In comparison to spheric lenses, aspheric ones have a curvature in order to sit optimally on the eyeball. But their edges are flattened. The flat curvature changes the optical properties of the lens. The latest manufacturing processes make it possible to produce this special shape.

Beam divergencecalculator

Let Df and Di be the beam diameters at two different points away from the rayleigh range and let l be the distance between them. Then beam divergence (θ) is given by,

But there is another element to bear in mind. The shape. This determines whether your contact lenses fit well and correct your vision properly. The curvature of the lens plays a big role when it comes to getting the best visual results. Read our guide to find out how the lens shape is crucial for your vision and the comfort of your eyes.

Parallel (Horizontal) beam divergence is the angular measure of the increase in the beam diameter along the optic axis, i.e. along the Z-axis as in the figure.

Beam divergenceultrasound

There are many considerations when choosing the right contact lenses. Do you pick daily, weekly or monthly lenses? There are also coloured lenses, multifocal or lenses specially made for presbyopia. Not to mention the different combinations of prescriptions that are possible today. Today, almost every refractive error can be corrected with the help of contact lenses.

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Beam divergenceRadiology

Spheric lenses have excellent imaging properties. But when it comes to severe ametropia, aspheric surfaces perform better. This is particularly evident in the marginal areas of the lenses. From there, the light is directed to the focal point of the visual aid.

Laserbeam divergenceangle

Beam Divergence of a laser beam is an angular measure of the increase in the beam diameter or the radius with the distance from the beam waist, from where the beam diverges.

For the wearer, this results in a clearer, brighter image, and a less restricted visual range, as more of the lens can be used for viewing.

Lentiamo offers you a wide range of daily, weekly and monthly lenses, extended-wear lenses and UV and blue light filters.

Perpendicular (Vertical) beam divergence is the angular measure of the increase in the beam diameter along the axis perpendicular to the optic axis, i.e. along the Y-axis as in the figure.

Beam divergencemeasurement

The situation is different for patients with cataracts. Since the effects of spheric aberration are stronger, ophthalmologists recommend aspheric contact lenses, or spectacle lenses in this case. In addition, the type of ametropia, as well as eye diseases, play a major role. Lenses with an aspheric front are the best choice in cases of severe nearsightedness or farsightedness. People with a large pupil diameter should also use this type of lens.

Beam divergenceangle

Check out Lenjoy, the most affordable aspheric lens in our online shop. The unique aspherical design reduces aberrations and improves visual acuity even in low light conditions.

Beam diameter is calculated in terms of beam diameters at two different points far from the rayleigh range and the distance between these points.

It is found that practically the laser beam cannot focus on a point, instead, there is a small beam thickness at the focal point. This smallest distance up to which a laser beam can converge is known as the beam waist (w0). It is basically the focal point of a laser beam.

Rayleigh range (ZR) is the distance from the beam waist where the beam radius has increased √2 times its initial value. This is the point at which the area of cross-section is doubled.

Laserbeam divergenceand spot size

The largely freely formable surface allows the avoidance or reduction of aberrations that are unavoidable with spherical lenses.

Beam divergenceformula

If you suffer from an eye disease, it is best to consult an ophthalmologist. He or she will determine whether your eyes are suitable for wearing contact lenses at all. Generally, ophthalmologists do not recommend wearing aspheric lenses if your hyperopia has been corrected by laser eye surgery.

Opticians call this phenomenon spherical aberration because it only occurs in spherically shaped optical lenses. It occurs because not all light rays that hit the lens surface subsequently converge at the same point. The rays' incidence in the area of the curved lens edge are refracted differently than those in the axis area. Thus it is not possible for the eye to focus all rays at the same time. This results in a blurred image.

Spherical contact lens models are more commonly worn than their aspherical counterpart. For a long time, there were no other forms of contact lenses at all. But they are not always the best choice due to their sometimes inadequate optical quality. They can cause aberrations that lead to blurred vision.

If a collimated beam is focused using a lens with a focal length f, then the diameter Dm of the beam at a point far from the rayleigh range is related to the beam divergence θ as,

The lenses can be better adapted to the curvature required by the eye. They deflect light rays as required by the wearer and avoid image errors. Therefore, an optimal visual result is achieved.