Super-depth-of-field imaging method and system and application method of system

Abstract

The embodiment of the invention provides a super-depth-of-field imaging method and system and an application method of the system, and belongs to the technical field of imaging, and the super-depth-of-field imaging method comprises the steps: enabling an illumination light source to form an illumination light needle through an illumination light path, and enabling the illumination light needle to irradiate a to-be-detected object; an object to be detected generates detection light after being irradiated by the irradiation light needle; the detection light forms a detection light needle through a detection light path; capturing the detection light at the detection light needle by a confocal imaging element; and receiving the captured detection light through a detector to obtain an image of the irradiated point of the to-be-detected object. According to the technical scheme, a higher imaging quality level and richer imaging information can be obtained in a short time, and an ultra-depth-of-field imaging effect is realized.

Description

Technical Field

[0001] The present application relates to the field of imaging technology, and in particular to a super-depth-of-field imaging method, system, and application method of the system. Background Art

[0002] Imaging technology uses one or more lens combinations to obtain images of samples from transmitted or reflected light, and can extract information about the samples. It is widely used in the biomedical field, especially neurobiology, ecology, genetics, and physiology, or in industrial inspection fields, such as mobile phone glass inspection, circuit board inspection, and semiconductor wafer inspection. However, traditional imaging technology usually has a trade-off between depth of field and spatial resolution. Clear imaging can only be performed within a limited depth range. Especially in systems with higher resolution and larger numerical aperture, the depth of field is often smaller, and slight defocusing can easily lead to information loss, resulting in blurred images.

[0003] There are three main solutions to the imaging depth of field problem, including optical sectioning scanning technology, light field technology and wavefront coding technology. Optical sectioning scanning technology refers to scanning samples of different thicknesses, collecting slice sequences and reconstructing images with a large depth of field through calculation. This method requires additional mechanical movement, sacrificing imaging time, and is suitable for the observation of static samples. It is difficult to apply to living biological samples or industrial detection applications that require high-speed scanning and detection. Light field technology reconstructs images through imaging devices such as microlens arrays, combined with position information and direction information, and can obtain images with a large depth of field with only one exposure, but it also sacrifices lateral spatial resolution and is difficult to apply in situations where high resolution is required. Wavefront coding technology regulates the wavefront phase at the system exit pupil. The core lies in the design of the phase template, so that the point spread function PSF or modulation transfer function MTF of the optical system maintains the same function form before and after the focus, and there is no zero point in the MTF within the system cutoff frequency. By deconvolving the image that is not related to the defocus amount and the prior template information, a clear image with a large depth of field range can be restored. This method can expand the depth of field by more than one order of magnitude with only one exposure while maintaining the original lateral resolution level of the system. It is conducive to solving the constraint problem between depth of field and spatial resolution and has strong application advantages.

[0004] When the phase template is used to control the optical wavefront, the ultra-depth imaging of the optical system can be achieved while maintaining the diffraction limit of the spatial resolution. Common phase templates include cubic phase templates, numerical phase templates, high-order phase templates, polynomial phase templates, exponential phase templates, free-form phase templates, and sinusoidal phase templates. In addition, Bessel beams have become one of the important choices for light field control phase templates due to their unique characteristics. As a self-imaging beam, Bessel beams have ultra-long focal depth and self-reconstruction. On the one hand, the lateral distribution of the Bessel beam can be described by a set of Bessel functions with concentric rings in cross section. Unlike Gaussian beams, their lateral distribution does not change with propagation distance. By shaping the imaging beam into a Bessel beam, ultra-depth imaging with a depth of field exceeding the conventional imaging depth of field can be achieved. Of course, the beam that realizes the ultra-depth imaging function is not limited to Bessel beams. Usually, in the PSF of the optical system, as long as the main lobe length in the Z-axis direction is longer than the main lobe length of the Gaussian beam with the same parameters, the effect of improving the imaging depth of field can also be achieved. The conditions of equivalent parameters refer to the conditions that the main lobe size of the PSF is similar, or the highest spatial frequency domain is similar, etc. The above-mentioned beam that can achieve ultra-depth imaging, the so-called light needle, refers to a special beam with a high aspect ratio characteristic, whose energy does not diverge over a long propagation distance, is concentrated on the optical axis for propagation, and the lateral size remains extremely small, such as non-diffraction beams such as Bessel beams or Airy beams, or needle-shaped beams achieved by multi-focus stacking, etc. are all classified here.

[0005] However, all the light needle beams that can achieve super-depth of field imaging have the problem of lower main lobe intensity at the center of the beam and higher side lobe intensity compared to Gaussian beams. This means that in the frequency domain, its high-frequency information is weak, which makes the MTF performance of the system poor. Although the depth of field is improved, there are problems of low imaging quality and low image contrast. This problem is also a common problem of the current wavefront coding super-depth of field method. It will compress the transfer function of the system to a certain extent. It is often necessary to further improve the overall performance by continuously optimizing the template form, aperture method, insertion position, evaluation method, etc., and no matter how it is optimized, it is impossible to recover all the information lost due to low high-frequency contrast. Summary of the invention

[0006] The present application provides a super depth of field imaging method, system and application method of the system.

[0007] On the one hand, the present application provides a super depth of field imaging method, comprising:

[0008] The illumination light source is formed into an illumination light needle through the illumination light path and illuminated onto the object to be detected;

[0009] The object to be detected generates detection light after being irradiated by the irradiation light needle;

[0010] The detection light forms a detection light needle through the detection light path;

[0011] capturing the detection light at the detection light needle by a confocal imaging element;

[0012] The captured detection light is received by a detector to obtain an image of the illuminated point of the object to be detected.

[0013] Optionally, the illuminating light needle is a Bessel beam or an Airy beam, and the detecting light needle is a Bessel beam or an Airy beam; and the step of forming an illuminating light needle from an illumination light source through an illumination light path and illuminating the object to be detected comprises:

[0014] After the illumination light source is collimated into parallel light by a lens;

[0015] The parallel light is formed into the illumination light needle by sequentially arranged annular aperture and lens, or sequentially arranged aconical lens and two lenses, or sequentially arranged phase template and lens; and the detection light is formed into the detection light needle through the detection light path, including:

[0016] The detection light first passes through a lens, and then passes through an annular aperture and a lens, or a conical lens, or a phase template and a lens, which are arranged in sequence, to form the detection light needle.

[0017] Optionally, the detection light path is a reverse light path of the illumination light path, or the detection light path and the illumination light path are arranged separately.

[0018] Optionally, when the detection light path is the reverse light path of the illumination light path, before the illumination light source is collimated into parallel light by a lens, the illumination light source from the side of the illumination light path is reflected by a beam splitter so that its illumination direction is aligned with the object to be detected; when the detection light path and the illumination light path are set separately, after the detection light first passes through the lens, the detection light is reflected by the beam splitter to change its propagation direction.

[0019] Optionally, the illumination light source and the detection light are both broad-spectrum light, and spectroscopic elements are respectively arranged in the illumination light path and the detection light path to disperse the illumination light source and the detection light to obtain light needles orderly distributed by wavelength;

[0020] The confocal imaging element is an optical fiber, a single pinhole element, an array pinhole element or a slit.

[0021] On the other hand, the present application provides a super depth of field imaging system, characterized in that it includes:

[0022] An illumination light path, wherein the illumination light path forms an illumination light needle from an illumination light source and irradiates the object to be detected;

[0023] A detection light path, wherein the detection light path converts the detection light generated by the object to be detected after being irradiated by the irradiation light needle into a detection light needle;

[0024] a confocal imaging element for capturing the detection light at the location where the detection light needle is formed;

[0025] The detector is used to receive the captured detection light to obtain an image of the irradiated point of the object to be detected.

[0026] Optionally, the illumination light path includes a first lens, an annular aperture, and a second lens sequentially arranged along the illumination direction of the illumination light source; or a first lens, a cone lens, a third lens, and a fourth lens sequentially arranged along the illumination direction of the illumination light source; or a first lens, a phase template, and a fifth lens sequentially arranged along the illumination direction of the illumination light source;

[0027] When the illumination light path is a first lens, an annular aperture, and a second lens sequentially arranged along the illumination direction of the illumination light source; or a first lens, a phase template, and a fifth lens sequentially arranged along the illumination direction of the illumination light source, the detection light path is a reverse light path of the illumination light path;

[0028] When the illumination light path is a first lens, an annular aperture and a second lens arranged in sequence along the illumination direction of the illumination light source,

[0029] The detection light path includes the second lens, the beam splitter and the aconic lens which are sequentially arranged in the propagation direction of the detection light;

[0030] Or the detection light path includes the second lens, the beam splitter, the phase template and the sixth lens which are sequentially arranged in the propagation direction of the detection light;

[0031] When the illumination light path is a first lens, an aconic lens, a third lens and a fourth lens arranged in sequence along the illumination light irradiation direction,

[0032] The detection light path includes the fourth lens, the beam splitter and the cone lens which are sequentially arranged in the propagation direction of the detection light;

[0033] Or the detection light path includes the fourth lens, the beam splitter, the annular aperture and the seventh lens which are sequentially arranged in the propagation direction of the detection light;

[0034] Or the detection light path includes the fourth lens, the beam splitter, the phase template and the eighth lens which are sequentially arranged in the propagation direction of the detection light;

[0035] When the illumination light path is a first lens, a phase template and a fifth lens arranged in sequence along the illumination direction of the illumination light source,

[0036] The detection light path includes the fifth lens, the beam splitter and the cone lens which are sequentially arranged in the propagation direction of the detection light;

[0037] Or the detection light path includes the fifth lens, the beam splitter, the annular aperture and the ninth lens which are sequentially arranged in the propagation direction of the detection light;

[0038] Among them, the beam splitter reflects the detection light to change the propagation direction of the detection light; the conical lens in the detection light path causes the detection light to form a Bessel beam; the phase template and the sixth lens in the detection light path cause the detection light to form an Airy beam; the annular aperture and the seventh lens in the detection light path cause the detection light to form a Bessel beam; the phase template and the eighth lens in the detection light path cause the detection light to form an Airy beam.

[0039] Optionally, the illumination light source and the detection light are both broad-spectrum lights. For the illumination light path, a spectroscopic element is arranged behind the annular aperture, or a spectroscopic element is arranged behind the conical lens, or a spectroscopic element is arranged behind the phase template; and on the path after the detection light passes through the confocal imaging element, a tenth lens, a spectroscopic element, an eleventh lens and a detector are arranged in sequence.

[0040] On the other hand, the present application provides an application method of a super-depth-of-field imaging system, using any of the super-depth-of-field imaging systems described above to perform line scanning, stripe structured light imaging, or dot matrix structured light imaging on the surface of a sample to be detected to obtain three-dimensional imaging data of the surface of the sample to be detected, wherein the illumination light source uses a wide-spectrum light source to irradiate the surface of the sample to be detected at a certain incident angle.

[0041] On the other hand, the present application provides an application method of a super-depth of field imaging system, using any of the super-depth of field imaging systems described above to perform three-dimensional imaging of a sample to be detected at multiple set positions or angles, or using two or more super-depth of field imaging systems as described above to perform three-dimensional imaging of a sample to be detected at different set positions or angles at the same time, and determining the three-dimensional super-depth of field depth imaging data of the sample to be detected based on the pixel difference between the three-dimensional imaging data acquired by the imaging systems at different set positions or angles.

[0042] In order to make the features and advantages of the present application more obvious and understandable, some embodiments are given below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. The drawings herein are incorporated into the specification and constitute a part of the specification. These drawings illustrate embodiments consistent with the present application and are used together with the specification to illustrate the technical solutions of the present application. It should be understood that the following drawings only illustrate certain embodiments of the present application and should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can also be obtained based on these drawings without creative work.

[0044] Figure 1 A schematic diagram of a process flow of a super depth of field imaging method provided in an embodiment of the present application;

[0045] Figure 2 A schematic diagram of an ultra-depth-of-field imaging system provided in Embodiment 1 of the present application;

[0046] Figure 3 A schematic diagram of an illumination light path of a super-depth-of-field imaging system provided in Example 1 of the present application;

[0047] Figure 4 A schematic diagram of a detection optical path of a super-depth-of-field imaging system provided in Example 1 of the present application;

[0048] Figure 5 A schematic diagram of an ultra-depth-of-field imaging system provided in Embodiment 2 of the present application;

[0049] Figure 6 A schematic diagram of an illumination light path of a super-depth-of-field imaging system provided in Embodiment 3 of the present application;

[0050] Figure 7 A schematic diagram of a detection optical path of a super-depth-of-field imaging system provided in Embodiment 4 of the present application;

[0051] Figure 8 A schematic diagram of an illumination light path of a super-depth-of-field imaging system provided in Example 5 of the present application;

[0052] Fig. 9 A schematic diagram of a partial detection optical path of a super-depth-of-field imaging system provided in Example 5 of the present application;

[0053] Fig.10 A schematic diagram of a super-depth-of-field imaging method provided in Example 6 of the present application;

[0054] Fig.11 A schematic diagram of an application method of a super-depth-of-field imaging system provided in Example 7 of the present application.

[0055] Explanation of the reference numerals: 1. illumination light source; 2. first beam splitter; 3. first lens; 4. annular aperture; 5. second lens; 6. object to be detected; 7. detection light; 8. detection Bessel beam; 9. pinhole element; 91. pinhole; 10. detector; 11. illumination light source generator; 12. first conical lens; 13. intermediate irradiation Bessel beam; 14. third lens; 15. second beam splitter; 16. fourth lens; 17. second conical lens; 18. circulator; 19. detection Airy beam; 20. phase template; 21. fifth lens; 22. irradiation Bessel beam; 23. irradiation Airy beam; 24. first grating; 25. λ1 irradiation light needle; 26. λ2 irradiation light needle; 27. tenth lens; 28. second grating; 29. ​​eleventh lens; 30. λ1 detection light needle; 31. λ2 detection light needle; 32. linear array camera; 33. optical path system; 100. imaging system. DETAILED DESCRIPTION

[0056] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application generally described and shown here can be arranged and designed in various configurations. Therefore, the following detailed description of the embodiments of the present application is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0057] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0058] The term "and / or" herein only describes an association relationship, indicating that three relationships may exist. For example, A and / or B may represent the following three situations: A exists alone, A and B exist at the same time, and B exists alone. In addition, the term "at least one" herein represents any combination of at least two of any one or more of a plurality of. For example, including at least one of A, B, and C may represent including any one or more elements selected from the set consisting of A, B, and C.

[0059] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0060] The confocal imaging system is based on the principle of conjugate focusing. By designing the illumination light source, the detection point and the detector at the conjugate position, the illumination pinhole and the detection pinhole are used to realize point illumination and point detection, and the image is further obtained by scanning and other methods. The point spread function PSF of the confocal imaging system can generally be expressed as:

[0061] PSF system (x,y,z) = PSF illumination (x,y,z) × [PSF detection (x,y,z) * H (x,y)]

[0062] Where * represents convolution, H(x,y) is the pinhole function, and when the pinhole tends to infinity, the point spread function PSF of the confocal imaging system is expressed as:

[0063] PSF system (x,y,z) = PSF illumination (x,y,z) × PSF detection (x,y,z)

[0064] From the expression of the point spread function PSF of the above confocal imaging system, it can be seen that the illumination PSF and detection PSF of the confocal imaging system are multiplied. When the illumination PSF and detection PSF are both light needles, the result of the product still has a long distance in the z-axis direction, maintaining the high aspect ratio characteristics of the light needle, and ultra-depth of field imaging can still be achieved. The sidelobe energy of the system PSF after the product will be suppressed relative to the illumination PSF or the detection PSF, so that the energy of the system PSF is more concentrated in the main lobe. From the frequency domain point of view, the high-frequency component of the system MTF increases, and the image contrast of the high-frequency details increases.

[0065] When the illumination PSF and detection PSF of the confocal system are both Bessel beams, which can be expressed as Bessel function B(x,y,z), if the pinhole diameter tends to infinitesimal, the PSF of the confocal system is: [B(x,y,z)]^2. It can be seen that the side lobes of the point spread function of the confocal system are greatly suppressed, and it can still have a high aspect ratio feature, which can achieve high image contrast and super depth of field imaging. Therefore, the illumination beam and imaging beam of the confocal imaging system are wavefront encoded by devices such as phase templates to generate a point spread function PSF in the form of a light needle, which can achieve high image contrast and super depth of field imaging. This is conducive to overcoming the disadvantage of low image contrast of the traditional wavefront coding super depth of field method.

[0066] The present invention proposes a method, system and application method of super-depth imaging. Based on the confocal imaging system, the light source passes through the illumination light path and the detection light path respectively, and the PSF of the illumination light beam and the detection light beam are modulated respectively, so that they both form the function form of the light needle. At this time, the PSF of the final optical system can be expressed as the square of the function form of the light needle. After being collected by the confocal imaging element, the contrast of the main lobe energy can be improved by suppressing the side lobe energy of the light beam, thereby improving the MTF performance of the optical system and achieving the imaging effect of super depth of field. It is possible to obtain a higher imaging quality level and richer imaging information in a shorter time.

[0067] like Figure 1 , Figure 2 As shown, the present application provides a super depth of field imaging method, comprising:

[0068] S10, using the illumination light source to form an illumination light needle through the illumination light path to illuminate the object to be detected;

[0069] S20, the object to be detected is irradiated by the irradiation light needle to generate detection light;

[0070] S30, the detection light forms a detection light needle through a detection light path;

[0071] S40, capturing the detection light at the detection light needle by a confocal imaging element;

[0072] S50, receiving the captured detection light through a detector to obtain an image of the irradiated point of the object to be detected.

[0073] Among them, the illumination light needle formed by the illumination light source and the detection light needle formed by the detection light through the optical path system 33, the light needle form refers to a special light beam with a high aspect ratio characteristic, whose energy does not diverge over a long propagation distance, is concentrated on the optical axis for propagation, and the lateral size is kept extremely small, such as a non-diffraction light beam such as a Bessel beam or an Airy beam, or a needle-shaped light beam realized by multi-focus stacking and the like. The detection light generated by the illumination light needle illuminating the sample point to be detected within the effective illumination range, the effective illumination range of the detection light needle formed by the optical system all falls on the confocal imaging element, and is captured and imaged by the detector after passing through the confocal imaging element. Among them, the detection light needle and the illumination light needle are in a conjugate imaging relationship, and the confocal imaging element is arranged within the position range of the detection light needle. Among them, the confocal imaging element includes but is not limited to elements such as pinhole elements, circulators or optical fiber output ports of optical fiber couplers.

[0074] Furthermore, the illumination light path includes a first lens, an annular aperture and a second lens arranged in sequence along the irradiation direction of the illumination light source; or a first lens, a conical lens, a third lens and a fourth lens arranged in sequence along the irradiation direction of the illumination light source; or a first lens, a phase template and a fifth lens arranged in sequence along the irradiation direction of the illumination light source.

[0075] When the illumination light path is a first lens, annular aperture and a second lens sequentially arranged along the illumination direction of the illumination light source; or a first lens, a phase template and a fifth lens sequentially arranged along the illumination direction of the illumination light source, the detection light path is a reverse light path of the illumination light path.

[0076] The confocal imaging element is a pinhole element, a circulator or an optical fiber output port of a fiber coupler.

[0077] And, when the illumination light path is a first lens, an annular aperture, and a second lens arranged in sequence along the illumination direction of the illumination light source,

[0078] The detection light path includes a second lens, a beam splitter and an aconic lens which are sequentially arranged in the propagation direction of the detection light;

[0079] Or the detection light path includes a second lens, a beam splitter, a phase template and a sixth lens which are sequentially arranged in the propagation direction of the detection light;

[0080] When the illumination light path is a first lens, an aconic lens, a third lens and a fourth lens arranged in sequence along the illumination direction of the illumination light source,

[0081] The detection light path includes a fourth lens, a beam splitter and an aconic lens which are sequentially arranged in the propagation direction of the detection light;

[0082] Or the detection light path includes a fourth lens, a beam splitter, an annular aperture and a seventh lens which are sequentially arranged in the propagation direction of the detection light;

[0083] Or the detection light path includes a fourth lens, a beam splitter, a phase template and an eighth lens which are sequentially arranged in the propagation direction of the detection light;

[0084] When the illumination light path is a first lens, a phase template and a fifth lens arranged in sequence along the illumination direction of the illumination light source,

[0085] The detection light path includes a fifth lens, a beam splitter and an aconic lens which are sequentially arranged in the propagation direction of the detection light;

[0086] Or the detection light path includes a fifth lens, a beam splitter, an annular aperture and a ninth lens which are sequentially arranged in the propagation direction of the detection light;

[0087] The beam splitter reflects the detection light to change the propagation direction of the detection light; the cone lens in the detection light path makes the detection light form a Bessel beam; the phase template and the sixth lens in the detection light path make the detection light form an Airy beam; the annular aperture and the seventh lens in the detection light path make the detection light form a Bessel beam; the phase template and the eighth lens in the detection light path make the detection light form an Airy beam. The details are described in the following embodiments.

[0088] Embodiment 1

[0089] like Figure 3 As shown, this embodiment discloses a super-depth imaging method. In the illumination light path, a point light source emits a light beam for illumination, which is reflected by the first beam splitter 2 to the first lens 3 for collimation, and most of the light is blocked by the annular aperture 4. The remaining light passes through the second lens 5 to generate an illuminating Bessel beam 22 in the conical area for the first time, and then reaches the detection surface of the object to be detected 6. Figure 4 As shown, in the detection light path, the detection light generated after the detection surface of the object to be detected 6 is irradiated by the illumination light needle returns to the second lens 5 and partially passes through the annular aperture 4, and then enters the first lens 3 to generate a second detection Bessel light beam 8. After being transmitted through the first beam splitter 2, the detection light is output to the detector through the pinhole 91 of the pinhole element 9 to be received, and an image of the point of the object to be detected is obtained. Furthermore, the detector scans the detection surface of the object to be detected by point scanning, and obtains the ultra-depth-of-field imaging of each point on the detection surface of the object to be detected, thereby obtaining a two-dimensional image of the detection surface of the object to be detected corresponding to the depth of field range.

[0090] According to the above embodiments, the illumination light source forms a light needle through the illumination light path to illuminate the object to be detected, and the detection light forms a light needle through the detection light path to be captured by the confocal imaging element for imaging, that is, the PSF of the illumination light beam and the detection light beam can be modulated respectively so that they both form the function form of the light needle. At this time, the PSF of the final optical system can be expressed as the square of the function form of the light needle. Compared with direct focus imaging, or the imaging method of forming a light needle only in the detection light path, the optical path system in which the illumination light source and the detection light both form light needles in the present scheme can make the beam energy more concentrated. It can be seen from its expression that: PSF system = PSF illumination × PSF detection.

[0091] Furthermore, the detection light needle formed by the optical system of the present solution is normalized after passing through a confocal imaging element such as a pinhole. At this time, the sidelobe energy of the light beam is significantly suppressed, that is, the energy of the light beam is more concentrated, and the modulus function of the Fourier transform of the PSF, namely the MTF, when the PSF is more concentrated, the MTF is more dispersed, and the corresponding high-frequency energy is also higher, thereby having better contrast. Therefore, the optical system of the present solution can achieve an imaging effect with super depth of field while improving the MTF performance of the system. Compared with the wide-field imaging system of the prior art that directly uses the PSF in the form of the Bessel function, the contrast is not high, and the energy of the PSF is dispersed, resulting in a lower main lobe energy. By using a confocal system, the present invention makes the sidelobe energy lower by normalization after multiplying the illumination PSF and the detection PSF, thereby increasing the proportion of the main lobe energy, thereby improving the high-frequency contrast of the system MTF.

[0092] Among them, the illumination light source generator 11 that generates the illumination light source 1 includes but is not limited to an LED lamp, or a halogen lamp, or a xenon lamp, or a laser. The detection light includes but is not limited to scattered light from the illumination light source, or fluorescence generated by the object to be detected after being illuminated by the illumination light source, or Raman light, Stokes light, high-order harmonic light, etc. In the case where the detection light is not the scattered light of the illumination light source, a galvanometer, a filter or a motion stage element can also be set in the optical path. And, the lens includes but is not limited to a plano-convex lens, a biconvex lens, a diffraction element or a metamaterial lens; the surface of the object to be detected can be a plane or a curved surface.

[0093] Among them, the longest non-diffraction distance Z of the Bessel beam generated by the annular aperture 4 and the second lens 5 is max for:

[0094]

[0095] Wherein, d is the diameter of the annular aperture 4, and R and f are respectively the radius and focal length of the second lens 5 immediately adjacent to the rear side of the annular aperture 4.

[0096] For the annular aperture 4, if the slit width of the annular aperture is smaller, the diffraction angle of the light beam after filtering is larger, and the obtained Bessel light beam is longer, thereby causing the sidelobe energy of the light beam to become larger, and thus the corresponding energy will be more dispersed. If the slit width is larger, the diffraction angle of the light beam after filtering is smaller, and the light needle is also shorter, so the corresponding energy will be more concentrated. More extreme, when the slit width is very large, the blocked part of the center of the ring will approach zero, and at this time the light spot will also approach a Gaussian light spot. Therefore, when the depth of field increases, the energy of the PSF will be more dispersed, the contrast of the image will be lower, and it will be difficult to obtain a good imaging effect. The PSF of a traditional confocal imaging system is close to the distribution of a Gaussian or Gaussian-like light beam, which makes the imaging depth of field limited.

[0097] Embodiment 2

[0098] like Figure 5 As shown, this embodiment discloses a super-depth-of-field imaging method, which is improved on the above-mentioned embodiment, or improves the efficiency of Bessel light beam generation by using a conical lens, or distinguishes the illumination light path from the detection light path by using a beam splitter, which is more flexible.

[0099] like Figure 5 As shown, the illumination light source generator 11 emits an illumination light source, which is collimated by the first lens 3, and generates an intermediate illuminating Bessel light beam 13 in the conical area after entering the first conical lens 12, and forms an illuminating Bessel light beam after being relayed by the third lens 14, the second beam splitter 15, and the fourth lens 16 to reach the detection surface of the object to be detected 6; the light reflected by the detection surface of the object to be detected 6 returns to the fourth lens 16 and is reflected by the second beam splitter 15, and then enters the second conical lens 17 to generate a Bessel light beam and a detection Bessel light beam again, and finally outputs the detection intensity to the detector 10 for reception after passing through the pinhole.

[0100] The device for generating the Bessel beam in this embodiment is an axicon. For a device using an annular aperture and a lens, such as Figure 3 , Figure 4 As shown in FIG. 1 , since the annular aperture 4 blocks most of the light beam, only a small part of the light beam passes through to form a Bessel beam, so the generation efficiency is low. The use of an aconic lens can avoid this problem, such as Figure 5 As shown, the wavefront phase of the light beam is modulated by the first lens 3, and the first conical lens 12 deflects the light beam to form a conical wave, generating an intermediate irradiated Bessel light beam 13 in the diamond area, and the maximum non-diffraction distance of the Bessel light beam corresponds to the long axis of the diamond area in the figure.

[0101] The optical path propagation in this embodiment is a dual optical path propagation. Figure 3 , Figure 4 As shown in the figure, the single optical path propagation path allows the illumination beam to be output into the optical path system, pass through a series of optical elements, and finally output the detection beam to the detector via the same optical path. Figure 5 As shown, in the dual-path transmission of this embodiment, the imaging light path no longer returns along the original light path, but changes the propagation direction of the light beam with the help of a beam splitter, and is finally received by the detector through a conical lens and a pinhole element. This method can adjust the light path elements more flexibly, but it will also increase the optical propagation distance to a certain extent. In the dual-path transmission optical path system, the illumination light path can pass through different optical elements such as an annular aperture and lens, or a conical lens, or a phase template and lens, so that the illumination light source of the illumination light path forms an illuminating light needle; the detection light path can also pass through an annular aperture and lens, or a conical lens, or a phase template and lens, so that the detection light forms a detection light needle.

[0102] Embodiment 3

[0103] like Figure 7As shown, this embodiment discloses a super-depth imaging method, which is improved with respect to the above embodiment. The illumination light needle in this embodiment is an Airy beam. After the illumination light source passes through the first lens 3, it passes through the phase template 20 and the fifth lens 21 to generate an illumination Airy beam 23. The detection light passes through the same optical path and is reversed to the first lens 3 to form a detection Airy beam 19, which is captured by the detector 10 through the circulator 18. The phase template 20 that generates the PSF of the light needle structure such as the Airy beam includes but is not limited to a cubic phase template, or a numerical phase template, or a high-order phase template, or a polynomial phase template, or an exponential phase template, or a free-form phase template, or a sinusoidal phase template.

[0104] In this embodiment, not only an Airy beam or other light needle structure illumination PSF is generated at the sample to be tested, but also an Airy beam or other light needle structure detection PSF is generated at the detection point.

[0105] The Bessel beam or Airy beam is generated in the illumination optical path by, but not limited to, the above-mentioned method. Similarly, the Bessel beam or Airy beam is generated in the detection optical path by, but not limited to, the above-mentioned method.

[0106] Embodiment 4

[0107] like Figure 6 , Figure 7 As shown, this embodiment discloses a super-depth-of-field imaging method, which is an improvement on the above-mentioned embodiment. In this embodiment, the illumination light source and the detection light are integrated and output, and the confocal imaging elements used include but are not limited to the circulator 18, or the fiber output port of the fiber coupler.

[0108] The confocal imaging element in this embodiment includes a fiber output port of a fiber laser, and its gain medium includes but is not limited to a crystal fiber laser, or a nonlinear optical fiber laser, or a rare-earth doped fiber laser, or a plastic fiber laser.

[0109] The optical fiber in this embodiment includes but is not limited to a single-mode optical fiber or a multi-mode optical fiber, which can realize the transmission of an illumination light beam and a detection light beam at the same time.

[0110] Embodiment 5

[0111] This embodiment discloses a method for ultra-depth imaging. Conventional confocal imaging systems are generally point scanning methods, which have the problem of slow imaging speed. This application uses a spectral encoding method, by inserting diffraction gratings or dispersion prisms and other light splitting elements in both the illumination light path and the detection light path, so that illumination lights of different wavelengths can illuminate different sample positions at the same time, and multi-pixel detectors such as linear array or area array cameras can be used to simultaneously receive detection lights of different wavelengths, so as to overcome the problem of slow imaging speed of the point scanning method.

[0112] like Figure 8 , Fig. 9 As shown, the above embodiment is improved by adding a beam splitter element in the imaging light path, aiming to increase the imaging speed of the optical system to reach the speed level of bright field imaging.

[0113] The light source in this embodiment includes, but is not limited to, a broadband laser light source, or a wide-spectrum light such as an LED white light source.

[0114] In this embodiment, the illumination light source 1 is dispersed after passing through the first grating 24 behind the annular aperture 4, and lights of different wavelengths form illumination light needles, such as λ1 illumination light needle and λ2 illumination light needle. The detection light after reflection is reversely formed after passing through the pinhole element 9, such as Figure 8 As shown, the light passes through the tenth lens 27, the second grating 28 and the eleventh lens 29 to form detection light needles such as λ1 detection light needle and λ2 detection light needle to the linear array camera 32 for imaging. Among them, the spectroscopic element includes but is not limited to a grating or a dispersion prism. After the light passes through the spectroscopic element, dispersion occurs. Lights of different wavelengths will be dispersed at different angles, thereby achieving wavelength separation, obtaining light needles orderly distributed with wavelengths, and combining spectral coding to obtain images of the irradiation points of light needles of different wavelengths on the surface of the sample to be detected.

[0115] The detection in this embodiment is different from the point detection in the above-mentioned embodiment. Instead, point scanning is changed to line scanning or surface scanning. Each exposure can obtain multiple intensity values ​​corresponding to light needles of different wavelengths, which is beneficial to improving the imaging speed of the optical system.

[0116] The confocal imaging optical element before the detector receiving the detection light in this embodiment includes but is not limited to an optical fiber, a single pinhole, or a pinhole array, or a slit. In the case of using a single pinhole, a linear array camera can be used; in the case of using a pinhole array or a slit, a planar array camera can be used.

[0117] Embodiment 6

[0118] Compared with two-dimensional imaging, three-dimensional imaging analysis of samples can obtain the morphology and structure information of samples more intuitively, which is conducive to more in-depth research on the samples.

[0119] like Fig.10 As shown, this embodiment discloses a three-dimensional super-depth-of-field imaging method, which is improved upon the above-mentioned embodiment. A wide-spectrum light such as a white light source with oblique incidence is used in the illumination light path 1. According to the principle of triangulation, the uneven surface of the object to be detected 6 is used to obtain three-dimensional depth information, thereby realizing three-dimensional super-depth-of-field imaging.

[0120] In this embodiment, after the oblique incident light source irradiates the sample, the reflected light is received by the linear array camera after passing through the imaging system 100. Since there is a certain angle between the light source and the detector, the object points with different heights on the surface of the object to be measured will be imaged at different positions on the camera. According to the trigonometric formula, the height distance of the sample to be measured can be deduced by calculation. The incident white light source is split into incident light needles of different wavelengths as in the fifth embodiment above, and is received at the linear array camera 32 as light needles of different wavelengths. As mentioned above, the imaging at a certain point is actually the line imaging covered by the light needles of different wavelengths at the point on the surface of the sample to be measured. When the scanning is performed in the vertical direction of the imaging line, the surface imaging of the scanned surface of the sample to be measured can be obtained, and according to the different positions of the imaging of different wavelengths on the camera on the imaging of the surface, the three-dimensional data of the sample to be measured can be obtained by calculation according to the trigonometric formula. In this way, by combining the existing line scanning, stripe structured light imaging or dot matrix structured light imaging technology, the three-dimensional imaging data of the surface of the sample to be detected can be obtained. Among them, the ultra-depth-of-field imaging system uses spectral encoding to form a high-speed confocal ultra-depth-of-field imaging system with high image contrast and high imaging speed, forming line scanning, stripe structured light imaging, and dot matrix structured light illumination. The light source uses a wide-spectrum light source to irradiate the surface of the sample to be detected at a certain incident angle.

[0121] It can be understood that the method of obtaining depth information by using triangulation in this embodiment is a prior art and will not be described in detail here.

[0122] Embodiment 7

[0123] By combining the above-mentioned high image contrast and high imaging speed confocal ultra-depth imaging method with binocular or multi-eye stereo imaging technology, or multi-angle stereo imaging technology, it is also possible to perform three-dimensional imaging analysis on the sample, and obtain a three-dimensional image with a greater depth of field than the traditional imaging method.

[0124] like Fig.11 As shown, this embodiment discloses an application method of a super depth of field imaging system, which uses an imaging system to detect the positions of the sample to be tested at different angles respectively, or uses two identical imaging systems 100 to simultaneously and synchronously detect the sample to be tested at different set positions or angles. According to the principle of binocular vision, the pixel difference between the two imaging cameras is used to obtain three-dimensional depth information, thereby realizing three-dimensional super depth of field imaging.

[0125] The method for extracting three-dimensional depth information in this embodiment includes but is not limited to binocular vision technology, multi-eye vision technology, or compound eye technology.

[0126] In this embodiment, binocular vision technology uses two cameras to collect images simultaneously and synchronously, and uses the pixel difference between the left and right cameras to image corresponding points of the sample to be tested to obtain depth information, and then obtain three-dimensional information, and realize three-dimensional reconstruction of the object according to relevant formulas.

[0127] It can be understood that the method of obtaining depth information using binocular vision technology in this embodiment is a prior art and will not be described in detail here.

[0128] The embodiments described above are part of the embodiments of the present application, but not all of them. Based on the embodiments in the embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the embodiments of the present application.

[0129] In the description of the embodiments of the present application, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or are the positions or positional relationships in which the product of the application is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the electric vehicle or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0130] In the description of the embodiments of the present application, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0131] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present application, which are used to illustrate the technical solutions of the present application, rather than to limit them. The protection scope of the present application is not limited thereto. Although the present application is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed in the present application, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A super depth of field imaging method, characterized in that: include: The illumination light source is formed into an illumination light needle through the illumination light path and illuminated onto the object to be detected; The object to be detected generates detection light after being irradiated by the irradiation light needle; The detection light forms a detection light needle through the detection light path; capturing the detection light at the detection light needle by a confocal imaging element; The captured detection light is received by a detector to obtain an image of the illuminated point of the object to be detected.

2. The super depth of field imaging method according to claim 1, characterized in that: The irradiation light needle is a Bessel beam or an Airy beam, and the detection light needle is a Bessel beam or an Airy beam; the step of forming an irradiation light needle from an illumination light source through an illumination light path and irradiating the irradiation light needle onto the object to be detected comprises: After the illumination light source is collimated into parallel light by a lens; The parallel light is formed into the illumination light needle by sequentially arranged annular aperture and lens, or sequentially arranged aconical lens and two lenses, or sequentially arranged phase template and lens; and the detection light is formed into the detection light needle through the detection light path, including: The detection light first passes through a lens, and then passes through an annular aperture and a lens, or a conical lens, or a phase template and a lens, which are arranged in sequence, to form the detection light needle.

3. The super depth of field imaging method according to claim 2, characterized in that: The detection light path is a reverse light path of the illumination light path, or the detection light path and the illumination light path are arranged separately.

4. The super depth of field imaging method according to claim 3, characterized in that: When the detection light path is the reverse light path of the illumination light path, before the illumination light source is collimated into parallel light by the lens, the illumination light source from the side of the illumination light path is reflected by the beam splitter so that its illumination direction is aligned with the object to be detected; when the detection light path and the illumination light path are set separately, after the detection light first passes through the lens, the detection light is reflected by the beam splitter to change its propagation direction.

5. The super depth of field imaging method according to any one of claims 1 to 4, characterized in that: The illumination light source and the detection light are both broad-spectrum light, and spectroscopic elements are respectively arranged in the illumination light path and the detection light path to disperse the illumination light source and the detection light to obtain light needles orderly distributed by wavelength; The confocal imaging element is an optical fiber, a single pinhole element, an array pinhole element or a slit.

6. A super depth of field imaging system, characterized in that: include: An illumination light path, wherein the illumination light path forms an illumination light needle from an illumination light source and irradiates the object to be detected; A detection light path, wherein the detection light path converts the detection light generated by the object to be detected after being irradiated by the irradiation light needle into a detection light needle; a confocal imaging element for capturing the detection light at the location where the detection light needle is formed; The detector is used to receive the captured detection light to obtain an image of the irradiated point of the object to be detected.

7. The ultra-depth-of-field imaging system according to claim 6, characterized in that: The illumination light path comprises a first lens, an annular aperture, and a second lens arranged in sequence along the illumination direction of the illumination light source; or a first lens, an aconic lens, a third lens, and a fourth lens arranged in sequence along the illumination direction of the illumination light source; or a first lens, a phase template, and a fifth lens arranged in sequence along the illumination direction of the illumination light source; When the illumination light path is a first lens, an annular aperture, and a second lens sequentially arranged along the illumination direction of the illumination light source; or a first lens, a phase template, and a fifth lens sequentially arranged along the illumination direction of the illumination light source, the detection light path is a reverse light path of the illumination light path; When the illumination light path is a first lens, an annular aperture and a second lens arranged in sequence along the illumination direction of the illumination light source, The detection light path includes the second lens, the beam splitter and the aconic lens which are sequentially arranged in the propagation direction of the detection light; Or the detection light path includes the second lens, the beam splitter, the phase template and the sixth lens which are sequentially arranged in the propagation direction of the detection light; When the illumination light path is a first lens, an aconic lens, a third lens and a fourth lens arranged in sequence along the illumination direction of the illumination light source, The detection light path includes the fourth lens, the beam splitter and the cone lens which are sequentially arranged in the propagation direction of the detection light; Or the detection light path includes the fourth lens, the beam splitter, the annular aperture and the seventh lens which are sequentially arranged in the propagation direction of the detection light; Or the detection light path includes the fourth lens, the beam splitter, the phase template and the eighth lens which are sequentially arranged in the propagation direction of the detection light; When the illumination light path is a first lens, a phase template and a fifth lens arranged in sequence along the illumination direction of the illumination light source, The detection light path includes the fifth lens, the beam splitter and the cone lens which are sequentially arranged in the propagation direction of the detection light; Or the detection light path includes the fifth lens, the beam splitter, the annular aperture and the ninth lens which are sequentially arranged in the propagation direction of the detection light; Among them, the beam splitter reflects the detection light to change the propagation direction of the detection light; the conical lens in the detection light path causes the detection light to form a Bessel beam; the phase template and the sixth lens in the detection light path cause the detection light to form an Airy beam; the annular aperture and the seventh lens in the detection light path cause the detection light to form a Bessel beam; the phase template and the eighth lens in the detection light path cause the detection light to form an Airy beam.

8. The ultra-depth-of-field imaging system according to claim 6 or 7, characterized in that: The illumination light source and the detection light are both broad-spectrum light. For the illumination light path, a spectroscopic element is arranged behind the annular aperture, or a spectroscopic element is arranged behind the conical lens, or a spectroscopic element is arranged behind the phase template; and on the path after the detection light passes through the confocal imaging element, a tenth lens, a spectroscopic element, an eleventh lens and a detector are arranged in sequence.

9. A three-dimensional imaging method of a super depth of field imaging system, characterized in that: The super-depth-of-field imaging system as described in claim 8 is used to perform line scanning, stripe structured light imaging or dot matrix structured light imaging on the surface of the sample to be detected to obtain three-dimensional imaging data of the surface of the sample to be detected, wherein the illumination light source uses a wide-spectrum light source to irradiate the surface of the sample to be detected at a certain incident angle.

10. An application method of a super depth of field imaging system, characterized in that: The super-depth imaging system as described in any one of claims 6 to 8 is used to perform three-dimensional imaging of the sample to be detected at multiple set positions or angles, or two or more super-depth imaging systems as described in any one of claims 11 to 17 are used to simultaneously image the sample to be detected at different set positions or angles, and the three-dimensional super-depth depth imaging data of the sample to be detected is determined according to the pixel difference between the imaging data acquired by the imaging systems at different set positions or angles.

Images