CN106371304A

CN106371304A - Safe compressed holographic imaging system and method

Info

Publication number: CN106371304A
Application number: CN201610861228.9A
Authority: CN
Inventors: 李军; 雷苗; 罗琪; 李娇声; 戴晓芳; 李榕; 唐志列
Original assignee: South China Normal University
Current assignee: South China Normal University
Priority date: 2016-09-28
Filing date: 2016-09-28
Publication date: 2017-02-01

Abstract

The invention discloses a safe compressed holographic imaging system, which decomposes a beam of light emitted by a light source into object light and reference light through a light source generating and beam splitting device; obtains an encrypted object light beam carrying an object image through an encryption device; The phase device obtains the reference light beam carrying the image of the host; the image generation and watermarking device generates an encrypted and watermarked interference hologram; the image acquisition device collects the interference hologram data and sends it to the image reconstruction device; the image reconstruction device Object images are reconstructed from the interference hologram data. The invention utilizes a three-step phase-shifting method to record interference holograms, simultaneously realizes image encryption, image watermarking and image compression in an all-optical environment, ensures the safety of information during transmission and storage, and avoids illegal manipulation of original object images. Steal or tamper with. The invention also provides a safe compressed holographic imaging method.

Description

A safe compressed holographic imaging system and its imaging method

技术领域technical field

本发明涉及图像安全成像领域，尤其涉及一种具有安全的压缩全息成像系统及其成像方法。The invention relates to the field of image security imaging, in particular to a secure compressed holographic imaging system and an imaging method thereof.

背景技术Background technique

大数据时代下，信息变的愈加透明，信息和数据的安全问题也变得越来越重要。图像安全主要包括图像加密和图像水印等。图像加密是将图像数据本身进行编码，使原始图像像素置乱成为秘密数据生成加密图像，其目的并不是只停留在生成一幅视觉上杂乱的图像，而是将其作为有效的辅助措施，应用到数字水印技术的预处理和后处理过程中，以达到图像安全传输的目的。图像水印是将加密图像信息嵌入到一幅宿主图像中，在保持宿主图像原始视觉信息大致不变的情况下，达到水印加密图像数据的目的，它既能保证信息在传输和存储过程中的安全，又能避免引起窃密者的注意，从而实现安全成像的要求。In the era of big data, information becomes more transparent, and information and data security issues become more and more important. Image security mainly includes image encryption and image watermarking. Image encryption is to encode the image data itself, so that the original image pixels are scrambled into secret data to generate encrypted images. In the pre-processing and post-processing process of digital watermarking technology, in order to achieve the purpose of safe image transmission. Image watermarking is to embed encrypted image information into a host image, and achieve the purpose of watermarking encrypted image data while keeping the original visual information of the host image roughly unchanged. It can not only ensure the security of information during transmission and storage , and can avoid attracting the attention of stealers, so as to meet the requirements of safe imaging.

不同于传统记录物体光强分布的成像方法，全息成像技术记录的是物体的复振幅波，即能同时记录物体的振幅与相位信息，再现物体的波前。因此，在相位物体和3D场景成像方面，全息技术有着明显的优势。而压缩感知技术为成像领域的研究提供了一个新的方向,它是用以远低于奈奎斯特采样速率采集信号的非自适应线性投影值，通过求解一个优化问题，精确地重构出原始信号,从而大大降低系统采集的数据量。因此，该理论为全息图在纯光域中的直接压缩采样提供了可能。而光学加密方法也有着高速操作和多维能力等特点。因此基于压缩传感技术的许多新的应用已经在全息领域内兴起。利用信号的稀疏性，加密和水印的对象可以被压缩为更少的数据。Different from the traditional imaging method that records the light intensity distribution of an object, holographic imaging technology records the complex amplitude wave of the object, that is, it can record the amplitude and phase information of the object at the same time, and reproduce the wavefront of the object. Therefore, holographic technology has obvious advantages in phase object and 3D scene imaging. The compressed sensing technology provides a new direction for the research in the field of imaging. It is used to acquire the non-adaptive linear projection value of the signal much lower than the Nyquist sampling rate. By solving an optimization problem, it can accurately reconstruct the The original signal, thus greatly reducing the amount of data collected by the system. Therefore, this theory opens the possibility for direct compressive sampling of holograms in the pure optical domain. The optical encryption method also has the characteristics of high-speed operation and multi-dimensional capabilities. Therefore, many new applications based on compressive sensing technology have emerged in the field of holography. By exploiting the sparsity of signals, encrypted and watermarked objects can be compressed into less data.

另外，国内外很多小组均采用了电荷耦合器件(以下简称“CCD”)等面阵成像方式，而后在数字域的电信号中实现安全图像的压缩，虽然能很好地压缩数据量；但是由于CCD需要通过光电二极管感应光线，而光电二极管对光线感应的局限性，使得国内外的很多成像方式均不能应用于纯光的系统中，比如在全光网上的应用；也不能充分发挥光学系统高速率和高并行性等特点，严重制约了其应用；更不能在光学成像系统中同时完成光学图像感知、光学图像安全处理和光学图像压缩等功能。In addition, many groups at home and abroad have adopted area array imaging methods such as charge-coupled devices (hereinafter referred to as "CCD"), and then implemented security image compression in electrical signals in the digital domain. Although the data volume can be well compressed; CCD needs to sense light through photodiodes, and the limitations of photodiodes to light sensing make many imaging methods at home and abroad cannot be applied to pure light systems, such as applications on all-optical networks; nor can they give full play to the high performance of optical systems The characteristics of high speed and high parallelism seriously restrict its application; it is even impossible to simultaneously complete functions such as optical image perception, optical image security processing and optical image compression in the optical imaging system.

发明内容Contents of the invention

本发明在于克服现有技术的缺点与不足，提供一种安全的压缩全息成像系统，其可同时实现图像加密、图像水印和图像压缩，且可保证信息在传输和存储过程中的安全，避免原始物体图像遭到非法窃取或篡改。The present invention overcomes the shortcomings and deficiencies of the prior art, and provides a secure compressed holographic imaging system, which can realize image encryption, image watermarking and image compression at the same time, and can ensure the security of information in the process of transmission and storage, avoiding original Object images are illegally stolen or tampered with.

本发明是通过以下技术方案实现的：一种安全的压缩全息成像系统，包括光源生成及分束装置、加密装置、调相装置、图像生成及水印装置、图像采集装置和图像重构装置；The present invention is realized through the following technical solutions: a safe compressed holographic imaging system, including a light source generation and beam splitting device, an encryption device, a phase modulation device, an image generation and watermark device, an image acquisition device and an image reconstruction device;

所述光源生成及分束装置，用于将光源发出的一束光分解为两束光，其中一束为照射在物体图像的物光，另一束为照射在宿主图像的参考光；The light source generation and beam splitting device is used to decompose one beam of light emitted by the light source into two beams, one of which is the object light irradiated on the object image, and the other is the reference light irradiated on the host image;

所述加密装置，用于将所述物光反射照向物体图像，并对所述物光信息进行加密，获得携带物体图像的加密物光光束；The encryption device is used to reflect the object light to the object image, and encrypt the object light information to obtain an encrypted object light beam carrying the object image;

所述调相装置，用于将所述参考光调相后照射在宿主图像，获得携带宿主图像的参考光光束；The phase modulation device is used to adjust the phase of the reference light and irradiate the host image to obtain a reference light beam carrying the host image;

所述图像生成及水印装置，用于同时接收携带物体图像的加密物光光束和携带宿主图像的参考光光束，并生成加密与水印叠加的干涉全息图；The image generating and watermarking device is used to simultaneously receive the encrypted object light beam carrying the object image and the reference light beam carrying the host image, and generate an encrypted and watermarked interference hologram;

所述图像采集装置，用于采集所述干涉全息图数据，并传送至所述图像重构装置；The image acquisition device is used to acquire the interference hologram data and transmit it to the image reconstruction device;

所述图像重构装置，用于根据干涉全息图数据重构出物体图像。The image reconstruction device is used for reconstructing an object image according to the interference hologram data.

相比于现有技术，本发明利用三步相移法记录干涉全息图，在全光域环境中同时实现图像加密、图像水印和图像压缩，保密性更强，保证了信息在传输和存储过程中的安全，避免了原始物体图像遭到非法窃取或篡改，实现了安全压缩成像的要求。Compared with the prior art, the present invention uses the three-step phase-shifting method to record the interference hologram, realizes image encryption, image watermarking and image compression simultaneously in an all-optical environment, and has stronger confidentiality, ensuring that the information is transmitted and stored The security in the system prevents the original object image from being illegally stolen or tampered with, and realizes the requirement of secure compression imaging.

进一步地，所述加密装置包括反射镜、第一随机相位板和第二随机相位板；沿着物光光路路径，在所述光源生成及分束装置后且在物体图像前设置所述反射镜，所述反射镜用于将所述物光进行反射后照向物体图像；在物体图像后方设置所述第一随机相位板；在所述第一随机相位板后方设置与之平行的第二随机相位板；所述物光透过所述物体图像后，依次通过所述第一随机相位板和第二随机相位板，获得携带物体图像的加密物光光束；该加密物光光束再照射到所述图像生成及水印装置；Further, the encryption device includes a reflector, a first random phase plate, and a second random phase plate; along the path of the object light path, the reflector is arranged after the light source generating and beam splitting device and in front of the object image, The reflector is used to reflect the object light and illuminate the object image; the first random phase plate is arranged behind the object image; the second random phase parallel to it is arranged behind the first random phase plate plate; after the object light passes through the object image, it passes through the first random phase plate and the second random phase plate in sequence to obtain an encrypted object light beam carrying the object image; the encrypted object light beam then irradiates the Image generation and watermarking device;

根据菲涅尔衍射公式，所述加密物光光束所表示的加密物体图像用复振幅分布表示为：According to the Fresnel diffraction formula, the encrypted object image represented by the encrypted object light beam is expressed by the complex amplitude distribution as:

$\begin{matrix} {ψ ψ}_{o o} ((ξ ξ,, η η)) = = A A ((ξ ξ,, η η)) exp exp ((i i φ φ ((ξ ξ,, η η)) \\ = = {Frt Frt}_{{z z}_{22}} {{{Frt Frt}_{{z z}_{11}} {{{K K}_{11} \times \times O o (({x x}_{00},, {y the y}_{00})) \times \times exp exp [[i i 22 π π \times \times p p (({x x}_{00},, {y the y}_{00}))]]}} \times \times exp exp [[i i 22 π π \times \times q q (({x x}_{11},, {y the y}_{11}))]]}},, \end{matrix}$

其中，K₁表示物光通路的光振幅；O(x₀,y₀)为物光在第一随机相位板处的复振幅分布；exp[i2π·p(x₀,y₀)]和exp[i2π·q(x₁,y₁)]分别为第一随机相位板和第二随机相位板的复振幅透过率；p(x₀,y₀)和q(x₁,y₁)均为分布在[0,1]区间上的统计独立的白噪声；Frt_Z表示衍射距离为Z的菲涅尔变换，第一随机相位板和第二随机相位板之间的距离为Z₁,第二随机相位板和数字微镜器件之间的距离为Z₂。Among them, K ₁ represents the light amplitude of the object light path; O(x ₀ ,y ₀ ) is the complex amplitude distribution of the object light at the first random phase plate; exp[i2π·p(x ₀ ,y ₀ )] and exp [i2π·q(x ₁ ,y ₁ )] are the complex amplitude transmittances of the first random phase plate and the second random phase plate respectively; p(x ₀ ,y ₀ ) and q(x ₁ ,y ₁ ) are both is a statistically independent white noise distributed on the [0,1] interval; Frt _Z represents the Fresnel transform with a diffraction distance of Z, the distance between the first random phase plate and the second random phase plate is Z ₁ , the first The distance between the two random phase plates and the digital micromirror device is Z ₂ .

进一步地，所述调相装置包括压电转换器和第二分束器，所述压电转换器将所述参考光分三次调相后，生成相位分别为0,π的干涉光源；所述第二分束器将调相后的参考光照射宿主图像，进而获得携带宿主图像的参考光光束；Further, the phase modulation device includes a piezoelectric converter and a second beam splitter, and the piezoelectric converter divides the phase of the reference light into three phases to generate phases of 0, 0, and 0 respectively. An interference light source of π; the second beam splitter irradiates the host image with the phase-modulated reference light, and then obtains a reference light beam carrying the host image;

所述参考光光束所表示的宿主图像复振幅分布可以表示为：The host image complex amplitude distribution represented by the reference light beam can be expressed as:

${ψ ψ}_{h h} ((ξ ξ,, η η;; {φ φ}_{R R})) = = {A A}_{h h} ((ξ ξ,, η η)) exp exp [[{iφ iφ}_{h h} ((ξ ξ,, η η))]] exp exp (({iφ iφ}_{R R})),, (({φ φ}_{R R} = = 00,, \frac{π π}{22},, π π)),,$

进一步地，所述图像生成及水印装置包括第三分束器；所述第三分束器同时接收携带宿主图像的参考光光束和携带物体图像的加密物光光束，以形成同轴的干涉光，并将这两种光束叠加生成干涉全息图，该干涉全息图携带了加密与水印后的物体图像信息；Further, the image generating and watermarking device includes a third beam splitter; the third beam splitter simultaneously receives the reference light beam carrying the host image and the encrypted object light beam carrying the object image to form coaxial interference light , and superimpose these two beams to generate an interference hologram, which carries the encrypted and watermarked object image information;

所述加密与水印叠加的干涉全息图的光强值表示为The light intensity value of the interference hologram superimposed by encryption and watermark is expressed as

I_H(ξ,η；φ_R)I _H (ξ,η; φ _R )

＝|ψ₀(ξ,η)+ψ_h(ξ,η；φ_R)|² ＝|ψ ₀ (ξ,η)+ψ _h (ξ,η; φ _R )| ²

＝A(ξ,η)²+A_h(ξ,η)² ＝A(ξ,η) ² +A _h (ξ,η) ²

+2A(ξ,η)A_h(ξ,η)cos[φ_h(ξ,η)+φ_R-φ(ξ,η)],+2A(ξ,η)A _h (ξ,η)cos[φ _h (ξ,η)+φ _R -φ(ξ,η)],

$(({φ φ}_{R R} = = 00,, \frac{π π}{22},, π π)),,$

进一步地，所述图像采集装置包括数字微镜器件、会聚透镜和单光子探测器；所述数字微镜器件对所述图像生成及水印装置生成的干涉全息图数据进行压缩和采样后，通过所述会聚透镜汇聚于一点，之后通过所述单光子探测器收集；Further, the image acquisition device includes a digital micromirror device, a converging lens and a single photon detector; after the digital micromirror device compresses and samples the interference hologram data generated by the image generation and watermarking device, the The converging lens is converged at one point, and then collected by the single photon detector;

所述单光子探测器的高灵敏度的光电二极管的输出电压表示为：The output voltage of the high-sensitivity photodiode of the single-photon detector is expressed as:

其中表示所述数字微镜器件平面上的m维伪随机测量矩阵；in Representing the m-dimensional pseudo-random measurement matrix on the plane of the digital micromirror device;

重复这个过程M次，可以得到的测量值Y为：Repeating this process M times, the measured value Y that can be obtained is:

Y＝[y₁,y₂,y₃]＝Ψ[I_H1,I_H2,I_H3],Y=[y ₁ ,y ₂ ,y ₃ ]=Ψ[I _H1 ,I _H2 ,I _H3 ],

其中，Ψ∈R^M×N是所述数字微镜器件平面获得的测量矩阵，Y∈R^M×3是测量值，y_k∈R^M×1，I_Hk∈R^N×1。in, Ψ∈RM ^×N is the measurement matrix obtained on the plane of the digital micromirror device, Y∈RM ^×3 is the measured value, y _k ∈RM ^×1 , I _Hk ∈RN ^×1 .

进一步地，所述图像重构装置包括模数转换模块、图像传输模块和图像重构模块；所述模数转换模块，用于将所述图像采集装置采集的模拟干涉全息图数据转换为数字干涉全息图数据；所述图像传输模块，用于将所述数字干涉全息图数据传送到所述图像重构模块；所述图像重构模块，用于根据图像传输装置传送的数字干涉全息图数据，利用两步迭代收缩算法、菲涅尔反变换算法和宿主图像的复振幅信息重构出原始的物体图像；Further, the image reconstruction device includes an analog-to-digital conversion module, an image transmission module, and an image reconstruction module; the analog-to-digital conversion module is used to convert the analog interference hologram data collected by the image acquisition device into digital interference Hologram data; the image transmission module is used to transmit the digital interference hologram data to the image reconstruction module; the image reconstruction module is used to transmit the digital interference hologram data according to the image transmission device, The original object image is reconstructed by using the two-step iterative shrinkage algorithm, the Fresnel inverse transform algorithm and the complex amplitude information of the host image;

利用压缩感知算法重建数字微镜器件上的叠加的干涉的光强度表达式为：The expression of the light intensity of the superimposed interference on the digital micromirror device reconstructed by compressive sensing algorithm is:

$\begin{matrix} \underset{{I I}_{H h k k}}{m m i i n no} \frac{μ μ}{22} | | | | {Y Y}_{k k} - - Ψ Ψ {\overset{^^}{I I}}_{H h k k} | | {| |}_{22}^{22} + + T T V V (({\overset{^^}{I I}}_{H h k k})) & s the s . . t t . . & {Y Y}_{k k} = = {ΨI ΨI}_{H h k k} \end{matrix},,$

其中，μ是常量，是一个最小二乘项，当与相关矢量量化值Y_k一致时它的值最小，是信号的全变分表示,具体为如下公式：where μ is a constant, is a least squares term, when Its value is the smallest when it is consistent with the relevant vector quantization value Y _k , is the total variational representation of the signal, specifically as the following formula:

$T T V V (({\overset{^^}{I I}}_{H h k k})) = = \underset{a a d d j j . . i i,, j j}{Σ Σ} | | {\overset{^^}{I I}}_{H h k k i i} - - {\overset{^^}{I I}}_{H h k k j j} | |,,))$

该公式中的下标i，j表示所有成对的相邻像素点，是离散梯度的l₁范数。The subscript i, j in this formula means All pairs of adjacent pixels, is the discrete gradient The l ₁ norm of .

所述数字微镜器件上的加密和水印后的物体图像的相位信息φ(ξ,η)和振幅信息A(ξ,η)如下： The phase information φ (ξ, η) and the amplitude information A (ξ, η) of the encrypted and watermarked object image on the digital micromirror device are as follows:

$A A ((ξ ξ,, η η)) = = \frac{{[[{(({\overset{^^}{I I}}_{H h 11} - - {\overset{^^}{I I}}_{H h 33}))}^{22} + + {((22 {\overset{^^}{I I}}_{H h 22} - - {\overset{^^}{I I}}_{H h 11} - - {\overset{^^}{I I}}_{H h 33}))}^{22}]]}^{11 / / 22}}{44 {A A}_{h h}},,$

其中，宿主图像的衍射分布φ_h，A_h利用马赫-增德尔干涉仪下的三步相移法提前获得；Among them, the diffraction distribution φ _h and A _h of the host image are obtained in advance by using the three-step phase shift method under the Mach-Zehnder interferometer;

通过菲涅尔反变换算法重构出所述物体图像，该过程表示为：The object image is reconstructed through the inverse Fresnel transform algorithm, and the process is expressed as:

其中，IFrt_Z代表衍射距离为Z的菲涅尔反变换。Among them, IFrt _Z represents the inverse Fresnel transform with a diffraction distance of Z.

本发明同时还提供一种安全的压缩全息成像方法，包括如下步骤：The present invention also provides a safe compressed holographic imaging method, which includes the following steps:

步骤S1：将光源发出的一束光分解为两束光，其中一束为照射在物体图像的物光，另一束为照射在宿主图像的参考光；Step S1: Decompose one beam of light emitted by the light source into two beams, one of which is the object light irradiated on the object image, and the other is the reference light irradiated on the host image;

步骤S2：将物光反射照向物体图像，并对物光进行加密，获得携带物体图像的加密物光光束；Step S2: reflect the object light onto the object image, and encrypt the object light to obtain an encrypted object light beam carrying the object image;

步骤S3：将参考光分别分三次调相后照射在宿主图像，获得携带宿主图像的参考光光束；Step S3: irradiate the reference light beam on the host image after phase modulation three times to obtain a reference light beam carrying the host image;

步骤S4：根据携带物体图像的加密物光光束和携带宿主图像的参考光光束，生成加密与水印叠加的干涉全息图；Step S4: Generate an encrypted and watermarked interference hologram based on the encrypted object light beam carrying the object image and the reference light beam carrying the host image;

步骤S5：采集干涉全息图数据，并根据该数字干涉全息图数据重构出物体图像。Step S5: collecting interference hologram data, and reconstructing an object image based on the digital interference hologram data.

为了更好地理解和实施，下面结合附图详细说明本发明。For better understanding and implementation, the present invention will be described in detail below in conjunction with the accompanying drawings.

附图说明Description of drawings

图1是本发明实施例中安全的压缩全息成像系统的原理框图；Fig. 1 is a functional block diagram of a secure compressed holographic imaging system in an embodiment of the present invention;

图2是本发明实施例中安全的压缩全息成像系统的结构示意图；Fig. 2 is a schematic structural diagram of a secure compressed holographic imaging system in an embodiment of the present invention;

图3是本发明实施例中安全的压缩全息成像方法的流程图；Fig. 3 is a flowchart of a secure compressed holographic imaging method in an embodiment of the present invention;

图4是图3所示步骤S2中的具体实施流程图；Fig. 4 is the specific implementation flowchart in step S2 shown in Fig. 3;

图5是图3所示步骤S5中的具体实施流程图；Fig. 5 is the specific implementation flowchart in step S5 shown in Fig. 3;

图6是本发明实施例中安全的压缩全息成像方法的实验仿真结果图。Fig. 6 is a diagram of the experimental simulation results of the secure compressed holographic imaging method in the embodiment of the present invention.

具体实施方式detailed description

请同时参阅图1和图2，图1是本发明实施例中安全的压缩全息成像系统的原理框图；图2是本发明实施例中安全的压缩全息成像系统的结构示意图。该安全的压缩全息成像系统包括光源生成及分束装置11、加密装置12、调相装置13、图像生成及水印装置14、图像采集装置15和图像重构装置16。Please refer to FIG. 1 and FIG. 2 at the same time. FIG. 1 is a functional block diagram of a secure compressed holographic imaging system in an embodiment of the present invention; FIG. 2 is a schematic structural diagram of a secure compressed holographic imaging system in an embodiment of the present invention. The secure compressed holographic imaging system includes a light source generation and beam splitting device 11 , an encryption device 12 , a phase modulation device 13 , an image generation and watermark device 14 , an image acquisition device 15 and an image reconstruction device 16 .

所述光源生成及分束装置11，用于将光源发出的一束光分解为两束光，其中一束为照射在物体图像17的物光，另一束为照射在宿主图像18的参考光。所述加密装置12，用于将所述物光反射照向物体图像17，并对所述物光进行加密，获得携带物体图像17的加密物光光束。所述调相装置13，用于将所述参考光调相后照射在宿主图像18，获得携带宿主图像18的参考光光束。所述图像生成及水印装置14，用于同时接收携带物体图像17的加密物光光束和携带宿主图像18的参考光光束，并生成加密与水印叠加的干涉全息图。所述图像采集装置15，用于采集所述干涉全息图数据，并传送至所述图像重构装置16。所述图像重构装置16，用于根据干涉全息图数据重构出物体图像17。The light source generating and beam splitting device 11 is used to decompose a beam of light emitted by the light source into two beams of light, one of which is the object light irradiated on the object image 17, and the other is the reference light irradiated on the host image 18 . The encryption device 12 is configured to reflect the object light toward the object image 17 and encrypt the object light to obtain an encrypted object light beam carrying the object image 17 . The phase modulation device 13 is configured to modulate the phase of the reference light and irradiate the host image 18 to obtain a reference light beam carrying the host image 18 . The image generating and watermarking device 14 is used to simultaneously receive the encrypted object light beam carrying the object image 17 and the reference light beam carrying the host image 18, and generate an encrypted and watermarked interference hologram. The image acquisition device 15 is configured to acquire the interference hologram data and transmit it to the image reconstruction device 16 . The image reconstruction device 16 is configured to reconstruct an object image 17 according to the interference hologram data.

所述光源生成及分束装置11包括激光器111、扩束器112和第一分束器113。所述激光器111发出的一束线性偏振激光经过所述扩束器112扩束和准直后，照向所述第一分束器113。所述第一分束器113将该束激光分为两束光，其中一束为照射在物体图像17的物光；另一束为照射在宿主图像18的参考光。The light source generating and beam splitting device 11 includes a laser 111 , a beam expander 112 and a first beam splitter 113 . A beam of linearly polarized laser light emitted by the laser 111 is expanded and collimated by the beam expander 112 , and then illuminates the first beam splitter 113 . The first beam splitter 113 splits the laser beam into two beams, one of which is the object light irradiated on the object image 17 ; the other is the reference light irradiated on the host image 18 .

所述加密装置12包括反射镜121、第一随机相位板122和第二随机相位板123。沿着物光光路路径，在所述第一分束器113后且在物体图像17前设置所述反射镜121，所述反射镜121用于将所述物光进行反射后照向物体图像17。在物体图像17后方设置所述第一随机相位板122；在所述第一随机相位板122后方设置与之平行的第二随机相位板123。所述物光透过所述物体图像17后，依次通过所述第一随机相位板122和第二随机相位板123，获得携带物体图像17的加密物光光束；该加密物光光束再照射到所述图像生成及水印装置14。所述物光通过反射镜121、物体图像17、第一随机相位板122和第二随机相位板123后，利用双随机相位编码技术即可获得物体图像17像素置乱后的加密图像。The encryption device 12 includes a mirror 121 , a first random phase plate 122 and a second random phase plate 123 . Along the optical path of the object light, the reflector 121 is arranged after the first beam splitter 113 and in front of the object image 17 , and the reflector 121 is used for reflecting the object light to illuminate the object image 17 . The first random phase plate 122 is arranged behind the object image 17 ; the second random phase plate 123 parallel thereto is arranged behind the first random phase plate 122 . After the object light passes through the object image 17, it sequentially passes through the first random phase plate 122 and the second random phase plate 123 to obtain an encrypted object light beam carrying the object image 17; the encrypted object light beam is then irradiated onto The image generating and watermarking device 14 . After the object light passes through the mirror 121 , the object image 17 , the first random phase plate 122 and the second random phase plate 123 , an encrypted image of the scrambled pixel of the object image 17 can be obtained by using double random phase encoding technology.

具体的，假设所述物光照射在物体图像17上的透过率为O(x₀,y₀)，则经过第一随机相位板122和第二随机相位板123获得的加密物光光束，其所表示的加密物体图像用复振幅的分布可以表示为：Specifically, assuming that the transmittance of the object light irradiated on the object image 17 is O(x ₀ , y ₀ ), then the encrypted object light beam obtained through the first random phase plate 122 and the second random phase plate 123, The distribution of the complex amplitude of the encrypted object image represented by it can be expressed as:

上述表达式描述了物体图像17加密后生成的加密图像的信息。其中,K₁表示物光通路的光振幅；exp[i2π·p(x₀,y₀)]和exp[i2π·q(x₁,y₁)]分别为第一随机相位板122和第二随机相位板123的复振幅透过率；p(x₀,y₀)和q(x₁,y₁)均为分布在[0,1]区间上的统计独立的白噪声；Frt_Z表示衍射距离为Z的菲涅尔变换，第一随机相位板122和第二随机相位板123之间的距离为Z₁,第二随机相位板123和图像采集装置15之间的距离为Z₂。The above expression describes the information of the encrypted image generated after the object image 17 is encrypted. Among them, K ₁ represents the optical amplitude of the object light path; exp[i2π·p(x ₀ ,y ₀ )] and exp[i2π·q(x ₁ ,y ₁ )] are the first random phase plate 122 and the second The complex amplitude transmittance of the random phase plate 123; p(x ₀ , y ₀ ) and q(x ₁ , y ₁ ) are both statistically independent white noise distributed on the [0,1] interval; Frt _Z represents diffraction For Fresnel transformation with a distance of Z, the distance between the first random phase plate 122 and the second random phase plate 123 is Z ₁ , and the distance between the second random phase plate 123 and the image acquisition device 15 is Z ₂ .

所述调相装置13包括压电转换器131和第二分束器132，所述压电转换器131将所述参考光分三次调相后，生成相位分别为0,π的干涉光源；所述第二分束器132将调相后的参考光照射宿主图像18，进而获得携带宿主图像18的参考光光束。The phase modulation device 13 includes a piezoelectric converter 131 and a second beam splitter 132. After the piezoelectric converter 131 divides the phase modulation of the reference light three times, the generated phases are respectively 0, π interference light source; the second beam splitter 132 illuminates the host image 18 with the phase-modulated reference light, and then obtains a reference light beam carrying the host image 18 .

经过调相的所述参考光光束所表示的宿主图像18复振幅分布可以表示为：The complex amplitude distribution of the host image 18 represented by the phase-modulated reference light beam can be expressed as:

上述表达式分别描述了步进相移φ_R用0，π/2,π相移的三幅宿主图像18的信息。The above expressions respectively describe the information of the three host images 18 that are shifted by 0, π/2, and π by step phase shift φ _R.

所述图像生成及水印装置14包括第三分束器141。所述第三分束器141同时接收携带宿主图像18的参考光光束和携带物体图像17的加密物光光束，以形成同轴的干涉光，并将这两种光束叠加生成干涉全息图，该干涉全息图携带了加密与水印后的物体图像信息。本实施例中，该干涉全息图根据加密物光光束和作为载体的参考光光束的光强及相位叠加生成。The image generating and watermarking device 14 includes a third beam splitter 141 . The third beam splitter 141 simultaneously receives the reference light beam carrying the host image 18 and the encrypted object light beam carrying the object image 17 to form coaxial interference light, and superposes these two light beams to generate an interference hologram, which The interference hologram carries the encrypted and watermarked object image information. In this embodiment, the interference hologram is generated according to the light intensity and phase superposition of the encrypted object light beam and the reference light beam as a carrier.

所述图像采集装置15包括数字微镜器件151、会聚透镜152和单光子探测器153。所述数字微镜器件151对所述图像生成及水印装置14生成的干涉全息图数据进行压缩和采样后，通过所述会聚透镜152汇聚于一点，之后通过所述单光子探测器153收集。The image acquisition device 15 includes a digital micromirror device 151 , a converging lens 152 and a single photon detector 153 . The digital micromirror device 151 compresses and samples the interference hologram data generated by the image generating and watermarking device 14 , converges them at one point through the converging lens 152 , and then collects them through the single photon detector 153 .

所述数字微镜器件151实际上是一个空间光调制器，它相当于一个随机测量矩阵，根据压缩感知中的受限等距性，数字微镜器件151的微小镜片处于一个特定的伪随机状态。由随机数字发生器来控制每个微镜片的方向，使它们可以依水平做+12°或-12°这两个方向偏转；其中，-12°的偏转对应图像没有被反射到单光子探测器153上，在测量矩阵中表现为0；+12°方向的偏转则对应于图像被反射到单光子探测器153上，在测量矩阵中表现为1；计算这些测量值作为输出电压。The digital micromirror device 151 is actually a spatial light modulator, which is equivalent to a random measurement matrix. According to the restricted equidistantness in compressed sensing, the tiny lenses of the digital micromirror device 151 are in a specific pseudo-random state . The direction of each microlens is controlled by a random number generator, so that they can be deflected in two directions of +12° or -12° horizontally; among them, the deflection of -12° corresponds to the image not being reflected to the single photon detector 153, represented as 0 in the measurement matrix; the deflection in the direction of +12° corresponds to the image being reflected onto the single photon detector 153, represented as 1 in the measurement matrix; these measured values are calculated as the output voltage.

具体的，在数字微镜器件151平面上叠加的三幅干涉全息图的光强值可以表示为：Specifically, the light intensity values of the three interference holograms superimposed on the plane of the digital micromirror device 151 can be expressed as:

I_H(ξ,η；φ_R)I _H (ξ,η; φ _R )

＝A(ξ,η)²+A_h(ξ,η)² ＝A(ξ,η) ² +A _h (ξ,η) ²

$(({φ φ}_{R R} = = 00,, \frac{π π}{22},, π π)),,$

单光子探测器153的高灵敏度的光电二极管的输出电压表示为：The output voltage of the highly sensitive photodiode of single photon detector 153 is expressed as:

其中，表示数字微镜器件151平面上的m维伪随机测量矩阵。in, represents the m-dimensional pseudo-random measurement matrix on the plane of the digital micromirror device 151 .

重复这个过程M次，得到的测量值Y为：Y＝[y₁,y₂,y₃]＝Ψ[I_H1,I_H2,I_H3],Repeat this process M times, the measured value Y obtained is: Y=[y ₁ ,y ₂ ,y ₃ ]=Ψ[I _H1 ,I _H2 ,I _H3 ],

其中，Ψ∈R^M×N是数字微镜器件平面获得的测量矩阵，Y∈R^M×3是测量值，y_k∈R^M×1，I_Hk∈R^N×1。in, Ψ∈RM ^×N is the measurement matrix obtained from the DMD plane, Y∈RM ^×3 is the measured value, y _k ∈RM ^×1 , I _Hk ∈RN ^×1 .

所述图像重构装置16包括模数转换模块161、图像传输模块162和图像重构模块163。所述模数转换模块161，用于将所述图像采集装置15采集的模拟干涉全息图数据转换为数字干涉全息图数据。所述图像传输模块162，用于将所述数字干涉全息图数据传送到所述图像重构模块163。所述图像重构模块163，用于根据图像传输装置传送的数字干涉全息图数据重构出物体图像17。The image reconstruction device 16 includes an analog-to-digital conversion module 161 , an image transmission module 162 and an image reconstruction module 163 . The analog-to-digital conversion module 161 is configured to convert the analog interference hologram data collected by the image acquisition device 15 into digital interference hologram data. The image transmission module 162 is configured to transmit the digital interference hologram data to the image reconstruction module 163 . The image reconstruction module 163 is configured to reconstruct the object image 17 according to the digital interference hologram data transmitted by the image transmission device.

进一步地，所述图像重构模块163通过优化算法重构出数字微镜器件151上的三幅干涉全息图，进而重构出物体图像17。Further, the image reconstruction module 163 reconstructs three interference holograms on the digital micromirror device 151 through an optimization algorithm, and then reconstructs the object image 17 .

具体地，先利用两步迭代收缩算法(TwIST)通过解决以下的最优化问题来重建干涉光强度：Specifically, a two-step iterative shrinkage algorithm (TwIST) is used to reconstruct the interference light intensity by solving the following optimization problem:

其中，μ是常量，是一个最小二乘项，当与相关矢量量化值Y_k一致时它的值最小，是信号的全变分表示；该公式中的下标i，j表示所有成对的相邻像素点，是离散梯度的l₁范数。至此，算法已经重构出在数字微镜器件151上的三幅干涉全息图。where μ is a constant, is a least squares term, when Its value is the smallest when it is consistent with the relevant vector quantization value Y _k , is the total variational representation of the signal; The subscript i, j in this formula means All pairs of adjacent pixels, is the discrete gradient The l ₁ norm of . So far, the algorithm has reconstructed three interference holograms on the DMD 151 .

利用得到的三幅全息图第一随机相位板122和第二随机相位板123间的距离Z₁,第二随机相位板123和数字微镜器件151间的距离Z₂、第一随机相位板122和第二随机相位板123的复振幅透过率来恢复原始物体图像17。Using the three holograms obtained The distance Z 1 between the first random phase plate 122 and the second random phase plate 123, the distance Z ₂ between the _second random phase plate 123 and the digital micromirror device 151, the first random phase plate 122 and the second random phase plate 123 The complex amplitude transmittance of , to recover the original object image17.

接着，计算出加密和水印后的物体图像的相位信息φ(ξ,η)和振幅信息A(ξ,η)如下：Next, calculate the phase information φ(ξ, η) and amplitude information A(ξ, η) of the encrypted and watermarked object image as follows:

$φ φ ((ξ ξ,, η η)) = = {tan the tan}^{- - 11} \frac{22 {\overset{^^}{I I}}_{H h 22} - - {\overset{^^}{I I}}_{H h 11} - - {\overset{^^}{I I}}_{H h 33}}{{\overset{^^}{I I}}_{H h 11} - - {\overset{^^}{I I}}_{H h 33}} + + {φ φ}_{h h} ((ξ ξ,, η η)),,$

其中，宿主图像的衍射分布φ_h，A_h是利用马赫-增德尔干涉仪下的三步相移法提前获得。Among them, the diffraction distribution φ _h and _Ah of the host image are obtained in advance by using the three-step phase shift method under the Mach-Zehnder interferometer.

最后，通过菲涅尔反变换算法重构出所述物体图像17，该过程表示为：Finally, the object image 17 is reconstructed through the inverse Fresnel transform algorithm, and the process is expressed as:

以下具体说明该安全的压缩全息成像步骤：This secure compressed holography step is described in detail below:

请参阅图3，其是本发明实施例中安全的压缩全息成像方法的流程图。Please refer to FIG. 3 , which is a flowchart of a secure compressed holographic imaging method in an embodiment of the present invention.

步骤S1：将光源发出的一束光分解为两束光，其中一束为照射在物体图像17的物光，另一束为照射在宿主图像18的参考光。Step S1 : Decompose one beam of light emitted by the light source into two beams, one of which is the object light irradiated on the object image 17 , and the other is the reference light irradiated on the host image 18 .

具体的，通过激光器111发出一束线性偏振激光光源；该线性偏振激光光源经过扩束器112扩束和准直后，照向第一分束器113。所述第一分束器113将该束激光分为两束光，其中一束为照射在物体图像17的物光；另一束为照射在宿主图像18的参考光。Specifically, a linearly polarized laser light source is emitted by the laser 111 ; The first beam splitter 113 splits the laser beam into two beams, one of which is the object light irradiated on the object image 17 ; the other is the reference light irradiated on the host image 18 .

步骤S2：将物光反射照向物体图像17，并对物光进行加密，获得携带物体图像17的加密物光光束。Step S2: Reflecting the object light onto the object image 17 and encrypting the object light to obtain an encrypted object light beam carrying the object image 17 .

请参阅图4，其是图3所示步骤S2中的具体实施流程图。Please refer to FIG. 4 , which is a specific implementation flowchart of step S2 shown in FIG. 3 .

步骤S21：沿着物光光路路径，在物体图像17前设置一反射镜121，通过所述反射镜121将物光进行反射后照向物体图像17；Step S21: along the optical path of the object light, a mirror 121 is arranged in front of the object image 17, and the object light is reflected by the mirror 121 and illuminated to the object image 17;

步骤S22：在物体图像17后方设置所述第一随机相位板122；在所述第一随机相位板122后方设置与之平行的第二随机相位板123；使透过物体图像17的物光依次通过所述第一随机相位板122和第二随机相位板123，以获得携带物体图像17的加密物光光束。Step S22: setting the first random phase plate 122 behind the object image 17; setting a second random phase plate 123 parallel to it behind the first random phase plate 122; making the object light passing through the object image 17 sequentially Pass through the first random phase plate 122 and the second random phase plate 123 to obtain an encrypted object light beam carrying the object image 17 .

所述物光通过反射镜121、物体图像17、第一随机相位板122和第二随机相位板123后，利用双随机相位编码技术即可获得物体图像17像素置乱后的加密图像。After the object light passes through the mirror 121 , the object image 17 , the first random phase plate 122 and the second random phase plate 123 , the encrypted image of the 17-pixel scrambled object image can be obtained by using double random phase encoding technology.

假设物光照射在物体图像17上的透过率为O(x₀,y₀)，则经过第一随机相位板122和第二随机相位板123获得的加密物光光束，其所表示的加密物体图像17用复振幅的分布可以表示为：Assuming that the transmittance of the object light irradiated on the object image 17 is O(x ₀ , y ₀ ), then the encrypted object light beam obtained through the first random phase plate 122 and the second random phase plate 123, the encrypted The distribution of the complex amplitude of the object image 17 can be expressed as:

上述表达式描述了物体图像17加密后生成的加密图像的信息。The above expression describes the information of the encrypted image generated after the object image 17 is encrypted.

其中,K₁表示物光通路的光振幅；exp[i2π·p(x₀,y₀)]和exp[i2π·q(x₁,y₁)]分别为第一随机相位板122和第二随机相位板123的复振幅透过率；p(x₀,y₀)和q(x₁,y₁)均为分布在[0,1]区间上的统计独立的白噪声；Frt_Z表示衍射距离为Z的菲涅尔变换，第一随机相位板122和第二随机相位板123之间的距离为Z₁,第二随机相位板123和数字微镜器件151之间的距离为Z₂。Among them, K ₁ represents the optical amplitude of the object light path; exp[i2π·p(x ₀ ,y ₀ )] and exp[i2π·q(x ₁ ,y ₁ )] are the first random phase plate 122 and the second The complex amplitude transmittance of the random phase plate 123; p(x ₀ , y ₀ ) and q(x ₁ , y ₁ ) are both statistically independent white noise distributed on the [0,1] interval; Frt _Z represents diffraction For Fresnel transformation with a distance of Z, the distance between the first random phase plate 122 and the second random phase plate 123 is Z ₁ , and the distance between the second random phase plate 123 and the DMD 151 is Z ₂ .

步骤S3：将参考光调相后照射在宿主图像18，获得携带宿主图像18的参考光光束。Step S3: Phase-modulate the reference light and irradiate the host image 18 to obtain a reference light beam carrying the host image 18 .

具体的，通过所述压电转换器131将所述参考光分三次调相后，生成相位分别为0,π的干涉光源；所述第二分束器132将调相后的参考光照射宿主图像18，进而获得携带宿主图像18的参考光光束。Specifically, after the phase modulation of the reference light is divided into three stages by the piezoelectric converter 131, the generated phases are respectively 0, π interference light source; the second beam splitter 132 illuminates the host image 18 with the phase-modulated reference light, and then obtains a reference light beam carrying the host image 18 .

经过调相的参考光光束，其所表示的宿主图像18复振幅分布可以表示为：The complex amplitude distribution of the host image 18 represented by the phase-modulated reference light beam can be expressed as:

上述表达式分别描述了步进相移φ_R用0,π相移的三幅宿主图像18的信息。The above expressions respectively describe the step phase shift φ _R with 0, Information of the three host images 18 shifted by π.

步骤S4：将携带物体图像17的加密物光光束和携带宿主图像18的参考光光束叠加，生成干涉全息图。Step S4: superpose the encrypted object light beam carrying the object image 17 and the reference light beam carrying the host image 18 to generate an interference hologram.

所述第三分束器141同时接收携带宿主图像18的参考光光束和携带物体图像17的加密物光光束，以形成同轴的干涉光，并将这两种光束叠加生成干涉全息图，该干涉全息图携带了加密与水印后的物体图像信息。The third beam splitter 141 simultaneously receives the reference light beam carrying the host image 18 and the encrypted object light beam carrying the object image 17 to form coaxial interference light, and superposes these two light beams to generate an interference hologram, which The interference hologram carries the encrypted and watermarked object image information.

步骤S5：采集干涉全息图数据，并根据该数字干涉全息图数据重构出物体图像17。Step S5: collecting interference hologram data, and reconstructing the object image 17 according to the digital interference hologram data.

具体的，所述步骤S5，还包括如下步骤：Specifically, the step S5 also includes the following steps:

请参阅图5，其是图3所示步骤S5中的具体实施流程图。Please refer to FIG. 5 , which is a specific implementation flowchart of step S5 shown in FIG. 3 .

步骤S51：通过一数字微镜器件151压缩采样所述干涉全息图数据；Step S51: compressing and sampling the interference hologram data through a digital micromirror device 151;

通过数字微镜器件151对叠加的干涉全息图进行高速采集，然后计算数字微镜器件151平面上的测量矩阵与干涉全息图的随机线性测量值，以得到压缩全息图的采样，再使得光束经过会聚透镜152，由单光子探测器153收集为模拟电信号。The superimposed interference hologram is collected at high speed by the digital micromirror device 151, and then the measurement matrix on the plane of the digital micromirror device 151 and the random linear measurement value of the interference hologram are calculated to obtain the sampling of the compressed hologram, and then the light beam passes through The converging lens 152 collects an analog electrical signal by the single photon detector 153 .

本实施例中，利用数字微镜器件151的微镜单元光控开关的特性，实现对叠加的干涉全息图信息的采集和压缩采样。本实施例中，数字微镜器件151的对应+12°方向偏转角的发射光经过会聚透镜152由单光子探测器153收集。In this embodiment, the characteristics of the optical switch of the micromirror unit of the digital micromirror device 151 are used to realize the collection and compressed sampling of the superimposed interference hologram information. In this embodiment, the emitted light of the digital micromirror device 151 corresponding to the deflection angle of +12° is collected by the single photon detector 153 through the converging lens 152 .

I_H(ξ,η；φ_R)I _H (ξ,η; φ _R )

＝A(ξ,η)²+A_h(ξ,η)² ＝A(ξ,η) ² +A _h (ξ,η) ²

$(({φ φ}_{R R} = = 00,, \frac{π π}{22},, π π)),,$

上述表达式描述了携带物体图像17的加密物光光束和携带宿主图像18的参考光光束叠加后的三幅干涉全息图。至此，利用一个改进的马赫增德尔干涉仪就可以在全光域的环境中实现物体图像17的加密和水印。The above expressions describe the three interference holograms after the superposition of the encrypted object light beam carrying the object image 17 and the reference light beam carrying the host image 18 . So far, the encryption and watermarking of the object image 17 can be realized in an all-optical environment by using an improved Mach-Zehnder interferometer.

其中表示数字微镜器件151平面上的m维伪随机测量矩阵。重复这个过程M次，可以得到的测量值Y为：in represents the m-dimensional pseudo-random measurement matrix on the plane of the digital micromirror device 151 . Repeating this process M times, the measured value Y that can be obtained is:

其中Ψ∈R^M×N是数字微镜器件151平面获得的测量矩阵，Y∈R^M×3是测量值，y_k∈R^M×1，I_Hk∈R^N×1。in Ψ∈RM ^×N is the measurement matrix obtained from the digital micromirror device 151 plane, Y∈RM ^×3 is the measured value, y _k ∈RM ^×1 , I _Hk ∈RN ^×1 .

以上，就完成了对所述叠加的干涉全息图信息的模拟信号采集和压缩采样。Above, the analog signal acquisition and compressed sampling of the superimposed interference hologram information are completed.

步骤S52：将该压缩全息图经过一会聚透镜152汇聚后，通过一单光子检测器对该压缩全息图数据进行单点检测和光电子计数，将光信号转换为模拟电信号，再通过模数转换器将模拟电信号转换成数字压缩全息图。Step S52: After the compressed hologram is converged by a converging lens 152, single-point detection and photoelectron counting are performed on the compressed hologram data by a single photon detector, and the optical signal is converted into an analog electrical signal, and then converted by analog to digital A converter converts an analog electrical signal into a digitally compressed hologram.

步骤S53：根据数字压缩全息图，利用压缩感知算法重构在数字微镜器件151上叠加的干涉全息图；利用菲涅尔反变换算法、宿主图像18的复振幅信息及电或者光的方法重构出原始物体图像17。Step S53: According to the digital compressed hologram, use the compressed sensing algorithm to reconstruct the interference hologram superimposed on the digital micromirror device 151; use the inverse Fresnel transform algorithm, the complex amplitude information of the host image 18, and electrical or optical methods An original object image 17 is constructed.

本实施例中，利用两步迭代收缩算法(TwIST)重构在数字微镜器件151上的叠加的干涉全息图。In this embodiment, a two-step iterative shrinkage algorithm (TwIST) is used to reconstruct the interferometric hologram superimposed on the digital micromirror device 151 .

利用两步迭代收缩算法(TwIST)通过解决以下的最优化问题来重建干涉光强度：A two-step iterative shrinkage algorithm (TwIST) is used to reconstruct the interference light intensity by solving the following optimization problem:

该公式中下标i，j表示所有成对的相邻像素点，是离散梯度的l₁范数。The subscript i, j in this formula means All pairs of adjacent pixels, is the discrete gradient The l ₁ norm of .

至此，算法已经重构出在数字微镜器件151上的三幅干涉全息图。So far, the algorithm has reconstructed three interference holograms on the DMD 151 .

具体的，计算出加密和水印后的物体图像的相位信息φ(ξ,η)和振幅信息A(ξ,η)如下：Specifically, the phase information φ(ξ, η) and amplitude information A(ξ, η) of the encrypted and watermarked object image are calculated as follows:

其中，宿主图像的衍射分布φ_h，A_h利用马赫-增德尔干涉仪下的三步相移法提前获得。Among them, the diffraction distribution φ _h and _Ah of the host image are obtained in advance by using the three-step phase shift method under the Mach-Zehnder interferometer.

通过菲涅尔反变换算法重构出所述物体图像17，该过程表示为：The object image 17 is reconstructed through the inverse Fresnel transform algorithm, and the process is expressed as:

请参阅图6，其是本发明实施例中安全的压缩全息成像方法的实验仿真结果图。Please refer to FIG. 6 , which is an experimental simulation result diagram of the secure compressed holographic imaging method in the embodiment of the present invention.

在实验中，氦氖激光波长为632.8nm，物光和参考光振幅比为0.000001:1，第一随机相位板122和第二随机相位板123间的距离Z₁为0.1m,,第二随机相位板123和数字微镜器件151间的距离Z₂为0.2m，宿主图像18的衍射距离Z₃为0.3m。物体图像17采用“光”的图片，宿主图像18为“Lena”图，两图像的大小均为256×256像素。在该仿真实验中，使用256×256×54.2％的加密水印图像的测量数据进行图像重建，利用加密水印图像的压缩数据，结合正确的密码和光学系统参数能实现对物体图像17的准确恢复。图6(a)为物体图像17“光”，图6(b)为宿主图像18“Lena”，图6(c)为DMD上的加密和水印的全息图,图6(d)为不经过压缩的重构图像，图6(e)为在该方法下使用256×256×54.2％的测量数据获得的重构图像。实验仿真结果证明，在菲涅尔域下的纯光学方案下，提出的具有安全特性的压缩全息成像系统是切实可行的。In the experiment, the wavelength of the He-Ne laser is 632.8nm, the amplitude ratio of the object light and the reference light is 0.000001: ₁ , the distance Z1 between the first random phase plate 122 and the second random phase plate 123 is 0.1m, and the second random phase plate 123 is 0.1m. The distance Z ₂ between the phase plate 123 and the digital micromirror device 151 is 0.2m, and the diffraction distance Z ₃ of the host image 18 is 0.3m. The object image 17 is a "light" image, and the host image 18 is a "Lena" image, both of which have a size of 256×256 pixels. In this simulation experiment, the measured data of the encrypted watermark image of 256×256×54.2% is used for image reconstruction, and the compressed data of the encrypted watermark image, combined with the correct password and optical system parameters can realize accurate restoration of the object image 17. Figure 6(a) is the object image 17 "Light", Figure 6(b) is the host image 18 "Lena", Figure 6(c) is the encrypted and watermarked hologram on the DMD, Figure 6(d) is the Compressed reconstructed image, Figure 6(e) is the reconstructed image obtained under this method using 256×256×54.2% measurement data. The experimental simulation results prove that the proposed compressed holographic imaging system with security features is feasible under the pure optical scheme in the Fresnel domain.

相比于现有技术，本发明利用三步相移法记录干涉全息图，在全光域环境中同时实现图像加密、图像水印和图像压缩，保密性更强，保证了信息在传输和存储过程中的安全，避免了原始物体图像遭到非法窃取或篡改，实现了安全压缩成像的要求。Compared with the prior art, the present invention uses the three-step phase-shifting method to record the interference hologram, realizes image encryption, image watermarking and image compression simultaneously in an all-optical environment, and has stronger confidentiality, ensuring that information is transmitted and stored The security in the system prevents the original object image from being illegally stolen or tampered with, and realizes the requirement of secure compression imaging.

本发明并不局限于上述实施方式，如果对本发明的各种改动或变形不脱离本发明的精神和范围，倘若这些改动和变形属于本发明的权利要求和等同技术范围之内，则本发明也意图包含这些改动和变形。The present invention is not limited to the above-mentioned embodiments, if the various changes or deformations of the present invention do not depart from the spirit and scope of the present invention, if these changes and deformations belong to the claims of the present invention and the equivalent technical scope, then the present invention is also It is intended that such modifications and variations are included.

Claims

1. A safe compressed holographic imaging system, characterized in that it includes a light source generation and beam splitting device, an encryption device, a phase modulation device, an image generation and watermarking device, an image acquisition device and an image reconstruction device;

The light source generation and beam splitting device is used to decompose one beam of light emitted by the light source into two beams, one of which is the object light irradiated on the object image, and the other is the reference light irradiated on the host image;

The encryption device is used to reflect the object light to the object image, and encrypt the object light information, to obtain an encrypted object light beam carrying the object image;

The phase modulation device is used to adjust the phase of the reference light and irradiate the host image to obtain a reference light beam carrying the host image;

The image generating and watermarking device is used to simultaneously receive the encrypted object light beam carrying the object image and the reference light beam carrying the host image, and generate an encrypted and watermarked interference hologram;

The image acquisition device is used to acquire the interference hologram data and transmit it to the image reconstruction device;

The image reconstruction device is used for reconstructing an object image according to the interference hologram data.

2. The secure compressed holographic imaging system according to claim 1, wherein the encryption device includes a mirror, a first random phase plate, and a second random phase plate; along the object light path, at the light source After generating and splitting the beam device and setting the reflector before the object image, the reflector is used to reflect the object light and illuminate the object image; set the first random phase plate behind the object image; A second random phase plate parallel to the first random phase plate is arranged behind the first random phase plate; after the object light passes through the object image, it passes through the first random phase plate and the second random phase plate in sequence to obtain the carrying object The encrypted object light beam of the image; the encrypted object light beam is then irradiated to the image generating and watermarking device;

According to the Fresnel diffraction formula, the encrypted object image represented by the encrypted object light beam is expressed by the complex amplitude distribution as:

\begin{matrix} {ψ ψ}_{o o} ((ξ ξ,, η η)) = = A A ((ξ ξ,, η η)) exp exp ((i i φ φ ((ξ ξ,, η η)) \\ = = {Frt Frt}_{{z z}_{22}} {{{Frt Frt}_{{z z}_{11}} {{{K K}_{11} \times \times O o (({x x}_{00},, {y the y}_{00})) \times \times exp exp [[i i 22 π π \times \times p p (({x x}_{00},, {y the y}_{00}))]]}} \times \times exp exp [[i i 22 π π \times \times q q (({x x}_{11},, {y the y}_{11}))]]}},, \end{matrix}

Among them, K ₁ represents the light amplitude of the object light path; O(x ₀ ,y ₀ ) is the complex amplitude distribution of the object light at the first random phase plate; exp[i2π·p(x ₀ ,y ₀ )] and exp [i2π·q(x ₁ ,y ₁ )] are the complex amplitude transmittances of the first random phase plate and the second random phase plate respectively; p(x ₀ ,y ₀ ) and q(x ₁ ,y ₁ ) are both is a statistically independent white noise distributed on the [0,1] interval; Frt _Z represents the Fresnel transform with a diffraction distance of Z, the distance between the first random phase plate and the second random phase plate is Z ₁ , the first The distance between the two random phase plates and the image acquisition device is Z ₂ .

3. The secure compression holographic imaging system according to claim 2, wherein the phase modulation device comprises a piezoelectric transducer and a second beam splitter, and the piezoelectric transducer splits the reference light into three After phase modulation, the generated phases are an interference light source; the second beam splitter irradiates the host image with the phase-modulated reference light, and then obtains a reference light beam carrying the host image;

The host image complex amplitude distribution represented by the reference light beam can be expressed as:

{ψ ψ}_{h h} ((ξ ξ,, η η;; {φ φ}_{R R})) = = {A A}_{h h} ((ξ ξ,, η η)) exp exp [[{iφ iφ}_{h h} ((ξ ξ,, η η))]] exp exp (({iφ iφ}_{R R})),, (({φ φ}_{R R} = = 00,, \frac{π π}{22},, π π)),,

4. The secure compressed holographic imaging system according to claim 3, wherein the image generating and watermarking device comprises a third beam splitter; the third beam splitter simultaneously receives the reference light beam carrying the host image and the encrypted object light beam carrying the object image to form coaxial interference light, and superimpose these two beams to generate an interference hologram, which carries the encrypted and watermarked object image information;

The light intensity value of the interference hologram superimposed by encryption and watermark is expressed as

I _H (ξ,η; φ _R )

＝|ψ ₀ (ξ,η)+ψ _h (ξ,η; φ _R )| ²

＝A(ξ,η) ² +A _h (ξ,η) ²

+2A(ξ,η)A _h (ξ,η)cos[φ _h (ξ,η)+φ _R -φ(ξ,η)],

(({φ φ}_{R R} = = 00,, \frac{π π}{22},, π π)),,

5. The safe compressed holographic imaging system according to claim 4, wherein the image acquisition device comprises a digital micromirror device, a converging lens and a single photon detector; the digital micromirror device generates and the interference hologram data generated by the watermarking device are compressed and sampled, converged at one point through the converging lens, and then collected by the single photon detector;

The output voltage of the high-sensitivity photodiode of the single-photon detector is expressed as:

in Representing the m-dimensional pseudo-random measurement matrix on the plane of the digital micromirror device;

Repeating this process M times, the measured value Y that can be obtained is:

Y=[y ₁ ,y ₂ ,y ₃ ]=Ψ[I _H1 ,I _H2 ,I _H3 ],

in, Ψ∈RM ^×N is the measurement matrix obtained on the plane of the digital micromirror device, Y∈RM ^×3 is the measured value, y _k ∈RM ^×1 , I _Hk ∈RN ^×1 .

6. The safe compressed holographic imaging system according to claim 5, wherein the image reconstruction device comprises an analog-to-digital conversion module, an image transmission module and an image reconstruction module; the analog-to-digital conversion module is used for Converting the analog interference hologram data collected by the image acquisition device into digital interference hologram data; the image transmission module is used to transmit the digital interference hologram data to the image reconstruction module; the image reconstruction The construction module is used to reconstruct the original object image according to the digital interference hologram data transmitted by the image transmission device, using the two-step iterative shrinkage algorithm, the Fresnel inverse transform algorithm and the complex amplitude information of the host image;

The expression of the light intensity of the superimposed interference on the digital micromirror device reconstructed by compressive sensing algorithm is:

\begin{matrix} \underset{{I I}_{H h k k}}{min min} \frac{μ μ}{22} | | | | {Y Y}_{k k} - - Ψ Ψ {\overset{^^}{I I}}_{H h k k} | | {| |}_{22}^{22} + + T T V V (({\overset{^^}{I I}}_{H h k k})) & s the s . . t t . . & {Y Y}_{k k} = = {ΨI ΨI}_{H h k k} \end{matrix},,

where μ is a constant, is a least squares term, when Its value is the smallest when it is consistent with the relevant vector quantization value Y _k , is the total variational representation of the signal, specifically as the following formula:

T T V V (({\overset{^^}{I I}}_{H h k k})) = = \underset{a a d d j j . . i i,, j j}{Σ Σ} | | {\overset{^^}{I I}}_{H h k k i i} - - {\overset{^^}{I I}}_{H h k k j j} | |,,))

The subscript i, j in this formula means All pairs of adjacent pixels, is the discrete gradient The l ₁ norm of .

The phase information φ (ξ, η) and the amplitude information A (ξ, η) of the encrypted and watermarked object image on the digital micromirror device are as follows:

A A ((ξ ξ,, η η)) = = \frac{{[[{(({\overset{^^}{I I}}_{H h 11} - - {\overset{^^}{I I}}_{H h 33}))}^{22} + + {((22 {\overset{^^}{I I}}_{H h 22} - - {\overset{^^}{I I}}_{H h 11} - - {\overset{^^}{I I}}_{H h 33}))}^{22}]]}^{11 / / 22}}{44 {A A}_{h h}},,

Among them, the diffraction distribution φ _h and A _h of the host image are obtained in advance by using the three-step phase shift method under the Mach-Zehnder interferometer;

The object image is reconstructed through the inverse Fresnel transform algorithm, and the process is expressed as:

Among them, IFrt _Z represents the inverse Fresnel transform with a diffraction distance of Z.

7. A safe compressed holographic imaging method, comprising the steps of:

Step S1: Decompose one beam of light emitted by the light source into two beams, one of which is the object light irradiated on the object image, and the other is the reference light irradiated on the host image;

Step S2: reflect the object light onto the object image, and encrypt the object light to obtain an encrypted object light beam carrying the object image;

Step S3: irradiate the reference light beam on the host image after phase modulation three times to obtain a reference light beam carrying the host image;

Step S4: Generate an encrypted and watermarked interference hologram based on the encrypted object light beam carrying the object image and the reference light beam carrying the host image;

Step S5: collecting interference hologram data, and reconstructing an object image based on the digital interference hologram data.

8. The safe compression holographic imaging method according to claim 7, characterized in that, in step S2, further comprising the following steps:

Step S21: along the optical path of the object light, a mirror is set in front of the object image, and the object light is reflected by the mirror to illuminate the object image;

Step S22: setting the first random phase plate behind the object image; setting a second random phase plate parallel to it behind the first random phase plate; allowing the object light passing through the object image to pass through the first random phase plate sequentially. A random phase plate and a second random phase plate are used to obtain an encrypted object light beam carrying an object image.

9. The safe compressed holographic imaging method according to claim 8, characterized in that, in step S5, further comprising the following steps:

Step S51: compressing and sampling the interference hologram data through a digital micromirror device;

Step S52: After the compressed hologram is converged by a converging lens, a single-photon detector is used to perform single-point detection and photoelectron counting on the optical signal of the compressed hologram, and the optical signal is converted into an analog electrical signal, and then through analog-to-digital conversion The converter converts the analog electrical signal into a digital signal;

Step S53: According to the digital compressed hologram, use the compressive sensing algorithm to reconstruct the interference hologram superimposed on the digital micromirror device; use the inverse Fresnel transform algorithm, the complex amplitude information of the host image, and the electrical or optical method to reconstruct the original object image.

10. The safe compressed holographic imaging method according to claim 9, characterized in that,

In step S2,

\begin{matrix} {ψ ψ}_{o o} ((ξ ξ,, η η)) = = A A ((ξ ξ,, η η)) exp exp ((i i φ φ ((ξ ξ,, η η)) \\ = = {Frt Frt}_{{z z}_{22}} {{{Frt Frt}_{{z z}_{11}} {{{K K}_{11} \times \times O o (({x x}_{00},, {y the y}_{00})) \times \times exp exp [[i i 22 π π \times \times p p (({x x}_{00},, {y the y}_{00}))]]}} \times \times exp exp [[i i 22 π π \times \times q q (({x x}_{11},, {y the y}_{11}))]]}},, \end{matrix}

Among them, K ₁ represents the light amplitude of the object light path; O(x ₀ ,y ₀ ) is the complex amplitude distribution of the object light at the first random phase plate; exp[i2π·p(x ₀ ,y ₀ )] and exp [i2π·q(x ₁ ,y ₁ )] are the complex amplitude transmittances of the first random phase plate and the second random phase plate respectively; p(x ₀ ,y ₀ ) and q(x ₁ ,y ₁ ) are both is a statistically independent white noise distributed on the [0,1] interval; Frt _Z represents the Fresnel transform with a diffraction distance of Z, the distance between the first random phase plate and the second random phase plate is Z ₁ , the first The distance between the two random phase plates and the digital micromirror device is Z ₂ ;

In step S3,

{ψ ψ}_{h h} ((ξ ξ,, η η;; {φ φ}_{R R})) = = {A A}_{h h} ((ξ ξ,, η η)) exp exp [[{iφ iφ}_{h h} ((ξ ξ,, η η))]] exp exp (({iφ iφ}_{R R})),, (({φ φ}_{R R} = = 00,, \frac{π π}{22},, π π)),,

In step S4,

I _H (ξ,η; φ _R )

＝|ψ ₀ (ξ,η)+ψ _h (ξ,η; φ _R )| ²

＝A(ξ,η) ² +A _h (ξ,η) ²

+2A(ξ,η)A _h (ξ,η)cos[φ _h (ξ,η)+φ _R -φ(ξ,η)],

(({φ φ}_{R R} = = 00,, \frac{π π}{22},, π π)),,

In step S5,

Repeating this process M times, the measured value Y that can be obtained is:

Y=[y ₁ ,y ₂ ,y ₃ ]=Ψ[I _H1 ,I _H2 ,I _H3 ],

in, Ψ ∈ R ^{M × N} is the measurement matrix obtained on the plane of the digital micromirror device, Y ∈ R M ^{× 3} is the measured value, y _k ∈ R ^{M × 1} , I _Hk ∈ R ^{N × 1} ;

The light intensity expression of the superimposed interference on the digital micromirror device reconstructed by compressive sensing algorithm is:

\begin{matrix} \underset{{I I}_{H h k k}}{min min} \frac{μ μ}{22} | | | | {Y Y}_{k k} - - Ψ Ψ {\overset{^^}{I I}}_{H h k k} | | {| |}_{22}^{22} + + T T V V (({\overset{^^}{I I}}_{H h k k})) & s the s . . t t . . & {Y Y}_{k k} = = {ΨI ΨI}_{H h k k} \end{matrix},,

T T V V (({\overset{^^}{I I}}_{H h k k})) = = \underset{a a d d j j . . i i,, j j}{Σ Σ} | | {\overset{^^}{I I}}_{H h k k i i} - - {\overset{^^}{I I}}_{H h k k j j} | |,,))

A A ((ξ ξ,, η η)) = = \frac{{[[{(({\overset{^^}{I I}}_{H h 11} - - {\overset{^^}{I I}}_{H h 33}))}^{22} + + {((22 {\overset{^^}{I I}}_{H h 22} - - {\overset{^^}{I I}}_{H h 11} - - {\overset{^^}{I I}}_{H h 33}))}^{22}]]}^{11 / / 22}}{44 {A A}_{h h}},,

Among them, the diffraction distribution φ _h and _Ah of the host image are obtained in advance by using the three-step phase shift method under the Mach-Zehnder interferometer; the object image is reconstructed by the inverse Fresnel transform algorithm, and the process is expressed as: