Spectral imaging system

Abstract

This invention provides a spectral imaging system that converges received signal light, improves the signal-to-noise ratio using a pinhole or slit, collimates the light using an optical system, disperses it using a dispersive element, and then refocuses it onto the image plane. The spectral distribution of the convergence region ranges from λ1 to λ2. n The lenses are arranged sequentially from short-wavelength to long-wavelength or vice versa along the y-axis, which helps control the spot size and enables spectral imaging. In the second lens group G2, there is at least one negative-power lens between the first and last lenses. The entire lens group before and after this negative-power lens has a positive power, forming a positive-negative-positive structure, which helps correct field curvature and improves the imaging quality of the outer field of view. The third lens group G4 also has a positive-negative-positive structure, with two positive-negative-positive structures placed on either side of the dispersive element, which helps correct off-axis aberration.

Description

Technical Field

[0001] This invention relates to the field of optical imaging, and more particularly to a spectral imaging system. Background Technology

[0002] A spectrometer is an instrument that can decompose and measure complex polychromatic light. After entering the spectrometer, polychromatic light is decomposed into different monochromatic lights by the dispersive elements. The collection and processing of these monochromatic lights yields a spectrum. Therefore, spectrometers are widely used in fields such as optical radiation measurement, environmental pollution detection, elemental analysis, geological analysis, and food safety testing. Commonly used spectrometers can be classified according to the type of dispersive device: dispersive, interferometric, and filter-type spectrometers.

[0003] Prism spectrometers are a type of dispersive spectrometer. They utilize the principle that prisms have different refractive indices for different wavelengths of light to decompose polychromatic light into monochromatic light. Grating spectrometers, on the other hand, utilize the diffraction properties of gratings to decompose polychromatic light into monochromatic light.

[0004] In existing technologies, most spectrometer designs can only achieve a numerical aperture of 0.25, resulting in insufficient light intake and coverage only of the near-infrared or visible light bands. This leads to problems such as large imaging spot size and insufficient testing accuracy. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned problems and provide a spectral imaging system that re-images a mixed-spectrum light source and arranges it on the image plane in a manner with different spectral imaging positions, thereby increasing the aperture value, ensuring the size of the imaging spot, and improving the testing accuracy.

[0006] To achieve the above objectives, the present invention provides a spectral imaging system for acquiring spectral information of a light source. The spectral imaging system comprises, sequentially from the light source to the image plane:

[0007] A first lens group for receiving and converging optical signals, wherein the first lens group is provided with at least one lens with positive optical power;

[0008] A second lens group with collimation function;

[0009] Spectroscopic elements with dispersive capabilities;

[0010] A third lens group used to converge and image the spectra dispersed by the beam-splitting element;

[0011] In the second lens group, there is at least one negative power lens between the first and last lenses, and in the third lens group, there is at least one negative power lens between the first and last lenses.

[0012] In the above technical solution, the total number of lenses in the first lens group, the second lens group, and the third lens group is not less than 17.

[0013] In the above technical solution, a small hole or slit is provided between the first lens group and the second lens group.

[0014] In the above technical solution, the first lens group contains at least six lenses, at least one lens has an Abbe number that satisfies Vd1 < 40, and at least one lens has a refractive index that satisfies nd > 1.7.

[0015] In the above technical solution, the second lens group contains at least 5 lenses, the first lens is a meniscus lens, which is bent toward the slit or small hole, and the last lens has positive optical power.

[0016] In the above technical solution, at least one lens with negative optical power in the second head lens group is disposed between the reflecting element and the last lens.

[0017] In the above technical solution, the second lens group includes at least one lens with an Abbe number Vd2 less than 40, and at least one lens with a refractive index nd greater than 1.7.

[0018] In the above technical solution, the third lens group includes at least six lenses. The incident height difference H1 between the zero field-of-view ray and the principal ray in the first lens of the third lens group and the lowest incident height difference H2 between the zero field-of-view ray and the principal ray in the third lens group satisfy the following relationship: 0.2 < H1 / H2 < 0.5.

[0019] In the above technical solution, the third lens group includes at least one lens with an Abbe number Vd3 of less than 40 and at least one lens with a refractive index nd of greater than 1.7.

[0020] In the above technical solution, the imaging range of the spectral imaging system is 450nm-1150nm.

[0021] In the above technical solution, the first lens group or the second lens group includes at least one reflective element for reversing the optical path, the distance between the reflective element and the small hole or slit is in the range of 5 to 40 mm, and the distance between the reflective element and the dispersive element is greater than 40 mm.

[0022] In the above technical solution, the lens closest to the image plane in the third lens group is a meniscus lens, with the meniscus direction facing the image plane.

[0023] This invention provides a spectral imaging system that converges received signal light, improves the signal-to-noise ratio using a pinhole or slit, collimates the light using an optical system, disperses it using a dispersive element, and then refocuses it onto the image plane. The spectral distribution of the convergence region ranges from λ1 to λ2. nThe lenses are arranged sequentially from short-wavelength to long-wavelength or vice versa along the y-axis, which facilitates control of the spot size and enables spectral imaging. By analyzing the energy and position of the convergent region of the imaging system, and using software algorithms to analyze the spectral information and energy values ​​of each spectral component of the light source, the system achieves both high spectral resolution and a wide spectral range through a reasonable lens configuration. The use of a bend-type design compresses the system's space, making it more compact and suitable for instruments with strict size requirements. In the second lens group G2, at least one negative power lens exists between the first and last lenses. The entire lens group before and after this negative power lens has a positive power, forming a positive-negative-positive structure, which helps correct field curvature and improves the imaging quality of the outer field of view. The third lens group G4 also has a positive-negative-positive structure, with two positive-negative-positive structures placed on either side of the dispersive element, which helps correct off-axis aberration.

[0024] This invention can achieve a numerical aperture of 0.3 or higher, design bands covering visible and near-infrared bands, a maximum field of view of 30mm, and ensure that the imaging spot size of the entire field of view is less than 10um, thereby improving the testing accuracy. Attached Figure Description

[0025] Figure 1 This is a planar schematic diagram of the transition spectral imaging system of Embodiment 1 of the present invention;

[0026] Figure 2 This is the 0-field spectral distribution diagram of the transition spectral imaging system in Embodiment 1 of the present invention;

[0027] Figure 3 This is a full-field lateral aberration map of the 450nm spectrum of the transition spectral imaging system of Embodiment 1 of the present invention.

[0028] Figure 4 This is a full-field lateral aberration map of the 500nm spectrum of the transition spectral imaging system of Embodiment 1 of the present invention.

[0029] Figure 5 This is a full-field lateral aberration map of the 650nm spectrum of the transition spectral imaging system of Embodiment 1 of the present invention.

[0030] Figure 6 This is a planar schematic diagram of the transition spectral imaging system of Embodiment 2 of the present invention;

[0031] Figure 7 This is the 0-field spectral distribution diagram of the transition spectral imaging system in Embodiment 2 of the present invention;

[0032] Figure 8This is a full-field lateral aberration map of the 450nm spectrum of the transition spectral imaging system in Embodiment 2 of the present invention.

[0033] Figure 9 This is a full-field lateral aberration map of the 500nm spectrum of the transition spectral imaging system in Embodiment 2 of the present invention.

[0034] Figure 10 This is a full-field lateral aberration map of the 650nm spectrum of the transition spectral imaging system in Embodiment 2 of the present invention.

[0035] Figure 11 This is a planar schematic diagram of the transition spectral imaging system of Embodiment 3 of the present invention;

[0036] Figure 12 This is the 0-field spectral distribution diagram of the transition spectral imaging system in Embodiment 3 of the present invention;

[0037] Figure 13 This is a full-field lateral aberration map of the 700nm spectrum of the transition spectral imaging system in Embodiment 3 of the present invention.

[0038] Figure 14 This is a full-field lateral aberration map of the 900nm spectrum of the transition spectral imaging system in Embodiment 3 of the present invention.

[0039] Figure 15 This is a full-field lateral aberration map of the 1150nm spectrum of the transition spectral imaging system in Embodiment 3 of the present invention. Detailed Implementation

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0041] When describing embodiments of the present invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer" express orientations or positional relationships based on the orientations or positional relationships shown in the relevant drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limitations on the present invention.

[0042] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The embodiments cannot be described in detail here, but the embodiments of the present invention are not limited to the following embodiments.

[0043] like Figures 1 to 15 As shown, a spectral imaging system of the present invention is used to acquire spectral information of a light source. The spectral imaging system comprises, sequentially from the light source to the image plane:

[0044] A first lens group (G1) for receiving and converging optical signals, wherein the first lens group (G1) is provided with at least one lens with positive optical power;

[0045] A second lens group (G2) with collimation function;

[0046] A spectroscopic element with dispersion function (G3);

[0047] The third lens group (G4) is used for spectral convergence imaging that disperses the beams of the beam-dispersing element;

[0048] In the second lens group (G2), there is at least one negative power lens between the first and last lenses, and in the third lens group (G4), there is at least one negative power lens between the first and last lenses.

[0049] In this embodiment, the received signal light is converged, and the signal-to-noise ratio is improved using a pinhole or slit. After collimation by an optical system and dispersion by a dispersive element, it is refocused onto the image plane. That is, the first lens group G1, the second lens group G2, the beam splitter G3, and the third lens group G4 work together to re-image the mixed-spectrum light source, arranging it on the image plane in different ways with different spectral imaging positions. The spectral distribution of the convergence region ranges from λ1 to λ2. n The light spot is arranged sequentially from short-wavelength to long-wavelength or vice versa in the y-direction from bottom to top, which is beneficial for controlling the light spot size and realizing the function of spectral imaging. By analyzing the energy, position and other information of the convergence area of ​​the imaging system, the spectral information and energy values ​​of each spectrum contained in the light source are analyzed by software algorithms. By reasonably configuring the lens, the system can simultaneously have high spectral resolution and wide spectral range.

[0050] This invention can achieve a numerical aperture of 0.3 or higher, design bands covering visible and near-infrared bands, a maximum field of view of 30mm, and ensure that the imaging spot size of the entire field of view is less than 10um, thereby improving the testing accuracy.

[0051] Furthermore, in the second lens group G2, there is at least one negative power lens between the first and last lenses. The entire lens group before and after this negative power lens has a positive power, forming a positive-negative-positive structure, which is beneficial for correcting field curvature and improving the imaging quality of the outer field of view. The third lens group G4 also has a positive-negative-positive structure. The two positive-negative-positive structures are placed on both sides of the dispersive element, which is beneficial for correcting off-axis aberration.

[0052] The convergence region is located on the image plane.

[0053] In one embodiment of the present invention, preferably, the total number of lenses in the first lens group G1, the second lens group G2 and the third lens group G4 is not less than 17.

[0054] In one embodiment of the present invention, preferably, a small hole or slit is provided between the first lens group (G1) and the second lens group G2.

[0055] In one embodiment of the present invention, preferably, the first lens group G1 contains at least six lenses, at least one lens has an Abbe number that satisfies Vd1 < 40, and at least one lens has a refractive index that satisfies Nd1 > 1.7.

[0056] In this embodiment, at least one lens has an Abbe number of Vd1 < 40 to correct spherical aberration and external field aberration; at least one lens has a refractive index of Nd1 > 1.7 to correct spherical aberration and external field aberration.

[0057] In one embodiment of the present invention, preferably, the second lens group G2 contains at least 5 lenses, the first lens being a meniscus lens, bent toward the slit or small hole, and the last lens having positive optical power.

[0058] In one embodiment of the present invention, preferably, at least one lens with negative optical power in the second head lens group G2 is disposed between the reflecting element and the last lens.

[0059] In one embodiment of the present invention, preferably, the second lens group G2 includes at least one lens with an Abbe number Vd2 less than 40 and at least one lens with a refractive index nd greater than 1.7.

[0060] In one embodiment of the present invention, preferably, the third lens group G4 includes at least six lenses, and the incident height difference H1 between the zero field-of-view ray and the principal ray in the first lens of the third lens group G4 and the lowest incident height difference H2 between the zero field-of-view ray and the principal ray in the third lens group G4 satisfy the following relationship: 0.2 < H1 / H2 < 0.5.

[0061] In this embodiment, the structural form is a variation of the Gaussian structure. The two parts before and after the lowest point of the light source have different functions. The part near the diffraction element is mainly used to correct the field curvature, while the part near the detector is mainly used to correct the magnification chromatic aberration.

[0062] In one embodiment of the present invention, preferably, the third lens group G4 includes at least one lens with an Abbe number Vd3 of less than 40 and at least one lens with a refractive index nd of greater than 1.7.

[0063] In one embodiment of the present invention, preferably, the imaging range of the spectral imaging system is 450nm-1150nm.

[0064] In one embodiment of the present invention, preferably, the first lens group G1 or the second lens group G2 includes at least one reflective element for reversing the optical path, the distance between the reflective element and the pinhole or slit is in the range of 5 to 40 mm, and the distance between the reflective element and the dispersive element is greater than 40 mm.

[0065] In this embodiment, the close distance between the slit and the reflective element can effectively reduce the lens aperture, save costs and space, and improve space utilization. The short distance between the reflective element and the dispersive element is beneficial to reducing the lateral dimension and the size of the equipment.

[0066] In one embodiment of the present invention, preferably, the plane where the light source is located and the optimal convergence plane are not necessarily 180 degrees apart, and the angle can be designed according to the appearance size and convenience and aesthetics.

[0067] The following four specific embodiments illustrate the spectral imaging system. In each of the following specific embodiments, the cemented surface of the cemented lens is referred to as one surface. For example, a cemented doublet composed of two cemented lenses has three surfaces.

[0068] Example 1

[0069] The first part of the zigzag spectral imaging system in this embodiment includes, from top to bottom, the following sequentially arranged elements: the seventh lens L7 is a plano-convex lens; the sixth lens L6 is a meniscus lens facing the direction of the incident light signal; the fifth lens L5 is a plano-convex lens with its flat surface facing the incident light signal; the fourth lens L4 is a meniscus lens facing away from the direction of the incident light signal; the third lens L3 is a biconcave lens; the second lens L2 is a meniscus lens facing away from the direction of the incident light signal; and the first lens L1 is a biconvex lens.

[0070] The second part of the zigzag spectral imaging system in this embodiment includes the following sequentially arranged elements: the eighth lens L8, a meniscus lens facing the slit, with a reflecting prism that bends the light path by 90 degrees; the ninth lens L9, a meniscus lens facing the reflecting prism; the tenth lens L10, with positive optical power; the eleventh lens L11, with negative optical power; the twelfth lens L12, a meniscus lens facing the reflecting prism; and the thirteenth lens L13, a plano-convex lens.

[0071] The third part of the inflection spectral imaging system in this embodiment includes, in sequence: a reflection grating D14.

[0072] The fourth part of the transition-type spectral imaging system in this embodiment includes the following sequentially arranged elements: the fifteenth lens L15 is a plano-convex lens with its plane facing the detector; the sixteenth lens L16 is a meniscus lens; the seventeenth lens L17 is a negative power lens; the eighteenth lens L18 is a negative power lens; the nineteenth lens L19 is a meniscus lens facing the grating direction; the twentieth lens L20 is a biconvex lens; and the twenty-first lens L21 is a meniscus lens facing the detector.

[0073] As a specific embodiment, the spectral imaging system of this embodiment has a spectral range of 450nm to 650nm. The reflective element in the second lens group G2 and the dispersive element in the beam splitter G3 deflect the light, forming a deflection-type spectral imaging system.

[0074] The relevant parameters of each lens in the first lens group G1 of the inflection-type spectral imaging system, including the radius of curvature R, thickness, refractive index Nd, and Abbe number Vd of the material, are shown in Table 1 below:

[0075] surface R value (mm) Thickness (mm) Nd Vd S1 Infinity 7 1.85 24 S2 -88.2 0.2 S3 151.4 6 1.62 60 S4 207.3 0.2 S5 121.5 6 1.62 60 S6 Infinity 12 S7 -201.1 8 1.62 60 S8 -88.2 1 S9 -107.5 7 1.85 24 S10 207.3 7 S11 -207.3 6 1.88 39 S12 -88.2 0.2 S13 357.6 8 1.62 60 S14 -157.5

[0076] Table 1

[0077] The relevant parameters of each lens in the second lens group G2 of the transition spectral imaging system, including the radius of curvature R, thickness, refractive index Nd, and Abbe number Vd of the material, are shown in Table 2 below:

[0078]

[0079]

[0080] Table 2

[0081] The beam splitter G3 of the inverted spectral imaging system is a grating.

[0082] The relevant parameters of each lens in the third lens group G4 of the inflection-type spectral imaging system, including the radius of curvature R, thickness, refractive index Nd, and Abbe number Vd of the material, are shown in Table 3 below:

[0083] surface R value (mm) Thickness (mm) Nd Vd S1 -61.3 10 1.62 60 S2 Infinity 0.5 S3 -41.4 10 1.62 60 S4 -39.9 6 1.85 24 S5 -58.3 3 S6 -175.6 7 1.85 24 S7 -15.7 9 S9 20.1 9 1.62 60 S10 25.4 0.5 S11 -25.4 9 1.62 60 S12 83.1 0.5 S13 -21.5 8 1.62 60 S14 -37.4

[0084] Table 3

[0085] Here, R value refers to the radius of curvature of the surface, and thickness refers to the axial distance from the current surface to the next surface. For example, the thickness of surface S1 is the distance from S1 to S2, which may be the axial thickness of the medium or lens, or it may be the axial air gap between them.

[0086] In addition, the ratio of the incident height difference H1 between the zero field ray and the principal ray at the first lens of G4 to the lowest incident height difference H2 between the zero field ray and the principal ray at G4 is: H2 / H1 = 0.35.

[0087] Figure 1 This is a planar schematic diagram of the inflection-type spectral imaging system of Embodiment 1. The first lens group G1 contains seven lenses, the second lens group G2 contains six lenses, the beam splitting element G3 is a dispersive element D14, and the third lens group G4 contains seven lenses, achieving dichroic focusing on the image plane.

[0088] Figure 2 The zero-field spectral distribution diagram of the transition spectral imaging system in Example 1 is shown. The spectral distribution is arranged from 450nm to 650nm from bottom to top. The dot plot shows that the spot size control is good and the function of sub-spectral imaging is realized.

[0089] Figure 3 This is a full-field lateral aberration map of the 450nm spectrum of the directional spectral imaging system of Example 1. The horizontal axes PY and PX represent the normalized entrance pupil size, the vertical axis represents the lateral aberration, the scale bar is ±20 micrometers, the Y direction is the meridional direction, and the X direction is the sagittal direction.

[0090] Figure 4 This is a full-field lateral aberration map of the 500nm spectrum of the directional spectral imaging system of Example 1. The horizontal axes PY and PX represent the normalized entrance pupil size, the vertical axis represents the lateral aberration, the scale bar is ±20 micrometers, the Y direction is the meridional direction, and the X direction is the sagittal direction.

[0091] Figure 5 This is a full-field lateral aberration map of the 650nm spectrum of the turn-type spectral imaging system of Example 1. The horizontal axes PY and PX represent the normalized entrance pupil size, the vertical axis represents the lateral aberration, the scale bar is ±20 micrometers, the Y direction is the meridional direction, and the X direction is the sagittal direction.

[0092] Example 2

[0093] The first part of the zigzag spectral imaging system in this embodiment includes, from top to bottom, the following sequentially arranged elements: the seventh lens L7 is a plano-convex lens; the sixth lens L6 is a meniscus lens facing the direction of the incident light signal; the fifth lens L5 is a plano-convex lens with its flat surface facing the incident light signal; the fourth lens L4 is a meniscus lens facing away from the direction of the incident light signal; the third lens L3 is a biconcave lens; the second lens L2 is a meniscus lens facing away from the direction of the incident light signal; and the first lens L1 is a biconvex lens.

[0094] In this embodiment, the second part of the deflection-type spectral imaging system includes the following sequentially arranged elements: the eighth lens L8, a meniscus lens facing the slit, with the reflecting plane mirror making a 90-degree bend to the light path; the ninth lens L9, a meniscus lens facing the reflecting plane mirror; the tenth lens L10, a meniscus lens facing the reflecting plane mirror; the eleventh lens L11, with positive optical power; the twelfth lens L12, with negative optical power; the thirteenth lens L13, a meniscus lens facing the reflecting plane mirror; and the fourteenth lens L14, a plano-convex lens.

[0095] In this embodiment, the beam splitter G3 of the transition spectral imaging system is a reflective grating D15.

[0096] The fourth part of the transition spectral imaging system in this embodiment includes the following sequentially arranged elements: the sixteenth lens L16 is a meniscus lens facing the image plane; the seventeenth lens L17 is a meniscus lens facing the image plane; the eighteenth lens L18 is a negative power lens; the nineteenth lens L19 is a negative power lens; the twentieth lens L20 is a negative power lens; the twenty-first lens L21 is a meniscus lens facing the reflection grating; the twenty-second lens L22 is a biconvex lens; and the twenty-third lens L23 is a meniscus lens facing the detector.

[0097] As a specific embodiment, the spectral imaging system of this embodiment has a spectral range of 450nm to 650nm. The reflective element in the second lens group G2 and the dispersive element in the beam splitter G3 deflect the light, forming a deflection-type spectral imaging system.

[0098] The relevant parameters of each lens in the first lens group G1 of the inflection-type spectral imaging system, including the radius of curvature R, thickness, refractive index Nd, and Abbe number Vd of the material, are shown in Table 4 below:

[0099] surface R value (mm) Thickness (mm) Nd Vd S1 Infinity 7 1.85 24 S2 -88.2 0.2 S3 151.4 6 1.62 60 S4 207.3 0.2 S5 121.5 6 1.62 60 S6 Infinity 12 S7 -201.1 8 1.62 60 S8 -88.2 1 S9 -107.5 7 1.85 24 S10 207.3 7 S11 -207.3 6 1.88 39 S12 -88.2 0.2 S13 357.6 8 1.62 60 S14 -157.5

[0100] Table 4

[0101] The relevant parameters of each lens in the second lens group G2 of the transition spectral imaging system, including the radius of curvature R, thickness, refractive index Nd, and Abbe number Vd of the material, are shown in Table 5 below:

[0102] surface R value (mm) Thickness (mm) Nd Vd S1 -19.4 5 1.85 24 S2 -32.8 27 S3 -39.4 6 1.88 39 S4 -28.9 8 1.62 60 S5 -37.5 20 S6 -221.8 8 1.62 60 S7 -47.1 4 1.85 24 S8 -221.8 8 S9 -221.8 7 1.85 24 S10 -75.6 0.2 S11 Infinity 7 1.62 60 S12 -75.6 5

[0103] Table 5

[0104] The beam splitter G3 of the inverted spectral imaging system is a grating.

[0105] The relevant parameters of each lens in the third lens group G4 of the inflection-type spectral imaging system, including the radius of curvature R, thickness, refractive index Nd, and Abbe number Vd of the material, are shown in Table 6 below:

[0106]

[0107]

[0108] Table 6

[0109] Here, radius refers to the radius of curvature of the surface, and thickness refers to the axial distance from the current surface to the next surface. For example, the thickness of surface S1 is the distance from S1 to S2, which may be the axial thickness of the medium or lens, or it may be the axial air gap between them.

[0110] In addition, the ratio of the incident height difference H1 between the zero field ray and the principal ray at the first lens of G4 to the lowest incident height difference H2 between the zero field ray and the principal ray at G4 is: H2 / H1 = 0.28.

[0111] Figure 6 This is a planar schematic diagram of the inflection-type spectral imaging system of Embodiment 2. The first lens group G1 contains seven lenses, the second lens group G2 contains seven lenses, the beam splitter G3 contains a dispersive element D15, and the third lens group G4 contains eight lenses, achieving dichroic focusing on the image plane.

[0112] Figure 7 The zero-field spectral distribution diagram of the transition spectral imaging system in Example 2 shows that the spectral distribution is arranged sequentially from 450nm to 650nm from bottom to top. The dot plot shows that the spot size control is good and the function of sub-spectral imaging is realized.

[0113] Figure 8 This is a full-field lateral aberration map of the 450nm spectrum of the directional spectral imaging system of Example 2. The horizontal axes PY and PX represent the normalized entrance pupil size, the vertical axis represents the lateral aberration, the scale bar is ±20 micrometers, the Y direction is the meridional direction, and the X direction is the sagittal direction.

[0114] Figure 9 This is a full-field lateral aberration map of the 500nm spectrum of the directional spectral imaging system of Example 2. The horizontal axes PY and PX represent the normalized entrance pupil size, the vertical axis represents the lateral aberration, the scale bar is ±20 micrometers, the Y direction is the meridional direction, and the X direction is the sagittal direction.

[0115] Figure 10 This is a full-field lateral aberration map of the 650nm spectrum of the directional spectral imaging system of Example 2. The horizontal axes PY and PX represent the normalized entrance pupil size, the vertical axis represents the lateral aberration, the scale bar is ±20 micrometers, the Y direction is the meridional direction, and the X direction is the sagittal direction.

[0116] Example 3

[0117] The first part of the zigzag spectral imaging system in this embodiment includes, from top to bottom, the following sequentially arranged elements: the sixth lens L6 is a meniscus lens, facing away from the incident light signal direction; the fifth lens L5 is a meniscus lens, facing away from the incident light signal direction; the fourth lens L4 is a meniscus lens, facing away from the incident light signal direction; the third lens L3 is a plano-convex lens, with its flat surface facing the incident light signal; the second lens L2 is a meniscus lens, facing the incident light signal direction; and the first lens L1 is a plano-concave lens, with its concave surface facing the light signal direction.

[0118] In this embodiment, the second part of the deflection-type spectral imaging system includes the following sequentially arranged elements: a seventh lens (L7, a meniscus lens facing the slit, with the reflecting plane mirror making a 90-degree bend to the light path); an eighth lens (L8, a meniscus lens facing the reflecting plane mirror); a ninth lens (L9, a meniscus lens facing the reflecting plane mirror); a tenth lens (L10, with positive optical power); an eleventh lens (L11, with negative optical power); a twelfth lens (L12, a meniscus lens facing the reflecting plane mirror); and a thirteenth lens (L13, a plano-convex lens). The planar surface faces the reflecting plane mirror.

[0119] In this embodiment, the beam splitter G3 of the transition spectral imaging system is a reflective grating D14.

[0120] The fourth part of the transition spectral imaging system in this embodiment includes the following sequentially arranged elements: the fifteenth lens L15 is a plano-convex lens with its plane facing the detector; the sixteenth lens L16 is a meniscus lens facing the detector; the seventeenth lens L17 is a negative power lens; the eighteenth lens L18 is a negative power lens; the nineteenth lens L19 is a meniscus lens facing away from the detector; the twentieth lens L20 is a biconvex lens; and the twenty-first lens L21 is a meniscus lens facing the detector.

[0121] As a specific embodiment, the spectral imaging system of this embodiment has a spectral range of 700nm to 1150nm. The reflective element in the second lens group G2 and the dispersive element in the beam splitter G3 deflect the light, forming a deflection-type spectral imaging system.

[0122] The relevant parameters of each lens in the first lens group G1 of the inflection-type spectral imaging system, including the radius of curvature R, thickness, refractive index Nd, and Abbe number Vd of the material, are shown in Table 7 below:

[0123]

[0124]

[0125] Table 7

[0126] The relevant parameters of each lens in the second lens group G2 of the transition spectral imaging system, including the radius of curvature R, thickness, refractive index Nd, and Abbe number Vd of the material, are shown in Table 8 below:

[0127] surface R value (mm) Thickness (mm) Nd Vd S1 -14.5 5 1.85 24 S2 -15.9 27 S3 -54.2 6 1.88 39 S4 -25.7 8 1.62 60 S5 -33.3 20 S6 -215.7 8 1.62 60 S7 -33.3 4 1.85 24 S8 -355.6 8 S9 -71.9 7 1.85 24 S10 -67.1 0.2 S11 Infinity 7 1.62 60 S12 -66.5

[0128] Table 8

[0129] The beam splitter G3 of the inverted spectral imaging system is a grating.

[0130] The relevant parameters of each lens in the third lens group G4 of the transition spectral imaging system, including the radius of curvature R, thickness, refractive index Nd, and Abbe number Vd of the material, are shown in Table 9 below:

[0131] surface R value (mm) Thickness (mm) Nd Vd S1 -44.1 12 1.85 24 S2 Infinity 0.5 S3 -44.1 10 1.88 39 S4 -31.8 4 1.62 60 S5 -44.1 3 S6 105.2 25 1.62 60 S7 -17.6 8 1.85 24 S8 24.1 0.2 S9 31.8 10 1.85 24 S10 -67.4 0.2 S11 105.2 9 1.62 60 S12 -39.4

[0132] Table 9

[0133] Here, radius refers to the radius of curvature of the surface, and thickness refers to the axial distance from the current surface to the next surface. For example, the thickness of surface S1 is the distance from S1 to S2, which may be the axial thickness of the medium or lens, or it may be the axial air gap between them.

[0134] In addition, the ratio of the incident height difference H1 between the zero field ray and the principal ray at the first lens of G4 to the lowest incident height difference H2 between the zero field ray and the principal ray at G4 is: H2 / H1 = 0.41.

[0135] Figure 11 This is a planar schematic diagram of the inflection-type spectral imaging system of Embodiment 3. The first lens group G1 contains six lenses, the second lens group G2 contains seven lenses, the beam splitter G3 contains a dispersive element D14, and the third lens group G4 contains seven lenses, achieving dichroic focusing on the image plane.

[0136] Figure 12 The zero-field spectral distribution diagram of the transition spectral imaging system in Example 3 shows that the spectral distribution is arranged sequentially from 700nm to 1150nm from bottom to top. The dot plot shows that the spot size control is good and the function of sub-spectral imaging is realized.

[0137] Figure 13This is a full-field lateral aberration map of the 700nm spectrum of the directional spectral imaging system of Example 3. The horizontal axes PY and PX represent the normalized entrance pupil size, the vertical axis represents the lateral aberration, the scale bar is ±20 micrometers, the Y direction is the meridional direction, and the X direction is the sagittal direction.

[0138] Figure 14 This is a full-field lateral aberration map of the 900nm spectrum of the spectral imaging system of Example 3. The horizontal axes PY and PX represent the normalized entrance pupil size, the vertical axis represents the lateral aberration, the scale bar is ±20 micrometers, the Y direction is the meridional direction, and the X direction is the sagittal direction.

[0139] Figure 15 This is a full-field lateral aberration map of the 1150nm spectrum of the turn-type spectral imaging system of Example 3. The horizontal axes PY and PX represent the normalized entrance pupil size, the vertical axis represents the lateral aberration, the scale bar is ±20 micrometers, the Y direction is the meridional direction, and the X direction is the sagittal direction.

[0140] This invention provides a spectral imaging system that converges received signal light, improves the signal-to-noise ratio using a pinhole or slit, collimates the light using an optical system, disperses it using a dispersive element, and then refocuses it onto the image plane. The spectral distribution of the convergence region ranges from λ1 to λ2. n The lenses are arranged sequentially from short-wavelength to long-wavelength or vice versa along the y-axis, which facilitates control of the spot size and enables spectral imaging. By analyzing the energy and position of the convergent region of the imaging system, and using software algorithms to analyze the spectral information and energy values ​​of each spectral component of the light source, the system achieves both high spectral resolution and a wide spectral range through a reasonable lens configuration. The use of a bend-type design compresses the system's space, making it more compact and suitable for instruments with strict size requirements. In the second lens group G2, at least one negative power lens exists between the first and last lenses. The entire lens group before and after this negative power lens has a positive power, forming a positive-negative-positive structure, which helps correct field curvature and improves the imaging quality of the outer field of view. The third lens group G4 also has a positive-negative-positive structure, with two positive-negative-positive structures placed on either side of the dispersive element, which helps correct off-axis aberration.

[0141] This invention can achieve a numerical aperture of 0.3 or higher, design bands covering visible and near-infrared bands, a maximum field of view of 30mm, and ensure that the imaging spot size of the entire field of view is less than 10um, thereby improving the testing accuracy.

[0142] The above description is merely one embodiment of the present invention and is not intended to limit the invention. Those skilled in the art will recognize that the present invention can be modified and varied in various ways. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A spectral imaging system, characterized by, The spectral imaging system comprises, in order from the light source to the image plane, for acquiring spectral information of a light source: a first lens group (G1) for receiving and converging the light signal, the first lens group (G1) being provided with at least one lens with positive refractive power; a second lens group (G2) with collimating function; a light splitting element (G3) with dispersion function; a third lens group (G4) for converging the dispersed light spectrum of the light splitting element into an image; there is at least one negative refractive power lens between the first and last lens in the second lens group (G2), and at least one negative refractive power lens between the first and last lens in the third lens group (G4); the third lens group (G4) comprises at least six lenses, and the difference in incident height H1 between the zero field external light and the chief ray at the first lens of the third lens group (G4) and the difference in incident height H2 between the zero field external light and the chief ray at the lowest point of the third lens group (G4) satisfy the following relationship: 0.2 < H1 / H2 < 0.

5.

2. The spectral imaging system of claim 1, wherein, The total number of lenses in the first lens group (G1), the second lens group (G2) and the third lens group (G4) is not less than 17.

3. The spectral imaging system of claim 1, wherein, A pinhole or slit is provided between the first lens group (G1) and the second lens group (G2).

4. The spectral imaging system of claim 1, wherein, The first lens group (G1) comprises at least six lenses, at least one lens has an Abbe number Vd1 < 40, and at least one lens has a refractive index nd > 1.

7.

5. The spectral imaging system of claim 3, wherein, The second lens group (G2) comprises at least five lenses, the first lens is a meniscus lens with the concave side facing the slit or pinhole, and the last lens has positive refractive power.

6. The spectral imaging system of claim 5, wherein, At least one lens with negative refractive power in the second lens group (G2) is arranged between the reflecting element and the last lens.

7. The spectral imaging system of claim 6, wherein, The second lens group (G2) comprises at least one lens with an Abbe number Vd2 < 40, and at least one lens with a refractive index nd > 1.

7.

8. The spectral imaging system of claim 1, wherein, The third lens group (G4) comprises at least one lens with an Abbe number Vd3 < 40, and at least one lens with a refractive index nd > 1.

7.

9. The spectral imaging system of claim 1, wherein, The imaging range of the spectral imaging system is 450nm-1150nm.

10. The spectral imaging system of claim 3, wherein, At least one reflecting element for turning the light path is included in the first lens group (G1) or the second lens group (G2), the distance between the reflecting element and the pinhole or slit is in the range of 5-40mm, and the distance between the reflecting element and the dispersion element is greater than 40mm.

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