阅读说明：本技术 基于超表面微透镜阵列的真三维立体成像技术 (True three-dimensional imaging technology based on super-surface micro-lens array ) 是由 郑国兴 付娆 李子乐 单欣 李仲阳 于 2019-11-25 设计创作，主要内容包括：本发明公开了一种基于超表面微透镜阵列的真三维立体成像技术,通过超表面微透镜阵列将一个完整的光波波前在空间上分成许多微小的部分,每一部分都被相应的超表面微透镜聚焦在三维像空间中不同的空间位置,模拟产生三维立体图像的一个体像素点,一系列超表面微透镜聚焦产生就可以得到一系列焦点,空间中这些焦点组成三维立体像素点阵,实现真三维立体成像。本发明不需要任何机械移动装置或雾屏等辅助装置,可直接在空气中投射出三维立体图像,无需佩戴任何额外的观看设备,可实现多人同时多角度观察,具有操作简单、更直观、更真实的优点。(The invention discloses a true three-dimensional imaging technology based on a super-surface micro-lens array, which divides a complete light wave front into a plurality of tiny parts in space through the super-surface micro-lens array, each part is focused at different spatial positions in a three-dimensional image space by a corresponding super-surface micro-lens, an individual pixel point of a three-dimensional image is generated in a simulation mode, a series of focuses can be obtained through the focusing of the super-surface micro-lenses, and the focuses in the space form a three-dimensional pixel lattice, so that true three-dimensional imaging is realized. The invention can directly project three-dimensional images in the air without any mechanical moving device or auxiliary devices such as a fog screen and the like, does not need to wear any additional watching equipment, can realize multi-person multi-angle observation at the same time, and has the advantages of simple operation, more intuition and more reality.)

1. A true three-dimensional imaging technology based on a super-surface micro-lens array is characterized in that: the method comprises the following steps:

(1) determining a working wavelength lambda, optimizing the size parameters of the nano brick unit structure through electromagnetic simulation software, and optimizing the nano brick unit structure with the half-wave plate characteristic, so that a group of size parameters with the highest transmittance of reverse circularly polarized light is obtained when circularly polarized light under the working wavelength is normally incident to the nano brick unit structure; the nano brick unit structure consists of a substrate and a nano brick etched on the substrate; the size parameters of the nano brick unit structure comprise the length L, the width W, the height H and the central interval C of the unit structure of the nano brick;

(2) supposing that the super-surface micro-lens array comprises M multiplied by N super-surface micro-lenses, each super-surface micro-lens is composed of t multiplied by t nano-brick unit structures, the center interval of the unit structures is C, and when circularly polarized light under the working wavelength is normally incident to the super-surface micro-lens array, the number of volume pixel points generated in a three-dimensional transmission image space is M multiplied by N;

(3) randomly selecting m individual pixel point P of transmission image space_m(x_m,y_m,Z_m) Assuming that the volume pixel point corresponds to the mth microlens in the super-surface microlens array, the central coordinate of the microlens is C_m(X_m,Y_m0), the phase of any one nano-brick unit structure with the center position coordinate of A (X, Y,0) is obtained:

m is less than or equal to MxN; the phase of the nano-brick unit structure with any one central position coordinate A (X, Y,0) on the mth super-surface micro-lens is as follows:

wherein | X-X_m|≤(t-1)C/2，|Y-Y_m|≤(t-1)C/2；

In the same way, phase values of all the nano-brick unit structures on the super-surface micro-lens array can be obtained according to other volume pixel points and the super-surface micro-lens central coordinates which form the three-dimensional image, and a phase distribution matrix is formed

(4) By the relational expression

2. The true three-dimensional stereo imaging technology based on the super-surface micro-lens array is characterized in that: the substrate material is silicon dioxide, and the nano brick material is silicon.

3. The true three-dimensional stereo imaging technology based on the super-surface micro-lens array is characterized in that: in the step (1), the working wavelength is 633 nm; when the working wavelength is 633nm, the length L of the nano brick is 150nm, the width W of the nano brick is 60nm, the height H of the nano brick is 385nm, and the central interval C of the unit structure is 300 nm.

Technical Field

The invention relates to the technical field of micro-nano optics, in particular to a true three-dimensional imaging technology based on a super-surface micro-lens array.

Background

In recent years, with the progress of optical technology, microelectronic technology, and computer technology, stereoscopic display technology has also been rapidly developed. The progress of display technology represents that human beings are pursuing more realistic visual enjoyment, and the two-dimensional plane image display cannot meet the requirements of people for the display of three-dimensional objects with physical depth information in some aspects, so that the three-dimensional stereo display is generated and becomes a research hotspot in the display field in recent years. Compared with two-dimensional image display, the three-dimensional imaging technology can truly reproduce objective objects, particularly depth information of the objects, namely three-dimensional information of a three-dimensional image is provided, so that an observer can obtain an immersive stereoscopic vision, and the three-dimensional imaging technology is more rich in practicability and participation. Most three-dimensional displays today require special glasses to be worn so that the viewer's field of view is limited by the instrument. The real three-dimensional imaging technology overcomes the defect that the traditional three-dimensional display technology needs auxiliary equipment, is more authentic, and has great significance for revolutionary change in the fields of virtual reality and simulation. The method can generate images with real physical depth, and has very important application value in national economy, national defense construction, life science, building design and biomedical engineering.

Disclosure of Invention

The invention aims to provide a true three-dimensional imaging technology based on a super-surface micro-lens array, which converts depth information of a three-dimensional object into focal length information of the super-surface micro-lens array and further converts the focal length information into phase distribution information of the super-surface micro-lens. A complete light wave front is divided into a plurality of tiny parts in space through the super-surface micro-lens array, each part is focused by the corresponding super-surface micro-lens at different space positions in a transmission three-dimensional image space to generate a focus, namely, an individual pixel point of a three-dimensional image is generated in a simulation mode, a series of focuses can be obtained through the focusing of the super-surface micro-lenses, and the focuses in the space form a three-dimensional pixel lattice, so that true three-dimensional imaging is realized.

In order to achieve the above object, the present invention provides a true three-dimensional stereo imaging technology based on a super-surface micro-lens array, which is characterized in that: the method comprises the following steps:

(1) determining a working wavelength lambda, optimizing the size parameters of the nano brick unit structure through electromagnetic simulation software, and optimizing the nano brick unit structure with the half-wave plate characteristic, so that a group of size parameters with the highest transmittance of reverse circularly polarized light is obtained when circularly polarized light under the working wavelength is normally incident to the nano brick unit structure; the nano brick unit structure consists of a substrate and a nano brick etched on the substrate; the size parameters of the nano brick unit structure comprise the length L, the width W, the height H and the central interval C of the unit structure of the nano brick;

(2) supposing that the super-surface micro-lens array comprises M multiplied by N super-surface micro-lenses, each super-surface micro-lens is composed of t multiplied by t nano-brick unit structures, the center interval of the unit structures is C, and when circularly polarized light under the working wavelength is normally incident to the super-surface micro-lens array, the number of volume pixel points generated in a three-dimensional transmission image space is M multiplied by N;

(3) randomly selecting m individual pixel point P of transmission image space_m(x_m,y_m,Z_m) Assuming that the volume pixel point corresponds to the mth microlens in the super-surface microlens array, the central coordinate of the microlens is C_m(X_m,Y_m0), the phase of any one nano-brick unit structure with the center position coordinate of A (X, Y,0) is obtained:

m is less than or equal to MxN; the phase of the nano-brick unit structure with any one central position coordinate A (X, Y,0) on the mth super-surface micro-lens is as follows:

wherein | X-X_m|≤(t-1)C/2，|Y-Y_m|≤(t-1)C/2；

In the same way, phase values of all the nano-brick unit structures on the super-surface micro-lens array can be obtained according to other volume pixel points and the super-surface micro-lens central coordinates which form the three-dimensional image, and a phase distribution matrix is formed

(4) By the relational expression

Calculating to obtain a direction angle arrangement matrix phi of the nano brick unit structure; arranging the nano brick unit structures with the same size and the same direction angle according to the direction angle arrangement matrix phi at equal intervals in the length direction and the width direction to form a super-surface micro-lens array; in step 4, the super-surface microlens array structure is composed of (M × t) × (N × t) nano-brick unit structures.

Preferably, the substrate material is silicon dioxide, and the nano brick material is silicon.

Further, in the step (1), the working wavelength is 633 nm; when the working wavelength is 633nm, the length L of the nano brick is 150nm, the width W of the nano brick is 60nm, the height H of the nano brick is 385nm, and the central interval C of the unit structure is 300 nm.

The invention has the following advantages and beneficial effects:

(1) the super-surface micro-lens array designed by the invention has the advantages of simple and compact structure, small volume, light weight, convenience for high integration and suitability for the development trend of miniaturization of an optical system.

(2) Compared with the prior art, the invention can directly project the three-dimensional image in the air without any mechanical moving device, fog screen and other auxiliary equipment.

(3) The invention can see the stereo image from different angles without wearing any additional watching equipment, and can realize multi-person multi-angle observation at the same time. The implementation method is simple, and has the advantages of simple operation, more intuition and trueness.

Drawings

FIG. 1 is a schematic diagram of the structure of a nano-brick unit according to the present invention;

FIG. 2 is the transmittance of the nano-brick unit structure designed in the present invention;

FIG. 3 is a schematic diagram of the phase distribution design of the super-surface microlens array of the present invention;

FIG. 4 is a schematic diagram of a super-surface microlens array according to the present invention, in which (M x t) x (N x t) nano-brick unit structures having the same size and different orientation angles are arranged at equal intervals in the length and width directions;

FIG. 5 is a schematic diagram of the phase distribution of any one of the super-surface microlenses in the present invention;

FIG. 6 is a diagram of the simulation effect of the focus of a voxel point at any spatial position in the three-dimensional image space in the present invention.

Detailed Description

The invention is further described in detail below with reference to the figures and specific examples.

1. The nano brick unit structure with the function of the half-wave plate is optimally designed.

The following description will be given taking the nano-brick unit structure as a rectangular parallelepiped. The length, width and height of the nano brick unit structure are all sub-wavelength.

As shown in fig. 1, an xyz rectangular coordinate system is established, the long side direction of the nano-brick unit structure represents a long axis, the short side direction represents a short axis, and Φ is an included angle between the long axis and the x axis of the nano-brick unit structure, i.e., a direction angle (the value range of Φ is 0 ° to 180 °) of the nano-brick unit structure, as shown in fig. 1.

Optimizing size parameters of a nano brick unit structure by using electromagnetic simulation software, wherein the size parameters comprise the height H, the length L, the width W and the side length C of a unit structure substrate of the nano brick unit structure 1, as shown in figure 1, when circularly polarized light under working wavelength is normally incident to the nano brick unit structure, a group of size parameters with the highest reverse circularly polarized light transmittance is obtained, namely the optimized size parameters, the function of the optimally designed nano brick unit structure can be equivalent to a half-wave plate, and a Jones matrix can be used

To show that when the incident light is circularly polarized

(the left circular polarized light is "+", the right circular polarized light is "-"), the emergent light passing through the nano brick unit structure can be expressed as:

as can be seen from the equation (1), the outgoing light is circularly polarized light, but the handedness is opposite to that of the incident light, and a phase retardation of 2 Φ, that is, a phase retardation amount is addedIs 2 times of the direction angle phi of the nano brick, so the phase adjustment can be realized by changing the direction angle of the nano brick.

2. A phase design method of a super-surface micro-lens array.

And (3) true three-dimensional imaging, wherein each three-dimensional pixel point of the image is positioned at a true position in a three-dimensional physical space, and the relative spatial position relationship between the voxels is truly embodied in the three-dimensional space. The observer can see different sides of the three-dimensional stereoscopic image from different angles by changing the observation position. Multiple observers can simultaneously observe the same three-dimensional stereo image from different angles as if observing a real three-dimensional object. The true three-dimensional stereo display can bring complete psychological and physiological three-dimensional perception information to an observer, and provides a unique means for understanding the spatial relationship between a three-dimensional image and an object therein. True three-dimensional imaging is to display volume pixel points of a three-dimensional image in a three-dimensional space and provide physical depth of field for an observer, so that a three-dimensional imaging space needs to be established.

As shown in fig. 3, an XYZ space rectangular coordinate system is established, the super-surface microlens array is located on the XOY plane, the super-surface microlens array includes M × N super-surface microlenses, each super-surface microlens is formed by t × t sub-wavelength nanoblock unit structures, the entire super-surface microlens array includes (M × t) × (N × t) sub-wavelength nanoblock unit structures, the center interval of the unit structures is C, and the mth individual pixel point P in the transmission image space is arbitrarily selected_m(x_m,y_m,Z_m) For the purpose of phase design description of the super-surface micro-lens, it is assumed that the volume pixel point corresponds to the M (M ≦ M × N) th micro-lens in the super-surface micro-lens array, and the center coordinate thereof is C_m(X_m,Y_m,0). The focal length of the super-surface microlens is defined as the optical path between the center of the microlens and the focused volume pixel point, and can be expressed as:

wherein n is₀Representing the refractive index in air. The optical path between the nano-brick unit structure with any one central position coordinate A (X, Y,0) on the mth super-surface micro-lens and the volume pixel point can be expressed as follows:

wherein, | X-X_m|≤(t-1)C/2，|Y-Y_mThe | < t-1) C/2. The phase of the nano-brick unit structure at that location can be expressed as:

similarly, the phase values of all the nano-brick unit structures on the super-surface micro-lens array can be obtained according to the formula (4) according to other volume pixel points and the super-surface micro-lens central coordinates forming the three-dimensional image to form a phase distribution matrix

By the relational expression

And calculating to obtain a direction angle distribution matrix phi of the nano brick unit structure. When the circularly polarized light is normally incident to the designed super-surface micro-lens array, the micro-lens array with the super-surface structure divides a complete light wave front into a plurality of tiny parts in space, and each part is focused on a three-dimensional image space by the corresponding super-surface micro-lensThe focal point is generated at different spatial positions to simulate an individual pixel point of the three-dimensional image, and the focusing of the MxN super-surface micro-lenses can obtain a three-dimensional pixel lattice consisting of the MxN individual pixel points in the transmission image space to form the true three-dimensional image. Wherein, the substrate is a silicon dioxide substrate, and the nano brick unit structure is a silicon nano brick, but not limited thereto. The super surface array structure has a transmissive operation mode, but is not limited thereto.

The invention will be further explained with reference to the drawings.

The expected realization function of the true three-dimensional stereo imaging technology based on the super-surface micro-lens array provided by the embodiment is that when circularly polarized light is normally incident to the designed super-surface micro-lens array, the micro-lens array with the super-surface structure divides a complete light wave front into a plurality of tiny parts in space, each part is focused by the corresponding super-surface micro-lens at different spatial positions in a transmission three-dimensional image space to generate a focus, an individual pixel point of a three-dimensional stereo image is simulated, and all focused generated volume pixel points form a three-dimensional volume pixel lattice to form a true three-dimensional stereo image, so that the true three-dimensional stereo imaging is finally realized.

In this embodiment, the nano-unit structure is composed of a silicon dioxide substrate and a silicon nano-brick etched on the substrate, as shown in fig. 1. Selecting a design wavelength of 633nm, and performing optimization simulation on the nano brick unit structure through electromagnetic simulation software CST aiming at the wavelength to obtain the optimized silicon nano brick with the size parameters as follows: the length is 150nm, the width is 60nm, the height is 385nm, and the side length of the unit structure substrate is 300 nm. The transmission of the nano-brick unit structure under the structural parameters is shown in FIG. 2, wherein T_cross、T_coRespectively, the transmittance of the reverse circularly polarized light and the transmittance of the same circularly polarized light. As can be seen from fig. 2, when the wavelength of incident light is 633nm, the transmittance of the reverse circularly polarized light carrying additional phase retardation is higher than 87%, and the transmittance of the same-direction circularly polarized light without additional phase retardation is lower than 1%, and the result shows that the optimized nano-brick unit structure has the function of a half-wave plate.

Based on the nano brick unit structure optimized by the simulation, an XYZ spatial rectangular coordinate system is established for a working wavelength λ of 633nm as shown in fig. 3, the super-surface microlens array is located on an XOY plane, the super-surface microlens array includes M × N super-surface microlenses, each super-surface microlens includes t × t sub-wavelength nano brick unit structures, the entire super-surface microlens array includes (M × t) × (N × t) sub-wavelength nano brick unit structures, and the unit structure center interval is C. Randomly selecting a volume pixel point P formed by space focusing of transmission image₁(5 μm,5 μm,5 μm) as an example, the phase design of the super-surface micro-lens is explained, and if the super-surface micro-lens corresponding to the volume pixel point is located at the center of the array, the center coordinate of the super-surface micro-lens is C₁(0,00), the super-surface microlens is composed of 50 × 50 sub-wavelength nanoblock unit structures, the center-to-center spacing of the unit structures is 300nm, and the phase distribution of the nanoblock unit structure of the super-surface microlens can be obtained by the formula (4), as shown in fig. 5. By the relational expression

And calculating to obtain the direction angle arrangement of the corresponding nano brick unit structure.

According to the obtained phase distribution, a Ralisofil formula is utilized to perform simulation calculation to obtain a volume pixel point P₁The spatial position in the transmission image space is completely matched with the three-dimensional spatial position of the designed volume pixel point as shown in fig. 6, and the correctness of the design method is further proved. Similarly, if the three-dimensional position coordinates of other pixel points in the image space are known, the phase distribution of all the nano-brick unit structures on the super-surface micro-lens array can be calculated according to the formula (4), and the true three-dimensional imaging is realized.

In this embodiment, taking any microlens in the super-surface microlens array as an example, when circularly polarized light is incident normally to the designed super-surface microlens, the microlens can focus light waves at any spatial position in a three-dimensional image space, and an individual pixel point of a three-dimensional image is simulated. If the super-surface micro-lens array comprises M multiplied by N super-surface micro-lenses, M multiplied by N individual pixel points can be generated in a transmission image space through focusing to form a three-dimensional pixel dot matrix, and finally true three-dimensional imaging is achieved.

The true three-dimensional imaging technology based on the super-surface micro-lens array provided by the embodiment of the invention at least comprises the following technical effects:

in the embodiment of the invention, a nano brick unit structure with a half-wave plate function is optimized, when circularly polarized light with working wavelength is normally incident to the nano brick unit structure, a group of size parameters with the highest reverse circularly polarized light transmittance is obtained, then the phase adjustment function of the nano brick unit structure is utilized to realize the focusing function of the super surface micro lens, a complete light wave front is spatially divided into a plurality of tiny parts through the super surface micro lens array, each part is focused at different spatial positions in a three-dimensional image space by the corresponding super surface micro lens, an individual pixel point of a three-dimensional image is simulated to be generated, a series of super surface micro lenses are focused to obtain a series of focuses, the focuses in the space form a three-dimensional pixel lattice to form the three-dimensional image, and finally true three-dimensional imaging is realized.