A far-field super-diffraction-limited resolution imaging system under high noise interference

Abstract

The present application discloses a far-field super-diffraction limit resolution imaging system under high noise interference, comprising: a computing unit and a monochromatic coherent light source, an illumination lens group, a first object platform, an imaging lens group, a first sub-wavelength pinhole and a photosensitive detector arranged in sequence according to an optical path; the optical center of the illumination lens group, the optical center of the imaging lens group and the center of the first sub-wavelength pinhole are on the first optical axis; the first object platform is arranged on the first focal plane of the illumination lens group for fixing the target to be measured; the first sub-wavelength pinhole is arranged on the second focal plane of the imaging lens group for generating a diffraction function; the computing unit is used to calculate the image information of the target to be measured using the light signal received by the photosensitive detector. Since the signal-to-noise ratio of light after passing through the first sub-wavelength pinhole is effectively amplified as the propagation distance increases, the present application can achieve far-field super-resolution optical imaging under severe noise interference.

Description

Technical Field

[0001] The present application relates to the technical field of far-field super-resolution optical imaging, and more specifically, to a far-field super-diffraction-limited resolution imaging system that can achieve high noise interference. Background Art

[0002] Super-resolution technology is an imaging technology that goes beyond the traditional "diffraction limit". For general far-field imaging optical systems, such as microscopes and telescopes, due to the existence of the "diffraction limit", the light emitted from a point on the object can only form a "diffraction spot" with a certain width on the image plane after passing through the imaging system; when the distance between two bright spots with a certain width is less than their "effective radius", the imaging patterns of the two points merge with each other and cannot be distinguished. The effective radius of this diffraction spot is generally considered to be no less than 0.5 wavelengths of the light source, so 0.5 wavelengths are generally considered to be the resolution limit of the far-field imaging system.

[0003] Many biological structures, such as the specific structures inside organelles, are smaller than 0.5 wavelengths of the optical band; these structures can be seen clearly by using ultraviolet light or electrons with smaller wavelengths, but these "light sources" are harmful to most biological tissues and will significantly damage the internal structure of organelles. In order to see structures smaller than 0.5 wavelengths, optical super-resolution technology came into being, with the goal of breaking through the diffraction limit on resolution to obtain a smaller resolution limit.

[0004] At present, the mainstream super-resolution technology can be generally divided into two categories according to the imaging distance: near-field super-resolution technology and far-field super-resolution technology. Near-field super-resolution technology includes near-field scanning microscopy (SNOM), single-molecule imaging technology, and super lenses based on "negative refractive index" and "hyperbolic refractive index". The basic principle of these near-field super-resolution technologies is to use the evanescent waves on the surface of an object to detect the details of the object. Therefore, in terms of design, its "lens" or detector needs to be close to the surface of the object, which is not conducive to the detection of objects with complex three-dimensional morphology, and also brings a lot of inconvenience to the actual operation process.

[0005] Unlike near-field super-resolution technology, far-field super-resolution technology does not require the use of evanescent waves. Depending on whether fluorescent dyes are used to mark objects, it can be divided into two categories: fluorescence super-resolution technology and non-fluorescence super-resolution technology. Fluorescence super-resolution technology mainly includes STED (Stimulated Emission Depletion Microscopy), STORM (Stochastic Optical Reconstruction Microscopy), PALM (Photo Activated Localization Microscopy), FPALM (Fluorescence Photo Activated Localization Microscopy) and SSIM (Saturated Structured Illumination Microscopy). These technologies use the special fluorescence effect of fluorescent dyes to obtain resolution beyond the diffraction limit, but the disadvantage is that these dyes are generally difficult to act on non-biological structures, and are often harmful to biological structures, which is not conducive to in vivo experiments.

[0006] Far-field non-fluorescence super-resolution technology can effectively overcome the difficulties of the above-mentioned technologies and is considered to be the most convenient and practical super-resolution technology. It can be divided into two categories: hardware and software. The hardware category mainly uses special optical paths to converge a light spot with an effective radius of less than 0.5 wavelengths, such as confocal microscopy and super-oscillation microscopy. The software category mainly uses calculations or numerical methods to restore the super-resolution details of blurred images. However, these two types of technologies still face a basic problem, that is, they are very sensitive to the noise of the light source. When a resolution of 0.1 wavelength is required, the required signal-to-noise ratio (SNR) is generally on the order of 10 to the -5th to -6th power, that is, the signal-to-noise ratio is very demanding; this signal-to-noise ratio can generally only be obtained under laboratory conditions, but it is very difficult to achieve in general application scenarios. Summary of the invention

[0007] In view of this, the present application provides a far-field super-diffraction-limited resolution imaging system for achieving high noise interference, so as to achieve far-field super-resolution optical imaging under severe noise interference.

[0008] To achieve the above objectives, the present application provides a far-field super-diffraction-limited resolution imaging system for high noise interference, comprising:

[0009] A computing unit and a monochromatic coherent light source, an illumination lens group, a first object-carrying platform, an imaging lens group, a first sub-wavelength pinhole and a photosensitive detector arranged in sequence along an optical path;

[0010] The optical center of the illumination lens group, the optical center of the imaging lens group, and the center of the first sub-wavelength aperture are on the first optical axis;

[0011] The first loading platform is arranged on the first focal plane of the illumination lens group and is used to fix the target to be measured;

[0012] The first sub-wavelength aperture is arranged on the second focal plane of the imaging lens group, and is used to generate a diffraction function;

[0013] The calculation unit is used to calculate the image information of the target to be measured using the light signal received by the photosensitive detector.

[0014] Preferably, the first loading platform can drive the target to be measured to move within the first focal plane.

[0015] Preferably, it also includes:

[0016] The second object-carrying platform is used to fix the first sub-wavelength pinhole and can drive the first sub-wavelength pinhole to move in the second focal plane.

[0017] Preferably, the monochromatic coherent light source is a monochromatic laser source.

[0018] Preferably, the process of the calculation unit calculating the image information of the target to be measured by using the light signal received by the photosensitive detector includes:

[0019] By moving the first object-carrying platform or the first sub-wavelength pinhole, the relative position of the first object-carrying platform and the first sub-wavelength pinhole is changed to obtain multiple sets of position relationships;

[0020] Using the photosensitive detector to receive the light signal in each group of positional relationships to obtain a signal sequence;

[0021] Based on the signal sequence and the object-image relationship, a numerical method is used to restore the image of the target to be measured.

[0022] Preferably, the expression of the signal sequence is:

[0023]

[0024] Among them, x pj is the position relationship of the jth group, a is the aperture of the first sub-wavelength aperture, s 2j (x i ) is the complex amplitude signal formed by the monochromatic correlated light source in the jth group position relationship, s 2j (x i ) is:

[0025]

[0026] The process of restoring the image of the target object to be measured by using a numerical method based on the signal sequence and the object-image relationship includes:

[0027] Substituting the values ​​in the signal sequence into the following equation, we can calculate F -1 [·];

[0028] E o (x o )≈F -1 [s j ]

[0029] Among them, F -1 [·] is the inverse mapping of the object-image relation F[·], and the expression of the object-image relation F[·] is:

[0030] E 1 (x p )=E[E o (x o )]

[0031] Based on F -1 [·] Restoring the image of the target object to be measured.

[0032] Preferably, it further comprises: a beam splitter, a second sub-wavelength pinhole, a first plane mirror and a second plane mirror;

[0033] The light beam of the monochromatic coherent light source passes through the beam splitter to form a first light beam and a second light beam with different directions;

[0034] An optical axis formed by the first light beam after being reflected by the first plane mirror is consistent with the first optical axis;

[0035] The second light beam is reflected by the second plane mirror and then passes through the second sub-wavelength aperture to be emitted to the photosensitive detector;

[0036] The second sub-wavelength small hole has the same aperture as the first sub-wavelength small hole;

[0037] The first light beam and the second light beam form an interference image on the photosensitive detector.

[0038] Preferably, it also includes:

[0039] The phase regulator is arranged between the beam splitter and the second plane mirror, and is used for modulating the phase of the second light beam.

[0040] Preferably, the process of the calculation unit calculating the image information of the target to be measured by using the light signal received by the photosensitive detector includes:

[0041] By moving the first object-carrying platform or the first sub-wavelength pinhole, the relative position of the first object-carrying platform and the first sub-wavelength pinhole is changed to obtain multiple sets of position relationships;

[0042] Using the photosensitive detector to receive the optical signals of the first light beam and the second light beam in each group of positional relationships, to obtain an interference signal sequence;

[0043] estimating an ideal complex amplitude using the interference signal sequence to obtain a second signal sequence;

[0044] Based on the second signal sequence and the object-image relationship, a numerical method is used to restore the image of the target to be measured.

[0045] Preferably, the interference signal sequence is expressed as:

[0046] I j (x i )=|E r (x i )+s 2j (x i )| 2

[0047] Among them, x i is a position point on the photosensitive detector, E r (x i ) is the optical signal of the second light beam, s 2j (x i ) is the complex amplitude signal formed by the first light beam in the jth group position relationship, s 2j (x i ) is:

[0048]

[0049] The expression of the second signal sequence is:

[0050]

[0051] Among them, x pj is the position relationship of the jth group, a is the aperture of the first sub-wavelength aperture;

[0052] The process of restoring the image of the target object by numerical method based on the second signal sequence and the object-image relationship includes:

[0053] Substituting the values ​​in the second signal sequence into the following equation, we can calculate F -1 [·];

[0054] E o (xo )≈F -1 [s j ]

[0055] Among them, F -1 [·] is the inverse mapping of the object-image relation F[·], and the expression of the object-image relation F[·] is:

[0056] E 1 (x p )=F[E o (x o )]

[0057] Based on F -1 [·] Restoring the image of the target object to be measured.

[0058] It can be known from the above technical scheme that the present application includes a calculation unit and a monochromatic coherent light source, an illumination lens group, a first carrier platform, an imaging lens group, a first sub-wavelength pinhole and a photosensitive detector arranged in sequence according to the optical path. Among them, the optical center of the illumination lens group, the optical center of the imaging lens group and the center of the first sub-wavelength pinhole are on the first optical axis; the first carrier platform is arranged on the first focal plane of the illumination lens group for fixing the target to be measured; the first sub-wavelength pinhole is arranged on the second focal plane of the imaging lens group for generating a diffraction function; the calculation unit is used to calculate the image information of the target to be measured using the light signal received by the photosensitive detector. Since the signal-to-noise ratio of light after passing through the first sub-wavelength pinhole is effectively amplified as the propagation distance increases, the present application can achieve far-field super-resolution imaging with a higher signal-to-noise ratio, and achieve far-field super-resolution optical imaging under severe noise interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0060] Figure 1 A schematic diagram of the optical path design disclosed in the embodiment of the present application;

[0061] Figure 2 A schematic diagram of a light path design with an illumination lens group disclosed in an embodiment of the present application;

[0062] Figure 3 A schematic diagram of the geometric relationship disclosed in the embodiment of this application;

[0063] Figure 4A schematic diagram of the signal-to-noise ratio improvement rate disclosed in the embodiment of the present application;

[0064] Figure 5 A schematic diagram of diffraction results at different propagation distances disclosed in an embodiment of the present application;

[0065] Figure 6 Another schematic diagram of diffraction results at different propagation distances disclosed in the embodiments of the present application;

[0066] Figure 7 A schematic diagram of an optical path design with a second loading platform disclosed in an embodiment of the present application;

[0067] Figure 8 A schematic diagram of an optical path design with a beam splitter disclosed in an embodiment of the present application;

[0068] Fig. 9 This is a schematic diagram of an optical path design with a phase adjuster disclosed in an embodiment of the present application. DETAILED DESCRIPTION

[0069] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0070] The following describes a far-field super-diffraction-limited resolution imaging system for high-noise interference provided by an embodiment of the present application. Figure 1 The far-field super-diffraction limit resolution imaging system under high noise interference provided by the embodiment of the present application may include: a computing unit 10 and a monochromatic coherent light source 20, a first object carrier platform 30, an imaging optical path 40, a first sub-wavelength pinhole 50 and a photosensitive detector 60 arranged in sequence according to the optical path.

[0071] The imaging optical path 40 may be an imaging lens group composed of multiple lenses, may be an optical processing device such as a grating, or may not use any optical device, and the light beam may be directly transmitted through the air medium. Figure 2 In order to adjust the light beam emitted by the monochromatic coherent light source 20 , an illumination lens group 70 may be further disposed between the monochromatic coherent light source 20 and the first loading platform 30 .

[0072] Specifically, the optical center of the illumination lens group 70, the optical center of the imaging lens group 40, and the center of the first sub-wavelength pinhole 50 are on the first optical axis. It should be noted that the center of the first sub-wavelength pinhole 50 falls on the first optical axis for the convenience of engineering calculations. In fact, the center of the first sub-wavelength pinhole 50 may also fall at other positions.

[0073] The monochromatic coherent light source 20 is a monochromatic laser source. The first loading platform 30 is arranged on the first focal plane of the illumination lens group 70, and is used to fix the object to be measured. It is understandable that if the illumination lens group 70 does not exist, the first loading platform 30 can be arranged at other positions between the monochromatic coherent light source 20 and the imaging lens group 40.

[0074] The first sub-wavelength pinhole 50 is disposed on the second focal plane of the imaging lens group 40 to generate a diffraction function. It is understandable that if the imaging optical path 40 is not composed of a lens group but a grating or other optical device, the first sub-wavelength pinhole 50 can be disposed at other positions between the imaging optical path 40 and the photosensitive detector 60.

[0075] The calculation unit 10 is used to calculate the image information of the target object by using the light signal received by the photosensitive detector 60 .

[0076] The first sub-wavelength aperture 50 mainly functions to improve the signal-to-noise ratio in the system. The function of the first sub-wavelength aperture 50 is specifically deduced below.

[0077] See also Figure 3 , consider the plane where the sub-wavelength aperture is located (axial spatial coordinate z 2 =0, the horizontal space coordinate is x p ) is distributed as follows:

[0078] s 1 (x p )=E 1 (x p )+n 1 (x p ) (1)

[0079] Among them, s 1 (x p ) is the total light field signal on the plane (lateral field in the x direction), E 1 (x p ) is the ideal image of the object on the plane, n 1 (x p ) is the input noise. After the light passes through the sub-wavelength aperture, according to the Rayleigh-Sommerfeld diffraction formula, the vector complex signal formed on the image plane can be expressed as:

[0080]

[0081] in,

[0082]

[0083] i is the imaginary unit, k≡2π / λ is the incident wave number, and are the unit vectors parallel and perpendicular to the plane where the subwavelength aperture is located.

[0084] Consider another function with spatial coordinates x p Unrelated functions:

[0085]

[0086] Using subscript v to represent subscript x or z, it is not difficult to find that formula (3) can be rewritten as:

[0087]

[0088] in is the expected value of the spatial integration of the signal at the sub-wavelength aperture opening, taking into account the noise have:

[0089]

[0090] ∈ v is the error coefficient, we have:

[0091]

[0092] With G 0v are all noise-independent quantities. Consider when the aperture a of the sub-wavelength aperture is very small, using is used as the light field of the ideal signal at the center of the sub-wavelength aperture opening. Then the original signal s is directly detected on the plane where the sub-wavelength aperture is located. 1 (See formula (1)) when the signal-to-noise ratio is:

[0093]

[0094] After the signal passes through the sub-wavelength aperture, the signal s on the image plane is used 2v Estimate (See formula (5)), then the signal-to-noise ratio is:

[0095]

[0096] The Cauchy inequality can be used to strictly prove (substituting equations (4), (6), and (7) into equation (5) and expanding):

[0097] |∈ v | 2 ≤∈ n ∈ 2v (10)

[0098] in,

[0099]

[0100]

[0101] Combining equations (8) to (10), it can be deduced that the minimum improvement rate of the signal-to-noise ratio after using a sub-wavelength aperture is:

[0102]

[0103] It is not difficult to see that for any position x on the image plane i ,∈ 2v With the propagation distance z 2 / a decreases with the increase and eventually tends to zero, which means that the signal-to-noise ratio is effectively amplified as the propagation distance increases after the light passes through the subwavelength aperture.

[0104] In order to explain the above theoretical results more intuitively, Figure 4 The curve of the signal-to-noise ratio improvement rate of the light signal after passing through the small hole as the propagation distance changes under 10,000 random numerical experiments is given. The original input signal-to-noise ratio SNR 1 ≈0.5, and the dotted line is the theoretical minimum signal-to-noise ratio improvement curve given by formula (13). Figure 5 , Figure 6 Several intuitive diffraction results of different input signals at different propagation distances are given. Formula (13) and Figure 4 , Figure 5 , Figure 6 The results in this paper show that subwavelength pinholes can effectively suppress noise and improve the signal-to-noise ratio of the input signal under coherent illumination, thus enabling us to achieve far-field super-resolution imaging under severe noise interference.

[0105] The present application includes a calculation unit and a monochromatic coherent light source, an illumination lens group, a first object carrier platform, an imaging lens group, a first sub-wavelength pinhole and a photosensitive detector arranged in sequence according to the optical path. Among them, the optical center of the illumination lens group, the optical center of the imaging lens group and the center of the first sub-wavelength pinhole are on the first optical axis; the first object carrier platform is arranged on the first focal plane of the illumination lens group for fixing the target to be measured; the first sub-wavelength pinhole is arranged on the second focal plane of the imaging lens group for generating a diffraction function; the calculation unit is used to calculate the image information of the target to be measured using the light signal received by the photosensitive detector. Since the signal-to-noise ratio of light after passing through the first sub-wavelength pinhole is effectively amplified as the propagation distance increases, the present application can achieve far-field super-resolution imaging with a higher signal-to-noise ratio, and achieve far-field super-resolution optical imaging under severe noise interference. In addition, the system of the present application does not require fluorescent dye reagents during use, and can perform super-resolution imaging of living biological tissues.

[0106] In some embodiments of the present application, in order to facilitate the collection of optical signals of the same target to be measured at different positions, the first loading platform 30 can drive the target to be measured to move within the first focal plane.

[0107] In addition, the above effects can also be obtained by changing the position of the first sub-wavelength aperture 50. Based on this, in some embodiments of the present application, please refer to Figure 7 The far-field super-diffraction-limited resolution imaging system for achieving high noise interference may also include a second loading platform 80, which is used to fix the first sub-wavelength aperture 50 and can drive the first sub-wavelength aperture 50 to move in the second focal plane.

[0108] like Figure 7 In the optical path shown, the object forms a light field function E on its rear surface under the monochromatic coherent light source 20. o (x o ) (usually referred to as the physical function), which forms an optical signal in the plane where the first sub-wavelength aperture 50 is located after passing through any imaging system (including direct diffraction imaging without any device):

[0109] s 1 (x p )=E 1 (x p )+n 1 (x p )

[0110] in,

[0111] E 1 (x p )=F[E o (x o )] (14)

[0112] is the ideal imaging result of the object, where F[·] is the mapping relationship between the object function and the ideal image function (considering the single-shot case, that is, one image corresponds to only one object); for a general imaging system, it can usually be expressed as a convolution form:

[0113] E 1 (x p )=E o (x o )*PSF(x p ,x o ) (15)

[0114] Where PSF(x p ,x 0 ) is the point spread function of the imaging system.

[0115] The first sub-wavelength aperture 50 is used to detect the optical signal at different positions. Assume that the center of the aperture is at the jth position x pj The complex amplitude signal formed on the signal receiver is:

[0116]

[0117] A reference beam E with the same frequency r (x i ) irradiates the signal receiver so that it is in contact with s 2j (x i ) forms an interference signal:

[0118] I j (x i )=|E r (x i )+s 2j (x i )| 2 (17)

[0119] In particular, when there is no reference beam with the same frequency, E r (x i )=0.

[0120] Use I j (x i ) Estimate the ideal complex amplitude of the ideal signal at the center of the hole:

[0121]

[0122] To form the signal sequence j , and then the object function E is restored through the following image processing process 0 (x 0 ).

[0123] In particular, when it is known that the object does not contain relative phase information, it is not necessary to use a reference beam to recover the object phase information.

[0124] The image processing process includes:

[0125] When the receiver receives the signal sequence s j , using the object-image relationship of formula (14), we can deduce:

[0126] E o (x o )≈F -1 [s j ] (19)

[0127] Among them, F -1 [·] is the inverse mapping of F[·]. Using numerical methods, we can obtain F -1 [·], thereby restoring the image.

[0128] Based on this, in some embodiments of the present application, the process of the computing unit 10 calculating the image information of the target to be detected by using the light signal received by the photosensitive detector 60 may include:

[0129] S1, by moving the first loading platform 30, or moving the first sub-wavelength aperture 50, the relative position of the first loading platform 30 and the first sub-wavelength aperture 50 is changed to obtain a plurality of sets of positional relationships.

[0130] S2, using a photosensitive detector to receive the light signal under each group of positional relationships to obtain a signal sequence.

[0131] S3, based on the signal sequence and the object-image relationship, the image of the target object to be measured is restored using a numerical method.

[0132] In some embodiments of the present application, the expression of the signal sequence is:

[0133]

[0134] Among them, x pj is the position relationship of the jth group, a is the aperture of the first sub-wavelength aperture 50, s 2j (x i ) is the complex amplitude signal formed by the monochromatic correlated light source 20 in the jth group position relationship, s 2j (x i ) is:

[0135]

[0136] The process of restoring the image of the target object to be measured by using a numerical method based on the signal sequence and the object-image relationship in S3 may include:

[0137] S31, substitute the value in the signal sequence into the following equation to calculate F -1 [·];

[0138] E o (x o )≈F -1 [s j ]

[0139] Among them, F -1 [·] is the inverse mapping of the object-image relation F[·], and the expression of the object-image relation F[·] is:

[0140] E 1 (x p )=F[E o (x o )]

[0141] S32, based on F -1 [·] Restore the image of the target object to be measured.

[0142] The above embodiments describe a far-field super-diffraction-limited resolution imaging system under high noise interference without involving a reference beam. The reason is that, generally, for a large-aperture far-field imaging system, the phase distribution of its point spread function can be ignored. Therefore, when the object itself does not contain relative phase information, the intensity function can be directly used to restore the object.

[0143] On the other hand, when the phase distribution of the point spread function is considered, a reference beam may be added. Based on this, in some embodiments of the present application, please refer to Figure 8 The far-field super-diffraction-limited resolution imaging system for achieving high noise interference may also include: a beam splitter 90, a second sub-wavelength aperture 100, a first plane mirror 110 and a second plane mirror 120.

[0144] The light beam of the monochromatic coherent light source 20 passes through the beam splitter 90 to form a first light beam and a second light beam with different directions. The optical axis formed by the first light beam after being reflected by the first plane mirror 110 is consistent with the first optical axis. The second light beam is reflected by the second plane mirror 120 and then passes through the second sub-wavelength aperture 100 to the photosensitive detector 60. It can be understood that the aperture of the second sub-wavelength aperture 120 is consistent with that of the first sub-wavelength aperture 110, and the first light beam and the second light beam form an interference image on the photosensitive detector 60.

[0145] In some embodiments of this application, please refer to Fig. 9 , the far-field super-diffraction-limited resolution imaging system for realizing high noise interference may also include:

[0146] The phase regulator 130 disposed between the beam splitter 90 and the second plane mirror 120 is used to modulate the phase of the second light beam.

[0147] Based on this, in some embodiments of the present application, the process of the computing unit 10 calculating the image information of the target to be detected by using the light signal received by the photosensitive detector 60 may include:

[0148] S1, by moving the first loading platform 30, or moving the first sub-wavelength aperture 50, the relative position of the first loading platform 30 and the first sub-wavelength aperture 50 is changed to obtain a plurality of sets of positional relationships.

[0149] S2, using the photosensitive detector 60 to receive the optical signals of the first light beam and the second light beam in each group of positional relationships, to obtain an interference signal sequence.

[0150] S3, using the interference signal sequence to estimate the ideal complex amplitude to obtain a second signal sequence.

[0151] S4, based on the second signal sequence and the object-image relationship, using a numerical method to restore the image of the target object.

[0152] In some embodiments of the present application, the expression of the interference signal sequence is:

[0153] I j (x i )=|E r (x i )+s 2j (x i )| 2

[0154] Among them, x i is a certain position point on the photosensitive detector 60, E r (x i ) is the optical signal of the second beam, s 2j (x i ) is the complex amplitude signal formed by the first beam in the jth group position relationship, s 2j (x i ) is:

[0155]

[0156] The expression of the second signal sequence is:

[0157]

[0158] Among them, x pj is the position relationship of the jth group, a is the aperture of the first sub-wavelength aperture 50;

[0159] The process of restoring the image of the target object to be measured by using a numerical method based on the second signal sequence and the object-image relationship equation in S4 may include:

[0160] S41, substitute the value in the second signal sequence into the following equation to calculate F -1 [·];

[0161] E o (x o )≈F -1 [s j ]

[0162] Among them, F -1 [·] is the inverse mapping of the object-image relation F[·], and the expression of the object-image relation F[·] is:

[0163] E 1 (x p )=F[E o (x o )]

[0164] S42, based on F -1 [·] Restore the image of the target object to be measured.

[0165] In summary:

[0166] The present application includes a calculation unit and a monochromatic coherent light source, an illumination lens group, a first carrier platform, an imaging lens group, a first sub-wavelength pinhole and a photosensitive detector arranged in sequence according to the optical path. Among them, the optical center of the illumination lens group, the optical center of the imaging lens group and the center of the first sub-wavelength pinhole are on the first optical axis; the first carrier platform is arranged on the first focal plane of the illumination lens group for fixing the target to be measured; the first sub-wavelength pinhole is arranged on the second focal plane of the imaging lens group for generating a diffraction function; the calculation unit is used to calculate the image information of the target to be measured using the light signal received by the photosensitive detector. Since the signal-to-noise ratio of light after passing through the first sub-wavelength pinhole is effectively amplified as the propagation distance increases, far-field super-resolution imaging with a higher signal-to-noise ratio can be achieved through the present application. In addition, the system of the present application does not require fluorescent dye reagents during use, and can perform super-resolution imaging of living biological tissues.

[0167] Furthermore, by inserting a scanning subwavelength aperture (aperture width is smaller than the incident wavelength and comparable to the target resolution) on the image plane under coherent illumination, noise can be effectively suppressed and the signal-to-noise ratio of the optical signal can be improved, thereby enabling us to achieve far-field super-resolution under severe noise interference.

[0168] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0169] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The various embodiments can be combined as needed, and the same or similar parts can refer to each other.

[0170] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A far-field super-diffraction-limited resolution imaging system for high noise interference, characterized in that: include: A computing unit and a monochromatic coherent light source, an illumination lens group, a first object-carrying platform, an imaging lens group, a first sub-wavelength pinhole and a photosensitive detector arranged in sequence along an optical path; The optical center of the illumination lens group, the optical center of the imaging lens group, and the center of the first sub-wavelength aperture are on the first optical axis; The first loading platform is arranged on the first focal plane of the illumination lens group and is used to fix the target to be measured; The first sub-wavelength aperture is arranged on the second focal plane of the imaging lens group, and is used to generate a diffraction function; The calculation unit is used to calculate the image information of the target object to be measured by using the light signal received by the photosensitive detector; The process of the calculation unit calculating the image information of the target to be measured by using the light signal received by the photosensitive detector includes: By moving the first object-carrying platform or the first sub-wavelength pinhole, the relative position of the first object-carrying platform and the first sub-wavelength pinhole is changed to obtain multiple sets of position relationships; Using the photosensitive detector to receive the light signal in each group of positional relationships to obtain a signal sequence; Based on the signal sequence and the object-image relationship, a numerical method is used to restore the image of the target to be measured; The expression of the signal sequence is: ； Among them, x pj is the position relationship of the jth group, a is the aperture of the first sub-wavelength aperture, s 2j (x i ) is the complex amplitude signal formed by the monochromatic coherent light source in the jth group position relationship, s 2j (x i ) is: ； The process of restoring the image of the target object to be measured by using a numerical method based on the signal sequence and the object-image relationship includes: Substituting the values ​​in the signal sequence into the following equation, we can calculate F -1 [·]; ； Among them, the parameters It represents the light field function formed by the object on its rear surface under the monochromatic coherent light source, F -1 [·] is the inverse mapping of the object-image relation F[·], and the expression of the object-image relation F[·] is: ； Based on F -1 [·] Restore the image of the target object to be measured, parameters Represents the ideal imaging result of an object.

2. The system according to claim 1, characterized in that The first loading platform can drive the target to be measured to move within the first focal plane.

3. The system according to claim 1, characterized in that Also includes: The second object-carrying platform is used to fix the first sub-wavelength pinhole and can drive the first sub-wavelength pinhole to move in the second focal plane.

4. The system according to claim 1, characterized in that The monochromatic coherent light source is a monochromatic laser source.

5. The system according to any one of claims 1 to 4, characterized in that: Also includes: a beam splitter, a second sub-wavelength aperture, a first plane mirror, and a second plane mirror; The light beam of the monochromatic coherent light source passes through the beam splitter to form a first light beam and a second light beam with different directions; An optical axis formed by the first light beam after being reflected by the first plane mirror is consistent with the first optical axis; The second light beam is reflected by the second plane mirror and then passes through the second sub-wavelength aperture to be emitted to the photosensitive detector; The second sub-wavelength small hole has the same aperture as the first sub-wavelength small hole; The first light beam and the second light beam form an interference image on the photosensitive detector.

6. The system according to claim 5, characterized in that Also includes: The phase regulator is arranged between the beam splitter and the second plane mirror, and is used for modulating the phase of the second light beam.

7. The system according to claim 6, characterized in that The process of the calculation unit calculating the image information of the target to be measured by using the light signal received by the photosensitive detector may also be: By moving the first object-carrying platform or the first sub-wavelength pinhole, the relative position of the first object-carrying platform and the first sub-wavelength pinhole is changed to obtain multiple sets of position relationships; Using the photosensitive detector to receive the optical signals of the first light beam and the second light beam in each group of positional relationships, to obtain an interference signal sequence; estimating an ideal complex amplitude using the interference signal sequence to obtain a second signal sequence; Based on the second signal sequence and the object-image relationship, a numerical method is used to restore the image of the target to be measured.

8. The system according to claim 7, characterized in that The expression of the interference signal sequence is: ； Among them, Estimate the ideal complex amplitude of the ideal signal at the center of the hole, x i is a position point on the photosensitive detector, E r (x i ) is the optical signal of the second light beam, s 2j (x i ) is the complex amplitude signal formed by the first light beam in the jth group position relationship, s 2j (x i ) is: ； The expression of the second signal sequence is: ； Among them, x pj is the position relationship of the jth group, a is the aperture of the first sub-wavelength aperture; The process of restoring the image of the target object by numerical method based on the second signal sequence and the object-image relationship includes: Substituting the values ​​in the second signal sequence into the following equation, we can calculate F -1 [·]; ； Among them, the parameters It represents the light field function formed by the object on its rear surface under the monochromatic coherent light source, F -1 [·] is the inverse mapping of the object-image relation F[·], and the expression of the object-image relation F[·] is: ； Based on F -1 [·] Restore the image of the target object to be measured, parameters Represents the ideal imaging result of an object.

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