Catadioptric zoom-panorama annular optical system and design method thereof

Abstract

This invention relates to a catadioptric zoom panoramic ring optical system and its design method, belonging to the field of optical system design technology. To address the problem that pipeline inspection systems cannot achieve both large field-of-view coarse inspection and small field-of-view fine inspection, the method includes: deriving the relationship between the curvature radius of the front-end mirror and the field of view angle of the zoom lens group, establishing the initial structure of the front-end mirror; deriving the positions of the sagittal and meridional image points of a certain inspection point after passing through the front-end mirror, with the optimal image point located between the meridional and sagittal image points and close to one-third of the meridional image point; solving for the optimal image point position of the front-end mirror; fitting the optimal image points for different inspection points to obtain the optimal image plane position and shape of the front-end mirror; the image plane of the front-end mirror is the object plane of the zoom lens group, and the zoom lens group is designed under this object plane position and curvature; after the zoom lens group design is completed, the zoom lens group and the front-end mirror are spliced ​​and optimized.

Description

Technical Field

[0001] This invention belongs to the field of optical system design technology, specifically relating to a catadioptric zoom panoramic ring optical system and its design method. Background Technology

[0002] In recent years, panoramic annular optical systems have been widely used in security, medical, aviation, and inspection fields. The catadioptric panoramic annular optical system, with its front-end reflector enabling ultra-wide field-of-view light collection, has become a typical representative of panoramic annular optical systems. Panoramic annular optical systems can achieve rapid panoramic imaging, eliminating the need for image stitching and scanning, thus improving processing speed and efficiency. Furthermore, their integrated design and small size offer significant potential for applications across various fields.

[0003] While catadioptric fixed-focus panoramic ring-type systems can achieve rapid, one-shot imaging across a panoramic field of view, their resolution is limited by the large field of view when paired with a subsequent single detector. This presents a contradiction: they cannot simultaneously obtain an ultra-wide field of view and discern object details, thus limiting their application in various situations and needs. Therefore, there is an urgent need to invent a new system that possesses both wide-area search and detail discrimination capabilities, capable of adapting to different scenarios and demands for both wide-field search and detail discrimination without adding additional detectors. Summary of the Invention

[0004] To address the problem that fixed-focus panoramic ring-band systems cannot simultaneously achieve wide-field search and high-resolution detail discrimination, this invention provides a catadioptric zoom panoramic ring-band optical system and its design method. By synchronously adjusting the zoom group and compensation group of the catadioptric panoramic ring-band optical system, the focal length and field of view coverage of the panoramic ring-band optical system are changed. Thus, when adapted to a single detector, it is possible to flexibly and quickly switch between short focal length wide-field search and long focal length high-resolution detail discrimination.

[0005] A catadioptric zoom panoramic ring optical system includes: a front mirror, an aperture stop, a zoom lens group, and a detector arranged sequentially along the optical axis from the object side to the image side. The light emitted from the front mirror passes through the aperture stop and the zoom lens group, and is then received by the detector to form an image. The front mirror expands the system's field of view. The aperture stop is located between the front mirror and the zoom lens group, limiting the aperture of the imaging optical beam. The zoom lens group adjusts the focal length of the catadioptric zoom panoramic ring optical system.

[0006] A design method for a catadioptric zoom panoramic ring optical system is characterized by using the inherent image plane curvature calculated by the front-end mirror as a basis, and performing a matching design under the condition that the object plane of the zoom lens group has the same curvature. Under this premise, the catadioptric zoom panoramic ring optical system can be designed and then spliced ​​together by separately designing the front-end mirror and the zoom lens group. The method includes the following steps:

[0007] Step 1: Calculate the field of view of the zoom lens group in the catadioptric zoom panoramic ring optical system. Calculate the angle between the principal ray emitted from the object point, passing through the center of the aperture stop, reflected by the front mirror with a given radius of curvature, and the optical axis when it reaches the center of the aperture stop. This angle is defined as the field of view of the zoom lens group in the catadioptric zoom panoramic ring optical system.

[0008] Step 2: Calculate the image point position of the front mirror in the reflective zoom panoramic ring optical system. Calculate the positions of the sagittal and meridional image points formed after the principal ray emitted from the object point reaches the center of the aperture stop and is reflected by the front mirror, thus obtaining the image point position of the front mirror. By calculating the corresponding image points of all object points according to Step 2 for different object points, a point cloud imaged by the front mirror is formed.

[0009] Step 3: Calculate the image plane curvature of the front mirror in the reflective zoom panoramic ring optical system. Approximate the image points corresponding to different object points of the front mirror as spheres, and use the spherical equation to approximate the point cloud of the front mirror's image plane to obtain the image plane curvature of the front mirror. This simplifies the mathematical representation and calculation of the front mirror's image plane curvature, making the design process more efficient.

[0010] Step 4: Load the field of view and object plane shape of the zoom lens group in the catadioptric zoom panoramic ring optical system. The field of view angle of the zoom lens group calculated in Step 1 is loaded onto the field of view parameters of the zoom lens group in the catadioptric zoom panoramic ring optical system. The spherical approximation equation for the curvature of the front reflector image plane in the catadioptric zoom panoramic ring optical system, obtained in Step 3, is loaded onto the object plane of the zoom lens group in the catadioptric zoom panoramic ring optical system. Under the premise of the loaded object plane position and curvature, the zoom lens group in the catadioptric zoom panoramic ring optical system is matched and adapted.

[0011] Step 5: Individual Design of the Zoom Lens Group in the Catadioptric Zoom Panoramic Ring Optical System. Following the settings in Step 4, and based on the existing zoom differential equation, determine the focal length of each component to ensure the zoom lens group has good zoom and compensation performance, achieving image plane stability while changing the focal length, thus completing the individual design of the zoom lens group in the catadioptric zoom panoramic ring optical system.

[0012] Step Six: Joining the front mirror and zoom lens group in the catadioptric zoom panoramic ring optical system. Join the front mirror of the catadioptric zoom panoramic ring optical system with the given radius obtained in Step One with the zoom lens group obtained in Step Five.

[0013] Step 7: Optimization of the catadioptric zoom panoramic ring optical system. Based on the stitching results of Step 6, and without changing the structural form, fine-tuning and optimization are performed on parameters such as the position and radius of curvature of some optical elements.

[0014] The beneficial effects of this invention are:

[0015] The catadioptric zoom panoramic ring optical system of this invention changes the focal length and field of view coverage of the panoramic ring optical system by adjusting the positions of the zoom group and compensation group. This allows for zooming of the catadioptric zoom panoramic ring optical system, enabling flexible and rapid switching between short focal length, large field of view wide-area search and long focal length, high-resolution detail resolution, even when adapted to a single detector. In short focal length mode, a wide field of view can be obtained; in long focal length mode, the system's imaging resolution can be improved, which is beneficial for detail resolution. This resolves the contradiction of simultaneously achieving a large field of view and high resolution in a single system without the need for additional detectors. The system has advantages such as low cost, low power consumption, integration, and compact size, and possesses wide applicability and flexibility.

[0016] The design method for a catadioptric zoom panoramic ring optical system of the present invention allows for the separate design and stitching of the front-end mirror and the zoom lens assembly with corresponding object plane curvature. This enables rapid design and optimization of the catadioptric zoom panoramic ring optical system, effectively guiding the design process of such systems. Addressing the image plane curvature caused by the catadioptric front-end mirror, the present invention provides a method for calculating the optimal image plane of the front-end mirror, as well as a method for calculating and fitting the image plane curvature. Based on the calculated image plane curvature, the method designs the object plane matching settings of the zoom lens assembly, providing a reasonable basis for the stitching of the front-end mirror and the zoom lens assembly. The design method for a catadioptric zoom panoramic ring optical system provided by the present invention effectively improves the design efficiency and effect of the system, ensuring the design results, avoiding blind optimization, and greatly simplifying the complexity of system design. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the catadioptric zoom panoramic ring optical system of the present invention;

[0018] Figure 2 This is a schematic diagram of the optical path of the catadioptric zoom panoramic ring optical system of the present invention;

[0019] Figure 3 A schematic diagram showing the determination of the noon image point, sagittal image point, and image point of the front-end reflecting mirror for a catadioptric zoom panoramic ring optical system.

[0020] Figure 4 A schematic diagram showing the determination of the noon image point, sagittal image point, and image point of the front-end reflecting mirror for a catadioptric zoom panoramic ring optical system.

[0021] Figure 5 This is a layout diagram of the catadioptric zoom panoramic ring optical system in Example 1 at short focal length.

[0022] Figure 6 This is a layout diagram of the catadioptric zoom panoramic ring optical system in the focal state in Example 1;

[0023] Figure 7 This is a layout diagram of the catadioptric zoom panoramic ring optical system in the telephoto state in Example 1;

[0024] Figure 8 The MTF of the catadioptric zoom panoramic ring optical system in Example 1 at short focal length;

[0025] Figure 9 The MTF in the telescoping zoom panoramic ring optical system of Example 1 in the focal state;

[0026] Figure 10 The MTF of the catadioptric zoom panoramic ring optical system in Example 1 in telephoto mode;

[0027] In the diagram, T1 is the object plane, T2 is the front mirror, T3 is the aperture stop, T4 is the zoom lens group, T5 is the detector (image plane), G1 is the front fixed group, G2 is the zoom group, G3 is the compensation group, G4 is the rear fixed group, S1 is the first cemented lens group, S2 is the second cemented lens group, S3 is the third cemented lens group, S4 is the fourth cemented lens group, 1 is the first lens, 2 is the second lens, 3 is the third lens, 4 is the fourth lens, 5 is the fifth lens, 6 is the sixth lens, 7 is the seventh lens, 8 is the eighth lens, 9 is the ninth lens, 10 is the tenth lens, 11 is the eleventh lens, 12 is the twelfth lens, Q1 is the sagittal image plane of the front mirror, Q2 is the image plane of the front mirror, and Q3 is the spherical image plane of the front mirror. Detailed Implementation

[0028] The present invention will now be described in further detail with reference to the accompanying drawings.

[0029] like Figure 1As shown, the catadioptric zoom panoramic ring optical system includes: a front mirror T2, an aperture stop T3, a zoom lens group T4, and a detector T5 arranged coaxially from the object side to the image side along the optical axis. The light rays emitted from the front mirror T2 pass through the aperture stop T3 and the zoom lens group T4, and are then received by the detector T5 to form an image. The front mirror T2 expands the system's field of view; the aperture stop T3, located between the front mirror T2 and the zoom lens group T4, limits the aperture of the imaging optical beam; and the zoom lens group T4 adjusts the focal length of the catadioptric zoom panoramic ring optical system.

[0030] The zoom lens group T4 consists of the front fixed group G1, the zoom group G2, the compensation group G3, and the rear fixed group G4.

[0031] The front fixation group G1 includes a first cemented lens group S1, which has positive optical power;

[0032] The first cemented lens group S1 is composed of two meniscus lenses, a first lens 1 and a second lens 2, cemented together. The first lens 1 has negative optical power and the second lens 2 has positive optical power.

[0033] The zoom group G2 includes a second cemented lens group S2, which has negative optical power;

[0034] The second cemented lens group S2 is composed of two meniscus lenses, a third lens 3 and a fourth lens 4, cemented together. The third lens 3 has negative optical power, and the fourth lens 4 has positive optical power.

[0035] The compensation group G3 includes a fifth lens 5 and a third cemented lens group S3 in sequence. The fifth lens 5 has positive optical power; the third cemented lens group S3 has positive optical power.

[0036] The third cemented lens group S3 includes a sixth lens 6 and a seventh lens 7 in sequence. The sixth lens 6 has positive optical power, and the seventh lens 7 has negative optical power.

[0037] The rear fixing group G4 sequentially includes a fourth cemented lens group S4, a tenth lens 10, an eleventh lens 11, and a twelfth lens 12. The fourth cemented lens group S4 and the twelfth lens 12 have negative optical power; the tenth lens 10 and the eleventh lens 11 have positive optical power; the fourth cemented lens group S4 sequentially includes an eighth lens 8 and a ninth lens 9. The eighth lens 8 has positive optical power, and the ninth lens 9 has negative optical power.

[0038] The present invention discloses a design method for a catadioptric zoom panoramic ring optical system, characterized in that, based on the calculated inherent image plane curvature of the front-end mirror, a matching design is performed with the zoom lens group having the same curvature. Under this premise, the catadioptric zoom panoramic ring optical system can be designed and then spliced ​​together by separately designing the front-end mirror and the zoom lens group, including the following steps:

[0039] Step 1: Calculate the field of view of zoom lens group T4 in the catadioptric zoom panoramic ring optical system;

[0040] Perform ray tracing on the principal ray emitted from the object point that passes through the center of the aperture stop T3; calculate the angle θ1 between the principal ray and the optical axis when it reaches the center of the aperture stop T3 after being reflected by the front mirror T2 with a given radius of curvature. This angle is defined as the field of view θ1 of the zoom lens group T4 in the catadioptric zoom panoramic ring optical system.

[0041] like Figure 2 As shown, according to the law of reflection, when the light ray emitted from object point A is reflected by the front mirror T2, the reflected ray will intersect at point B on the optical axis. Let θ1 be the angle between the principal ray emitted from object point A and the optical axis at the center of the aperture stop T3 after reflection by the front mirror T2. θ1 also represents the field of view of the zoom lens group T4. Point A is the point being tested, point A2 is the intersection of the principal ray and the front mirror T2, point B is the intersection of the principal ray and the optical axis, point C is the center of curvature of the front mirror T2, point B1 is the intersection of the extension of the principal ray and the optical axis, d is the distance from point B to the vertex of the front mirror T2, R is the radius of curvature of the front mirror T2, I1 is the angle of incidence of the principal ray, I2 is the angle of reflection, and I3 and I4 are the vertical angles of I2 and I1, respectively. Establish a coordinate system with the vertex of the front reflector T2 as the origin. The positive x-axis is to the right along the optical axis, and the positive y-axis is to the up perpendicular to the optical axis. The coordinates of point A are (a, D / 2) and the coordinates of point B1 are (-d, 0).

[0042] Applying the law of sine to ΔBA2C and ΔAA2C, we have the following expressions:

[0043]

[0044]

[0045] In ΔBA2C, there is

[0046] I1+I2=θ1+θ 11

[0047] According to the law of reflection, then we have

[0048] I1=I2=I3=I4=I

[0049] θ 11=θ2+∠ACB1

[0050]

[0051] The final relationship between the radius of curvature of the front reflecting mirror T2 and the field of view of the zoom lens group T4 is as follows:

[0052]

[0053] Given an object point A(a, D / 2), the values ​​of parameters a and D are known. By fixing the position of the aperture stop T3, the distance d from the aperture stop to the vertex of the front mirror T2 can be obtained. Then, the relationship between the field of view of the zoom lens group T4 and the radius of curvature of the front mirror T2 can be obtained. The field of view of the zoom lens group T4 can be calculated using this formula.

[0054] Step 2: Calculate the image point position of the front mirror T2 in the catadioptric zoom panoramic ring optical system; calculate the positions of the sagittal image point A1 and the meridional image point A3 formed by the principal ray emitted from the object point through the center of the aperture stop T3 and reflected by the front mirror T2, thereby calculating the image point position of the front mirror T2.

[0055] like Figure 3 As shown, A is the object point, A1 is the intersection of line BA1 and AC, and A1 is the sagittal focus; A2 is the intersection of the principal ray BA1 and the mirror; A3 is the meridional focus; C is the center of curvature of the mirror; B is the intersection of the principal ray and the optical axis; -t represents the length of line segment AA2, and t' represents the length of line segment A2A3.

[0056] Solving the system of equations for lines BA1 and AC simultaneously, we can obtain the intersection point, which is the image point of the arc sagitta, A1(x). s y s Coordinates are

[0057]

[0058] By simultaneously solving the equations of line BA1 and the surface shape of the front reflecting mirror T2, we can obtain the intersection point A2(x). A2 y A2 Coordinates are

[0059]

[0060]

[0061] Meridian image point A3(x t y t The coordinates can be obtained by the following formula.

[0062]

[0063] Image point (x) my m Coordinates are

[0064]

[0065] Step 3: Calculate the image plane curvature of the front mirror T2 in the catadioptric zoom panoramic ring optical system;

[0066] Step 2 is followed to calculate the corresponding image points of all object points as imaged by the front-end mirror T2. The image points corresponding to different object points on the front-end mirror T2 are approximated as spheres, and the point cloud of the image surface of the front-end mirror T2 is approximated by the spherical equation, thereby simplifying the mathematical description and computation of the system and making the design process more efficient.

[0067] like Figure 4 As shown, Q1 is the sagittal image plane of the front reflector, Q2 is the image plane of the front reflector, and Q3 is the approximate spherical image plane of the front reflector.

[0068] Step 4: Adjust the field of view and object plane shape of zoom lens group T4 in the catadioptric zoom panoramic ring optical system; the specific process is as follows:

[0069] S4-1 Calculation of the object distance and object surface curvature of the zoom lens group T4;

[0070] Step two allows us to calculate the meridional and sagittal image point positions of the front-end mirror T2, thus determining its image point position. Step three involves drawing image points for different object points, forming a point cloud of the front-end mirror T2. This point cloud may exhibit complex and varied shapes, making it difficult to represent with simple equations. To simplify calculations and facilitate the design of the zoom lens assembly T4, we employ an approximation method, approximating the image points corresponding to different object points of the front-end mirror T2 with a spherical equation. This spherical equation transforms into the spherical image plane of the front-end mirror T2. The object plane of the zoom lens assembly T4 is also the image plane of the front-end mirror T2. The approximate spherical equation obtained in step three is then applied to the object plane of the zoom lens assembly T4, and the zoom lens assembly T4 is designed to match and adapt to the position and curvature of this object plane.

[0071] S4-2. Load the field of view of zoom lens group T4 in the catadioptric zoom panoramic ring optical system calculated in step one as the field of view parameters of zoom lens group T4 designed separately.

[0072] The field of view of zoom lens group T4 can be calculated through step one;

[0073] Step 5: Individual design of zoom lens group T4 in catadioptric zoom panoramic ring optical system; following the design in Step 4, and based on the existing zoom differential equation, determine the focal length of each component to ensure that zoom lens group T4 has good zoom and compensation performance, achieve focal length change while ensuring image plane stability, and complete the individual design of zoom lens group T4.

[0074] Step Six: Joining the front mirror T2 and zoom lens group T4 in the catadioptric zoom panoramic ring optical system; Join the front mirror T2 of the given radius obtained in Step One with the optical model of zoom lens group T4 obtained in Step Five.

[0075] Step Seven: Based on the stitching results of Step Six, and without changing the structural form, fine-tune and optimize parameters such as the position and radius of curvature of some optical elements. This further improves the optical performance and image clarity of the system. Building upon the first six steps, the optimization time in Step Seven is significantly reduced, effectively improving optimization efficiency. Simultaneously, the design results of the catadioptric zoom panoramic ring optical system are also superior, and the design quality is improved accordingly.

[0076] This provides a design methodology for a catadioptric zoom panoramic ring optical system that can adapt to zoom requirements in different situations.

[0077] Example 1:

[0078] The front reflector T2 is a convex reflector with a radius of curvature of 40 mm. After the object point on the object plane T1 passes through the front reflector T2, the angle between the principal ray and the optical axis is 9.5° and 16.9°. Therefore, it can be seen that the field of view of the zoom lens group T4 is 16.9° at short focal length and 9.5° at long focal length.

[0079] In this embodiment, the coordinates of the front-end reflector T2 sagittal image point are calculated, as shown in Table 1.

[0080] Table 1:

[0081]

[0082] The coordinates of the T2 meridional image point of the front reflector are calculated and shown in Table 2.

[0083] Table 2:

[0084]

[0085] The coordinates of the image point T2 of the front reflector are calculated and shown in Table 3.

[0086] Table 3:

[0087]

[0088] In this embodiment, the image points corresponding to different object points of the front reflector T2 are approximated as spheres. The image point cloud of the front reflector T2 is approximated by the spherical equation to obtain the image curvature of the front reflector T2. The image curvature is a convex spherical surface with a curvature radius of 74mm.

[0089] In this embodiment, a convex spherical surface with a radius of curvature of 74 mm is loaded onto the object surface of the zoom lens group T4, and the field of view of the zoom lens group T4 is set to 9.5° for telephoto and 16.9° for short focal length.

[0090] In this embodiment, in order to ensure smooth docking of the front reflector T2 and the zoom lens group T4, the aperture stop T3 is placed between the two. Therefore, the exit pupil position of the front reflector T2 is the same as the entrance pupil position of the zoom lens group T4, and the size of the exit pupil of the front reflector T2 and the size of the entrance pupil of the zoom lens group T4 are equal, both being 4mm.

[0091] In this embodiment, the zoom lens group T4 is designed in the form of positive group compensation, and is divided into four parts: front fixed group G1, zoom group G2, compensation group G3 and rear fixed group G4. The focal length of each component of the zoom lens group T4 is calculated by the zoom differential equation as shown in Table 4.

[0092] Table 4:

[0093] Front fixed group Variable multiplication group Compensation Group Rear fixed group 210mm -55mm 30mm 220mm

[0094] The specific structural parameters of the zoom lens group T4 are shown in Table 5.

[0095] Table 5:

[0096]

[0097] like Figure 5 , Figure 6 and Figure 7 As shown, the front reflector T2 of the catadioptric zoom panoramic imaging optical system is stitched together with the zoom lens group T4 of the catadioptric zoom panoramic imaging optical system.

[0098] In this embodiment, the stitched catadioptric zoom panoramic imaging optical system is optimized and adjusted using Zemax software. The final imaging quality of the catadioptric zoom panoramic imaging optical system is as follows: Figure 8 , Figure 9 and Figure 10As shown, at short focal lengths, the MTF of the catadioptric zoom panoramic imaging optical system is greater than 0.42 across the entire field of view at a spatial frequency of 93 mm / lp. At medium focal lengths, the MTF is greater than 0.5 across the entire field of view at a spatial frequency of 93 mm / lp. At long focal lengths, the MTF is greater than 0.5 across the entire field of view. The MTF of the catadioptric zoom panoramic ring optical system is close to the diffraction limit, indicating good image quality.

Claims

1. A catadioptric zoom panoramic ring optical system, characterized in that, It includes a front reflector (T2), an aperture stop (T3), a zoom lens group (T4), and a detector (T5) arranged sequentially from the object side to the image side along the optical axis and coaxially disposed. The light rays emitted from the front reflector (T2) are received by the detector (T5) and imaged after passing through the aperture stop (T3) and the zoom lens group (T4). The front mirror (T2) expands the system's field of view; the aperture stop (T3) is located between the front mirror (T2) and the zoom lens group (T4) to limit the imaging optical beam aperture; the zoom lens group (T4) adjusts the focal length of the catadioptric zoom panoramic ring optical system. The zoom lens group (T4) consists of a front fixed group (G1), a zoom group (G2), a compensation group (G3), and a rear fixed group (G4); The front fixation group (G1) includes a first cemented lens group (S1) having positive optical power; The first cemented lens group (S1) is composed of two meniscus lenses, a first lens (1) and a second lens (2), cemented together. The first lens (1) has negative optical power, and the second lens (2) has positive optical power. The zoom group (G2) includes a second cemented lens group (S2) which has negative optical power; The second cemented lens group (S2) is composed of two meniscus lenses cemented together: a third lens (3) and a fourth lens (4). The third lens (3) has negative optical power, and the fourth lens (4) has positive optical power. The compensation group (G3) includes a fifth lens (5) and a third cemented lens group (S3) in sequence. The fifth lens (5) has positive optical power; the third cemented lens group (S3) has positive optical power. The third cemented lens group (S3) includes a sixth lens (6) and a seventh lens (7) in sequence. The sixth lens (6) has positive optical power and the seventh lens (7) has negative optical power. The rear fixing group (G4) sequentially includes a fourth cemented lens group (S4), a tenth lens (10), an eleventh lens (11), and a twelfth lens (12). The fourth cemented lens group (S4) and the twelfth lens (12) have negative optical power; the tenth lens (10) and the eleventh lens (11) have positive optical power; the fourth cemented lens group (S4) sequentially includes an eighth lens (8) and a ninth lens (9). The eighth lens (8) has positive optical power, and the ninth lens (9) has negative optical power. The zoom lens group (4) has a total of 12 lenses with optical power.

2. A design method for a catadioptric zoom panoramic ring optical system according to claim 1, characterized in that, Based on the inherent image plane curvature calculated by the front-end mirror (T2), a matching design is performed with the zoom lens group (T4) having the same curvature. Under this premise, the catadioptric zoom panoramic ring optical system is designed by separately designing the front-end mirror (T2) and the zoom lens group (T4) and then stitching them together. This method includes the following steps: Step 1: Calculate the field of view of the zoom lens group (T4) in the catadioptric zoom panoramic ring optical system; perform ray tracing on the principal ray emitted from the object point that passes through the center of the aperture stop (T3); calculate the angle between the principal ray and the optical axis when it reaches the center of the aperture stop (T3) after being reflected by the front mirror (T2) with a given radius of curvature. This angle is defined as the field of view of the zoom lens group (T4) in the catadioptric zoom panoramic ring optical system. Step 2: Calculate the image point position of the front mirror (T2) in the catadioptric zoom panoramic ring optical system; calculate the positions of the sagittal and meridional image points formed by the principal ray emitted from the object point through the center of the aperture stop (T3) after reflection by the front mirror (T2), thus obtaining the image point position of the front mirror (T2). Step 3: Calculate the image plane curvature of the front mirror (T2) in the catadioptric zoom panoramic ring optical system; calculate the corresponding image points of all object points imaged by the front mirror (T2) according to Step 2; approximate the image points corresponding to different object points of the front mirror (T2) as spheres, and use the spherical equation to approximate the image plane point cloud of the front mirror (T2); Step 4: Load the field of view and object plane shape of the zoom lens group (T4) in the catadioptric zoom panoramic ring optical system; load the field of view angle of the zoom lens group (T4) in the catadioptric zoom panoramic ring optical system calculated in Step 1 as the field of view parameters of the separately designed zoom lens group (T4); load the approximate spherical equation obtained in Step 3 onto the object plane of the zoom lens group (T4), and perform matching and adaptation design on the zoom lens group (T4) under this object plane position and curvature. Step 5: Individual design of zoom lens group (T4) in catadioptric zoom panoramic ring optical system; according to the design in Step 4, and based on the existing zoom differential equation, determine the focal length of each component to ensure that the zoom lens group (T4) has good zoom and compensation performance, realize the image plane stability while changing the focal length, and complete the individual design of zoom lens group (T4). Step 6: Joining the front mirror (T2) and zoom lens group (T4) in the catadioptric zoom panoramic ring optical system; Join the front mirror (T2) of the given radius obtained in Step 1 with the optical model of the zoom lens group (T4) obtained in Step 5. Step 7: Optimization of the catadioptric zoom panoramic ring optical system; Based on the stitching results in Step 6, while keeping the structural form unchanged, the positions and radii of curvature of some optical elements are finely adjusted and optimized.

3. The design method of the catadioptric zoom panoramic ring optical system according to claim 2, characterized in that, Step one specifically involves: Based on the position and direction of the principal ray, the equations for the distance d between the aperture stop (T3) and the vertex of the front mirror (T2), the detection position (a, D / 2), the field of view angle θ1 of the zoom lens group (T4), and the radius of curvature R of the front mirror (T2) are derived, and the relationships are as follows: ， Point C is the curvature center of the front mirror (T2). For a given test point A(a,D / 2) on the object surface, fix the position of the aperture stop, obtain the value of the distance d from the aperture stop (T3) to the vertex of the front mirror (T2), and obtain the relationship between the field of view of the zoom lens group (T4) and the curvature radius of the front mirror (T2). The field of view of the zoom lens group (T4) can be calculated using this formula.

4. The design method of the catadioptric zoom panoramic ring optical system according to claim 3, characterized in that, Step two specifically involves: Step 1: Determine the coordinates of the sagittal image point of the front reflector (T2); The sagittal image point of the front reflector (T2) is obtained using the following formula. coordinate: ； The second step is to determine the coordinates of the meridional image point of the front reflector (T2); First, the intersection point of the principal ray and the front reflector (T2) is derived. The coordinates are: ； Meridian Image Point A3 The coordinates can be obtained by the following formula: ， in, It is the angle of incidence of the principal ray. It is the reflection angle. for Vertical angles, -t represents line segment The length of the line segment, t' represents the length of the line segment. Length; Step 3: Solve for the image point coordinates; Like a point ( The coordinates are: .

5. The design method of the catadioptric zoom panoramic ring optical system according to claim 4, characterized in that, Step three specifically involves: According to step two, calculate the corresponding image points of different object points after passing through the front mirror (T2) to obtain the image point distribution point cloud formed by the front mirror (T2); approximate the corresponding image points of different object points after passing through the front mirror (T2) using the spherical equation to achieve the spherical equation approximation fitting of the image point cloud of the front mirror (T2).

Images