CN116774328A - Aspherical lens and preparation method thereof - Google Patents

Abstract

The invention discloses an aspherical lens and a preparation method thereof. The aspherical lens includes a first aspherical surface and a second aspherical surface that are opposite to each other. The first aspherical surface is a concave surface. The first aspherical surface is provided with two The binary surface includes several diffraction gratings arranged along the center of the optical axis. The second aspherical surface is a convex surface. A first aspherical surface is formed between the first aspherical surface and the side surface of the aspherical lens. A second transition arc is formed between the second aspheric surface and the side surface of the aspheric lens. Embodiments of the present invention can reduce the number of lenses, reduce costs, facilitate miniaturization and production, and can be widely used in the field of optical device technology.

Description

Aspherical lens and preparation method thereof

Technical field

The present invention relates to the technical field of optical devices, and in particular to an aspherical lens and a preparation method thereof.

Background technique

In the actual application of optical systems, it is necessary to perform some preset processing on the incident light through the optical system according to the usage requirements, such as correcting spherical aberration, adjusting chromatic aberration or improving transmittance, etc. If a traditional lens combination is used to achieve a certain function, multiple lenses need to be combined, resulting in a larger volume and weight of the lens combination, higher cost, and inconvenience for miniaturization of the optical system.

Contents of the invention

In view of this, the purpose of embodiments of the present invention is to provide an aspherical lens and a preparation method thereof, which can reduce the number of lenses, reduce costs, and facilitate miniaturization and production.

On the one hand, embodiments of the present invention provide an aspherical lens. The aspherical lens includes a first aspherical surface and a second aspherical surface that are opposite to each other. The first aspherical surface is a concave surface, and the first aspherical surface is provided with a A binary surface, the binary surface includes several diffraction gratings arranged along the center position of the optical axis, the second aspherical surface is a convex surface, and a third aspherical surface is formed between the first aspherical surface and the side surface of the aspherical lens. A transition arc is formed between the second aspheric surface and the side surface of the aspheric lens.

Optionally, the material of the aspheric lens includes chalcogenide glass.

Optionally, the phase distribution of the diffraction grating meets the following conditions:

Among them, φ represents the phase value, M represents the diffraction order, N represents the total number of rings of the diffraction grating, A _i represents the coefficient of ρ to the power of 2i, ρ represents the normalized radius, and i represents the i-th ring.

Optionally, the annular zone depth of the diffraction grating meets the following conditions:

Where, h represents the annulus depth, λ represents the central wavelength, and n represents the material refractive index of the aspheric lens.

Optionally, the first transition arc meets the following conditions:

0.03D≤R1≤0.04D

Wherein, D represents the diameter of the aspherical lens, and R1 represents the radius of the first transition arc.

Optionally, the second transition arc meets the following conditions:

0.02D≤R2≤0.03D

Wherein, D represents the diameter of the aspheric lens, and R2 represents the radius of the second transition arc.

Optionally, the first thickness at the center of the aspheric lens meets the following conditions:

0.18D≤d1≤0.21D

Wherein, D represents the diameter of the aspheric lens, and d1 represents the first thickness.

Optionally, the second thickness at the edge of the aspherical lens meets the following conditions:

0.07D≤d2≤0.09D

Wherein, D represents the diameter of the aspheric lens, and d2 represents the second thickness.

On the other hand, embodiments of the present invention provide a method for preparing an aspheric lens, which is applied to the above-mentioned aspheric lens, including:

Calculate the phase distribution of several diffraction gratings, and calculate the position distribution of the diffraction gratings based on the phase distribution;

Determine the material of the aspheric lens, and calculate the annular depth of the diffraction grating based on the refractive index of the material;

Prepare the mold according to the position distribution and ring zone depth of the diffraction grating;

Through molding, the pattern of the mold is transferred to the first aspherical surface of the aspherical lens to form a binary surface.

Implementing the embodiments of the present invention includes the following beneficial effects: the aspherical lens in this embodiment includes a first aspherical surface and a second aspherical surface that are opposite to each other. The first aspherical surface is a concave surface, and the first aspherical surface is provided with a binary surface. The surface includes several diffraction gratings arranged along the center position of the optical axis. The second aspheric surface is a convex surface. A first transition arc is formed between the first aspheric surface and the side surface of the aspheric lens. The second aspheric surface is connected to the aspheric lens. A second transition arc is formed between the side surfaces, and spherical aberration is eliminated to the maximum extent by adjusting the aspherical coefficients of the first aspherical surface and the second aspherical surface, and the resolution is further improved through several diffraction gratings set at the center, so that the aspherical lens On the basis of the refraction effect, various phase differences such as chromatic aberration can be further eliminated by overlapping the diffraction effect. That is, this embodiment can realize the function of multiple lens combinations through an aspherical lens, reducing the number of lenses, reducing costs, and reducing The size and weight are reduced, making it easier to miniaturize; in addition, mass production using molding allows a large number of lenses with consistent performance to be obtained in a short time. The production cycle and production costs are greatly reduced.

Description of drawings

Figure 1 is a schematic structural diagram of an aspherical lens provided by an embodiment of the present invention;

FIG. 2 is a schematic flow chart of a method for preparing an aspherical lens according to an embodiment of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. The step numbers in the following embodiments are only set for the convenience of explanation. The order between the steps is not limited in any way. The execution order of each step in the embodiments can be adapted according to the understanding of those skilled in the art. sexual adjustment.

Note, however, that in some cases, the steps shown or described in the flowcharts are performed sequentially. The terms "first", "second", etc. in the description, claims, and above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific sequence or sequence. It is to be understood that the data so used are interchangeable under appropriate circumstances so that the embodiments of the application described herein can, for example, be practiced in sequences other than those illustrated or described herein. Furthermore, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terms used herein are only for the purpose of describing the embodiments of the present application and are not intended to limit the present application.

As shown in Figure 1, Figure 1(a) shows a top view of an aspherical lens, and Figure 1(b) shows a cross-section of the aspherical lens along AA. An embodiment of the present invention provides an aspherical lens. The aspherical lens includes a relative The first aspherical surface ASP1 and the second aspherical surface ASP2 are composed of a concave surface, the first aspherical surface ASP1 is provided with a binary surface, and the binary surface includes several diffraction gratings arranged along the center position of the optical axis. The two aspheric surfaces ASP2 are convex surfaces, a first transition arc R1 is formed between the first aspheric surface ASP1 and the side surface of the aspheric lens, and a second transition arc R2 is formed between the second aspheric surface ASP2 and the side surface of the aspheric lens.

Specifically, the aspheric surface formula is as follows:

Among them, z represents the sagittal height of the lens surface, y is the radius value, R is the radius of curvature at the aspheric vertex, K is the cone constant, and A ₄ to A ₁₂ are the aspheric coefficients.

It should be noted that the specific values of A ₄ to A ₁₂ are determined according to actual applications, and are not specifically limited in this embodiment. In a specific embodiment, refer to the parameters in Table 1.

ASP1 ASP2 R -10.837 -9.235 K -3.081 -0.412 A ₄ 1.379e-005 0.0001 A ₆ 5.397e-005 -9.098e-005 A ₈ 3.119e-005 -1.763e-005 A ₁₀ -7.336e-005 4.889e-005 A ₁₂ 3.191e-005 -6.205e-005

It should be noted that ASP1 and ASP2 can also be coated with an anti-reflective film. The material and thickness of the film are determined according to the actual application, and are not specifically limited in this embodiment.

In Figure 1(b), D represents the diameter of the aspheric lens, D1 represents the diameter of ASP2, D2 represents the diameter of ASP1, and D3 represents the starting diameter of the aspheric lens. The non-curved surface of the aspheric lens and the side surface are transitioned through an arc to form a protective chamfer. Transition arcs and protective chamfers can enable rapid molding and mold ejection during the production process, improving molding yield and mold service life.

It should be noted that several diffraction gratings are concentric.

Optionally, the material of the aspherical lens includes chalcogenide glass.

As an infrared lens material, chalcogenide glass has unique advantages, such as excellent temperature and viscosity characteristics, high production efficiency, short cycle, and low cost. The molding method can be used to mass-produce complex surface optical components with consistent performance in a short time, and the processing efficiency is relatively high. Diamond turning is improved by more than 10 times. In addition, the refractive index temperature coefficient and dispersion coefficient of chalcogenide glass are small, which is beneficial to achromatic and athermal optical designs.

Optionally, the phase distribution of the diffraction grating meets the following conditions:

Among them, φ represents the phase value, M represents the diffraction order, N represents the total number of rings of the diffraction grating, A _i represents the coefficient of ρ to the power of 2i, ρ represents the normalized radius, and i represents the i-th ring.

It should be noted that the phases at different positions of the diffraction grating are different, and the positions of different annular zones of the diffraction grating are different. The phases at different positions can be calculated based on the annular zones of the diffraction grating. The total number of ring zones of the diffraction grating is determined according to the actual application, and is not specifically limited in this embodiment.

Optionally, the annular zone depth of the diffraction grating meets the following conditions:

Among them, h represents the depth of the annulus, λ represents the central wavelength, and n represents the refractive index of the aspheric lens material.

After the material of the aspherical lens is determined, the refractive index of the material of the aspherical lens is determined, and the annular depth of the diffraction grating can be determined based on the known parameters.

Optionally, referring to Figure 1, the first transition arc R1 satisfies the following conditions:

0.03D≤R1≤0.04D

Among them, D represents the diameter of the aspheric lens, and R1 represents the radius of the first transition arc.

It should be noted that the specific value of the first transition arc is determined according to the actual application, and is not specifically limited in this embodiment.

Optionally, referring to Figure 1, the second transition arc R2 satisfies the following conditions:

0.02D≤R2≤0.03D

Among them, D represents the diameter of the aspheric lens, and R2 represents the radius of the second transition arc.

It should be noted that the specific value of the second transition arc is determined according to the actual application, and is not specifically limited in this embodiment.

Optionally, referring to Figure 1, the first thickness d1 at the center position of the aspheric lens satisfies the following conditions:

0.18D≤d1≤0.21D

Among them, D represents the diameter of the aspheric lens, and d1 represents the first thickness.

It should be noted that the specific value of the first thickness at the center position is determined according to the actual application, and is not specifically limited in this embodiment.

Optionally, referring to Figure 1, the second thickness d2 at the edge position of the aspherical lens satisfies the following conditions:

0.07D≤d2≤0.09D

Among them, D represents the diameter of the aspheric lens, and d2 represents the second thickness.

It should be noted that the specific value of the second thickness at the edge position is determined according to the actual application, and is not specifically limited in this embodiment.

Implementing the embodiments of the present invention includes the following beneficial effects: the aspherical lens in this embodiment includes a first aspherical surface and a second aspherical surface that are opposite to each other. The first aspherical surface is a concave surface, and the first aspherical surface is provided with a binary surface. The surface includes several diffraction gratings arranged along the center position of the optical axis. The second aspheric surface is a convex surface. A first transition arc is formed between the first aspheric surface and the side surface of the aspheric lens. The second aspheric surface is connected to the aspheric lens. A second transition arc is formed between the side surfaces, and spherical aberration is eliminated to the maximum extent by adjusting the aspherical coefficients of the first aspherical surface and the second aspherical surface, and the resolution is further improved through several diffraction gratings set at the center, so that the aspherical lens On the basis of the refraction effect, various phase differences such as chromatic aberration can be further eliminated by overlapping the diffraction effect. That is, this embodiment can realize the function of multiple lens combinations through an aspherical lens, reducing the number of lenses, reducing costs, and reducing The size and weight are reduced to facilitate miniaturization.

Referring to Figure 2, an embodiment of the present invention provides a method for preparing an aspheric lens, which is applied to the above-mentioned aspheric lens, including:

S100. Calculate the phase distribution of several diffraction gratings, and calculate the position distribution of the diffraction gratings based on the phase distribution;

S200. Determine the material of the aspheric lens, and calculate the annular depth of the diffraction grating based on the refractive index of the material;

S300. Prepare the mold according to the position distribution and ring depth of the diffraction grating;

S400. Transfer the pattern of the mold to the first aspherical surface of the aspherical lens through molding to form a binary surface.

Specifically, first of all, based on the light diffraction theory and computer technology, modern microelectronics technology is used as a processing and measurement method to realize optical system coupling. Through diffraction theory and computer numerical calculation, a binary surface nonlinear device that meets certain functions is designed. For the phase distribution of spherical optical elements, calculate the position distribution of the diffraction grating based on the phase distribution and the phase distribution equation of the binary plane; then, determine the material of the aspheric lens and calculate the ring of the diffraction grating based on the refractive index and ring depth of the material. Then, the mold is prepared according to the position distribution of the diffraction grating and the depth of the ring zone; finally, through molding, a relief-shaped structure composed of sub-micron discrete pixels is formed on the chalcogenide glass substrate, and a two-dimensional lens is copied. .

Implementing the embodiments of the present invention includes the following beneficial effects: In this embodiment, first, the phase distribution of several diffraction gratings is calculated, and the position distribution of the diffraction gratings is calculated based on the phase distribution. Then, the material of the aspherical lens is determined, and the position distribution of the diffraction grating is calculated based on the phase distribution. The refractive index is used to calculate the annular depth of the diffraction grating. Then, a mold is prepared based on the position distribution and annular depth of the diffraction grating. Finally, the pattern of the mold is transferred to the first aspherical surface of the aspherical lens through molding to form a binary surface, by calculating the phase distribution and ring depth of several diffraction gratings, and making a mold. Through molding, the pattern of the mold is transferred to the first aspherical surface of the aspherical lens to form a binary surface, and batch processing is carried out using molding. Through centralized production, large quantities of lenses with consistent performance can be obtained in a short time. The production cycle and production costs are greatly reduced.

The above is a detailed description of the preferred implementation of the present invention, but the present invention is not limited to the embodiments. Those skilled in the art can also make various equivalent modifications or substitutions without violating the spirit of the present invention. , these equivalent modifications or substitutions are included in the scope defined by the claims of this application.

Claims (9)

1. An aspherical lens, characterized in that the aspherical lens includes an opposite first aspherical surface and a second aspherical surface, the first aspherical surface is a concave surface, and the first aspherical surface is provided with a binary surface , the binary surface includes several diffraction gratings arranged along the center of the optical axis, the second aspherical surface is a convex surface, and a first transition circle is formed between the first aspherical surface and the side surface of the aspherical lens. Arc, a second transition arc is formed between the second aspherical surface and the side surface of the aspherical lens. 2. The aspherical lens according to claim 1, wherein the material of the aspherical lens includes chalcogenide glass. 3. The aspheric lens according to claim 1, characterized in that the phase distribution of the diffraction grating satisfies the following conditions: Among them, φ represents the phase value, M represents the diffraction order, N represents the total number of rings of the diffraction grating, A _i represents the coefficient of ρ to the power of 2i, ρ represents the normalized radius, and i represents the i-th ring. 4. The aspheric lens according to claim 1, characterized in that the ring zone depth of the diffraction grating satisfies the following conditions: Where, h represents the annulus depth, λ represents the central wavelength, and n represents the material refractive index of the aspheric lens. 5. The aspheric lens according to claim 1, characterized in that the first transition arc satisfies the following conditions: 0.03D≤R1≤0.04D Wherein, D represents the diameter of the aspherical lens, and R1 represents the radius of the first transition arc. 6. The aspheric lens according to claim 1, characterized in that the second transition arc satisfies the following conditions: 0.02D≤R2≤0.03D Wherein, D represents the diameter of the aspheric lens, and R2 represents the radius of the second transition arc. 7. The aspherical lens according to claim 1, characterized in that the first thickness at the center position of the aspherical lens satisfies the following conditions: 0.18D≤d1≤0.21D Wherein, D represents the diameter of the aspheric lens, and d1 represents the first thickness. 8. The aspherical lens according to claim 1, wherein the second thickness at the edge of the aspherical lens satisfies the following conditions: 0.07D≤d2≤0.09D Wherein, D represents the diameter of the aspheric lens, and d2 represents the second thickness. 9. A method for preparing an aspheric lens, characterized in that it is applied to the aspheric lens according to any one of claims 1 to 8, including: Calculate the phase distribution of several diffraction gratings, and calculate the position distribution of the diffraction gratings based on the phase distribution; Determine the material of the aspheric lens, and calculate the annular depth of the diffraction grating based on the refractive index of the material; Prepare the mold according to the position distribution and ring zone depth of the diffraction grating; Through molding, the pattern of the mold is transferred to the first aspherical surface of the aspherical lens to form a binary surface.