Athermalization common-image-plane short-focus objective optical system and application thereof
By using a thermalized co-image plane short-focal-length objective lens optical system with specific lens materials and a rotating light-blocking plate design, the problem of existing short-focal-length systems being unable to search over a wide area is solved, achieving high-definition imaging of targets and environmental adaptability, simplifying the optical structure, and reducing processing and assembly requirements.
Patent Information
- Application Number
- CN202511535510.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-27
- Publication Date
- 2026-02-27
AI Technical Summary
Existing short-focus systems cannot perform large-scale searches of targets within a certain distance range, and they also suffer from problems such as complex structure, inability to achieve calorimetric design, high processing requirements, and poor environmental adaptability.
An athermal co-image plane short-focal-length objective lens optical system is adopted, including objective lens group A, a mirror, a prism group, objective lens group B, and an objective lens group switching device. The short-focal-length objective lens is switched between the upper and lower optical axes by rotating the light-blocking plate. Co-image plane imaging is achieved by using specific lens materials and optical structure design.
It achieves high-definition imaging of targets, simplifies optical structure, reduces processing and assembly requirements, improves environmental adaptability and economy, and ensures that imaging quality remains unchanged at different temperatures.
Smart Images
Figure CN121578468A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of optical assemblies or optical lenses, and particularly relates to athermalized co-image plane short-focus objective optical system and application thereof. BACKGROUND
[0002] Short-focus objectives are widely used in environmental monitoring, digital video recording and other fields, and are mainly used for obtaining target video images, and can meet the technical requirements of searching and capturing target scenes in a large range, and are very advantageous in searching for moving targets.
[0003] Most short-focus systems in the prior art adopt a technical scheme of a single short-focus objective, and can only search a target in a fixed distance, and cannot search a target in a certain distance range. In order to solve the above problems, a short-focus continuous zoom objective is usually used in a traditional design scheme. This objective mainly adopts a sliding mode of a plurality of lens combinations, or adopts a mode of special materials and high-order aspheric surfaces to reduce the number of lenses and the length and size of the objective. However, this objective has many shortcomings and deficiencies, such as complex structure, inability to realize athermalized design, high processing requirements, poor environmental adaptability, high assembly requirements, poor process and economic performance, and the like.
[0004] Therefore, it is particularly important to develop an athermalized co-image plane short-focus objective optical system. SUMMARY
[0005] The main purpose of the present application is to overcome the above-mentioned problems and deficiencies in the prior art, and to provide an athermalized co-image plane short-focus objective optical system. The system comprises an objective group A, a mirror 2, a prism group 4, an objective group B, and an objective group switching device. The objective group A and the objective group B are arranged side by side on the side close to the object, the mirror 2 is arranged obliquely behind the objective group A and its reflection direction is towards the prism group 4, the objective group B, the prism group 4 and the objective group switching device are coaxially arranged in sequence, and the objective group switching device can be switched up and down behind the objective group A and behind the objective group B, so as to switch the short-focus objective for imaging.
[0006] In the above scheme, the objective group A is specifically a front fixed objective group a 1. The front fixed objective group a 1 comprises a first lens a, a second lens b and a third lens c coaxially arranged in sequence from the object side to the image side, wherein the first lens a and the second lens b are glued together to form a first glued lens.
[0007] More specifically, the first lens a is specifically a biconvex lens with positive focal power, and the material thereof is H-ZK20, and the curvature radii of the front and back surfaces satisfy 20mm
[0008] More specifically, the second lens b is specifically a double-concave lens with negative focal length, and the material thereof is H-ZLAF53B, and the radii of curvature of the front and back surfaces thereof satisfy -40mm
[0009] More specifically, the third lens c is specifically a double-convex lens with positive focal length, and the material thereof is H-ZK20, and the radii of curvature of the front and back surfaces thereof satisfy 20mm
[0010] In the above scheme, the mirror 2 (i.e. d) is specifically a plane mirror arranged at an angle of 45°. The light passes through the objective lens group A, is reflected vertically downward by the mirror 2, enters the prism group 4, and is emitted to the right.
[0011] In the above scheme, the system further comprises a rear objective lens group a 3. The rear objective lens group a 3 is arranged between the mirror 2 and the prism group 4, and is used to compensate for the remaining aberration of the objective lens group A.
[0012] More specifically, the rear objective lens group a 3 (i.e. the fourth lens e) is specifically a meniscus lens with negative focal length, and the concave surface thereof faces the mirror 2.
[0013] More specifically, the material of the meniscus lens is H-QK3L, and the radii of curvature of the front and back surfaces thereof satisfy -15mm
[0014] In the above scheme, the prism group 4 is formed by cementing two split prisms g and h of the same size along the inclined surface. The prism group 4 can refract the light from the objective lens group A, or can transmit the light from the objective lens group B.
[0015] In the above scheme, the objective lens group B comprises, in order from the object side to the image side, a front fixed objective lens group b 6, a diaphragm 7, and a rear objective lens group b 8, which are coaxially arranged.
[0016] In the above scheme, the front fixed objective lens group b 6 comprises, coaxially arranged from the object side to the image side, a fifth lens m and a sixth lens l, and the rear objective lens group b 8 comprises, coaxially arranged from the object side to the image side in order, a seventh lens j and an eighth lens i, and the seventh lens j and the eighth lens i are cemented together to form a second cemented lens. The diaphragm 7 is coaxially arranged between the sixth lens l and the seventh lens j.
[0017] More specifically, the fifth lens m is specifically a double-convex lens with positive focal length, and the material thereof is H-ZLAF53B, and the radii of curvature of the front and back surfaces thereof satisfy 10mm
[0018] More specifically, the sixth lens l is specifically a double-concave lens with negative focal length, the material is H-ZK20, the front and back surface curvature radii are respectively -10mm < R1 < -5mm, 5mm < R2 < 10mm.
[0019] More specifically, the seventh lens j is specifically a meniscus lens with negative focal length, the material is H-ZF52, the front and back surface curvature radii are respectively 40mm < R1 < 50mm, 2mm < R2 < 10mm.
[0020] More specifically, the eighth lens i is specifically a double-convex lens with positive focal length, the material is H-ZLAF53B, the front and back surface curvature radii are respectively 2mm < R1 < 10mm, -15mm < R2 < -5mm.
[0021] In the above scheme, the objective lens group switching device is specifically a light shield plate 9.
[0022] In the above scheme, the system further comprises a filter lens group 5 and a target surface detector 10 coaxially arranged on the side close to the image side, and the filter lens group 5 is arranged between the prism group 4 and the target surface detector 10.
[0023] The application also provides application of the athermalized common image plane short focal length objective lens optical system in environmental monitoring, digital video recording, civilian monitoring, national defense monitoring and control and the like.
[0024] The application utilizes the front fixed objective lens group a 1, the mirror 2, the rear objective lens group a 3, the prism group 4 and the filter lens group 5 to form a short focal length objective lens, and natural light in the target and the background passes through the short focal length objective lens and converges on the detector target surface 10 to form an image, so that wide range high definition video recording of the target can be realized.
[0025] Compared with the prior art, the application has the following beneficial technical effects: 1) The optical structure layout form of eight spherical mirrors is adopted, various aberrations are effectively reduced and balanced, and finally good common image plane short focal length objective lens imaging effect is realized, the optical structure is simple, the image quality is excellent, and the processing and assembly requirements are low.
[0026] 2) The design of optical power is adopted, the type and material of each lens are strictly screened, four kinds of optical glass are adopted only under the condition of meeting the imaging quality, and each glass is made of common material, the athermalization design of the common image plane short focus objective is realized, the optical structure form of the common image plane short focus objective is simplified, and the environmental adaptability, process and economy are good.
[0027] 3) The design of rotating light blocking plate is adopted, the switching problem of the upper and lower short focus objectives is effectively solved, there is no light leakage and image color deviation during the switching process, and the imaging quality of each is ensured. BRIEF DESCRIPTION OF DRAWINGS
[0028] Figure 1 It is a light path schematic diagram when the light blocking plate is rotated to the lower side.
[0029] Figure 2 It is a light path schematic diagram when the light blocking plate is rotated to the upper side.
[0030] Figure 3 It is a transmission function diagram of the athermalization common image plane short focus objective optical system at 50mm and 20 DEG C.
[0031] Figure 4 It is a transmission function diagram of the athermalization common image plane short focus objective optical system at 50mm and -55 DEG C.
[0032] Figure 5 It is a transmission function diagram of the athermalization common image plane short focus objective optical system at 50mm and 70 DEG C.
[0033] Figure 6 It is a transmission function diagram of the athermalization common image plane short focus objective optical system at 5mm and 20 DEG C.
[0034] Figure 7 It is a transmission function diagram of the athermalization common image plane short focus objective optical system at 5mm and -55 DEG C.
[0035] Figure 8 It is a transmission function diagram of the athermalization common image plane short focus objective optical system at 5mm and 70 DEG C.
[0036] The figure mark: 1 front fixed objective group a, 2 reflector, 3 rear objective group a, 4 prism group, 5 filter group, 6 front fixed objective group b, 7 diaphragm, 8 rear objective group b, 9 light blocking plate, 10 target surface detector. DETAILED DESCRIPTION
[0037] For those skilled in the art to fully understand the technical solutions and beneficial effects of the present application, the following will be described in detail in combination with specific embodiments and drawings. It is emphasized that the following embodiments are only a small part of the numerous embodiments of the present application, and in addition to this, the present application can have many other embodiments, and any simple improvement based on these embodiments will fall within the protection scope of the present application.
[0038] The athermalized common image plane short focal length objective optical system developed by the present application is shown in Figures 1-2 , mainly including front fixed objective group a 1, mirror 2, rear objective group a 3, prism group 4, filter group 5, front fixed objective group b 6, diaphragm 7, rear objective group b 8, light shield 9, target surface detector 10. Among them, the front fixed objective group a 1, the mirror 2 are arranged from left to right in the upper row, the front fixed objective group b 6, the diaphragm 7, the rear objective group b 8, the prism group 4, the filter group 5, the target surface detector 10 are sequentially coaxially arranged from left to right in the lower row, the rear objective group a 3 is located between the mirror 2 and the prism group 4, and the light shield 9 can be switched in the upper and lower light paths. The front fixed objective group a 1, the mirror 2, the rear objective group a 3, the prism group 4, the filter group 5 together constitute the upper row short focal length objective, while the front fixed objective group b 6, the diaphragm 7, the rear objective group b 8, the prism group 4, the filter group 5 together constitute the lower row short focal length objective. By rotating the light shield 9 to move it to the upper row or the lower row, the upper and lower row short focal length objectives are switched to realize imaging.
[0039] In another embodiment, the front fixed objective group a 1 and the mirror 2 can also be arranged in the lower row, while the prism group 4, the filter group 5, the front fixed objective group b 6, the diaphragm 7, the rear objective group b 8, the light shield 9 and the target surface detector 10 are arranged in the upper row, but the position of the rear objective group a 3 remains unchanged and is still located between the mirror 2 and the prism group 4.
[0040] Figure 1 The left side is the object side and the right side is the image side, at this time the light reflected by the target enters the optical system from the front fixed objective group a 1 or the front fixed objective group b 6, and after a series of refraction and reflection, an image is formed on the target surface detector 10. In another embodiment, when the left side is the image side and the right side is the object side, the athermalized common image plane short focal length objective optical system only needs to be flipped along the longitudinal axis on the basis of Figure 1 .
[0041] The athermalized common image plane short focal length objective optical system developed by the present application is shown in Figure 1The outer diameter of the front fixed objective lens group a1 is about 15mm, which includes a first cemented lens and a third lens c arranged in order along the optical axis direction from the object side to the image side (i.e. from left to right), both of which belong to spherical mirrors. The first cemented lens is formed by the first lens a and the second lens b through photosensitive cement, wherein the first lens a, the second lens b and the third lens c are respectively a biconvex lens with positive focal power, a biconcave lens with negative focal power and a biconvex lens with positive focal power. The front surface curvature radius of the first lens a satisfies 20mm
[0042] In addition, the first lens a, the second lens b and the third lens c are respectively made of H-ZK20, H-ZLAF53B and H-ZK20 materials. These materials all belong to conventional materials, which have the advantages of low thermal expansion coefficient and good processability. In general, the front fixed objective lens group a1 can effectively reduce the chromatic aberration of the system, improve the imaging quality, converge the light entering the system and reduce the light height, and thus reduce the tolerance sensitivity of the system by the cooperation of three different types and materials of lenses.
[0043] The reflecting mirror 2 (i.e. Figure 1 in d) is arranged at an angle of 45°, and its reflecting surfaces respectively face the front fixed objective lens group a1 and the rear objective lens group a3, which is used for reflecting the light passing through the front fixed objective lens group a1 to the rear objective lens group a3, so as to convert the horizontally right light into vertically downward light. The material of the reflecting mirror 2 is H-K9L.
[0044] The outer diameter of the rear objective lens group a3 is about 10mm, which includes a horizontally arranged fourth lens e. The fourth lens e belongs to a spherical mirror, which is a meniscus lens with negative focal power, and the front surface curvature radius satisfies -15mm
[0045] The material of the fourth lens e is H-QK3L, which is conducive to correcting the high-order aberration of the system and ensuring the imaging quality. In addition, this material belongs to a conventional material, which has the advantages of low thermal expansion coefficient and good processability. The main function of the rear objective lens group a3 is to compensate for the residual aberration of the front fixed objective lens group a1, so as to better image.
[0046] Prism assembly 4 comprises two beam-splitting prisms, g and h, stacked together along an inclined plane, both with dimensions of 10mm × 10mm × 10mm. Both beam-splitting prisms g and h in prism assembly 4 are made of H-ZK20 material. The main function of prism assembly 4 is to split visible light, ensuring that 50% of the light can be imaged on the target detector 10, achieving co-image plane imaging of the upper and lower row of short-focal-length objectives, i.e., achieving imaging using two types of short-focal-length objectives.
[0047] The filter group 5 includes a visible light filter f, which is made of H-K9L material, has a thickness of 1mm, and an outer diameter of 10mm. The filter group 5 is mainly used for high-definition imaging of the target in visible light mode.
[0048] The front fixed objective lens group b6 has an outer diameter of approximately 7 mm. Along the optical axis from the object side to the image side (i.e., from left to right), it contains a fifth lens m and a sixth lens l, both of which are spherical mirrors. The fifth lens m is a positive optical power biconvex lens, and the sixth lens l is a negative optical power biconcave lens. The combination of these two different types of lenses effectively reduces coma and astigmatism in the system, thereby improving image quality.
[0049] The fifth lens m has a front surface radius of curvature satisfying 10mm < R1 < 20mm, and a rear surface radius of curvature satisfying -40mm < R2 < -30mm. The sixth lens l has a front surface radius of curvature satisfying -10mm < R1 < -5mm, and a rear surface radius of curvature satisfying 5mm < R2 < 10mm. The fifth lens m and the sixth lens l are made of H-ZLAF53B and H-ZK20 materials, respectively. On the one hand, the combination of these two materials can effectively correct the chromatic aberration of the system; on the other hand, both materials are conventional materials and have advantages such as low coefficient of thermal expansion and good processability.
[0050] Aperture 7 (i.e.) Figure 1 The main function of k in the formula is to limit the amount of light entering the sensor.
[0051] The rear objective group b 8 has an outer diameter of 7mm and mainly consists of the second cemented lens. The second cemented lens comprises a seventh lens j and an eighth lens i arranged sequentially along the optical axis from the object side to the image side (i.e., from left to right). Both are spherical mirrors bonded together with photosensitive adhesive. The seventh lens j and the eighth lens i are respectively a meniscus lens with negative optical power and a biconvex lens with positive optical power. Through the cooperation of these two different types of lenses, the residual aberrations of the front fixed objective group b 6 are effectively compensated, and the light entering the system is converged, reducing the light beam height and improving image quality, i.e., reducing and correcting the system's transverse chromatic aberration and spherical aberration.
[0052] The front surface radius of curvature of the seventh lens j satisfies 40mm < R1 < 50mm, and the back surface radius of curvature satisfies 2mm < R2 < 10mm. The front surface radius of curvature of the eighth lens i satisfies 2mm < R1 < 10mm, and the back surface radius of curvature satisfies -15mm < R2 < -5mm. The materials of the seventh lens j and the eighth lens i are H-ZF52 and H-ZLAF53B respectively. The two materials cooperate with each other to effectively reduce and correct the on-axis chromatic aberration and spherical aberration of the system, and ensure the imaging quality of the system. In addition, the two materials belong to conventional materials, and have the advantages of low thermal expansion coefficient, good processability and the like.
[0053] The material of the light barrier 9 is aluminum, and the surface thereof is treated as black, so that the interference of stray light can be eliminated, and there are no problems such as light leakage and image color deviation. The main function of the light barrier 9 is to facilitate switching between the upper row of short focal lenses and the lower row of short focal lenses, so as to realize high-definition imaging of targets at different distances.
[0054] The specific information of each optical lens or lens in the athermalized common image plane short focal lens optical system is shown in the following table:
[0055] The focal length values of the upper row of short focal lenses and the lower row of short focal lenses in the athermalized common image plane short focal lens optical system are 50mm and 5mm respectively, the light barrier 9 can be rotated to quickly switch between the two short focal lenses, and high-definition imaging can be performed respectively (as shown in Figures 1-2 The transmission function graphs of the upper and lower rows of short focal lenses of the athermalized common image plane short focal lens optical system at 20℃, -55℃ and 70℃ are shown in Figures 3-5 , 6-8.
[0056] As can be seen from the figure, in the temperature range of -55℃ to +70℃, various aberrations of different focal lengths are well corrected, the on-axis MTF is greater than 0.5 (145lp / mm), which has reached the basic requirements of system design, and shows good imaging quality.
[0057] As can be seen from the figure, in the temperature range of -55℃ to +70℃, various aberrations of different focal lengths are well corrected, the on-axis MTF is greater than 0.5 (145lp / mm), which has reached the basic requirements of system design, and shows good imaging quality.
[0057] As can be seen from the figure, in the temperature range of -55℃ to +70℃, various aberrations of different focal lengths are well corrected, the on-axis MTF is greater than 0.5 (145lp / mm), which has reached the basic requirements of system design, and shows good imaging quality.
[0057] As can be seen from the figure, in the temperature range of -55℃ to +70℃, various aberrations of different focal lengths are well corrected, the on-axis MTF is greater than 0.5 (145lp / mm), which has reached the basic requirements of system design, and shows good imaging quality.
Claims
1. An athermalized, co-afocal, short focal length objective optical system characterized by: The system comprises objective lens group A, a mirror, a prism group, objective lens group B, and an objective lens group switching device, the objective lens group A and the objective lens group B are arranged side by side on the side close to the object, the mirror is arranged obliquely behind the objective lens group A and its reflection direction is towards the prism group, the objective lens group B and the prism group are coaxially arranged in sequence, and the objective lens group switching device can be switched to the rear of the objective lens group A or the rear of the objective lens group B.
2. The athermalized, co-afocal, short focal length objective optical system of claim 1, wherein: The objective lens group A comprises first lens a, second lens b and third lens c coaxially arranged in sequence from the object side to the image side, wherein the first lens a and the second lens b are glued together, the first lens a is a biconvex lens with positive focal power, the second lens b is a biconcave lens with negative focal power, and the third lens c is a biconvex lens with positive focal power.
3. The athermalized co-afocal short focal length objective optical system of claim 2, wherein: The material of the first lens a is H-ZK20, and the radii of curvature of the front and back surfaces satisfy 20mm 4. The athermalized, co-afocal, short focal length objective optical system of claim 1, wherein: The mirror is specifically a plane mirror arranged at an angle of 45°, and the objective lens group switching device is specifically a light shield plate.
5. The thermal-free co-image plane short-focal-length objective lens optical system as described in claim 1, characterized in that: The system further comprises rear objective lens group a, filter lens group and target surface detector, the rear objective lens group a is arranged between the mirror and the prism group, and the filter lens group is arranged between the prism group and the target surface detector.
6. The athermalized co-afocal short focal length objective optical system of claim 5, wherein: The rear objective lens group a is specifically a meniscus lens with negative focal power, and the concave surface of the rear objective lens group a faces the mirror; the material of the rear objective lens group a is H-QK3L, and the radii of curvature of the front and back surfaces satisfy -15mm 7. The athermalized, co-afocal, short focal length objective optical system of claim 1, wherein: The prism group is formed by gluing two same-sized light splitting prisms g and h along the inclined surface.
8. The athermalized, co-afocal, short focal length objective optical system of claim 1, wherein: The objective lens group B comprises fifth lens m, sixth lens l, diaphragm, seventh lens j and eighth lens i coaxially arranged in sequence from the object side to the image side, wherein the seventh lens j and the eighth lens i are glued together, the fifth lens m is a biconvex lens with positive focal power, the sixth lens l is a biconcave lens with negative focal power, the seventh lens j is a meniscus lens with negative focal power, and the eighth lens i is a biconvex lens with positive focal power.
9. The athermalized co-afocal short focal length objective optical system of claim 8, wherein: The material of the fifth lens m is H-ZLAF53B, and the radii of curvature of the front and back surfaces satisfy 10mm The material of the fifth lens m is H-ZLAF53B, and the radii of curvature of the front and back surfaces satisfy 10mm 10. The use of the athermalized co-axial short focal length objective optical system according to any one of claims 1-9 in environmental monitoring, digital video recording, civil surveillance, and defense monitoring and control.