A spectral confocal dispersion lens group architecture based on functional partitioning and a design method

Abstract

The present application belongs to the technical field of spectral confocal displacement sensors, and particularly relates to a spectral confocal dispersion lens group architecture based on functional partitioning and a design method thereof, which comprises front, middle and rear lens groups coaxially arranged in sequence along an optical axis, and air gaps are arranged between the front and middle lens groups and between the middle and rear lens groups; the front, middle and rear lens groups each have different functions; equivalent focal power proportion and blue-red light focal power difference proportion are jointly determined by the number of lenses, material combination and air gap of each lens group. The present application realizes unified optimization of axial dispersion capability and aberration control capability to maintain good focusing performance and image quality stability within a large numerical aperture range, reduces aberration deterioration of traditional high numerical aperture spectral confocal probes, has good multiplexing and platform expansion capabilities, and is suitable for rapid development and engineering application of spectral confocal displacement sensors of different specifications.

Description

Technical Field

[0001] This invention relates to the field of spectral confocal displacement sensor technology, and in particular to a spectral confocal dispersive mirror group architecture and design method based on functional partitioning. Background Technology

[0002] A spectral confocal displacement sensor is an optical sensing device that utilizes the axial dispersion characteristics of a broadband light source to achieve non-contact displacement and thickness measurement. It is widely used in precision manufacturing, semiconductor inspection, and surface topography measurement. Its core component is a dispersive objective lens, which establishes a correlation between wavelength and displacement by focusing light of different wavelengths to different positions on the optical axis. Existing dispersive objectives typically employ a two-lens architecture consisting of a front and rear group, with the front and rear groups respectively responsible for power distribution and dispersion generation. However, when extending the numerical aperture (NA) or dispersion range, this two-lens architecture suffers from drawbacks. The lack of an independent large-aperture transition and aberration transfer unit between the front and rear groups results in a coupling of adjustment freedom among the system aperture, aberration, and dispersion. When a significant change occurs in any of these parameters, a complete reconfiguration of the entire lens architecture is often required. This makes it difficult to achieve a series of designs from low NA to high NA, and from small dispersion range to large dispersion range, within the same architecture, resulting in limited adaptability.

[0003] For example, Chinese invention patent application CN119667900A discloses a grouped spectral confocal dispersive objective. This design includes a front lens group and a rear lens group for the dispersive objective. The aperture stop is positioned between the two lens groups and its position is adjustable. The rear lens group handles most of the dispersive requirements, and the two groups transmit approximately collimated light. Therefore, this design lacks an independent intermediate functional unit and cannot independently handle aperture transition and aberration / dispersion coordination in large aperture regions. Furthermore, the adjustment degrees of freedom of the two groups are coupled, requiring reconfiguration when the numerical aperture or dispersive range changes significantly. Moreover, it does not disclose the platform-based scalability of this architecture. In summary, existing two-lens architectures are poorly adaptable to NA or dispersive range expansion and are difficult to integrate into a unified platform design architecture. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of the aforementioned background technology by providing a lens assembly architecture scheme with a functional division of labor among the front, middle, and rear groups, which facilitates the wide-range expansion of numerical aperture and the range expansion of axial dispersion through a unified platform design.

[0005] To achieve the above objectives, the present invention provides a spectral confocal dispersive lens group architecture based on functional partitioning, comprising a front lens group, a middle lens group, and a rear lens group arranged coaxially along the optical axis, wherein inter-group air gaps are provided between the front lens group and the middle lens group, and between the middle lens group and the rear lens group. The front lens group is located at the incident end. The front lens group consists of at least two lenses, including at least one lens made of a low Abbe number material or a high refractive index material. The front lens group is used to introduce the dispersion slope while controlling the spherical aberration, coma, and incident aperture of the incident beam, and to complete dispersion pre-shaping and front-end optical power allocation at the incident end. The middle lens group consists of at least two lenses. The middle lens group is used to receive the light beam formed by the front lens group and to perform transition correction for spherical aberration, coma, and dispersion, maintaining an adjustable balance of numerical aperture, aberration, and dispersion during the numerical aperture expansion process of the system. The rear lens group is located at the exit end. The rear lens group consists of at least two lenses, including at least one lens made of low Abbe number material. The rear lens group is used to complete high numerical aperture convergence, working distance compression, and to finally place the axial dispersive focus shift formed by the front lens group and the middle lens group onto the measurement space, so that the focal points of different wavelengths are controlled to be separated within the axial measurement range. The blue-red light power difference of the rear lens group is greater than the blue-red light power difference of the front lens group and the middle lens group; The equivalent optical power ratio and the blue-red optical power difference ratio of each of the front lens group, the middle lens group, and the rear lens group are determined by the number of lenses, the material combination, and the air gap between the groups.

[0006] Furthermore, the equivalent optical power of the front lens group adopts a configuration in which positive and negative optical power surfaces cancel each other out. In a higher numerical aperture design, the front lens group increases the proportion of the total equivalent optical power, while in a lower numerical aperture design, the front lens group decreases the proportion of the total equivalent optical power.

[0007] Furthermore, the middle lens group is positioned at the maximum beam aperture of the system between the front lens group and the rear lens group. When the numerical aperture increases, the middle lens group increases the proportion of dispersion and focal shift.

[0008] This invention also provides a method for designing a spectral confocal dispersive mirror group architecture based on functional differentiation, comprising the following steps: S1, the total equivalent optical power of the system and the required total blue-red optical power difference are determined by the target numerical aperture, working distance and axial dispersion range; S2, based on a three-group architecture, scans or solves the equivalent optical power of the front lens group, the equivalent optical power of the middle lens group, and the equivalent optical power of the rear lens group, while adjusting the air gap between the two components to make the total optical power formula of the system meet the target value. S3, under the constraints of selectable materials and low Abbe number materials, calculate or estimate the blue-red light power difference of the front lens group, the blue-red light power difference of the middle lens group, and the blue-red light power difference of the rear lens group, so that the total blue-red light power difference of the system meets the target value. S4, calculate the normalized contribution of each lens group to the axial dispersion focus shift of the system, and determine the functional allocation of the rear lens group as the main dispersion focus shift group, the front lens group as the pre-shaping group, and the middle lens group as the transition and correction group. S5 uses numerical aperture relation and aberration scale relation to eliminate combinations of excessively large beam aperture, excessively strong single lens group coupled optical focal length, or uncontrollable aberrations, to obtain an implementable parameter envelope. Based on the parameter envelope, further testing is conducted to obtain a design scheme that meets specific requirements for numerical aperture, working distance, axial dispersion range, and aberration correction.

[0009] Furthermore, in S2, the front lens group is arranged sequentially along the optical axis. Middle lens group Rear lens group The air interval between the two groups is denoted as . and ; System total equivalent optical power The expression is: .

[0010] Furthermore, the sensitivity coefficient is defined in S2. ,but:

[0011]

[0012]

[0013] in, Indicates the first The sensitivity of each lens group This is to reflect the degree of influence of changes in the equivalent optical power of different lens groups on the total equivalent optical power of the system.

[0014] Furthermore, in S3, the first The equivalent optical power of a lens group as a function of wavelength is expressed as follows:

[0015] in, Indicates the first The difference in blue and red light power between the lens groups Indicates the wavelength of blue light. Indicates the wavelength of red light. This represents the equivalent geometric coefficients formed by the curvature, thickness, and structure of the lens assembly. Indicates the first The refractive index of the optical materials used in each lens group; Total equivalent optical power of the system Performing a first-order expansion, we obtain the total blue-red optical power difference of the system:

[0016] in, The total blue-red light intensity difference of the system.

[0017] Furthermore, in S4, the first The normalized contribution of each lens group to the axial dispersion focal shift of the system is expressed as:

[0018] in, This indicates the normalization contribution.

[0019] The above-described solution of the present invention has the following beneficial effects: The functional partition-based spectral confocal dispersive lens group architecture and design method provided by this invention adopts a modular design approach with functional partitions, which can achieve rapid expansion and construction of different numerical apertures and different measurement ranges on the basis of a unified optical architecture. Through the coordinated design of dispersion control, aberration compensation and focusing, the axial dispersion capability and aberration control capability are optimized in a unified manner, so as to maintain good focusing performance and image quality stability over a wide numerical aperture range and reduce the aberration deterioration problem of traditional high numerical aperture spectral confocal probes. In this invention, the equivalent optical power ratio and the blue-red optical power difference ratio of the front lens group, middle lens group, and rear lens group can be adjusted in a coordinated manner by changing the number of lenses in each group, the combination of glass materials, and the air gap between groups. This allows for coverage of different numerical apertures, different working distances, and different axial dispersive focal shift ranges while maintaining the three-group architecture. This enables a series of platform-based designs with good reusability and platform expansion capabilities, making it suitable for the rapid development and engineering application of spectral confocal displacement sensors of different specifications. Other beneficial effects of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the three-group architecture of the present invention, which includes nine lenses; Figure 2 This is a schematic diagram of another three-group architecture of the present invention, comprising nine lenses; Figure 3 This is a schematic diagram of another three-group architecture of the present invention, comprising nine lenses; Figure 4 This is a schematic diagram of the three-group architecture of the present invention, which includes eight lenses; Figure 5 This is a schematic diagram of the three-group architecture of the present invention, which includes ten lenses; Figure 6 This is a flowchart of the method steps of the present invention.

[0021] [Explanation of Labels in the Attached Image] 1-First lens; 2-Second lens; 3-Third lens; 4-Fourth lens; 5-Fifth lens; 6-Sixth lens; 7-Seventh lens; 8-Eighth lens; 9-Ninth lens; 10-Tenth lens. Detailed Implementation

[0022] The following specific examples illustrate the implementation of this disclosure. Those skilled in the art can easily understand other advantages and effects of this disclosure from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. This disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this disclosure. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0023] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this disclosure, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0024] It should also be noted that the illustrations provided in the following embodiments are merely schematic representations of the basic concept of this disclosure. The illustrations only show components relevant to this disclosure and are not drawn according to the actual number, shape, and size of components in implementation. In actual implementation, the type, quantity, and proportion of each component can be arbitrarily changed, and the component layout may be more complex. Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details.

[0025] like Figures 1-5As shown, an embodiment of the present invention provides a spectral confocal dispersive lens group architecture based on functional partitioning, including a front lens group, a middle lens group, and a rear lens group arranged coaxially along the optical axis, with an inter-group air gap formed between adjacent lens groups. The front lens group is located at the incident end of the optical axis, the rear lens group is located at the exit end of the optical axis, and the middle lens group is located between the front and rear lens groups.

[0026] In this embodiment, the front lens group consists of at least two lenses, including at least one lens made of a low Abbe number material or a high refractive index material. The equivalent optical power of the front lens group can be configured with positive and negative optical power surfaces canceling each other out. This allows the front lens group to introduce dispersion slope while controlling the spherical aberration, coma, and incident aperture of the incident beam, thereby completing dispersion pre-shaping and front-end optical power allocation at the incident end. Based on implemented examples, the total equivalent optical power of the front lens group accounts for approximately 14.5% to 47.5%, and the blue-red optical power difference accounts for approximately 5.0% to 29.0%. In high numerical aperture designs, the front lens group can increase the proportion of total equivalent optical power to establish large numerical aperture beam conditions in advance; in medium- and low numerical aperture designs, the front lens group can reduce the proportion of total equivalent optical power, mainly undertaking dispersion pre-shaping and front-end aberration control.

[0027] In this embodiment, the middle lens group is positioned at the system's maximum beam aperture between the front and rear lens groups. The middle lens group consists of at least two lenses. It receives the beam formed by the front lens group and provides transitional correction for spherical aberration, coma, and dispersion. During system numerical aperture expansion, it maintains an adjustable balance of numerical aperture, aberrations, and dispersion. The middle lens group does not always need to be the primary contributor to the total equivalent optical power. When the system expands from a low to a high numerical aperture, the middle lens group can increase the proportion of dispersion and focal shift, thereby reducing the burden on the rear lens group.

[0028] The rear lens group consists of at least two lenses, including at least one lens made of a low Abbe number material. The rear lens group is used to achieve high numerical aperture convergence, working distance compression, and to ultimately focus the axial dispersive focus shift formed by the front and middle lens groups onto the measurement space, enabling controlled separation of focal points at different wavelengths within the axial measurement range. The rear lens group can be composed of low Abbe number materials, high refractive index materials, and aspherical surfaces to simultaneously achieve large-angle convergence, axial dispersive focus shift, and residual aberration correction. Based on implemented cases, the rear lens group typically bears the main dispersive focus shift, accounting for approximately 40.4% to 77.5% of the blue-red light focal power difference.

[0029] Based on this, the equivalent optical power ratio and the blue-red optical power difference ratio of the front lens group, middle lens group and rear lens group can be adjusted in a coordinated manner by changing the number of lenses in each group, the combination of glass materials and the air gap between groups, so as to cover different numerical apertures, different working distances and different axial dispersion focal shift ranges while keeping the three-group architecture unchanged, and realize serialized platform design.

[0030] The following theoretical analysis further illustrates this scheme. First, a paraxial matrix model with a three-group architecture is constructed, and the front lens groups are arranged sequentially along the optical axis. Middle lens group Rear lens group Each lens group can be represented by a paraxial transmission matrix, and the air gap between two groups is denoted as . and Therefore, in air, the matrix of any lens group can be written as:

[0031] in, It is the first The paraxial transmission matrix of a lens group is used to describe the height of light rays after passing through this lens group. and angle How it changes, that is Indicates the first The height magnification factor of each lens group Indicates the first Translation / displacement coefficients of each lens group Approximately equal to the equivalent optical power of this lens group, i.e., equivalent optical power , Indicates the first The angular magnification factor of each lens group.

[0032] To illustrate the design principles, each lens group is equivalent to a thin lens, with the following equivalent optical powers: , , The paraxial transfer matrix of the system can then be expressed as:

[0033] in, Represents the translation matrix. Indicates light from the front lens group After it comes out, it spreads in the air. The distance to the middle lens group , Indicates light rays from the middle lens group After it comes out, it spreads in the air. The distance, reaching the rear lens group .

[0034] The total equivalent optical power of the system is obtained by matrix multiplication. for:

[0035] This formula illustrates that the total equivalent optical power of the system is not only determined by… , , The decision was also influenced by , The coupling effect means that the total equivalent optical power of the three-group architecture is not a simple sum of the equivalent optical power of the three lens groups, but is simultaneously controlled by the inter-group air gap and the inter-group coupling term.

[0036] Taking the partial derivative of the formula for the total equivalent optical power of the system, we can obtain the effect of changes in the equivalent optical power of a certain lens group on the total equivalent optical power of the system. A sensitivity coefficient is defined. ,but:

[0037]

[0038]

[0039] It should be noted that the sensitivity coefficient reflects the degree to which changes in the equivalent optical power of different lens groups affect the total equivalent optical power of the system. The sensitivity coefficient indicates that when the equivalent optical power of the front, middle, or rear lens groups is changed, its effect is amplified, canceled out, or transferred by the equivalent optical power of other lens groups and the air gap between the groups. This is the theoretical reason why the three-group architecture can be extended across different numerical apertures and working distances.

[0040] Understandably, spectral confocal dispersive objectives require focusing different wavelengths at different axial positions. For the first... A lens group, whose equivalent optical power is wavelength The function, denoted as Under the first-order approximation, the... The equivalent optical power of a lens group as a function of wavelength can be expressed as:

[0041] in, Indicates the wavelength of blue light. Indicates the wavelength of red light. This represents the equivalent geometric coefficients formed by the curvature, thickness, and structure of the lens assembly. Indicates the first The formula reflects the refractive index of the optical material used in the first lens group. The greater the difference in blue and red light power between the lenses, that is, the greater the difference in refractive index of the glass used in the lens group under blue and red light, the stronger the dispersion of the material itself. This can be understood as the ability of this lens group to convert "changes in the material's refractive index" into "changes in optical power." Combining this with the definition of the Abbe number, the lower the Abbe number, the stronger the material dispersion, the greater the difference between the blue and red refractive indices, and therefore the easier it is to produce larger... Therefore, under the same geometric dimensions, low Abbe number materials can produce larger [materials / materials]. .

[0042] Due to the system's total equivalent optical power Simultaneously dependent , , By performing a first-order expansion, the total blue-red optical power difference of the system can be obtained:

[0043] That is, the total blue-red light power difference (dispersion) of the system is not a simple sum of the dispersions of the three lens groups themselves, but rather the dispersion of each lens group is multiplied by the coupling sensitivity of that lens group. This means that the dispersive ability of the low Abbe number material in a certain lens group does not determine the system dispersion in isolation, but is also modulated by the position of the lens group, the air gap between the groups, and the equivalent optical power of other lens groups.

[0044] Calculate the first Normalized contribution of each lens group to the axial dispersion focal shift of the system:

[0045] in, Represents the normalized contribution, used to calculate the th The contribution percentage of each lens group to the axial dispersion and focal shift of the system can be used to determine which of the front, middle, and rear lens groups is the main contributor to dispersion and focal shift. Generally, this formula can explain why the rear lens group is the main contributor to dispersion and focal shift. However, in some high numerical aperture designs, the contribution percentage of the middle lens group to dispersion and focal shift can also be increased.

[0046] If the system's equivalent focal length The change in focal length caused by the change in wavelength can be approximated by differentiation:

[0047] Therefore, when different wavelengths cause changes in the system's optical power... At that time, the focal position will move axially. The three-group architecture can control the axial dispersion range required for spectral confocal measurements by adjusting the Abbe number of the material, the air gap between groups, and the optical power ratio of each lens group. While maintaining the target numerical aperture and working distance, the three-group architecture provides at least three types of adjustable means: adjust , , ; Change the air interval between groups , ,adjust , , This alters the amplification factor of the dispersion of each lens group on the system's dispersion focal shift; it also changes the ratio of optical power of the front, middle, and rear lens groups, allowing the system to achieve a balance between total focal length, working distance, and axial dispersion range.

[0048] When designing numerical aperture, working distance, and the convergence capability of the rear lens group, the object-side or image-side numerical aperture should meet the following requirements: Under the paraxial approximation, Therefore, for a given working distance The geometric aperture relationship formed by the edge rays in the workspace can be written as:

[0049] in, Indicates horizontal height. This represents the convergence angle, i.e., the given working distance. To achieve a given numerical aperture, the required lateral height of the rim rays in the workspace is crucial. Therefore, as the numerical aperture increases, the rim ray height and convergence angle increase rapidly. If a single lens group were to achieve large-angle convergence, spherical aberration, coma, field curvature, and chromatic aberration would all increase simultaneously. The three-group architecture distributes the high numerical aperture requirement across multiple design degrees of freedom through pre-shaping by the front lens group, large beam diameter reception by the middle lens group, and high numerical aperture convergence by the rear lens group.

[0050] The expression based on the system matrix can be written as:

[0051] Therefore, the focal length of the rear lens group can be approximately expressed as:

[0052] This formula estimates the focal length / working distance of the rear lens group using a system matrix, indicating that high numerical aperture and short working distance cannot be solved simply by increasing the equivalent optical power of the rear lens group alone. It requires a coordinated effort from the front lens group (pre-shaping), the middle lens group (large beam diameter reception), and the rear lens group (final convergence). This supports the rear lens group's functional definition of "final convergence, working distance compression, and aberration focus shift" in a three-group architecture.

[0053] Regarding aberration distribution, considering the scale relationship of the third-order aberrations, higher-order errors such as spherical aberration and coma are highly sensitive to the height of edge rays and the equivalent optical power of a single lens group, and their trend can be expressed in the following form:

[0054]

[0055] in, Indicates ball difference, Indicates coma. For the first The height of the edge rays at each lens group Main light height, , This is a coefficient related to the surface shape, glass, curvature, and aperture position. This formula illustrates that spherical aberration is highly sensitive to the height of the rim ray and the equivalent optical power of a single lens group, especially at high numerical apertures where it is rapidly amplified. Coma also increases significantly with increasing rim ray height, principal ray height, and equivalent optical power of a single lens group. Therefore, high numerical aperture spectral confocal dispersive objectives cannot rely solely on a single lens group for forced convergence. Instead, the pressure of optical power, dispersive aberration, and aberrations should be distributed through pre-shaping with the front lens group, large beam diameter reception and correction with the middle lens group, final convergence with the rear lens group, and aberration focus shift. That is: If the total equivalent optical power is concentrated in a single lens group, the higher-order terms of the equivalent optical power and edge ray height of the single lens group will rapidly amplify aberrations under high numerical apertures. Distributing the equivalent optical power among the front, middle, and rear lens groups can reduce the pressure of higher-order aberrations caused by the excessive equivalent optical power of a single lens group. When the middle lens group is located in the region of a large beam aperture, it has a high correction leverage for spherical aberration, coma, and dispersion transition, making it suitable for arranging large-aperture lenses, cemented structures, or aspherical surfaces. The rear lens group, with low Abbe number materials, high refractive index materials, or aspherical surfaces at the final high-angle convergence point, can simultaneously control axial dispersion focus shift and residual aberrations.

[0056] Based on the above analysis, a design method for a spectral confocal dispersive mirror group architecture based on functional differentiation can be summarized, such as... Figure 4 As shown, it includes the following steps: S1 is determined by the target numerical aperture, working distance, and axial dispersion range. Determine the total equivalent optical power of the system and the required total blue-red light power difference .

[0057] S2, based on a three-group architecture, scans or solves for the equivalent optical power of the front lens group. Equivalent optical power of the middle lens group Equivalent optical power of the rear lens group The air gap between the two components is calculated as follows: and To make the total optical power formula of the system satisfy the target .

[0058] S3, under the constraints of available materials and low Abbe number materials, calculate or estimate. , , ,make The target total blue-red light intensity difference is satisfied.

[0059] S4. Calculate the normalized contribution of each lens group to the axial dispersion and focus shift of the system, and determine the functional allocation of the rear lens group as the main dispersion and focus shift group, the front lens group as the pre-shaping group, and the middle lens group as the transition and correction group.

[0060] S5 uses numerical aperture relation and aberration scale relation to eliminate combinations of excessively large beam aperture, excessively strong single lens group coupled optical focal length, or uncontrollable aberrations, to obtain an implementable parameter envelope. Based on the parameter envelope, further testing is conducted to obtain a design scheme that meets specific requirements for numerical aperture, working distance, axial dispersion range, and aberration correction.

[0061] For example, S1 first determines that the front lens group uses a first cemented joint consisting of a first lens 1 and a second lens 2, and a third lens 3; the middle lens group uses a fourth lens 4 and a fifth lens 5; the rear lens group uses a second cemented joint consisting of a sixth lens 6 and a seventh lens 7, and a third cemented joint consisting of an eighth lens 8 and a ninth lens 9. The first cemented joint is used to form a combination of positive and negative optical power and different dispersive materials at the incident end, thereby achieving dispersion pre-shaping and suppressing the initial growth of spherical aberration, coma, or chromatic aberration at the front end, and generating a controlled initial blue-red optical power difference by utilizing the Abbe number difference of the materials. The second cemented joint is used to achieve a continuous transition of optical power, dispersion, and aberrations between the large beam aperture receiving area and the final convergence area, reducing spherical aberration, coma, and axial chromatic aberration caused by changes in ray height and convergence angle between the middle lens group and the rear lens group. The third cemented component is located at the end of the rear lens group and is used to form controlled dispersion focus shift and residual aberration correction in the final high numerical aperture convergence region, so that the focal points of different wavelengths are separated within the axial measurement range. The third cemented component contains a low Abbe number material to enhance the blue-red light focal power difference of the rear lens group, making the rear lens group the main axial dispersion focus shift bearing group.

[0062] By adjusting the parameters through S3 to S5, a parameter envelope that simultaneously meets the requirements of numerical aperture, working distance, axial dispersion range, and aberration correction is obtained. The equivalent optical power, total equivalent optical power ratio, blue-red optical power difference, and dispersion focus shift ratio of the front lens group, middle lens group, and rear lens group preferably fall within the range of Table 1.

[0063] Table 1. Envelope of Parameters for Three-Group Architecture Design

[0064] The resulting feasible design examples, including eight-lens, nine-lens, and ten-lens designs (including the tenth lens 10), are shown in Table 2: Table 2 Completed Design Cases

[0065] Therefore, this three-group architecture, through the cooperation of the front, middle, and rear lens groups, achieves high-quality dispersion, focus shift, and aberration control over a wide numerical aperture range with a limited number of lenses. Each lens group undertakes a specific optical function, and the three lens groups are interconnected through the inter-group air gap and their respective equivalent optical power adjustments, enabling a series of expansions at different numerical apertures, working distances, and axial dispersion ranges. The specific number of lenses, material combinations, and inter-group air gaps of the front, middle, and rear lens groups can be adjusted according to the design requirements of the target numerical aperture, working distance, and axial dispersion range, smoothly expanding from low to high numerical apertures without requiring a complete reconfiguration.

[0066] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0067] The above embodiments are merely illustrative of several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A spectral confocal dispersive mirror assembly architecture based on functional partitioning, characterized in that, It includes a front lens group, a middle lens group, and a rear lens group arranged coaxially along the optical axis, with inter-group air gaps provided between the front lens group and the middle lens group, and between the middle lens group and the rear lens group; The front lens group is located at the incident end. The front lens group consists of at least two lenses, including at least one lens made of a low Abbe number material or a high refractive index material. The front lens group is used to introduce the dispersion slope while controlling the spherical aberration, coma, and incident aperture of the incident beam, and to complete dispersion pre-shaping and front-end optical power allocation at the incident end. The middle lens group consists of at least two lenses. The middle lens group is used to receive the light beam formed by the front lens group and to perform transition correction for spherical aberration, coma, and dispersion, maintaining an adjustable balance of numerical aperture, aberration, and dispersion during the numerical aperture expansion process of the system. The rear lens group is located at the exit end. The rear lens group consists of at least two lenses, including at least one lens made of low Abbe number material. The rear lens group is used to complete high numerical aperture convergence, working distance compression, and to finally place the axial dispersive focus shift formed by the front lens group and the middle lens group onto the measurement space, so that the focal points of different wavelengths are controlled to be separated within the axial measurement range. The blue-red light power difference of the rear lens group is greater than the blue-red light power difference of the front lens group and the middle lens group; The equivalent optical power ratio and the blue-red optical power difference ratio of each of the front lens group, the middle lens group, and the rear lens group are determined by the number of lenses, the material combination, and the air gap between the groups.

2. The spectral confocal dispersive mirror group architecture based on functional partitioning according to claim 1, characterized in that, The equivalent optical power of the front lens group is configured with positive and negative optical power surfaces canceling each other out. In a higher numerical aperture design, the front lens group increases the proportion of the total equivalent optical power, while in a lower numerical aperture design, the front lens group decreases the proportion of the total equivalent optical power.

3. The spectral confocal dispersive mirror group architecture based on functional partitioning according to claim 1, characterized in that, The middle lens group is located at the maximum beam aperture of the system between the front lens group and the rear lens group. When the numerical aperture increases, the middle lens group increases the proportion of dispersion and focus shift.

4. A method for designing a spectral confocal dispersive mirror assembly architecture based on functional differentiation, characterized in that, Includes the following steps: S1, the total equivalent optical power of the system and the required total blue-red optical power difference are determined by the target numerical aperture, working distance and axial dispersion range; S2, based on a three-group architecture, scans or solves the equivalent optical power of the front lens group, the equivalent optical power of the middle lens group, and the equivalent optical power of the rear lens group, while adjusting the air gap between the two components to make the total optical power formula of the system meet the target value. S3, under the constraints of selectable materials and low Abbe number materials, calculate or estimate the blue-red light power difference of the front lens group, the blue-red light power difference of the middle lens group, and the blue-red light power difference of the rear lens group, so that the total blue-red light power difference of the system meets the target value. S4, calculate the normalized contribution of each lens group to the axial dispersion focus shift of the system, and determine the functional allocation of the rear lens group as the main dispersion focus shift group, the front lens group as the pre-shaping group, and the middle lens group as the transition and correction group. S5 uses numerical aperture relation and aberration scale relation to eliminate combinations of excessively large beam aperture, excessively strong single lens group coupled optical focal length, or uncontrollable aberrations, to obtain an implementable parameter envelope. Based on the parameter envelope, further testing is conducted to obtain a design scheme that meets specific requirements for numerical aperture, working distance, axial dispersion range, and aberration correction.

5. The method for designing a spectral confocal dispersive mirror group architecture based on functional partitioning according to claim 4, characterized in that, In S2, the front lens group is arranged sequentially along the optical axis. Middle lens group Rear lens group The air interval between the two groups is denoted as follows: and ; System total equivalent optical power The expression is: 。 6. The method for designing a spectral confocal dispersive mirror group architecture based on functional partitioning according to claim 5, characterized in that, Sensitivity coefficient is defined in S2. ,but: in, Indicates the first The sensitivity of each lens group This is to reflect the degree of influence of changes in the equivalent optical power of different lens groups on the total equivalent optical power of the system.

7. The method for designing a spectral confocal dispersive mirror group architecture based on functional partitioning according to claim 6, characterized in that, S3 The equivalent optical power of a lens group as a function of wavelength is expressed as follows: in, Indicates the first The difference in blue and red light power between the lens groups Indicates the wavelength of blue light. Indicates the wavelength of red light. This represents the equivalent geometric coefficients formed by the curvature, thickness, and structure of the lens assembly. Indicates the first The refractive index of the optical materials used in each lens group; Total equivalent optical power of the system Performing a first-order expansion, we obtain the total blue-red optical power difference of the system: in, The total blue-red light intensity difference of the system.

8. The method for designing a spectral confocal dispersive mirror group architecture based on functional partitioning according to claim 7, characterized in that, S4 The normalized contribution of each lens group to the axial dispersion focal shift of the system is expressed as: in, This indicates the normalization contribution.

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