CN105911792A - Nonlinear optical imaging device based on multiple phase matching processes - Google Patents

Abstract

The invention provides a nonlinear optical imaging device based on multiple phase matching processes, including: an illumination laser module, an image receiving module, a spatial frequency selection module, a parameter matching imaging module, and an image processing module; the illumination laser module emits illumination light to irradiate the target Object; the image receiving module receives the light reflected by the target object from the illumination light, and enters the parameter matching imaging module after forming an image of the target object; the spatial frequency selection module adjusts the phase matching parameters; the parameter matching imaging module obtains the enhancement of the target object at different spatial frequencies Image; the image processing module performs frequency-domain operations on multiple enhanced images obtained by the parameter matching imaging module according to the preset spatial frequency transfer function to realize image fusion and obtain a high-fidelity fusion image after the image of the target object is enhanced. The device can overcome the problem of poor image resolution caused by the limited frequency domain bandwidth of a single nonlinear optical process, and obtain a high-fidelity fusion image after image enhancement.

Description

Nonlinear Optical Imaging Device Based on Multiple Phase Matching Process

technical field

The invention relates to the technical field of nonlinear optics and imaging optics, in particular to a nonlinear optical imaging device based on multiple phase matching processes.

Background technique

At present, image enhancement methods are mainly divided into electrical methods and optical methods. Electron multiplier charge-coupled devices (EMCCD) and enhanced charge-coupled devices (ICCD) are mainly used in electrical methods, and these devices are widely used. The main techniques of optical methods include stimulated Raman scattering, stimulated Brillouin scattering, and optical parametric processes. Compared with the electrical method, the main advantage of the optical method is that it can realize frequency conversion, thereby improving the overall quantum efficiency, obtaining high gain, and reducing noise, so it has a good application prospect in the biomedical field.

However, currently used optical methods, such as optical parametric amplification (OPA), sum frequency (SFG) and other methods can only provide limited spatial frequency domain bandwidth, and the full width at half maximum of the gain transfer function (ATF) curve of these bandwidths is smaller than that of the optical system The full width at half maximum of the Modulation Transfer Function (MTF) curve can only enhance the image at certain spatial frequencies, so the effect is not ideal; as shown in Figure 1, Figure 1A is the input signal image, and Figure 1B is the existing As a result of enhancing the image in Figure 1A at a certain spatial frequency by means of optical parametric amplification in the technology, it can be seen that the enhanced single image is not ideal. The root cause is that single nonlinear optical imaging and a single phase matching condition correspond to a limited bandwidth in the spatial frequency domain, which cannot transmit and image low-frequency and high-frequency components at the same time, resulting in poor image resolution and difficult high-fidelity imaging .

In view of this, how to overcome the problems of poor image resolution and difficulty in high-fidelity imaging caused by the limited frequency-domain bandwidth of a single nonlinear optical process in the existing image enhancement methods, and obtaining high-fidelity images has become a technology that needs to be solved at present. question.

Contents of the invention

In order to solve the above technical problems, the present invention provides a nonlinear optical imaging device based on multiple phase matching processes, which can enhance images at different spatial frequencies and perform information fusion on images under different spatial frequency transfer functions. Thus obtaining high-fidelity images.

In the first aspect, the present invention provides a nonlinear optical imaging device based on multiple phase matching processes, including: an illumination laser module, an image receiving module, a spatial frequency selection module, a parameter matching imaging module, and an image processing module; wherein:

The illumination laser module emits illumination light to irradiate the target object; the image receiving module receives the light reflected by the illumination light by the target object, forms an image of the target object and then enters the parameter matching imaging module; the spatial frequency selection module adjusts Phase matching parameters; the parameter matching imaging module performs image enhancement on the target object image at different spatial frequencies according to the phase matching parameters adjusted by the spatial frequency selection module, and obtains enhanced images of the target object at different spatial frequencies; The image processing module performs frequency-domain operations on the enhanced images of the target object at different spatial frequencies obtained by the parameter matching imaging module according to the preset spatial frequency transfer function to realize image fusion and obtain high-fidelity fusion of the enhanced image of the target object image;

Wherein, the phase matching parameter is preset according to the one-to-one correspondence between the phase matching parameter and the spatial frequency transfer function in the nonlinear optical process.

Optionally, the image receiving module is an imaging lens group.

Optionally, the illumination laser module includes: an illumination laser, shaping and emitting optical elements;

The laser light emitted by the illumination laser is irradiated to the target object after being shaped by the shaping and emitting optical element.

Optionally, the spatial frequency selection module includes: a pump laser, a pump laser shaping optical element, an input coupling mirror and a phase matching controller;

After the pumping laser light emitted by the pumping laser is shaped by the pumping laser shaping optical element, it enters the parameter matching imaging through the input coupling mirror at the same time as the laser light of the target object image formed by the image receiving module The nonlinear optical element in the module; the phase matching controller controls the amount of phase mismatch by adjusting the angle or temperature of the nonlinear optical element, thereby realizing different spatial frequency selections.

Optionally, the phase matching controller is an angle controller, including: a rotating platform or a mirror frame, which is used to adjust the angle of the nonlinear optical element, so as to control the amount of phase mismatch, thereby achieving different spatial frequencies choose.

Optionally, the phase matching controller is a temperature regulator, which is used to monitor and adjust the temperature of the nonlinear optical element, so as to control the amount of phase mismatch, thereby realizing different spatial frequency selections.

Optionally, the spatial frequency selection module further includes: a synchronous control module, configured to perform delay control on the illumination laser and the pump laser to realize distance gating, and to obtain different depth positions by changing the time delay. image of the target object.

Optionally, the parameter matching imaging module includes: a nonlinear optical element, an output coupling mirror, a beam collector, an image transfer lens group, and a linear charge-coupled device CCD;

The light passing through the nonlinear optical element is incident on the linear charge-coupled element CCD through the image transfer mirror group after the output coupling mirror, and the obtained enhanced image of the target object at different spatial frequencies is sent to to the image processing module; the beam collector collects stray light passing through the nonlinear optical element.

Optionally, the image processing module includes: an image acquisition card and a processor;

The image acquisition card receives the enhanced image of the target object at different spatial frequencies formed by the linear array charge-coupled device CCD, and the processor performs an analysis of the target object at different spatial frequencies according to a preset spatial frequency transfer function. The enhanced image is operated in the frequency domain to achieve image fusion and obtain a high-fidelity fusion image of the target object image after enhancement.

Optionally, the processor performs frequency-domain operations on the enhanced images of the target object at different spatial frequencies to achieve image fusion, and the algorithm for obtaining a high-fidelity fusion image after the image of the target object is enhanced includes: based on wavelet transform, Algorithms for Fourier Transform, Principal Component Analysis PCA or Intensity Hue Saturation IHS Transform.

It can be seen from the above technical solution that the nonlinear optical imaging device based on multiple phase matching processes of the present invention can overcome the difficulty of poor image resolution caused by the limited frequency domain band block of a single nonlinear optical process, and realize image Enhancement at different spatial frequencies, and information fusion of images under different spatial frequency transfer functions, so as to obtain high-fidelity fusion images.

Description of drawings

Fig. 1 is a schematic diagram of using optical parametric amplification to enhance an image at a certain spatial frequency in the prior art, wherein Fig. 1A is an input signal image, and Fig. 1B is a schematic diagram of using optical parametric amplification in the prior art to enhance The schematic diagram of the result of enhancing the image at a certain spatial frequency in Fig. 1A;

FIG. 2 is a schematic structural diagram of a nonlinear optical imaging device based on multiple phase matching processes provided by the first embodiment of the present invention;

3 is a schematic structural diagram of a nonlinear optical imaging device based on multiple phase matching processes provided by the second embodiment of the present invention;

Fig. 4 is the ATF curve of the second embodiment of the present invention at different phase mismatch amounts;

5 is a schematic diagram of the relationship between the phase mismatch Δk and the angle Δθ of the nonlinear crystal provided by the second embodiment of the present invention;

Figure 6 shows the different spaces when the phase mismatches corresponding to A, B, C, and D provided by the second embodiment of the present invention are 1.7cm ^-1 , -3.7cm ^-1 , -6.3cm ^-1 , -8.3cm ^-1 respectively Enhanced image at frequency;

Fig. 7 is a schematic diagram of the second embodiment of the present invention adopting the direct image fusion method based on Fourier transform to fuse the respective preferred parts of the four images in Fig. 6, and Fig. 7A is the second embodiment adopting the direct image fusion method based on Fourier transform The high-fidelity image obtained after fusion of the respective preferred parts of the four images in Fig. 6 by the method, and Fig. 7B is the input signal image;

FIG. 8 is a schematic structural diagram of a nonlinear optical imaging device based on multiple phase matching processes provided by the third embodiment of the present invention.

detailed description

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is only some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

first embodiment

Fig. 2 shows a schematic structural diagram of a nonlinear optical imaging device based on multiple phase matching processes provided by the first embodiment of the present invention. As shown in Fig. 2, the nonlinear optical imaging device based on multiple phase matching processes in this embodiment Optical imaging device, including: illumination laser module 1, image receiving module 2, spatial frequency selection module 3, parameter matching imaging module 4 and image processing module 5; wherein:

The illumination laser module 1 emits illumination light to illuminate the target object 0; the image receiving module 2 receives the light reflected by the illumination light by the target object 0, forms an image of the target object and then enters the parameter matching imaging module 4; The spatial frequency selection module 3 adjusts the phase matching parameters; the parameter matching imaging module 4 performs image enhancement on the target object image at different spatial frequencies according to the phase matching parameters adjusted by the spatial frequency selection module 3, and obtains the target object 0 at Enhanced images at different spatial frequencies; the image processing module 5 performs frequency-domain operations on the enhanced images of the target object 0 obtained by the parameter matching imaging module 4 at different spatial frequencies according to a preset spatial frequency transfer function to realize image Fusion, to obtain a high-fidelity fusion image after the image of the target object is enhanced;

Wherein, the phase matching parameter is preset according to the one-to-one correspondence between the phase matching parameter and the spatial frequency transfer function in the nonlinear optical process.

Specifically, the phase matching parameter is a gain transfer function AFT, and different ATFs can be preset according to the gain transfer function ATF and the phase mismatch amount Δk.

In a specific application, the image receiving module 2 may preferably be an imaging lens group.

In a specific application, the illumination laser module may include: an illumination laser, shaping and emitting optical elements;

The laser light emitted by the illumination laser is irradiated to the target object after being shaped by the shaping and emitting optical element.

In a specific application, the spatial frequency selection module 3 may include: a pump laser, a pump laser shaping optical element, an input coupling mirror and a phase matching controller;

After the pumping laser light emitted by the pumping laser is shaped by the pumping laser shaping optical element, it enters the parameter matching imaging through the input coupling mirror at the same time as the laser light of the target object image formed by the image receiving module The nonlinear optical element in module 4; the phase matching controller controls the amount of phase mismatch by adjusting the angle or temperature of the nonlinear optical element, thereby realizing different spatial frequency selections.

Further, the phase matching controller can be an angle controller, including: a rotating platform or a mirror frame, which is used to adjust the angle of the nonlinear optical element to realize the control of the phase mismatch amount, thereby realizing different spatial frequency Selection; specifically, according to the relationship between the gain transfer function ATF and the phase mismatch Δk, and the relationship between the phase mismatch Δk and the angle Δθ of the nonlinear optical element, different ATFs can be preset, by adjusting the rotating platform or the mirror frame By changing the angle Δθ of the nonlinear optical element, different phase mismatch amounts Δk are obtained, so that the image of the target object is enhanced at different spatial frequencies.

Further, the phase matching controller can also be a temperature regulator, which is used to monitor and adjust the temperature of the nonlinear optical element, so as to control the amount of phase mismatch, thereby realizing different spatial frequency selections.

In a specific application, the spatial frequency selection module 3 may also include: a synchronous control module (not shown in the figure), which is used to perform delay control on the illumination laser and the pump laser to realize distance gating , by changing the time delay to obtain target object images at different depth positions.

In a specific application, the operation mode of the illumination laser in the illumination laser module 1 and the pump laser in the spatial frequency selection module 3 can be continuous operation or pulse operation, and for pulse operation, the pulse width can be nanometers. One of seconds, picoseconds, or femtoseconds.

In a specific application, the parameter matching imaging module 4 includes: a nonlinear optical element, an output coupling mirror, a beam collector, an image transfer mirror group, and a linear charge-coupled device CCD;

The light passing through the nonlinear optical element is incident on the linear charge-coupled element CCD through the image transfer mirror group after the output coupling mirror, and the obtained enhanced image of the target object O at different spatial frequencies Send to the image processing module 5; the beam collector collects the stray light passing through the nonlinear optical element.

Specifically, the nonlinear optical element may preferably be a nonlinear crystal.

In a specific application, the image processing module 5 may include: an image acquisition card and a processor;

The image acquisition card receives the enhanced image of the target object 0 at different spatial frequencies formed by the linear array charge-coupled device CCD, and the processor performs the processing of the target object 0 at different spatial frequencies according to a preset spatial frequency transfer function. The frequency-domain operation is performed on the enhanced image at the location to realize image fusion, and a high-fidelity fusion image after the target object image is enhanced is obtained.

Specifically, the processor may use algorithms based on wavelet transform, Fourier transform, principal component analysis (PCA) or intensity-hue-saturation-saturation (IHS) transform to perform frequency-domain operations on the enhanced images of the target object 0 at different spatial frequencies to realize image Fusion to obtain a high-fidelity fusion image of the target object image after enhancement.

In the nonlinear optical imaging device based on multiple phase matching processes in this embodiment, the image of the target object is enhanced at different spatial frequencies by using the optical parametric amplification process, or the image signal of the target object is processed by using the method of sum-frequency up-conversion Frequency conversion, improve the overall efficiency, and then use the fusion algorithm to obtain high-fidelity images. The device of the present invention is especially effective for weak image signals, which is extremely important for remote detection and weak light detection

second embodiment

Fig. 3 shows a schematic structural diagram of a nonlinear optical imaging device based on multiple phase matching processes provided by the second embodiment of the present invention. As shown in Fig. 3, the nonlinear optical imaging device based on multiple phase matching processes in this embodiment An optical imaging device, comprising: an illumination laser module 1, an image receiving module 2, a spatial frequency selection module 3, a parameter matching imaging module 4 and an image processing module 5;

The image receiving module 2 is an imaging lens group; the illumination laser module includes: an illumination laser 101, a shaping and emitting optical element 102; the spatial frequency selection module 3 includes: a pumping laser 303, a pumping laser shaping optical element 304 , an input coupling mirror 302 and a rotating platform 301; the parameter matching imaging module 4 includes: a nonlinear crystal 401, an output coupling mirror 402, a beam collector 403, an image transfer mirror group 404 and a linear charge-coupled element CCD405;

Wherein, the illumination laser emitted by the illumination laser 101 is irradiated to the target object 0 after being shaped by the shaping and emitting optical element 102; the imaging mirror group 2 receives the light reflected by the illumination laser by the target object to form an image of the target object; After the pump laser light emitted by the pump laser 303 is shaped by the pump laser shaping optical element 304, the laser light of the target object image formed by the imaging mirror group 2 enters the nonlinear crystal 401 through the input coupling mirror 302 at the same time. ; According to the gain transfer function ATF and the phase mismatch Δk, and the relationship between the phase mismatch Δk and the angle Δθ of the nonlinear crystal 401 (see Figure 5), different ATFs are preset, and the nonlinearity is adjusted by the rotating platform 301 The angle Δθ of the crystal 401, so as to obtain different phase mismatches Δk, so that the image of the target object is enhanced at different spatial frequencies; the light passing through the nonlinear crystal 401 passes through the output coupling mirror 402 and then passes through the image The mirror group 404 is incident on the linear charge-coupled element CCD405 for imaging, and the obtained enhanced images of the target object 0 at different spatial frequencies are sent to the image processing module 5; stray light; the image processing module 5 performs frequency-domain operations on the enhanced images of the target object 0 obtained by the parameter matching imaging module 4 at different spatial frequencies according to the preset spatial frequency transfer function to realize image fusion and obtain the target High-fidelity fusion image after object image enhancement.

In a specific application, the image processing module 5 may include: an image acquisition card and a processor;

The image acquisition card receives the enhanced images of the target object 0 at different spatial frequencies formed by the linear array charge-coupled element CCD405, and the processor performs the processing of the target object 0 at different spatial frequencies according to a preset spatial frequency transfer function. The frequency-domain operation is performed on the enhanced image at the location to realize image fusion, and a high-fidelity fusion image after the target object image is enhanced is obtained.

Specifically, the processor may use algorithms based on wavelet transform, Fourier transform, principal component analysis (PCA) or intensity-hue-saturation-saturation (IHS) transform to perform frequency-domain operations on the enhanced images of the target object 0 at different spatial frequencies to realize image Fusion to obtain a high-fidelity fusion image of the target object image after enhancement.

In this embodiment, the laser wavelength emitted by the illumination laser module 1 of this embodiment may preferably be 1064nm, the output wavelength of the pump laser 303 may preferably be 532nm laser, the pump light power density may preferably be 1GW/cm ² , and the parameters match The imaging module 4 can perform optical parametric amplification on the weak reflected light of the target object 0 to increase the light energy, wherein the nonlinear crystal 401 is a BBO crystal with a length of 12.5mm, and then adopts the direct image fusion method based on Fourier transform to obtain high-fidelity Image; Figure 4 is the ATF curves of the second embodiment at different phase mismatches, including phase mismatches of 1.7cm ^-1 , -3.7cm ^-1 , -6.3cm ^-1 , ^-8.3cm -1 ATF curve at time ¹ ; Figure 6 shows that the phase mismatches corresponding to A, B, C, and D provided by the second embodiment are 1.7cm ^-1 , -3.7cm ^-1 , -6.3cm ^-1 , -8.3cm ^{- 1.} Images after enhancement at different spatial frequencies; FIG. 7 is a schematic diagram of the second embodiment adopting the direct image fusion method based on Fourier transform to fuse the respective preferred parts of the four images in FIG. 6, and FIG. 7A is the second implementation For example, a high-fidelity image is obtained by fusing the best parts of each of the four images in Figure 6 by using the direct image fusion method based on Fourier transform, and Figure 7B is the input signal image.

The nonlinear optical imaging device based on multiple phase matching processes in this embodiment can enhance images at different spatial frequencies and perform information fusion of images under different spatial frequency transfer functions, thereby obtaining high-fidelity images.

third embodiment

Fig. 8 shows a schematic structural diagram of a nonlinear optical imaging device based on multiple phase matching processes provided by the third embodiment of the present invention. As shown in Fig. 8, the nonlinear optical imaging device based on multiple phase matching processes in this embodiment The difference between the optical imaging device and the second embodiment is: the rotating platform 301 is replaced by a temperature regulator 301';

Wherein, the illumination laser emitted by the illumination laser 101 is irradiated to the target object 0 after being shaped by the shaping and emitting optical element 102; the imaging mirror group 2 receives the light reflected by the illumination laser by the target object to form an image of the target object; After the pump laser light emitted by the pump laser 303 is shaped by the pump laser shaping optical element 304, the laser light of the target object image formed by the imaging mirror group 2 enters the nonlinear crystal 401 through the input coupling mirror 302 at the same time. ; The temperature regulator 301' realizes the control of the phase mismatch by adjusting the temperature of the nonlinear crystal 401, thereby realizing different spatial frequency selections; the light passing through the nonlinear crystal 401 passes through the output coupling mirror 402 The image transmission lens group 404 is incident on the linear charge-coupled element CCD405 for imaging, and the obtained enhanced images of the target object 0 at different spatial frequencies are sent to the image processing module 5; Stray light behind the linear crystal 401; the image processing module 5 performs frequency-domain operations on the enhanced images of the target object 0 obtained by the parameter matching imaging module 4 at different spatial frequencies according to the preset spatial frequency transfer function to realize image Fusion to obtain a high-fidelity fusion image of the target object image after enhancement.

In this embodiment, the wavelength of the laser light emitted by the illumination laser 101 in this embodiment may preferably be 1.55 μm, which belongs to the atmospheric window and has low atmospheric loss. The output wavelength of the pump laser 303 can preferably be 1064nm, and the 631nm laser is generated after the neutralization frequency of the nonlinear crystal 401, and the infrared laser is converted to the visible light band, thereby converting the range of the detected laser signal from the wavelength band with low quantum efficiency of the detector to In the wavelength band with high quantum efficiency, the pump light power density is 1GW/cm ² , and the nonlinear crystal 401 is a PPLN crystal. The temperature of the crystal is adjusted by the temperature regulator 301 to change the phase mismatch amount Δk.

The nonlinear optical imaging device based on multiple phase matching processes in this embodiment can enhance images at different spatial frequencies and perform information fusion of images under different spatial frequency transfer functions, thereby obtaining high-fidelity images.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: It is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the various embodiments of the present invention. scope.

Claims (10)

1. A nonlinear optical imaging device based on multiple phase matching processes, comprising: an illumination laser module, an image receiving module, a spatial frequency selection module, a parameter matching imaging module and an image processing module; wherein: The illumination laser module emits illumination light to irradiate the target object; the image receiving module receives the light reflected by the illumination light by the target object, forms an image of the target object and then enters the parameter matching imaging module; the spatial frequency selection module adjusts Phase matching parameters; the parameter matching imaging module performs image enhancement on the target object image at different spatial frequencies according to the phase matching parameters adjusted by the spatial frequency selection module, and obtains enhanced images of the target object at different spatial frequencies; The image processing module performs frequency-domain operations on the enhanced images of the target object at different spatial frequencies obtained by the parameter matching imaging module according to the preset spatial frequency transfer function to realize image fusion and obtain high-fidelity fusion of the enhanced image of the target object image; Wherein, the phase matching parameter is preset according to the one-to-one correspondence between the phase matching parameter and the spatial frequency transfer function in the nonlinear optical process. 2. The device according to claim 1, wherein the image receiving module is an imaging lens group. 3. The device according to claim 1, wherein the illumination laser module comprises: an illumination laser, shaping and emitting optical elements; The laser light emitted by the illumination laser is irradiated to the target object after being shaped by the shaping and emitting optical element. 4. The device according to claim 3, wherein the spatial frequency selection module comprises: a pump laser, a pump laser shaping optical element, an input coupling mirror and a phase matching controller; After the pumping laser light emitted by the pumping laser is shaped by the pumping laser shaping optical element, it enters the parameter matching imaging through the input coupling mirror at the same time as the laser light of the target object image formed by the image receiving module The nonlinear optical element in the module; the phase matching controller controls the amount of phase mismatch by adjusting the angle or temperature of the nonlinear optical element, thereby realizing different spatial frequency selections. 5. The device according to claim 4, wherein the phase matching controller is an angle controller, comprising: a rotating platform or a mirror frame, which is used to adjust the angle of the nonlinear optical element to realize the adjustment of the phase misalignment. Dosing control, so as to realize different spatial frequency selection. 6. The device according to claim 4, characterized in that, the phase matching controller is a temperature regulator, which is used to monitor and adjust the temperature of the nonlinear optical element to realize the control of the phase mismatch, thereby Different spatial frequency selections are realized. 7. The device according to claim 4, wherein the spatial frequency selection module further comprises: a synchronous control module for performing delay control on the illumination laser and the pump laser to realize distance selection By changing the time delay, the images of the target object at different depth positions can be obtained. 8. The device according to claim 4, wherein the parameter matching imaging module includes: a nonlinear optical element, an output coupling mirror, a beam collector, an image transfer mirror group, and a linear charge-coupled device CCD; The light passing through the nonlinear optical element is incident on the linear charge-coupled element CCD through the image transfer mirror group after the output coupling mirror, and the obtained enhanced image of the target object at different spatial frequencies is sent to to the image processing module; the beam collector collects stray light passing through the nonlinear optical element. 9. The device according to claim 8, wherein the image processing module comprises: an image acquisition card and a processor; The image acquisition card receives the enhanced image of the target object at different spatial frequencies formed by the linear array charge-coupled device CCD, and the processor performs an analysis of the target object at different spatial frequencies according to a preset spatial frequency transfer function. The enhanced image is operated in the frequency domain to achieve image fusion and obtain a high-fidelity fusion image of the target object image after enhancement. 10. The device according to claim 9, wherein the processor performs frequency domain operations on the enhanced images of the target object at different spatial frequencies to achieve image fusion and obtain a high-fidelity image of the target object after enhancement Algorithms for fused images, including: algorithms based on wavelet transform, Fourier transform, principal component analysis PCA or intensity-hue-saturation-saturation IHS transform.