Design features of free surface optical lenses

Optical lens manufacturers believe that the design of optical lenses for a reasonable telescope is the key to the success of the progressive multi focus lens. Although the multi focus of the multi focus is the basic design basis, it still exists in a variety of different designs in the design of the tapered multi focus lens.

Mainly:

(1) the refractive index of the lens remains unchanged, but some lenses also change in the hyperopic area.

(2) designing a longer gradient region to slow the gradual change of velocity is called "soft design". And the design of a relatively short gradient area is called "hard design", and (3) in the whole additional area, the design of the same base bending is called "simple" design.

(3) the lens can be used in the left eye or right eye as the "symmetrical design", while the different design of the left and right glasses is called "asymmetric design".

The design methods of progressive lenses are mainly rigid design method and soft design method. The lens gradient surface obtained by hard design method is the sphere with single optical focal length in the near and far regions. The central transition zone is short and narrow, and the change rate of the optical focal length is fast. Although this lens has a wide visual and optic area, there is a severe astigmatism mutation in the junction of the transition zone and the optic and optic near area. In addition, the width of the central transition zone is lack of consideration and the aberration is concentrated in the marginal transition region, which seriously affects the visual effect.

The soft design allows a certain degree of focal degree change in the optic and optic regions, which makes the gradient area of the lens longer, the rate of the focal degree gradually changing, the aberration of the central transition zone and the edge of the near area is slow, the aberration is gently and softly distributed on the wider area, and the aberration in the edge transition area is greatly reduced. The clinic shows that the wearer is easier to adapt.