass) and a condenser lens (such as a Fresnel lens
for concentrating and concentrating solar energy)
Fresnel lenses are mostly thin sheets made
of plastic materials. They are also made of
glass. One side of the lens surface is smooth, and the other side is burned
with small to large concentric circles. Its texture is made of light.
The requirements
of the lens are very high. A high-quality lens must have a smooth surface and a
clear texture. Its thickness varies with the application, mostly around mm
thickness and long detection distance.
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