A sham lens

Abstract

The application discloses a Schmidt lens and relates to the technical field of optical lenses, comprising a first lens, a second lens, a third lens and a fourth lens which are sequentially arranged along an optical axis from an object side to an image side; an aperture diaphragm is arranged between the second lens and the third lens; the first lens has positive focal power; the second lens has positive focal power; the third lens has negative focal power; and the fourth lens has positive focal power; the first lens satisfies a condition formula 1<=F1 / F<=3, wherein F1 is the focal length of the first lens, and F is the focal length of the Schmidt lens. The Schmidt lens can realize focusing in the meridional direction and the sagittal direction and can maintain a small amount of focusing shift in a large temperature change environment.

Description

Technical Field

[0001] This invention relates to the field of optical lens technology, and in particular to a SAM lens. Background Technology

[0002] A Schamme lens is a special optical lens designed based on Schamme's Law. Its principle is that when the extended planes of the subject, lens, and imaging planes intersect on a straight line, the focal plane can be expanded, allowing objects that are not originally on the same plane to be imaged clearly simultaneously. Schamme lenses are commonly used in industrial inspection to inspect objects on tilted or complex surfaces, ensuring sharpness across the entire field of view.

[0003] Among the existing SAM lenses, none can achieve simultaneous meridional and sagittal focusing. Summary of the Invention

[0004] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a SAM lens that can focus in both the meridional and sagittal directions, and can maintain a small focus shift even in environments with large temperature variations.

[0005] According to an embodiment of the present invention, a Sham lens includes a first lens, a second lens, a third lens, and a fourth lens arranged sequentially along the optical axis from the object side to the image side; An aperture stop is provided between the second lens and the third lens. The first lens has positive optical power, the second lens has positive optical power, the third lens has negative optical power, and the fourth lens has positive optical power. The first lens satisfies the following condition. 1≤F1 / F≤3, Wherein, F1 is the focal length of the first lens, and F is the focal length of the Sham lens.

[0006] The SAM lens according to embodiments of the present invention has at least the following beneficial effects: it can achieve meridional and sagittal focusing, enabling the SAM lens to be applied in 3D modeling. The image clearly shows that horizontal lines are sharp while vertical lines are blurred, and vice versa, with different focal positions, making it suitable for 3D modeling photography. Furthermore, it can control the focus shift within 0.02mm within a temperature range of -30℃ to 80℃.

[0007] According to some embodiments of the present invention, the first lens also satisfies the following condition: Nd ≤ 1.8, where Nd is the refractive index of the first lens at a wavelength of 587.56 nm.

[0008] According to some embodiments of the present invention, the second lens also satisfies the following condition: 0.5≤F2 / F≤2.5, where F2 is the focal length of the second lens.

[0009] According to some embodiments of the present invention, the third lens also satisfies the following condition: -3≤F3 / F≤-0.1, where F3 is the focal length of the third lens.

[0010] According to some embodiments of the present invention, the fourth lens also satisfies the following condition: 0.5≤F4 / F≤3, where F4 is the focal length of the fourth lens.

[0011] According to some embodiments of the present invention, the Sham lens also satisfies the following condition: TTL / IH≤7, where TTL is the distance from the front surface of the first lens to the image plane, and IH is the half-image height of the diagonal of the rectangular detector.

[0012] According to some embodiments of the present invention, the Sham lens satisfies the condition TTL / IH=6.

[0013] According to some embodiments of the present invention, the first lens satisfies the condition F1 / F=2.5.

[0014] According to some embodiments of the present invention, the first lens is provided with a filter in the direction facing the object side.

[0015] According to some embodiments of the present invention, the fourth lens is provided with protective glass in the direction facing the image side, and the protective glass is parallel to the image plane.

[0016] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 This is a schematic diagram of the structure of the Sham lens according to an embodiment of the present invention; Figure 2 This is a dot diagram of the Sham lens according to the first embodiment of the present invention; Figure 3 This is a fan-shaped diagram of the Sham lens according to the first embodiment of the present invention; Figure 4 The distortion and field curvature diagram of the Sham lens according to the first embodiment of the present invention; Figure 5 This is the MTF diagram of the Sham lens according to the first embodiment of the present invention; Figure 6 This is the defocus MTF diagram of the Sham lens according to the first embodiment of the present invention; Figure 7 This is a relative illumination diagram of the Schahm lens according to the first embodiment of the present invention; Figure 8This is a dot diagram of the Sham lens according to the second embodiment of the present invention; Figure 9 This is a fan-shaped diagram of the Sham lens according to the second embodiment of the present invention; Figure 10 The distortion and field curvature diagram of the Sham lens according to the second embodiment of the present invention; Figure 11 This is the MTF diagram of the Sham lens according to the second embodiment of the present invention; Figure 12 This is the defocus MTF diagram of the Sham lens according to the second embodiment of the present invention; Figure 13 This is a relative illumination diagram of the Sham lens according to the second embodiment of the present invention.

[0018] Icon labels: Filter 001; First lens 100, second lens 200, third lens 300, fourth lens 400. Detailed Implementation

[0019] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0020] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, etc., are based on the orientation or positional relationship shown in the drawings and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0021] In the description of this invention, "multiple" refers to two or more. The use of "first" and "second" is for distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features or their sequential relationship.

[0022] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0023] Meridional focusing is the specific manifestation of astigmatism in an optical system along the meridional direction; sagittal focusing is the specific manifestation of astigmatism in an optical system along the sagittal direction. The Sham lens of this invention can achieve both meridional and sagittal focusing. That is, utilizing the principle of astigmatism, the image is characterized by horizontal lines being sharp while vertical lines are blurry, and vice versa, with different focal points for each direction. This can be applied to 3D modeling scenarios.

[0024] Reference Figure 1 As shown, a Sham lens according to an embodiment of the present invention includes a first lens 100, a second lens 200, a third lens 300 and a fourth lens 400 arranged sequentially along the optical axis from the object side to the image side.

[0025] An aperture stop is provided between the second lens 200 and the third lens 300. The first lens 100 has positive optical power, the second lens 200 has positive optical power, the third lens 300 has negative optical power, and the fourth lens 400 has positive optical power. The first lens 100 satisfies the following condition. 1≤F1 / F≤3, where F1 is the focal length of the first lens 100 and F is the focal length of the Sham lens.

[0026] Understandably, with further optimization, the first lens 100 also satisfies the following condition: Nd≤1.8, where Nd is the refractive index of the first lens 100 at a wavelength of 587.56nm.

[0027] Understandably, with further optimization, the second lens 200 also satisfies the following condition: 0.5≤F2 / F≤2.5, where F2 is the focal length of the second lens 200.

[0028] Understandably, with further optimization, the third lens 300 also satisfies the following condition: -3≤F3 / F≤-0.1, where F3 is the focal length of the third lens 300.

[0029] Understandably, with further optimization, the fourth lens 400 also satisfies the following condition: 0.5≤F4 / F≤3, where F4 is the focal length of the fourth lens at 400°.

[0030] Understandably, the Sham lens also satisfies the following conditional expression: TTL / IH≤7, where TTL is the distance from the front surface of the first lens to the image plane, and IH is the half-image height of the rectangular detector diagonally.

[0031] Preferably, and understandably, the Sham lens satisfies the condition TTL / IH=6.

[0032] Preferably, it is understood that the first lens 100 satisfies the condition F1 / F=2.5.

[0033] It is understandable that the first lens 100 is provided with a filter 001 in the direction facing the object side.

[0034] It is understandable that the fourth lens 400 has a protective glass facing the image side, and the protective glass is parallel to the image plane.

[0035] Example 1: A Sham lens comprises, along the optical axis from the object side to the image side, a filter 001, a first lens 100, a second lens 200, an aperture stop, a third lens 300, a fourth lens 400, and a protective glass. The protective glass is parallel to the image plane. The angle between the target plane and the optical axis of this Sham lens is α, and α = 40°. The effective focal length (EFL) of this Sham lens is 21 mm, the aperture (Fno) is 5.4, and the half-image height (IH) of the rectangular detector diagonal is 7.0 mm. It also satisfies the following condition: F1 / F=2.5; Nd=1.68; F2 / F=0.76; F3 / F=-0.3; F4 / F=0.92; TTL / IH=6. F1 is the focal length of the first lens 100, Nd is the refractive index of the first lens 100 at a wavelength of 587.56nm, F2 is the focal length of the second lens 200, F3 is the focal length of the third lens 300, F4 is the focal length of the fourth lens 400, F is the focal length of the SAM lens, TTL is the distance from the front surface of the first lens to the image plane, and IH is the half-image height of the rectangular detector diagonally.

[0036] The remaining parameters of the Sham lens in Example 1 are shown in Table 1, and the optical structure is as follows: Figure 1 As shown.

[0037] Table 1. Other parameters of the Sham lens in Example 1

[0038] The SAM lens in this embodiment 1 can achieve meridional and sagittal focusing, enabling its application in 3D modeling. The image clearly shows that horizontal lines are sharp while vertical lines are blurry, and vice versa, with different focal points for each, making it suitable for 3D modeling photography. Furthermore, this SAM lens can control the focus shift within 0.02mm across temperature variations ranging from -30℃ to 80℃.

[0039] The dot diagram of the Sham lens in this embodiment is as follows: Figure 2 As shown. The light fan diagram of this Sham lens is as follows. Figure 3 As shown. The distortion and field curvature diagram of this Sham lens are as follows. Figure 4 As shown. The MTF graph of this Sham lens is as follows. Figure 5As shown. The out-of-focus MTF graph of this Sham lens is as follows. Figure 6 As shown. The relative illumination diagram of the Schahm lens is as follows. Figure 7 As shown.

[0040] Example 2: A Sham lens comprises, along the optical axis from the object side to the image side, a filter 001, a first lens 100, a second lens 200, an aperture stop, a third lens 300, a fourth lens 400, and a protective glass. The protective glass is parallel to the image plane. The angle between the target plane and the optical axis of this Sham lens is α, and α = 40°. The effective focal length (EFL) of this Sham lens is 21 mm, the aperture (Fno) is 5.4, and the half-image height (IH) of the rectangular detector diagonal is 7.0 mm. It also satisfies the following condition: F1 / F=2.5; Nd=1.68; F2 / F=0.76; F3 / F=-0.3; F4 / F=0.92; TTL / IH=6. F1 is the focal length of the first lens 100, Nd is the refractive index of the first lens 100 at a wavelength of 587.56nm, F2 is the focal length of the second lens 200, F3 is the focal length of the third lens 300, F4 is the focal length of the fourth lens 400, F is the focal length of the SAM lens, TTL is the distance from the front surface of the first lens to the image plane, and IH is the half-image height of the rectangular detector diagonally.

[0041] The remaining parameters of the Sham lens in Example 2 are shown in Table 2, and the optical structure is as follows: Figure 1 As shown.

[0042] Table 2. Other parameters of the Sham lens in Example 2

[0043] The SAM lens in this embodiment 2 can achieve meridional and sagittal focusing, enabling its application in 3D modeling. The image clearly shows that horizontal lines are sharp while vertical lines are blurry, and vice versa, with different focal points for each, making it suitable for 3D modeling photography. Furthermore, this SAM lens can control the focus shift within 0.02mm across temperature variations ranging from -30℃ to 80℃.

[0044] The dot diagram of the Sham lens in this embodiment is as follows: Figure 8 As shown. The light fan diagram of this Sham lens is as follows. Figure 9 As shown. The distortion and field curvature diagram of this Sham lens are as follows. Figure 10 As shown. The MTF graph of this Sham lens is as follows. Figure 11 As shown. The out-of-focus MTF graph of this Sham lens is as follows. Figure 12 As shown. The relative illumination diagram of the Schahm lens is as follows. Figure 13 As shown.

[0045] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A Sham lens, comprising a first lens, a second lens, a third lens, and a fourth lens, characterized in that, The first lens, the second lens, the third lens, and the fourth lens are arranged sequentially from the object side to the image side along the optical axis; An aperture stop is provided between the second lens and the third lens. The first lens has positive optical power, the second lens has positive optical power, the third lens has negative optical power, and the fourth lens has positive optical power. The first lens satisfies the following condition. 1≤F1 / F≤3, Wherein, F1 is the focal length of the first lens, and F is the focal length of the Sham lens.

2. The Sham lens according to claim 1, characterized in that, The first lens also satisfies the following condition. Nd≤1.8, Nd is the refractive index of the first lens at a wavelength of 587.56 nm.

3. The Sham lens according to claim 1, characterized in that, The second lens also satisfies the following condition: 0.5≤F² / F≤2.5 F2 is the focal length of the second lens.

4. The Sham lens according to claim 1, characterized in that, The third lens also satisfies the following condition. -3≤F3 / F≤-0.1, F3 is the focal length of the third lens.

5. The Sham lens according to claim 1, characterized in that, The fourth lens also satisfies the following condition. 0.5≤F4 / F≤3 F4 is the focal length of the fourth lens.

6. The Sham lens according to any one of claims 1 to 5, characterized in that, The Sham lens also satisfies the following condition. TTL / IH≤7, TTL is the distance from the front surface of the first lens to the image plane, and IH is the half-image height of the rectangular detector diagonally.

7. The Sham lens according to claim 6, characterized in that, The Sham lens satisfies the condition TTL / IH=6.

8. The Sham lens according to claim 1, characterized in that, The first lens satisfies the condition F1 / F=2.

5.

9. The Sham lens according to claim 1, characterized in that, The first lens has a filter in the direction facing the object.

10. The Sham lens according to claim 1, characterized in that, The fourth lens is provided with protective glass in the direction facing the image side, and the protective glass is parallel to the image plane.

Images