CN115718357A - Ultrashort type long-focus system and imaging module comprising same - Google Patents

Abstract

The embodiment of the application provides an ultrashort type long-focus system and an imaging module comprising the ultrashort type long-focus system, and belongs to the technical field of optical imaging. The ultrashort type long-focus system comprises a substrate, a first ultrasurface and a light shifter; the first super surface is arranged on a first surface of the substrate facing to the object side; the light shifter is arranged on a second surface of the substrate, which is far away from the first surface; and isThe phase of the beam shifter satisfies the following relation to reduce the back focus of the ultrashort-type long-focus system:

wherein the content of the first and second substances,

is the phase of the shifter, k is the vector wave number, k _x 、k _y Components of a vector wave number in a direction perpendicular to an optical axis of the substrate, respectively; d _eff Is the equivalent thickness of the light shifter in free space. The ultra-short type long focus system is combined with the light shifter through the first ultra surface, and miniaturization of the ultra-short type long focus system is promoted.

Description

Ultrashort type long-focus system and imaging module comprising same

Technical Field

The application relates to the technical field of optical imaging, in particular to an ultra-short type long focus system and an imaging module comprising the same.

Background

With the development of technology, more and more electronic devices are integrated with optical devices. The system length of the optical device in the prior art is large, which hinders the progress of miniaturization and light weight of electronic equipment. The system Length (TTL) of the optical device corresponds to the sum of the distance from the first mirror to the last mirror in the light incidence direction and the back focal Length of the optical device. With the miniaturization development of electronic components, the existing optical systems have been difficult to meet the demands of the industrial and consumer electronics markets for miniaturization of electronic devices. The main reason is that the ratio of the total system length to the focal length (f) (hereinafter referred to as the body-to-focus ratio) of the existing optical system is greater than or equal to 1, which greatly limits the miniaturization of the optical system. The prior art has reduced the overall length of the optical device system, primarily by compressing the distance from the first mirror to the last mirror in the direction of light incidence.

Therefore, a miniaturized ultrashort tele system is needed to make the minimum value of the optical system body-to-focus ratio break through the limit of 1.

Disclosure of Invention

In order to solve the technical problem that an ultra-short type long focus system in the prior art is difficult to miniaturize, the application provides an ultra-short type long focus system and an imaging module comprising the same.

In one aspect, the present application provides an ultrashort-type long focus system comprising a substrate, a first ultrasurface and a light shifter;

the first super surface is arranged on a first surface of the substrate facing to the object side;

the light shifter is arranged on a second surface of the substrate, which is opposite to the first surface;

and, the phase of the optical shifter satisfies the following relation to reduce the back focal length of the ultra-short type long focus system:

wherein,

is the phase of the shifter, k is the vector wave number, k _x 、k _y Components of a vector wave number in a direction perpendicular to an optical axis of the substrate, respectively; d is a radical of _eff Is the equivalent thickness of the light shifter in free space.

Optionally, the substrate is a single-layer structure.

Optionally, the substrate is a multilayer structure.

Optionally, the substrate includes a first sub-board, a second sub-board, and a glue layer;

the glue layer is used for gluing the first sub-board and the second sub-board;

the surface of the first sub-plate facing to the object side is a first surface, and the surface of the first sub-plate facing away from the object side is a third surface;

the surface of the second sub-plate facing the object side is a fourth surface, and the surface of the second sub-plate facing away from the object side is a second surface;

the third surface is opposite to the fourth surface and is connected through the adhesive layer;

and the third surface is shape-matched to the fourth surface.

Optionally, the first surface and the second surface are planar.

Optionally, the first surface is a curved surface.

Optionally, any one or more of the first surface, the third surface and the fourth surface is a curved surface.

Optionally, the ultrashort-type tele system further comprises a second hypersurface;

the second super surface is arranged on the third surface.

Optionally, the ultra-short tele system further comprises a third ultra-surface;

the third super surface is arranged on the fourth surface.

Optionally, the first sub-board and the second sub-board are made of the same material.

Optionally, the first sub-board and the second sub-board are made of different materials.

Optionally, the light shifter comprises a single layer of a spatial truncation medium.

Optionally, the light shifter comprises a stack of at least two media having different refractive indices.

Optionally, the light shifter comprises a stack of at least three media of different refractive index.

Optionally, the number of layers of the medium with different refractive indexes in the light shifter is greater than or equal to 10.

Optionally, the light shifter comprises any two or more of amorphous silicon, silicon oxide, silicon nitride and titanium oxide.

Optionally, the light shifter comprises a fourth super surface and a fifth super surface;

the fourth super surface and the fifth super surface are opposite to each other and form a Fabry-Perot resonant cavity.

In a second aspect, the present application further provides an imaging module, where the imaging module includes the ultrashort long-focus system and the detector provided in any of the above embodiments;

the detector is arranged on one side of the ultrashort type long-focus system, which is provided with the light shifter.

The technical scheme of the application obtains the following technical effects at least:

the ultrashort type long-focus system provided by the application is provided with a super surface on the object side surface of a substrate, and a light shifter on the surface of the substrate, which is opposite to the object side surface. The super-surface is used for compressing the thickness of the super-short type long-focus system, and the back focal length of the super-short type long-focus system is compressed through the phase position of the light shifter, so that the miniaturization of the super-short type long-focus system is promoted.

Drawings

The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the application and, together with the description, serve to explain the principles of the application.

FIG. 1 is a schematic diagram illustrating an alternative structure of an ultra-short type long focus system provided by an embodiment of the present application;

fig. 2 is a schematic diagram illustrating an optical path of a light shifter provided in an embodiment of the present application;

fig. 3 is a schematic diagram illustrating a further alternative structure of an ultra-short type long focus system provided in an embodiment of the present application;

FIG. 4 is a schematic diagram illustrating an alternative structure of an ultra-short type long focus system provided in an embodiment of the present application;

FIG. 5 is a schematic diagram illustrating an alternative structure of an ultra-short type long focus system provided by an embodiment of the present application;

FIG. 6 is a schematic diagram illustrating an alternative structure of an ultra-short type long focus system provided by an embodiment of the present application;

FIG. 7 is a schematic diagram illustrating an alternative structure of an ultra-short type long focus system provided by an embodiment of the present application;

FIG. 8 is a schematic diagram illustrating an alternative structure of a light shifter provided in an embodiment of the present application;

FIG. 9 is a schematic diagram illustrating an alternative structure of a light shifter provided in an embodiment of the present application;

FIG. 10 is a schematic diagram illustrating an alternative structure of a light shifter provided in an embodiment of the present application;

FIG. 11 is a schematic diagram illustrating an alternative arrangement of nanostructures of a super-surface provided by an embodiment of the present application;

FIG. 12 is a schematic diagram illustrating yet another alternative arrangement of nanostructures for a super-surface provided by an embodiment of the present application;

FIG. 13 is a schematic diagram illustrating yet another alternative arrangement of nanostructures for a super-surface provided by an embodiment of the present application;

FIG. 14 is a schematic diagram illustrating an alternative nanostructure of the super surface provided by embodiments of the present application;

FIG. 15 is a schematic diagram illustrating an alternative nanostructure of the super-surface provided by embodiments of the present application;

fig. 16 is a schematic structural diagram illustrating an alternative structure of an imaging module according to an embodiment of the present disclosure;

FIG. 17 shows a phase diagram of the beam shifter in the imaging module provided in FIG. 16;

fig. 18 is a schematic structural diagram illustrating yet another alternative imaging module provided in an embodiment of the present application;

FIG. 19 shows a phase diagram of the beam shifter in the imaging module provided in FIG. 18;

fig. 20 shows a phase diagram of a beam shifter in an embodiment of the present application.

In the drawings, reference numerals denote:

10-a substrate; 20-a first super-surface; 30-a light shifter; 40-a second super-surface; 50-a third super-surface; 60-a detector; 70-a diaphragm; 80-an optical filter; 110-a first daughter board; 120-a second daughter board; 130-a glue layer; 101-a first surface; 102-a second surface; 103-a third surface; 104-a fourth surface; 310-a fourth super-surface; 320-fifth super surface; 001-nanostructure; 002-a substrate; 003-a filler material; l1-incident light; l2-equivalent emergent ray; l3-actual outgoing ray.

Detailed Description

The present application will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments are shown. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Like reference numerals refer to like parts throughout. Also, in the drawings, the thickness, ratio and size of the components are exaggerated for clarity of explanation.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, "a," "an," "the," and "at least one" do not denote a limitation of quantity, but rather are intended to include both the singular and the plural, unless the context clearly dictates otherwise. For example, "a component" means the same as "at least one component" unless the context clearly dictates otherwise. "at least one of" should not be construed as limited to the quantity "one". "or" means "and/or". The term "and/or" includes any and all combinations of one or more of the associated listed items.

Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms defined in commonly used dictionaries should be interpreted as having the same meaning as in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

The meaning of "comprising" or "comprises" indicates a property, a quantity, a step, an operation, a component, a part, or a combination thereof, but does not exclude other properties, quantities, steps, operations, components, parts, or combinations thereof.

Embodiments are described herein with reference to cross-sectional views that are idealized embodiments. Variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments described herein should not be construed as limited to the particular shapes of regions as illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, a region shown or described as flat may typically have rough and/or nonlinear features. Also, the acute angles shown may be rounded. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region and are not intended to limit the scope of the claims.

Hereinafter, exemplary embodiments according to the present application will be described with reference to the accompanying drawings.

In view of the fact that the body-to-focus ratio of the conventional optical system is difficult to break through the limit of 1, the optical system with the body-to-focus ratio less than 1 is herein referred to as an ultra-short long-focus system. Referring to fig. 1, the present application provides an ultrashort-type long-focus system including a substrate 10, a first hypersurface 20 and a light shifter 30. The substrate 10 is a medium that can transmit radiation in the operating band. Alternatively, the substrate 10 is a single layer structure. The first super-surface 20 is disposed on a first surface 101 of the substrate 10 facing the object side. The first meta-surface 20 is used for focusing and/or aberration correction. According to an embodiment of the present application, as illustrated in a of fig. 1, the first surface 101 may be a plane; as shown by B in fig. 1, the first surface 101 may also be a curved surface. Accordingly, the first super-surface 20 may be a planar super-surface or a curved super-surface. It is to be noted that the curved surface mentioned herein includes a spherical surface, an aspherical surface, and the like, such as a hyperboloid, a free-form surface, and the like.

A Light Shifter 30 (LS) is arranged on the second surface 102 of the substrate 10 facing away from the object side. The light shifter 30 is disposed on a second surface 102 of the substrate 10 facing away from the object side. The beam shifter 30 is a phase responsive medium that depends on the angle of incidence. The working principle of the light shifter 30 is shown in fig. 2: the incident light L1 propagates in free space as equivalent emergent light L2; when the incident ray L1 enters the beam shifter 30 from free space, the exit angle is kept equal to the incident angle when leaving the beam shifter 30, but the actual exit ray L3 is shifted toward the optical axis Z of the beam shifter 30 with respect to the equivalent exit ray L2 of the incident ray L1 propagating in free space. This corresponds to a reduction in the projection on the optical axis of the propagation path in free space before the light reaches the focal point, which is equivalent to a shortening of the length of the free space in which the light propagates. Such an incident angle dependent phase response medium is therefore referred to as a spatial truncation medium.

According to the embodiment of the present application, the phase of the spatial chopping beam shifter 30 satisfies formula (1):

wherein,

is the phase of the beam shifter 30, k is the vector wave number, k _x 、k _y Components of the vector wave number in a direction perpendicular to the optical axis of the substrate 10, respectively; d _eff Is the equivalent thickness of the light shifter 30 in free space. Therefore, the incident light L1 is emitted from the second surface 102, and then modulated by the light shifter 30 to be emitted as the actual emergent light L3. It should be noted that, without limitation, after being modulated by the light shifter 30, the actual outgoing light ray L3 has the same exit angle as the equivalent outgoing light ray L2 that has not been modulated by the light shifter. Further, in the direction perpendicular to the substrate 10, the exit position of the actual outgoing ray L3 is closer to the optical axis of the substrate 10 than the exit position of the equivalent outgoing ray L2. Thus, the thickness d of the light shifter 30 _Ls Smaller than the equivalent thickness d of the free space corresponding to the light shifter 30 _eff 。

The performance of the beam shifter 30 is evaluated by the cutoff coefficient, which is the following for the beam shifter 30:

R＝d _eff /d _LS ；(2)

wherein R is the truncation coefficient of the beam shifter 30; d _LS Is the thickness of the displacer; d _eff Is the equivalent thickness of the free space corresponding to the light shifter 30.

The inventors of the present application have found that when a single spatially truncated medium is used for the light shifter 30, the truncation factor is limited to only between 1.1 and 1.5. In order to further reduce the body-to-focus ratio of the ultra-short long focus system, the focal power of the first super surface needs to be further increased to reduce the back focus of the ultra-short long focus system. This increases the design difficulty of the first super surface. Which is described in detail below.

In this regard, as shown in fig. 1B and fig. 3 to 7, the inventors have introduced the glue layer 130 into the substrate 10 to combine the superlens and the light shifter and ensure the light to pass through.

Specifically, in an alternative embodiment, as shown in fig. 3-7, the present application provides an ultra-short type long focus system, wherein the substrate 10 comprises a first sub-board 110, a second sub-board 120, and a glue layer 130. The first sub-board 110, the glue layer 130 and the second sub-board 120 are sequentially arranged along the incident direction of the light. The surface of the first sub-board 110 facing the object side is a first surface 101 of the substrate 10, and the surface of the second sub-board 120 facing away from the object side is a second surface 102 of the substrate 10. The surface of the first sub-board 110 facing away from the object side is a third surface 103, and the surface of the second sub-board 120 facing towards the object side is a fourth surface 104. The third surface 103 and the fourth surface 104 are disposed opposite to each other, and the glue layer 130 is disposed between the third surface 103 and the fourth surface 104. The adhesive layer 130 is attached to the first sub-board 110 and the second sub-board 120 through the third surface 103 and the fourth surface 104. Alternatively, the glue layer 130 may be firmly connected to the first sub-board 110 and the second sub-board 120 by curing means such as ultraviolet irradiation, heating, and the like.

In some alternative embodiments, as shown in fig. 3, the third surface 103 and the fourth surface 104 are planar. In still other alternative embodiments, as shown in fig. 4, the third surface 103 and the fourth surface 104 are curved surfaces. It should be understood that when any one or more of the first surface 101, the third surface 103 and the fourth surface 104 provided by the embodiment of the present application is an aspheric surface, the surface type thereof satisfies:

in the formula (3), z is a surface vector parallel to the optical axis of the substrate 10, c is the curvature of the center point of the surface type, k is a conic constant, and a to J correspond to high-order coefficients, respectively.

According to the embodiment of the present application, as shown in fig. 2 to 6, the first sub-board 110 and the second sub-board 120 are made of the same material. In some exemplary embodiments, as shown in fig. 7, the first sub-board 110 and the second sub-board 120 are made of different materials. When the first sub-board 110 and the second sub-board 120 are made of different materials, the color difference can be effectively suppressed by matching the abbe numbers of the two sub-boards.

Next, the light shifter 30 provided in the embodiment of the present application is described in detail with reference to fig. 8 to 10.

Alternatively, the light shifter 30 may be constructed of a single layer of a spatially truncated medium, such as a non-axial material. Illustratively, the material of the light shifter 30 is calcite. But the non-axial material requires a greater thickness and a smaller cutoff coefficient as the light shifter 30.

Alternatively, as shown in fig. 8 and 9, the present embodiment provides a light shifter 30 having a multilayer structure. The light shifter 30 having such a structure is formed by alternately laminating at least two media having different refractive indexes such that the phase of the light shifter 30 satisfies the formula (1) within a preset incident angle range. Preferably, the number of layers of the medium having different refractive indexes in the light shifter 30 is 10 or more. The selection of the at least two media with different refractive indexes is related to the working wavelength band of the optical system provided by the embodiment of the application. According to the embodiment of the present application, the operating wavelength band of the ultrashort type long-focus system can be broadband light such as visible light (400 nm-700 nm), near infrared (900 nm-1700 nm), far infrared (8 μm-12 μm), and the like. Optionally, the operating wavelength band of the ultrashort-type tele system can also be narrow-band light, such as 532nm, 633nm, 850nm, 940nm, 1550nm. Preferably, the ratio of the bandwidth of the narrow-band light to the center wavelength is less than or equal to 0.1.

Illustratively, as shown in fig. 8, for the near infrared with a wavelength of 940nm, the light shifter 30 provided in the embodiment of the present application is formed by stacking 30 layers of silicon oxide (low refractive index medium) and amorphous silicon (high refractive index medium). The phase of the light shifter 30 shown in fig. 8 satisfies the formula (1) when the incident angle of the light shifter 30 is less than or equal to 20 °.

Illustratively, as shown in fig. 9, for green light having a wavelength of 532nm, a light shifter 30 provided in the embodiment of the present application is formed by stacking 30 layers of silicon oxide (low refractive index medium), silicon nitride (medium refractive index medium), and titanium oxide (high refractive index medium).

In still other exemplary embodiments, as shown in FIG. 10, light mover 30 includes a fourth super-surface 310 and a fifth super-surface 320. The fourth 310 and fifth 320 hyper-surfaces are opposite and form a Fabry-Perot resonator. As shown in fig. 10, the incident light L1 enters the light shifter 30, and is continuously reflected in the Fabry-Perot cavity to exit as the actual exiting light L3.

Next, the first to fifth super-surfaces provided by the embodiments of the present application are described in detail with reference to fig. 11 to 14.

The super-surface is a layer of sub-wavelength artificial nanostructure film, and the amplitude, phase and polarization of incident light can be modulated by the periodically arranged nanostructures 001. In the embodiment of the present application, as shown in fig. 1, 5 and 6, the nanostructures 001 may be directly disposed on the first surface 101, the third surface 103 and the fourth surface 104 of the substrate 10, or may be disposed on a separate base 002 as shown in fig. 10. It should be noted that the nanostructure 001 can be understood as a sub-wavelength structure containing all dielectric or plasmon and capable of causing phase jump, and the nanostructure unit is a structural unit centered on each nanostructure obtained by dividing the super surface. The nanostructures are periodically arranged in the super surface, wherein the nanostructures in each period form a super structure unit, the super structure unit is a close-packed pattern, such as a regular quadrangle, a regular hexagon and the like, each period comprises a group of nanostructures, and the vertexes and/or the centers of the super structure units can be provided with the nanostructures, for example. In the case where the superstructure unit is a regular hexagon, at least one nanostructure is provided at each vertex and center position of the regular hexagon. Alternatively, in the case of a square, at least one nanostructure is disposed at each vertex and center position of the square. Ideally, the superstructure unit should be a hexagon vertex and center arranged nanostructure, or a square vertex and center arranged nanostructure, and it should be understood that the actual product may have nanostructure loss at the edge of the super surface due to the limitation of the super surface shape, so that it does not meet the complete hexagon/square. Specifically, as shown in fig. 11 to 13, the superstructure units are formed by regularly arranging nanostructures, and a plurality of superstructure units are arranged in an array to form a super surface structure.

As shown in fig. 11, in one embodiment, the superstructure unit comprises a central nanostructure and 6 peripheral nanostructures surrounding the central nanostructure and having a distance equal to the distance between the central nanostructure and the peripheral nanostructures, and the peripheral nanostructures are uniformly distributed along the periphery to form a regular hexagon, which can also be understood as a combination of regular triangles formed by a plurality of nanostructures.

As one example shown in fig. 12, the superstructure unit comprises a central nanostructure and 4 surrounding nanostructures at equal distances from the central nanostructure, forming a square.

The superstructure unit and its close-packed/array form can also be a circle-arranged fan shape, as shown in fig. 13, including two arc-shaped sides, or a fan shape with one arc-shaped side, as shown in the lower left corner area in fig. 13, and the nano-structure is arranged at the intersection point and the center of each side of the fan shape.

Illustratively, the nanostructures 001 provided by the embodiments of the present application may be polarization-independent structures, which impose a propagation phase on incident light. According to embodiments of the present application, the nanostructures 001 may be a positive structure or a negative structure. For example, the shape of the nanostructure 001 includes a cylinder, a hollow cylinder, a square prism, a hollow square prism, and the like. Fig. 14 shows a schematic of the structure of the nanostructure elements when the nanostructure 001 is a cylinder.

Illustratively, the nanostructure 001 may be a polarization dependent structure that imparts a geometric phase to incident light. The nanostructures 001 may be positive or negative structures. For example, the nanostructures 001 may be elliptical pillars, nanofins, or the like. Fig. 15 shows a schematic structural view of a nanostructure unit when the nanostructure 001 is a nanofin. According to an embodiment of the present application, the nanostructures have a characteristic dimension greater than or equal to 0.2 λ _c And is less than or equal to 0.8 lambda _c ；λ _c The center wavelength of the incident radiation.

According to an embodiment of the present application, the nanostructures optionally have an alignment period greater than or equal to 0.3 λ _c And is less than or equal to 2 lambda _c (ii) a Wherein λ is _c The center wavelength of the operating band. According to an embodiment of the application, optionally, sodiumThe height of the rice structure is greater than or equal to 0.3 lambda _c And is less than or equal to 5 lambda _c (ii) a Wherein λ is _c The center wavelength of the operating band. According to embodiments of the present application, the nanostructures illustratively have a characteristic dimension of greater than or equal to 0.2 λ _c And is less than or equal to 0.8 lambda _c ；λ _c The central wavelength of the incident radiation.

According to the embodiment of the present application, the super-surface further includes a filling material 003, the filling material 003 is filled between the nano-structures 001, and an extinction coefficient of the filling material 003 to the operating band is less than 0.01. Optionally, the filler material 003 comprises air or other material that is transparent or translucent in the operating band. According to embodiments of the present application, the absolute value of the difference between the refractive index of the filler material and the refractive index of the nanostructures 001 should be greater than or equal to 0.5. For the ultrashort type long-focus system provided by the embodiment of the present application, it is preferable that the filling material 003 is filled between the nanostructures 001 of the second and third super surfaces 40 and 50. The filler material 003 facilitates protection of the nanostructures 001 and surface smoothing of the second and third super-surfaces 40, 50, thereby facilitating the first and second sub-boards 110, 120 to be attached to the glue layer 130 through the second and third super-surfaces 40, 50, respectively.

It should be noted that the super-surface provided by the embodiment of the present application can be processed by a semiconductor process, and has the advantages of light weight, thin thickness, simple structure and process, low cost, high consistency of mass production, and the like.

In a second aspect, the present application provides an imaging module, as shown in fig. 16, 17 and 19, including the ultrashort type tele system and the detector 60 provided in any of the above embodiments; the detector 60 is disposed on the side of the ultra-short long-focus system having the beam shifter 30. Preferably, the detector 60 is disposed at an image plane of the ultra-short type tele system. May be a Complementary Metal Oxide Semiconductor (CMOS) or a Charge Coupled Device (CCD). Optionally, the imaging module further includes a diaphragm 70, and the diaphragm 70 is disposed on the side of the ultra-short type long-focus system having the first super-surface 20, for forming a huygens optical system. Optionally, the imaging module further comprises a filter 80.

Example 1

Example 1 provides an exemplary imaging module, as shown in fig. 17, with specific parameters as shown in table 1. When the ultra-short type long-focus system in the imaging module is only an ultra lens, the back focal length of the ultra-short type long-focus system is 3.7mm; when the ultrashort type long-focus system in the imaging module is the ultrashort type long-focus system provided by the embodiment of the application, the back focal length is 1mm. In the ultra-short type long focus system provided by the embodiment of the present application, the light shifter 30 is a 30-layer plate structure formed by alternately stacking amorphous silicon and silicon oxide. Therefore, the truncation factor of the ultrashort type tele system provided by the embodiment of the application is R =3.7. Fig. 18 shows a phase diagram of the light shifter 30.

TABLE 1

Item	Parameter(s)
		Operating band	940nm
Focal length	3.7mm
		Field of view	40°
Entrance pupil diameter	1mm
		Back focal length (without optical shifter)	3.7mm
Back focal length (with light shifter)	1mm

Example 2

Example 2 provides an exemplary imaging module, as shown in fig. 19, with specific parameters as shown in table 2. The structure of the ultrashort tele system in the module is shown in fig. 5, which includes a third ultrasurface. When the ultra-short type long-focus system in the imaging module does not comprise the light shifter, the back focal length of the ultra-short type long-focus system is 1mm; when the ultrashort type long-focus system in the imaging module is the ultrashort type long-focus system provided by the embodiment of the application, the back focal length is 0.17mm. In the ultrashort long-focus system provided by the embodiment of the application, the light shifter 30 is a 30-layer plate-shaped structure formed by alternately laminating silicon oxide, silicon nitride and titanium oxide. Therefore, the truncation factor of the ultrashort type tele system provided by the embodiment of the application is R =3.7. Fig. 20 shows a phase diagram of the light shifter 30.

TABLE 2

Item	Parameter(s)
		Operating band	532nm
Focal length	1mm
		Field of view	30°
Diameter of entrance pupil	0.35mm
		Back focal length (without optical shifter)	1mm
Back focal length (with light shifter)	0.17mm

In summary, the object side surface of the substrate of the ultrashort type telephoto system provided in the embodiment of the present application is provided with a super surface, and a light shifter is disposed on a surface of the substrate facing away from the object side surface. The super-surface is used for compressing the thickness of the super-short type long-focus system, and the back focal length of the super-short type long-focus system is compressed through the phase position of the light shifter, so that the miniaturization of the super-short type long-focus system is promoted.

The imaging module that this application embodiment provided is through adopting the light shifting ware and surpassing the surface to combine, has compressed back focal length and the total length of system of imaging module, has promoted the compactification of imaging module.

The above description is only a specific implementation of the embodiments of the present application, but the scope of the embodiments of the present application is not limited thereto, and any person skilled in the art can easily conceive of changes or substitutions within the technical scope of the embodiments disclosed in the present application, and all the changes or substitutions should be covered by the scope of the embodiments of the present application. Therefore, the protection scope of the embodiments of the present application shall be subject to the protection scope of the claims.

Claims (18)

1. An ultrashort-type long-focus system, comprising a substrate (10), a first hypersurface (20) and a beam shifter (30);

the first super surface (20) is arranged on a first surface (101) facing to the object side of the substrate (10);

the light shifter (30) is arranged on a second surface (102) of the substrate (10) opposite to the first surface (101);

and the phase of the light shifter (30) satisfies the following relation to reduce the back focal length of the ultra-short type long-focus system:

wherein,

is the phase of the beam shifter (30), k is the vector wave number, k _x 、k _y Are components of a vector wave number in a direction perpendicular to an optical axis of the substrate (10), respectively; d is a radical of _eff Is the equivalent thickness of the light shifter (30) in free space.

2. Ultrashort-type tele system according to claim 1, wherein the substrate (10) is of single-layer structure.

3. Ultrashort-type tele system according to claim 1, wherein the substrate (10) is a multilayer structure.

4. The ultra short tele system of claim 3, wherein the substrate (10) comprises a first sub-board (110), a second sub-board (120), and a glue layer (130);

the glue layer (130) is used for gluing the first sub-board (110) and the second sub-board (120);

the surface of the first sub-board (110) facing the object side is a first surface (101), and the surface of the first sub-board (110) facing away from the object side is a third surface (103);

the surface of the second sub-board (120) facing the object side is a fourth surface (104), and the surface of the second sub-board (120) facing away from the object side is a second surface (102);

said third surface (103) is opposite to said fourth surface (104) and is connected by said glue layer (130);

and the third surface (103) is shape-matched to the fourth surface (104).

5. Ultrashort-type tele system according to claim 1, wherein the first surface (101) and the second surface (102) are planar.

6. Ultrashort-type tele system according to claim 1, wherein the first surface (101) is curved.

7. The ultra short tele system of claim 4, wherein any one or more of the first surface (101), the third surface (103), and the fourth surface (104) are curved.

8. Ultrashort-type tele system according to claim 4 or 7, further comprising a second super surface (40);

the second super surface (40) is arranged on the third surface (103).

9. Ultrashort-type tele system according to claim 4 or 7, further comprising a third hypersurface (50);

the third super surface (50) is disposed on the fourth surface (104).

10. Ultrashort-type tele system according to claim 4, wherein the first sub-plate (110) and the second sub-plate (120) are of the same material.

11. Ultrashort-type tele system according to claim 4, wherein the first sub-plate (110) and the second sub-plate (120) are of different material.

12. Ultrashort-type tele system according to claim 1, wherein the light shifter (30) comprises a single layer of spatially truncated medium.

13. Ultrashort-type tele system according to claim 1, wherein the light shifter (30) comprises a stack of at least two media having different refractive indices.

14. Ultrashort-type tele system according to claim 13, wherein the light shifter (30) comprises a stack of at least three media with different refractive indices.

15. Ultrashort-type tele system according to claim 13 or 14, wherein the number of layers of media with different refractive indices in the light shifter (30) is greater than or equal to 10.

16. Ultrashort-type tele system according to claim 13 or 14, wherein the light shifter (30) comprises any two or more of amorphous silicon, silicon oxide, silicon nitride and titanium oxide.

17. The ultra short tele system of claim 1, wherein said light shifter (30) comprises a fourth super surface (310) and a fifth super surface (320);

the fourth (310) and fifth (320) hypersurfaces are opposite and form a Fabry-Perot cavity.

18. An imaging module comprising an ultrashort tele system according to any one of claims 1 to 17 and a detector;

the detector is arranged on one side of the ultrashort type long-focus system, which is provided with the light shifter (30).

Images