BROADBAND SUPER-RAYLEIGH SPECKLE CORRELATED IMAGING SPECTRAL CAMERA BASED ON DISPERSION COMPENSATION AND IMAGING METHOD THEREOF

Abstract

A broadband super-Rayleigh speckle correlated imaging spectral camera based on dispersion compensation is provided. The imaging scheme comprises, but is not limited to, a pre-compensation scheme, a post-compensation scheme, or a pre-post joint compensation scheme. The device comprises components such as a pre-imaging module, a light filter, a phase modulation module, a relay imaging module, an area array detector, and a computer. According to the present invention, the super-Rayleigh speckle modulation in a broadband is realized by matchining the dispersion characteristic of the pre-imaging module or the relay imaging module with the phase modulation module, which is applied to the correlated imaging spectral camera, so that the imaging quality of the correlated imaging spectral camera at a low signal-to-noise ratio is improved.

Claims

1. A broadband super-Rayleigh speckle correlated imaging spectral camera based on dispersion compensation, comprising a pre-imaging module (1), the pre-imaging module (1) having a focal length f.sub.1(λ), a band-pass light filter (2), a phase modulation module (3), a relay imaging module (4), an area array detector (5), and a computer (6), wherein the phase modulation module (3) is configured for loading a phase distribution diagram generating super-Rayleigh speckles and performing phase modulation on a light field, and the pre-imaging module (1) or the relay imaging module (4) realizes the super-Rayleigh speckle modulation in broadband through imaging relationship compensation.

2. The broadband super-Rayleigh speckle correlated imaging spectral camera based on dispersion compensation according to claim 1, wherein the focal length f.sub.1(λ) of the pre-imaging module (1) meets following conditions: $\frac{1}{f_1\left(\lambda \right)}=\frac{1}{D_1}+\frac{1}{D_2-z_1\left(\lambda \right)},$ wherein D.sub.1 is a distance from an imaging target (a) to the pre-imaging module (1), D.sub.2 is a distance from the pre-imaging module (1) to the phase modulation module (3), wherein the pre-imaging module (1) images an object image with a wavelength of λ to a position z.sub.1(λ) in front of the phase modulation module (3), and the distance z.sub.1(λ) meets: $z_1\left(\lambda \right)=\frac{{\lambda }_1{z}_2}{\lambda z_2^{\prime }-{\lambda }_1{z}_2}{z}_2^{\prime }\frac{1}{D_3-z_2^{\prime }}+\frac{1}{D_4}=\frac{1}{f_2},$ wherein λ.sub.1 and z.sub.2 are a reverse propagation wavelength and a distance at which the super-Rayleigh speckles are reversely propagated by a reverse propagation method to obtain a phase distribution diagram required by the phase modulation module (3); the super-Rayleigh speckles at a distance of z.sub.2′ from the phase modulation module (3) are imaged to the area array detector (5) by the relay imaging module (4), and an imaging formula is met: $\frac{1}{D_3-z_2^{\prime }}+\frac{1}{D_4}=\frac{1}{f_2}$ wherein D.sub.3 is a distance from the phase modulation module (3) to the relay imaging module (4), D.sub.4 is a distance from the relay imaging module (4) to the area array detector (5), and f.sub.2 is a focal length of the relay imaging module (4), and is either a constant, or f.sub.2 is a focal length of the relay imaging module (4) that is f.sub.2(λ) and meets the following conditions: $\frac{1}{f_2\left(\lambda \right)}=\frac{1}{D_4}+\frac{1}{D_3-z_2^{\prime }\left(\lambda \right)}$ wherein D.sub.3 is the distance from the phase modulation module (3) to the relay imaging module (4), D.sub.4 is the distance from the relay imaging module (4) to the area array detector (5), wherein the distance z.sub.2′(λ) meets $z_2^{\prime }\left(\lambda \right)=\frac{{\lambda }_1{z}_2}{\lambda z_1-{\lambda }_1{z}_2}{z}_1,$ wherein λ.sub.1 and z.sub.2 are a reverse propagation wavelength and a distance at which the super-Rayleigh speckles are reversely propagated by a reverse propagation method to obtain the phase distribution diagram required by the phase modulation module (3), where the distance z.sub.1 meets the following imaging formula: $\frac{1}{D_2-z_1}+\frac{1}{D_1}=\frac{1}{f_1},$ where D.sub.1 is the distance from the imaging target (a) to the pre-imaging module (1), D.sub.2 is the distance from the pre-imaging module (1) to the phase modulation module (3), and at the moment, the focal length f.sub.1 of the pre-imaging module (4) is a constant.

3. The broadband super-Rayleigh speckle correlated imaging spectral camera based on dispersion compensation according to claim 1, wherein the band-pass light filter (2) is configured for filtering out stray light outside a working spectrum band and improving a signal-to-noise ratio of the imaging system.

4. The broadband super-Rayleigh speckle correlated imaging spectral camera based on dispersion compensation according to claim 1, wherein the phase modulation module (3) comprises a photoetching phase plate, a polarizer and a transmission-type spatial light modulator, or a reflection-type spatial light modulator.

5. A method for performing spectral imaging by using the broadband super-Rayleigh speckle correlated imaging spectral camera based on dispersion compensation according to claim 1, comprising: (i) using phase retrieval to obtain the phase distribution diagram required by super-Rayleigh speckles, or reversely propagating the super-Rayleigh speckles at a wavelength of λ.sub.1 and a distance of z.sub.2 by the reverse propagation of the light field to obtain the phase distribution diagram of the corresponding field, and then loading the phase distribution diagram onto a phase modulator; (ii) calibration process: calibrating a measurement matrix A in advance, storing in the computer (6), and at the moment, the area array detector (5) obtains a series of super-Rayleigh speckle fields subjected to dispersion compensation, and there is a relatively large speckle contrast in the working spectrum band; (iii) detection process: placing an object to be detected in the field of view of the system, and exposing the area array detector once to obtain a corresponding detection light signal Y, which is stored in the computer; and (iv) reconstruction process: reconstructing to obtain a multi-spectral reconstructed image of the target according to the calibrated measurement matrix A and the detection light signal Y.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 shows the structure of the broadband super-Rayleigh speckle correlated imaging spectral camera based on dispersion compensation where the phase modulation module is a photoetching phase plate in the first embodiment of the present invention.

[0026] FIG. 2 shows the structure of the broadband super-Rayleigh speckle correlated imaging spectral camera based on dispersion compensation where the phase modulation module is a transmission-type spatial light modulator in the second embodiment of the present invention.

[0027] FIG. 3 shows the structure of the broadband super-Rayleigh speckle correlated imaging spectral camera based on dispersion compensation where the structure of the broadband super-Rayleigh speckle correlated imaging spectral camera based on dispersion compensation where the phase modulation module is a reflection-type spatial light modulator in the third embodiment of the present invention.

[0028] Reference numbers used in the figures are: 1—pre-imaging module, 2—band-pass light filter, 3—photoetching phase plate, a 4—relay imaging module, 5—area array detector, and 6—computer.

DETAILED DESCRIPTION OF THE INVENTION

[0029] Drawings and embodiments are combined below for further illustrating the broadband super-Rayleigh speckle correlated imaging spectral camera based on dispersion compensation provided by the present invention, but are not intended to limit the scope of protection of the present invention.

Embodiment I. Phase Modulation Module Being Photoetching Phase Plate

[0030] As shown in FIG. 1, the broadband super-Rayleigh speckle correlated imaging spectral camera based on dispersion compensation comprises a pre-imaging module 1, a band-pass light filter 2, a photoetching phase plate 3, a relay imaging module 4, an area array detector 5, and a computer 6. Incident light passes through the pre-imaging module 1 in turn; then the light passes through the band-pass light filter 2 and is irradiated to the photoetching phase plate 3; and finally, the light is imaged to the area array detector 5 by the relay imaging system 4 and collected by the detector.

Embodiment II. Phase Modulation Module Being Transmission-Type Spatial Light Modulator

[0031] As shown in FIG. 2, the broadband super-Rayleigh speckle correlated imaging spectral camera based on dispersion compensation comprises the pre-imaging module 1, the band-pass light filter 2, a polarizer 3, the transmission-type spatial light modulator 4, the relay imaging module 5, the area array detector 6, and the computer 7. Incident light passes through the pre-imaging module 1 in turn; then the light passes through the band-pass light filter 2 and the polarizer 3 and is irradiated to the transmission-type spatial light modulator 4; and finally, the light is imaged to the area array detector 5 by the relay imaging system 4 and collected by the detector.

Embodiment III. Phase Modulation Module Being Reflection-Type Spatial Light Modulator

[0032] As shown in FIG. 3, the broadband super-Rayleigh speckle correlated imaging spectral camera based on dispersion compensation comprises the pre-imaging module 1, the band-pass light filter 2, the polarizer 3, a beam splitter 4, the reflection-type spatial light modulator 5, the relay imaging module 6, the area array detector 7, and the computer 8. Incident light passes through the pre-imaging module 1 in turn; then the light passes through the band-pass light filter 2, the polarizer 3, and the beam splitter 4, and is irradiated to the reflection-type spatial light modulator 5; and the light returns along the original path after being modulated by the reflection-type spatial light modulator 5, then is reflected by the beam splitter 4, and is imaged to the area array detector 7 by the relay imaging system 6 and collected by the detector.

[0033] An imaging method of the broadband super-Rayleigh speckle correlated imaging spectral camera based on dispersion compensation in the present invention comprises the following specific steps:

[0034] Step one. phase loading: using phase retrieval to obtain a phase distribution diagram required by a super-Rayleigh light field, or reversely propagating the super-Rayleigh speckles at a wavelength and a distance by a reverse propagation method of the light field to obtain the phase distribution diagram of the corresponding field, and then loading the phase distribution diagram onto the phase modulator, or machining a corresponding phase plate by using photoeteching.

[0035] Step two. calibration process: calibrating a measurement matrix A of the super-Rayleigh modulation correlated imaging spectral camera based on dispersion compensation in advance by using the patent “Acquisition Method of Measurement Matrix of Compressed Spectral Imaging System” (Chinese Patent number: ZL201410161282.3), and storing in the computer. At the moment, the area array detector will obtain a series of super-Rayleigh speckle fields subjected to dispersion compensation, and there is a relatively large speckle contrast in the working spectrum band.

[0036] Step three. detection process: placing an object to be detected in the field of view of the system, and exposing the area array detector once to obtain a corresponding detection light signal Y, which is stored in the computer.

[0037] Step four. reconstruction process: reconstructing by an image recovery algorithm or a deep learning network and the like to obtain a multi-spectral reconstructed image of the target according to the calibrated measurement matrix A and the detection light signal Y.

[0038] In summary, the present invention relates to a broadband super-Rayleigh speckle correlated imaging spectral camera based on dispersion compensation. The super-Rayleigh speckle field is generated in the broadband by the use of the dispersion characteristics of the pre-imaging module or the relay imaging module; and this method is applied to the correlated imaging spectral camera, so that a high-quality reconstructed image can be obtained at a low signal-to-noise ratio.