Infrared camera
By using a curved cover glass silicon window in the infrared camera to guide reflected light outside the focal plane, the stray light and ghosting problem of automotive infrared cameras is solved, improving image quality and product performance.
Patent Information
- Application Number
- CN202520323293.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-26
- Publication Date
- 2026-02-10
- Estimated Expiration
- 2035-02-26
AI Technical Summary
The front protective window of existing vehicle infrared cameras reflects light, causing multiple reflections and creating stray light ghost images, which affects image quality.
Design an infrared camera that uses a curved cover silicon window as a silicon lens to reflect the light reflected by the chip protection silicon window back to an area outside the focal plane of the detector, thereby reducing stray light convergence.
It effectively reduces or eliminates ghosting, improves image quality, maintains protection against dust and debris, and enhances product performance.
Smart Images
Figure CN223899273U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the technical field of optical lenses, and in particular to an infrared camera. Background Technology
[0002] Vehicle-mounted infrared cameras typically have a silicon-based front protective window to prevent dust and gravel impacts. However, the most serious ghosting issue in vehicle-mounted infrared cameras arises from light reflected from the rear protective window in front of the detector. This reflected light is then reflected back by the front protective window, ultimately reaching the image plane (detector) and creating stray ghosting. Existing front protective windows are silicon flat sheets with zero curvature and no optical power; their infrared long-wave transmittance is around 75%. When installed in front of a vehicle-mounted infrared camera, the light reflected at the rear protective window reaches the front protective window and undergoes secondary reflection. This results in multiple reflected light converging on the focal plane array (detector), creating stray ghosting, causing image layering, deteriorating lens image quality, and reducing product performance.
[0003] like Figure 1 and Figure 2 The image shown illustrates an existing imaging system and ghost image optical path for an in-vehicle infrared camera. Among them, Figure 1 A diagram of an infrared vehicle imaging system with a traditional front protective window is provided. Figure 1 The optical structure of the vehicle-mounted infrared camera consists of a fourth lens 1, a fifth lens 2, a third aperture 3, a sixth lens 4, a seventh lens 5, and a first detector 6. The fourth lens 1 is the front protective window as described above, namely a silicon flat cover plate, also known as a flat cover plate silicon window. The fifth lens 2, the third aperture 3, and the sixth lens 4 form the imaging optical system of the vehicle-mounted infrared camera. The seventh lens 5 is the rear protective window as described above. Figure 2 This is an optical path diagram for analyzing stray light appearing on the focal plane array of the detector of an automotive infrared camera equipped with a traditional front protective window. Figure 2 The image shows that a portion of the light reflected from the front surface of the seventh lens 5 returns along the same path at a small reflection angle, passes through the third aperture 3, is reflected a second time at the rear surface of the fourth lens 1, and is imaged again by the imaging system, forming a distinct ghost image on the focal plane of the first detector 6.
[0004] Therefore, how to reduce stray light convergence to the detector to reduce ghosting is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention
[0005] In view of this, this application provides an infrared camera that can effectively improve the problem of severe stray light and ghosting in existing vehicle-mounted infrared cameras.
[0006] This application provides an infrared camera, including a cover silicon window, a lens group, a chip protection silicon window, and a detector arranged coaxially from the object side to the image side. The detector is used for photosensitive imaging, and the cover silicon window is a silicon lens with curvature, used to reflect at least part of the light reflected from the chip protection silicon window to an area outside the focal plane of the detector.
[0007] In one embodiment, the cover plate silicon window is a spherical lens, and the lens group includes a first lens, a first aperture, and a second lens arranged coaxially from the object side to the image side. The first lens and the second lens are both aspherical lenses, and the first lens, the first aperture, and the second lens form the imaging optical system of the infrared camera.
[0008] In one embodiment, the cover glass window has a convex surface facing the object side and a concave surface facing the image side, and the focal length of the cover glass window is positive; the first lens has a convex surface facing the object side and a concave surface facing the image side, and the focal length of the first lens is negative; the second lens has a concave surface facing the object side and a convex surface facing the image side, and the focal length of the second lens is positive.
[0009] In one embodiment, the radius of curvature of the cover glass silicon window facing the object side ranges from 47mm < R1 < 165mm, and the radius of curvature of the side facing the image side ranges from 55mm < R2 < 75mm; the radius of curvature of the first lens facing the object side ranges from 5.5mm < R3 < 8mm, and the radius of curvature of the side facing the image side ranges from 5.1mm < R4 < 6.3mm; the radius of curvature of the second lens facing the object side ranges from -34mm < R5 < -30.4mm, and the radius of curvature of the side facing the image side ranges from -10.7mm < R6 < -8mm.
[0010] In one embodiment, the thickness of the cover plate silicon window ranges from 0.5mm < D1 < 3mm; the thickness of the first lens ranges from 3mm < D2 < 4.6mm; the thickness of the second lens ranges from 3.5mm < D3 < 5.1mm; and the thickness of the chip protection silicon window ranges from 3.5mm < D4 < 5.1mm.
[0011] In one embodiment, the distance between the cover plate silicon window and the first lens ranges from 1mm < Z1 < 3.1mm; the distance between the first lens and the first aperture ranges from 0.5mm < Z2 < 2.1mm; the distance between the first aperture and the second lens ranges from 2.9mm < Z3 < 4.1mm; the distance between the second lens and the chip protection silicon window ranges from 5.9mm < Z4 < 7.1mm; and the distance between the chip protection silicon window and the detector ranges from 0.05mm < Z5 < 1.7mm.
[0012] In one embodiment, the cover silicon window is an aspherical lens, and the lens group includes a second aperture and a third lens arranged coaxially from the object side to the image side. The third lens is an aspherical lens, and the cover silicon window, the second aperture, and the third lens form the imaging optical system of the infrared camera.
[0013] In one embodiment, the cover glass window has a convex surface facing the object side and a concave surface facing the image side, and the focal length of the cover glass window is positive; the third lens has a convex surface facing the object side and a concave surface facing the image side, and the focal length of the third lens is positive.
[0014] In one embodiment, the radius of curvature of the cover glass silicon window facing the object side is in the range of 7.2mm < R7 < 9mm, and the radius of curvature of the side facing the image side is in the range of 7.1mm < R8 < 8.3mm; the radius of curvature of the third lens facing the object side is in the range of 11.8mm < R9 < 15.3mm, and the radius of curvature of the side facing the image side is in the range of 49mm < R1 < 53mm.
[0015] In one embodiment, the thickness of the cover plate silicon window ranges from 1.4mm < D5 < 2.6mm; the thickness of the third lens ranges from 2.4mm < D6 < 2.6mm.
[0016] In one embodiment, the distance between the cover plate silicon window and the second aperture ranges from 2.1mm < Z6 < 3.1mm; the distance between the second aperture and the third lens ranges from 0.9mm < Z7 < 2.7mm; the distance between the third lens and the chip protection silicon window ranges from 3.5mm < Z8 < 4.1mm; and the distance between the chip protection silicon window and the detector ranges from 0.1mm < Z9 < 2.1mm.
[0017] In summary, this application provides an infrared camera, including a cover silicon window, a lens group, a chip protection silicon window, and a detector, coaxially arranged from the object side to the image side. The detector is used for photosensitive imaging. The cover silicon window is a silicon lens with curvature, used to reflect at least a portion of the light reflected from the chip protection silicon window to an area outside the focal plane of the detector. By designing the cover silicon window as a silicon lens with a certain curvature, this application enables the cover silicon window to have optical power, reducing stray light converging on the focal plane of the detector. This improves the ghosting caused by multiple reflections between the cover silicon window and the chip protection silicon window, and even prevents multiple reflections between the cover silicon window and the chip protection silicon window from converging on the focal plane, thus preventing visible ghosting on the focal plane. At the same time, it does not affect the basic protective function of the cover silicon window against dust and gravel impacts, improving the imaging quality of the infrared camera and thus enhancing product performance. Attached Figure Description
[0018] Figure 1 This is a diagram of an infrared vehicle-mounted imaging system using a traditional silicon wafer cover plate.
[0019] Figure 2 This is a ghost image optical path diagram of a traditional silicon wafer cover plate.
[0020] Figure 3 Ghost optical path diagram of the infrared camera configured with a spherical cover plate silicon window in this application.
[0021] Figure 4 Ghost optical path diagram of the infrared camera configured with an aspherical cover plate silicon window in this application.
[0022] Figure reference numerals: a-object side; b-image side; 10-infrared camera; 12-cover silicon window; 14-chip protection silicon window; 16-detector; 18-first lens; 20-first aperture; 22-second lens; 24-first surface; 26-second surface; 28-third surface; 30-fourth surface; 32-fifth surface; 34-sixth surface; 36-second aperture; 38-third lens; 40-seventh surface; 42-eighth surface; 44-ninth surface; 46-tenth surface. Detailed Implementation
[0023] Before describing the embodiments in detail, it should be understood that this application is not limited to the detailed structures or element arrangements described below or in the accompanying drawings. This application can be implemented in other ways. Furthermore, it should be understood that the wording and terminology used herein are for descriptive purposes only and should not be construed as limiting. The terms "comprising," "including," "having," and similar expressions used herein mean to include the items listed thereafter, their equivalents, and other additional items. In particular, when describing "an element," this application does not limit the number of elements to one, but may include multiple elements.
[0024] Please refer to Figure 3 and Figure 4 As shown, this application provides an infrared camera 10, which can be applied to scenarios such as vehicle-mounted cameras. The infrared camera 10 includes a cover silicon window 12, a lens group, a chip protection silicon window 14, and a detector 16 arranged coaxially from the object side a to the image side b. In order to protect the components inside the infrared camera 10 from the impact of dust and gravel, the cover silicon window 12 is made of silicon protective glass to seal the entire camera, which has an important impact on image quality. The detector 16 is, for example, a photosensitive chip, which includes a focal plane array (hereinafter referred to as the focal plane) for imaging and is used for photosensitive imaging. The cover silicon window 12 is a silicon lens with curvature, which is used to reflect at least part of the light reflected from the chip protection silicon window 14 to an area outside the focal plane of the detector 16. A protective glass is also needed in front of the photosensitive chip. In the infrared field, silicon material is usually used to make it. For easy distinction, this application refers to the front protective glass of the camera as the cover silicon window 12 and the protective glass in front of the photosensitive chip as the chip protection silicon window 14. The chip protection silicon window 14 can be a silicon flat sheet, that is, a flat structure with a curvature of 0, or it can be set to have a certain curvature.
[0025] This application aims to process the cover silicon window 12 of the infrared camera 10 into a silicon lens with curvature, thereby giving the cover silicon window 12 a certain optical power, thus reducing stray light. The cover silicon window 12 can reflect at least part of the light reflected from the chip protection silicon window 14 to an area outside the focal plane, instead of converging on the focal plane to form a clearly visible ghost image. This can effectively reduce or even eliminate the ghost image caused by this reason, improving the imaging effect. The cover silicon window 12 can be part of the imaging system or set independently without being part of the imaging system, thereby improving the ghost image caused by multiple reflections between the cover silicon window 12 and the chip protection silicon window 14. Since the cover silicon window 12 has optical power, the multiple reflected light between the cover silicon window 12 and the chip protection silicon window 14 will not converge on the focal plane of the photosensitive chip, thus preventing the formation of a visible ghost image on the focal plane.
[0026] Based on this approach, this application provides two implementation schemes, in such cases... Figure 3 In the illustrated embodiment, the cover silicon window 12 is not part of the imaging system. Instead, it is fabricated as a spherical lens with curvature. A replaceable structure can be added to the lens structure, allowing for the replacement of spherical cover silicon windows 12 with different curvatures as needed. This has minimal impact on the system's imaging and reduces ghosting. Because the cover silicon window 12 is spherical, it can be mass-produced using cold processing, resulting in lower costs. The drawback of this approach is that it affects the lens length, for example, by increasing the lens length. In such cases… Figure 4In the embodiment shown, the cover silicon window 12 is part of the imaging system. The cover silicon window 12 can be directly processed into an aspherical silicon lens with curvature. While reducing the number of camera lenses, although it cannot completely eliminate ghosting, it can effectively reduce ghosting, which is beneficial to driving safety. The drawback of this solution is that the addition of the aspherical silicon lens will affect the lens tolerance, and the processing cost is relatively high.
[0027] Specifically, such as Figure 3 As shown, Figure 3 This describes the ghosting optical path of an infrared camera when a spherical silicon lens is added. According to... Figure 3 In the provided embodiment, the optical structure of the infrared camera 10 consists of a cover silicon window 12, a first lens 18, a first aperture 20, a second lens 22, a chip protection silicon window 14, and a detector 16. That is, the lens group includes a first lens 18, a first aperture 20, and a second lens 22 arranged coaxially from the object side a to the image side b. The cover silicon window 12 is a spherical lens with curvature, and the first lens 18 and the second lens 22 are both aspherical lenses. The first lens 18, the first aperture 20, and the second lens 22 constitute the imaging optical system of the infrared camera 10.
[0028] In this embodiment, the cover silicon window 12 has a convex surface on the object side a (first surface 24) and a concave surface on the image side b (second surface 26), and the focal length of the cover silicon window 12 is positive; the first lens 18 has a convex surface on the object side a (third surface 28) and a concave surface on the image side b (fourth surface 30), and the focal length of the first lens 18 is negative; the second lens 22 has a concave surface on the object side a (fifth surface 32) and a convex surface on the image side b (sixth surface 34), and the focal length of the second lens 22 is positive.
[0029] Furthermore, the radius of curvature of the cover glass silicon window 12 facing the object side a (first surface 24) ranges from 47mm < R1 < 165mm, and the radius of curvature of the face facing the image side b (second surface 26) ranges from 55mm < R2 < 75mm; the radius of curvature of the first lens 18 facing the object side a (third surface 28) ranges from 5.5mm < R3 < 8mm, and the radius of curvature of the face facing the image side b (fourth surface 30) ranges from 5.1mm < R4 < 6.3mm; the radius of curvature of the second lens 22 facing the object side a (fifth surface 32) ranges from -34mm < R5 < -30.4mm, and the radius of curvature of the face facing the image side b (sixth surface 34) ranges from -10.7mm < R6 < -8mm.
[0030] Preferably, the thickness of the cover plate silicon window 12 is in the range of 0.5mm < D1 < 3mm; the thickness of the first lens 18 is in the range of 3mm < D2 < 4.6mm; the thickness of the second lens 22 is in the range of 3.5mm < D3 < 5.1mm; and the thickness of the chip protection silicon window 14 is in the range of 3.5mm < D4 < 5.1mm.
[0031] Preferably, the distance between the cover plate silicon window 12 and the first lens 18 is in the range of 1mm < Z1 < 3.1mm; the distance between the first lens 18 and the first aperture 20 is in the range of 0.5mm < Z2 < 2.1mm; the distance between the first aperture 20 and the second lens 22 is in the range of 2.9mm < Z3 < 4.1mm; the distance between the second lens 22 and the chip protection silicon window 14 is in the range of 5.9mm < Z4 < 7.1mm; and the distance between the chip protection silicon window 14 and the detector 16 is in the range of 0.05mm < Z5 < 1.7mm.
[0032] from Figure 3 As can be seen from the stray light analysis optical path diagram, after the light undergoes secondary reflection between the front surface of the chip protection silicon window 14 and the rear surface of the spherical cover plate silicon window 12, the ghost image formed on the focal plane is weakened.
[0033] like Figure 4 As shown, Figure 4 The ghost image optical path of an infrared camera when an aspherical silicon lens is added. According to Figure 4 In the provided embodiment, the optical structure of the infrared camera 10 consists of a cover silicon window 12, a second aperture 36, a third lens 38, a chip protection silicon window 14, and a detector 16. That is, the lens group includes a second aperture 36 and a third lens 38 arranged coaxially from the object side a to the image side b. The cover silicon window 12 is an aspherical lens with curvature, and the third lens 38 is an aspherical lens. The cover silicon window 12, the second aperture 36, and the third lens 38 form the imaging optical system of the infrared camera 10.
[0034] In this embodiment, the cover silicon window 12 has a convex surface on the object side a (seventh surface 40) and a concave surface on the image side b (eighth surface 42), and the focal length of the cover silicon window 12 is positive; the third lens 38 has a convex surface on the object side a (ninth surface 44) and a concave surface on the image side b (tenth surface 46), and the focal length of the third lens 38 is positive.
[0035] Furthermore, the radius of curvature of the cover glass silicon window 12 facing the object side a (seventh surface 40) ranges from 7.2mm < R7 < 9mm, and the radius of curvature of the face facing the image side b (eighth surface 42) ranges from 7.1mm < R8 < 8.3mm; the radius of curvature of the third lens 38 facing the object side a (ninth surface 44) ranges from 11.8mm < R9 < 15.3mm, and the radius of curvature of the face facing the image side b (tenth surface 46) ranges from 49mm < R1 < 53mm.
[0036] Preferably, the thickness of the cover plate silicon window 12 is in the range of 1.4mm < D5 < 2.6mm; the thickness of the third lens 38 is in the range of 2.4mm < D6 < 2.6mm.
[0037] Preferably, the distance between the cover plate silicon window 12 and the second aperture 36 is in the range of 2.1mm < Z6 < 3.1mm; the distance between the second aperture 36 and the third lens 38 is in the range of 0.9mm < Z7 < 2.7mm; the distance between the third lens 38 and the chip protection silicon window 14 is in the range of 3.5mm < Z8 < 4.1mm; and the distance between the chip protection silicon window 14 and the detector 16 is in the range of 0.1mm < Z9 < 2.1mm.
[0038] from Figure 4 As can be seen from the stray light analysis optical path diagram, after the light undergoes secondary reflection between the front surface of the chip protection silicon window 14 and the rear surface of the aspherical cover silicon window 12, the ghost image formed on the focal plane is weakened.
[0039] In summary, this application provides an infrared camera, including a cover silicon window, a lens group, a chip protection silicon window, and a detector, coaxially arranged from the object side to the image side. The detector is used for photosensitive imaging. The cover silicon window is a silicon lens with curvature, used to reflect at least a portion of the light reflected from the chip protection silicon window to an area outside the focal plane of the detector. By designing the cover silicon window as a silicon lens with a certain curvature, this application enables the cover silicon window to have optical power, reducing stray light converging on the focal plane of the detector. This improves the ghosting caused by multiple reflections between the cover silicon window and the chip protection silicon window, and even prevents multiple reflections between the cover silicon window and the chip protection silicon window from converging on the focal plane, thus preventing visible ghosting on the focal plane. At the same time, it does not affect the basic protective function of the cover silicon window against dust and gravel impacts, improving the imaging quality of the infrared camera and thus enhancing product performance.
[0040] The concepts described herein may be implemented in other forms without departing from their spirit and characteristics. The specific embodiments disclosed should be considered illustrative rather than restrictive. Therefore, the scope of this application is determined by the appended claims, and not by the preceding description. Any changes within the literal meaning and equivalent scope of the claims should fall within the scope of those claims.
Claims
1. An infrared camera, characterized in that, The device includes a cover silicon window (12), a lens group, a chip protection silicon window (14), and a detector (16) arranged coaxially from the object side (a) to the image side (b). The detector (16) is used for photosensitive imaging. The cover silicon window (12) is a silicon lens with curvature, used to reflect at least part of the light reflected from the chip protection silicon window (14) back to the area outside the focal plane of the detector (16).
2. The infrared camera as described in claim 1, characterized in that, The cover plate silicon window (12) is a spherical lens. The lens group includes a first lens (18), a first aperture (20), and a second lens (22) arranged coaxially from the object side (a) to the image side (b). The first lens (18) and the second lens (22) are both aspherical lenses. The first lens (18), the first aperture (20), and the second lens (22) form the imaging optical system of the infrared camera (10).
3. The infrared camera as described in claim 2, characterized in that, The cover plate silicon window (12) has a convex surface facing the object side (a) and a concave surface facing the image side (b), and the focal length of the cover plate silicon window (12) is positive; the first lens (18) has a convex surface facing the object side (a) and a concave surface facing the image side (b), and the focal length of the first lens (18) is negative; the second lens (22) has a concave surface facing the object side (a) and a convex surface facing the image side (b), and the focal length of the second lens (22) is positive.
4. The infrared camera as described in claim 3, characterized in that, The radius of curvature of the cover plate silicon window (12) facing the object side (a) is in the range of 47mm < R1 < 165mm, and the radius of curvature of the side facing the image side (b) is in the range of 55mm < R2 < 75mm; the radius of curvature of the first lens (18) facing the object side (a) is in the range of 5.5mm < R3 < 8mm, and the radius of curvature of the side facing the image side (b) is in the range of 5.1mm < R4 < 6.3mm; the radius of curvature of the second lens (22) facing the object side (a) is in the range of -34mm < R5 < -30.4mm, and the radius of curvature of the side facing the image side (b) is in the range of -10.7mm < R6 < -8mm.
5. The infrared camera as described in claim 2, characterized in that, The thickness of the cover plate silicon window (12) ranges from 0.5mm < D1 < 3mm; the thickness of the first lens (18) ranges from 3mm < D2 < 4.6mm; the thickness of the second lens (22) ranges from 3.5mm < D3 < 5.1mm; and the thickness of the chip protection silicon window (14) ranges from 3.5mm < D4 < 5.1mm.
6. The infrared camera as described in claim 2, characterized in that, The distance between the cover plate silicon window (12) and the first lens (18) is in the range of 1mm < Z1 < 3.1mm; the distance between the first lens (18) and the first aperture (20) is in the range of 0.5mm < Z2 < 2.1mm; the distance between the first aperture (20) and the second lens (22) is in the range of 2.9mm < Z3 < 4.1mm; the distance between the second lens (22) and the chip protection silicon window (14) is in the range of 5.9mm < Z4 < 7.1mm; and the distance between the chip protection silicon window (14) and the detector (16) is in the range of 0.05mm < Z5 < 1.7mm.
7. The infrared camera as described in claim 1, characterized in that, The cover silicon window (12) is an aspherical lens. The lens group includes a second aperture (36) and a third lens (38) arranged coaxially from the object side (a) to the image side (b). The third lens (38) is an aspherical lens. The cover silicon window (12), the second aperture (36), and the third lens (38) form the imaging optical system of the infrared camera (10).
8. The infrared camera as described in claim 7, characterized in that, The cover plate silicon window (12) has a convex surface facing the object side (a) and a concave surface facing the image side (b), and the focal length of the cover plate silicon window (12) is positive; the third lens (38) has a convex surface facing the object side (a) and a concave surface facing the image side (b), and the focal length of the third lens (38) is positive.
9. The infrared camera as described in claim 7, characterized in that, The radius of curvature of the cover plate silicon window (12) facing the object side (a) is in the range of 7.2mm < R7 < 9mm, and the radius of curvature of the side facing the image side (b) is in the range of 7.1mm < R8 < 8.3mm; the radius of curvature of the third lens (38) facing the object side (a) is in the range of 11.8mm < R9 < 15.3mm, and the radius of curvature of the side facing the image side (b) is in the range of 49mm < R1 < 53mm.
10. The infrared camera as described in claim 7, characterized in that, The thickness of the cover plate silicon window (12) ranges from 1.4mm < D5 < 2.6mm, and the thickness of the third lens (38) ranges from 2.4mm < D6 < 2.6mm; and / or, The distance between the cover plate silicon window (12) and the second aperture (36) is in the range of 2.1mm < Z6 < 3.1mm, the distance between the second aperture (36) and the third lens (38) is in the range of 0.9mm < Z7 < 2.7mm, the distance between the third lens (38) and the chip protection silicon window (14) is in the range of 3.5mm < Z8 < 4.1mm, and the distance between the chip protection silicon window (14) and the detector (16) is in the range of 0.1mm < Z9 < 2.1mm.