Folding optical system

Abstract

A single-fold optical system comprising a refractive prism and a lens stack including two or more refractive lens elements. This single-fold optical system can provide a long mechanical back focal length without increasing the Z-axis height of the optical system. Providing optical power on the prism reduces the overall optical length and the X-axis length of the optical system. Compared to a conventional double-fold optical system with similar optical properties, this single-fold optical system provides a reduced Z-axis height and a reduced X-axis length. Additionally, the optical system can include a morphing lens oriented to correct astigmatism caused by surface errors of the prism's reflective surface.

Description

Technical Field

[0001] This disclosure relates generally to camera systems, and more specifically, to folding optical systems.

[0002] Related technical descriptions

[0003] The emergence of small, multi-purpose mobile devices such as smartphones and tablets or tablets has led to a need for lightweight, compact cameras capable of capturing high-resolution, high-quality images at low aperture numbers for integration into these devices. However, due to limitations in conventional camera technology, conventional small cameras used in such devices tend to capture images at lower resolutions and / or lower image quality than achievable with larger, higher-quality cameras. Achieving high resolution with a small-package camera typically requires image sensors with small pixel sizes and good, compact imaging lens systems. Technological advancements have enabled reductions in the pixel size of image sensors. However, as image sensors become more compact and powerful, the demand for compact imaging lens systems with improved image quality performance has increased. Furthermore, there is a growing expectation that small-package cameras will be equipped with image sensors with higher pixel counts and / or larger pixel sizes (one or both of which may require larger image sensors) while still maintaining a sufficiently compact module height for integration into portable electronic devices. Therefore, the challenge from an optical system design perspective is to provide an optical system capable of capturing high-brightness, high-resolution images within the physical constraints imposed by the small-package camera. Summary of the Invention

[0004] An embodiment of a single-fold optical system is described, comprising a single prism (referred to as a refractive prism) having optical power, and a lens stack comprising two or more refractive lens elements. The refractive prism may be referred to as a first lens group, and the lens stack may be referred to as a second lens group. Compared to a conventional double-fold optical system with similar optical properties, this single-fold optical system can provide a reduced Z-axis height and a reduced X-axis length. Embodiments of the single-fold optical system can be used, for example, in small-form-factor cameras in mobile multi-purpose devices such as smartphones and tablet computers or tablet devices.

[0005] In some embodiments, the refracting prism is formed of an optically plastic material, and the object-side surface of the prism is a curved spherical or aspherical surface to provide refractive force. In some embodiments, the refracting prism is an optical glass triangular prism with a refractive lens attached to the object-side of the prism to provide refractive force, the refractive lens being formed of optical plastic. In some embodiments, the refracting prism is an optical glass triangular prism with a refractive lens attached to the object-side of the prism, the refractive lens being formed of optical glass.

[0006] Additionally, embodiments of a folding optical system are described, including at least one deformable lens oriented to correct aberrations, including astigmatism caused by surface errors of the reflecting surfaces of prisms in the folding optical system. The deformable lens described herein can, for example, be used in embodiments of a single-folding optical system comprising a single refractive prism as described herein. However, the deformable lens described herein can also be used in other single-folding or double-folding optical systems to correct aberrations, including astigmatism caused by surface errors of the reflecting surfaces of prisms in the folding optical system. The deformable lens described herein can be used to correct aberrations caused by the flat reflecting surfaces of a refractive or triangular prism or by the curved reflecting surfaces of a prism (such as a freeform prism).

[0007] A manufacturing process for a folded optical system is also described, the folded optical system including a deformable lens to correct aberrations, including astigmatism caused by surface errors of the reflective surface of a prism. Attached Figure Description

[0008] Figure 1 An example single-fold optical system comprising a refracting prism made of optical plastic is shown according to some embodiments.

[0009] Figure 2 An example single-fold optical system comprising a glass prism and a plastic lens located on the object side of the prism, according to some embodiments, is shown.

[0010] Figure 3 An example single-fold optical system comprising a glass prism and a glass lens located on the object side of the prism, according to some embodiments, is shown.

[0011] Figure 4 As shown Figure 1 The example optical characteristics and performance metrics of the example optical system shown are illustrated.

[0012] Figure 5A and Figure 5B The double-fold optical system is compared with a single-fold optical system according to some embodiments.

[0013] Figure 6A Another example of a single-fold optical system, comprising a refracting prism made of optical plastic, is shown according to some embodiments.

[0014] Figure 6B Show Figure 6A The optical characteristics and performance metrics of the example optical system shown are illustrated.

[0015] Figure 7AAnother example of a single-fold optical system, comprising a glass prism and a plastic lens located on the object side of the prism, is shown according to some embodiments.

[0016] Figure 7B Show Figure 7A The optical characteristics and performance metrics of the example optical system shown are illustrated.

[0017] Figure 8A Another example of a single-fold optical system, including a glass prism and a glass lens located on the object side of the prism, is shown according to some embodiments.

[0018] Figure 8B Show Figure 8A The optical characteristics and performance metrics of the example optical system shown are illustrated.

[0019] Figure 9A Another example of a single-fold optical system including a refracting prism is shown according to some implementation schemes.

[0020] Figure 9B Show Figure 9A The optical characteristics and performance metrics of the example optical system shown are illustrated.

[0021] Figure 10 It is for use according to some implementation schemes, such as Figure 1 The flowchart shows a method for capturing images using an embodiment of the single-fold optical system as shown in Figure 9.

[0022] Figure 11 The surface of an example single-fold optical system, as mentioned in the table, is shown.

[0023] Figures 12A to 12D The illustration shows the use of morphing lenses in a lens stack to correct aberrations, including astigmatism caused by surface errors of the reflecting surfaces of prisms in a folded optical system, according to some embodiments.

[0024] Figure 13 The illustration shows the use of morphing lenses in a lens stack to correct aberrations, including astigmatism caused by surface errors of the reflecting surfaces of prisms in a double-folded optical system, according to some embodiments.

[0025] Figure 14 The illustration shows the use of morphing lenses to correct aberrations, including astigmatism caused by freeform prisms, according to some implementation schemes.

[0026] Figure 15 This is a high-level flowchart of a method for manufacturing a folded optical system according to some embodiments, the folded optical system including a deformable lens oriented to correct aberrations, the aberrations including astigmatism caused by surface errors of the reflecting surfaces of prisms in the folded optical system.

[0027] Figure 16 An example computer system is shown.

[0028] This specification includes references to "one embodiment" or "implementation". The use of the phrase "in one embodiment" or "in an embodiment" does not necessarily refer to the same embodiment. Specific features, structures, or characteristics may be combined in any suitable manner consistent with this disclosure.

[0029] The term "comprising" is open-ended. As used in the appended claims, it does not exclude additional structures or steps. Consider the following claim: "An apparatus comprising one or more processor units..." Such claims do not exclude the inclusion of additional components (e.g., network interface units, graphics circuitry, etc.).

[0030] "Configured as" refers to various units, circuits, or other components that can be described or stated as being "configured as" to perform one or more tasks. In such a context, "configured as" is used to imply a structure by indicating that the unit / circuit / component includes a structure (e.g., a circuit) that performs this one or more tasks during operation. Thus, a unit / circuit / component is allegedly configured to perform the task even when the specified unit / circuit / component is currently inoperable (e.g., not switched on). Units / circuits / components used with the language "configured as" include hardware—e.g., circuits, memory storing program instructions that can be executed to perform the operation, etc. The statement that a unit / circuit / component is "configured as" to perform one or more tasks is explicitly intended to not invoke 35 U.S.SC §112(f) for that unit / circuit / component. Furthermore, "configured as" can include general structures (e.g., general circuits) manipulated by software and / or firmware (e.g., FPGAs or general-purpose processors executing software) in a manner capable of performing one or more tasks to be solved. "Configured to" may also include adjusting the manufacturing process (e.g., a semiconductor manufacturing facility) to manufacture equipment (e.g., an integrated circuit) suitable for performing one or more tasks.

[0031] "First," "second," etc. As used herein, these terms serve as labels for the nouns preceding them and do not imply any type of ordering (e.g., spatial, temporal, logical, etc.). For example, a buffer circuit may be described herein as performing write operations on a "first" value and a "second" value. The terms "first" and "second" do not necessarily imply that the first value must be written before the second value.

[0032] "Based on." As used herein, this term describes one or more factors that influence the determination. This term does not exclude additional factors influencing the determination. That is, the determination may be based solely on these factors or at least partially on them. Consider the phrase "A is determined based on B." In this case, B is the factor influencing the determination of A, and such phrases do not exclude the possibility that the determination of A may also be based on C. In other instances, A may be determined solely on B. Detailed Implementation

[0033] This document describes an implementation of a single-fold optical system, which can be used, for example, in small-form-factor cameras in mobile multi-purpose devices such as smartphones and tablet computers or tablet devices. A conventional double-fold optical system may include two prisms and a lens stack comprising two or more refractive lens elements. The first prism redirects light from a first optical axis to the lens stack on a second optical axis. The second prism, located on the image side of the lens stack, folds the optical axis onto a third axis, where an image is formed at or near the surface of the light sensor in an image plane.

[0034] Compared to a double-fold optical system with similar optical properties, an embodiment of a single-fold optical system, as described herein, provides an optical system with a long focal length and reduced thickness (Z-height) and X-length. This single-fold optical system comprises a single prism (called a refractive prism) with optical power, and a lens stack including two or more refractive lens elements. Generally, the Z-height of a double-fold optics device is defined by the prism size and the mechanical back focal length. This embodiment of the single-fold optical system can provide a long mechanical back focal length without increasing the Z-height of the optical system. Providing optical power on the prism reduces the overall optical length and the X-length of the optical system.

[0035] In some embodiments, the refracting prism in a single-fold optical system is formed of an optically plastic material, and the object-side surface of the prism is a curved spherical or aspherical surface to provide refractive force. In some embodiments, the refracting prism is an optical glass triangular prism with a refractive lens attached to the object side of the prism to provide refractive force, the refractive lens being formed of optical plastic. The first surface of the lens can be an aspherical or spherical surface. In some embodiments, the refracting prism is an optical glass triangular prism with a refractive lens attached to the object side of the prism, the refractive lens being formed of optical glass. The first surface of the lens can be an aspherical or spherical surface. It should be noted that a refracting prism has more than three surfaces; however, only the three surfaces of a refracting prism are discussed: the object-side surface with curvature providing refractive force; the reflecting surface for folding the optical axis; and the image-side surface through which light from the reflecting surface exits the refracting prism toward the lens stack or a second lens group.

[0036] Additionally, embodiments of a folded optical system are described, including at least one deformable lens oriented to correct aberrations, including astigmatism caused by surface errors of the reflecting surfaces of a prism in the folded optical system. The deformable lens described herein can, for example, be used in embodiments of a single-folded optical system comprising a single refractive prism as described herein. However, the deformable lens described herein can also be used in other single-folded or double-folded optical systems to correct aberrations, including astigmatism caused by surface errors of the reflecting surfaces of a prism in the folded optical system. The deformable lens described herein can be used to correct aberrations caused by the flat reflecting surfaces of a refractive prism or triangular prism, or by the curved reflecting surfaces of a prism (such as a freeform prism). Freeform optics involve optical designs having at least one surface that does not have translational or rotational symmetry about an axis perpendicular to the average plane of the surface. Therefore, a freeform prism is a prism having at least one surface that does not have translational or rotational symmetry about an axis perpendicular to the average plane of the surface.

[0037] A manufacturing process for a folded optical system is also described, the folded optical system including a deformable lens to correct aberrations, including astigmatism caused by surface errors of the reflective surface of a prism.

[0038] Figures 1 to 3 A side sectional view is shown of an example embodiment of a single-fold optical system as described herein. Figures 1 to 3 As shown, a single-fold optical system may include:

[0039] • A first lens group, comprising lenses formed of an optically plastic material having, for example, Figure 1 The aspherical object side surface refractive prism shown in the figure, or including a triangular glass prism with a positive lens formed of optical plastic or glass material, the triangular glass prism having, for example, a refractive prism with, a ... Figure 2 and Figure 3 The aspherical object side surface shown in the image, as well as the flat or planar image side surface of the object side surface attached to the prism; and

[0040] A second lens group comprising two or more refractive lens elements (four in these embodiments). The refractive lenses in the second lens group may be formed of optical plastic or glass. In some embodiments, all the refractive lenses in the second lens group may be formed of the same material. In some embodiments, at least two of the refractive lenses in the second lens group may be formed of different materials.

[0041] In some implementations of a single-fold optical system, the first (object-side) surface of the first lens group is aspherical, and the angle between the principal ray passing through the first surface of the first lens group and the principal ray at the image plane formed on the image side of the second lens group may, but is not necessarily, less than 90 degrees.

[0042] The implementation scheme of a single-fold optical system can satisfy the following conditional expression:

[0043] 0.6

[0044] Where A is the optical power of the entire optical system, and B is the optical power of the first lens group. If B / A is greater than the range expressed in the conditional expression, the droop may be too large to manufacture. On the other hand, if B / A is less than the range expressed in the conditional expression, the X length of the optical system cannot be reduced effectively.

[0045] The implementation scheme of a single-fold optical system can satisfy the following conditional expression:

[0046] -0.2 <CD<0.1,

[0047] Where C is the optical power of the second lens group, and D is the length of the second lens group. CD applies to the sensitivity of the second lens group. If CD is not within the range expressed in the conditional expression, the tolerance of the second lens group may be poor, and / or the size (length) of the second lens group may be enlarged.

[0048] In some implementations, the prisms in the first lens group are composed of an Abbe number V. d Optical materials that meet the following conditions are constituted:

[0049] V d >50.

[0050] An implementation of the single-fold optical system described herein can have a Z height of <7.3 mm and an X length of <18 mm.

[0051] In some embodiments, one or more optical elements in an optical system may be formed using an injection molding process. However, in some embodiments, one or more of these elements may be formed using other methods (e.g., 3D printing, extrusion, blow molding, casting, rotational molding, die casting, overmolding, compression molding, computer numerical control (CNC) machining, thermoforming, etc.).

[0052] Figure 1 ​A single-fold optical system comprising a refracting prism made of optical plastic is illustrated according to some embodiments. The optical system 100 may include a refracting prism 110 (also referred to as a first lens group) and a lens stack 120 (also referred to as a second lens group) comprising two or more refractive lenses. In this example, the lens stack 120 includes four refractive lenses: lens 121, lens 122, lens 123, and lens 124. However, it should be noted that some embodiments may include more or fewer lenses in the lens stack 120. An aperture stop 102 may be located on or near the object side of the refracting prism 110.

[0053] The refractive prism 110 may be formed of an optically plastic material. In some embodiments, the object-side surface 112 of the prism 110 is a curved aspherical surface that provides a positive refractive force to the prism 110. The second surface 114 of the prism 110 is a flat or planar surface that reflects light received from the object field through the object-side surface 112 of the prism 110 via total internal reflection (TIR) ​​or via specular coating, thereby folding the optical axis of the optical system 100. The light reflected by the second surface 114 leaves the prism 110 through a third flat or planar surface 116 and reaches the first lens 121 in the lens stack 120. The lenses in the lens stack 120 then refract the light to form an image at the image plane.

[0054] Figure 1 An example lens stack 120 is shown, comprising four refractive lenses: a lens 121 with positive refractive power, a lens 122 with negative refractive power, a lens 123 with negative refractive power, and a lens 124 with positive refractive power. However, it should be noted that some embodiments may include more or fewer lenses in the lens stack 120. Furthermore, the materials, shapes, optical powers, power orders, positions, and distances between the lenses are given by way of example and are not intended to be limiting.

[0055] Figure 1 The single-fold optical system 100 can form an image at or near the image plane of the image sensor 140 on the image side of the lens stack 120. In some embodiments, an infrared (IR) filter 130 may be located between the lens stack 120 and the image sensor 140. The optical system 100, sensor 140, and filter 130 (if present) may be components of a camera, which may be used, for example, as a small-form-factor camera in a mobile multi-purpose device such as a smartphone or tablet computer or tablet device.

[0056] Figure 2An example single-fold optical system, comprising a glass prism and a plastic lens located on the object side of the prism, is shown according to some embodiments. The optical system 200 may include a lens 204 formed of an optical plastic material and a prism 210 formed of an optical glass material (collectively referred to as a first lens group), and a lens stack 220 comprising two or more refractive lenses (also referred to as a second lens group). In this example, the lens stack 220 includes four refractive lenses: lens 221, lens 222, lens 223, and lens 224. However, it should be noted that some embodiments may include more or fewer lenses in the lens stack 220. An aperture stop 202 may be located on or near the object side of lens 204.

[0057] Prism 210 may be formed of an optical glass material. The object-side surface 212 of prism 210 is flat or planar. A plastic lens 204 with positive refractive power may be attached to the object-side surface 212 of prism 210, for example, using an adhesive material. The object-side surface of lens 204 may be spherical or aspherical convex; the image-side surface of lens 204 is flat or planar. A second surface 214 of prism 210 is flat or planar, which reflects light received from the object field through the object-side surface 212 of prism 210 via total internal reflection (TIR) ​​or via specular coating, thereby folding the optical axis of optical system 200. Light reflected by the second surface 214 exits prism 210 through a third flat or planar surface 216 and reaches the first lens 221 in lens stack 220. The lenses in lens stack 220 then refract the light to form an image at the image plane.

[0058] Figure 2 An example lens stack 220 is shown, comprising four refractive lenses: a lens 221 with positive refractive power, a lens 222 with negative refractive power, a lens 223 with negative refractive power, and a lens 224 with positive refractive power. However, it should be noted that some embodiments may include more or fewer lenses in the lens stack 220. Furthermore, the materials, shapes, optical powers, power orders, positions, and distances between the lenses are given by way of example and are not intended to be limiting.

[0059] Figure 2 The single-fold optical system 200 can form an image at or near the image plane of the image sensor 240 on the image side of the lens stack 220. In some embodiments, an infrared (IR) filter 230 may be located between the lens stack 220 and the image sensor 240. The optical system 200, sensor 240, and filter 230 (if present) may be components of a camera, which may be used, for example, as a small-form-factor camera in a mobile multi-purpose device such as a smartphone or tablet computer or tablet device.

[0060] Figure 3 An example single-fold optical system, comprising a glass prism and a glass lens located on the object side of the prism, is shown according to some embodiments. The optical system 300 may include a lens 304 formed of an optical glass material and a prism 310 formed of an optical glass material (collectively referred to as a first lens group) and a lens stack 320 comprising two or more refractive lenses (also referred to as a second lens group). In this example, the lens stack 320 includes four refractive lenses: lens 321, lens 322, lens 323, and lens 324. However, it should be noted that some embodiments may include more or fewer lenses in the lens stack 320. An aperture stop 302 may be located on or near the object side of lens 304.

[0061] Prism 310 may be formed of an optical glass material. The object-side surface 312 of prism 310 is flat or planar. A glass lens 304 with positive refractive power may be attached to the object-side surface 312 of prism 310, for example, using an adhesive material. The object-side surface of lens 304 may be spherical or aspherical convex; the image-side surface of lens 304 is flat or planar. A second surface 314 of prism 310 is flat or planar, which reflects light received from the object field through the object-side surface 312 of prism 310 via total internal reflection (TIR) ​​or via specular coating, thereby folding the optical axis of optical system 300. Light reflected by the second surface 314 leaves prism 310 through a third flat or planar surface 316 and reaches the first lens 321 in lens stack 320. The lenses in lens stack 320 then refract the light to form an image at the image plane.

[0062] Figure 3 An example lens stack 320 is shown, comprising four refractive lenses: a lens 321 with positive refractive power, a lens 322 with negative refractive power, a lens 323 with negative refractive power, and a lens 324 with positive refractive power. However, it should be noted that some embodiments may include more or fewer lenses in the lens stack 320. Furthermore, the materials, shapes, optical powers, power orders, positions, and distances between the lenses are given by way of example and are not intended to be limiting.

[0063] Figure 3 The single-fold optical system 300 can form an image at or near the image plane of the image sensor 340 on the image side of the lens stack 320. In some embodiments, an infrared (IR) filter 330 may be located between the lens stack 320 and the image sensor 340. The optical system 300, sensor 340, and filter 330 (if present) may be components of a camera, which may be used, for example, as a small-form-factor camera in a mobile multi-purpose device such as a smartphone or tablet computer or tablet device.

[0064] Figure 4 As shown Figure 1 The example optical system shown exhibits example optical characteristics and performance metrics. The example optical system may have an X length of 15.5 mm and a Z height of 6.8 mm. The distortion of the optical system may be <+ / -0.25%. The graphs show the modulation transfer function (MTF) of the single-fold optical system at infinity (inf) and at micro-pitch.

[0065] Figure 5A and Figure 5B The double-fold optical system is compared with a single-fold optical system according to some embodiments. Figure 5A The example demonstrates a conventional double-folding optical system 500A, which, from the object side to the image side, sequentially includes a first prism for first folding the optical axis, a lens stack, and a second prism or mirror for second folding the optical axis; an image is formed at or near the sensor in an image plane. The Z-height of the optical system 500A can be approximately 7.1 mm, and the X-length can be approximately 22.3 mm. Figure 5B An example embodiment of the single-fold optical system 500B described herein is shown, which, from the object side to the image side, includes a first lens group (refractive prism) that folds the optical axis, and a second lens group (lens stack) that refracts light received from the first lens group to form an image at or near the sensor in an image plane. The Z-height of the optical system 500B can be approximately 6.8 mm, and the X-length can be approximately 15.5 mm.

[0066] like Figure 5A and Figure 5B As demonstrated, when compared to a conventional double-fold optical system with similar optical properties, an embodiment of the single-fold optical system described herein can provide an optical system with a long focal length and reduced thickness (Z-height) and X-length. Generally, the Z-height of a double-fold optics device is defined by the prism size and the mechanical back focal length. This single-fold optical system embodiment can provide a long mechanical back focal length without increasing or even decreasing the Z-height of the optical system. Providing optical power on the prism reduces the overall optical length and the X-length of the optical system.

[0067] Figures 6A to 6B , Figures 7A to 7B , Figures 8A to 8B Figure 9 shows a side sectional view of an additional example implementation of a single-fold optical system as described herein.

[0068] Figure 6AAnother example of a single-fold optical system, comprising a refracting prism made of optical plastic, is shown according to some embodiments. The optical system 600 may include a refracting prism 610 (also referred to as a first lens group) and a lens stack 620 (also referred to as a second lens group), the lens stack comprising four refractive lenses: lens 621, lens 622, lens 623, and lens 624. However, it should be noted that some embodiments may include more or fewer lenses in the lens stack 620. An aperture stop 602 may be located on or near the object side of the refracting prism 610.

[0069] The refractive prism 610 may be formed of an optically plastic material. In some embodiments, the object-side surface 612 of the prism 610 is a curved aspherical surface that provides a positive refractive force to the prism 610. The second surface 614 of the prism 610 is a flat or planar surface that reflects light received from the object field through the object-side surface 612 of the refractive prism 610 via total internal reflection (TIR) ​​or via specular coating, thereby folding the optical axis of the optical system 600. The light reflected by the second surface 614 leaves the prism 610 through a third flat or planar surface 616 and reaches the first lens 621 in the lens stack 620. The lenses in the lens stack 612 then refract the light to form an image at the image plane.

[0070] Figure 6A An example lens stack 620 is shown, comprising four refractive lenses: a lens 621 with positive refractive power, a lens 622 with negative refractive power, a lens 623 with negative refractive power, and a lens 624 with positive refractive power. However, it should be noted that some embodiments may include more or fewer lenses in the lens stack 620. In some embodiments, at least one surface of at least one lens in the second lens group may be an aspherical surface. The refractive lenses in the second lens group may be formed of optical plastic or glass material. Furthermore, the materials, shapes, optical powers, power orders, positions, and distances between lenses are given by way of example and are not intended to be limiting.

[0071] Figure 6A The single-fold optical system 600 can form an image at or near an image plane on the image side of the image sensor 640, located on the lens stack 620. In some embodiments, an infrared (IR) filter 630 may be located between the lens stack 620 and the image sensor 640. The optical system 600, sensor 640, and filter 630 (if present) may be components of a camera, which may be used, for example, as a small-form-factor camera in a mobile multi-purpose device such as a smartphone or tablet computer.

[0072] Figure 6B Show Figure 6AThe optical characteristics and performance metrics of the example optical system 600 shown are illustrated. The example optical system 600 may have an X length of 17.2 mm and a Z height of 6.8 mm. The distortion of the optical system may be <+ / -0.25%. The graphs show the modulation transfer function (MTF) of the single-fold optical system at infinity (inf) and at micro-pitch.

[0073] Figure 7A Another example of a single-fold optical system, including a glass prism and a plastic lens located on the object side of the prism, is shown according to some embodiments. The optical system 700 may include a lens 704 formed of an optical plastic material and a prism 710 formed of an optical glass material (collectively referred to as a first lens group) and a lens stack 720 (also referred to as a second lens group) comprising four refractive lenses: lens 721, lens 722, lens 723, and lens 724. However, it should be noted that some embodiments may include more or fewer lenses in the lens stack 720. An aperture stop 702 may be located on or near the object side of lens 704.

[0074] Prism 710 may be formed of an optical glass material. The object-side surface 712 of prism 710 is a flat or planar surface. A plastic lens 704 with positive refractive power may be attached to the object-side surface 712 of prism 710, for example, using an adhesive material. The object-side surface of lens 704 may be a spherical or aspherical convex surface; the image-side surface of lens 704 is a flat or planar surface. A second surface 714 of prism 710 is a flat or planar surface that reflects light received from the object field through the object-side surface 712 of prism 710 via total internal reflection (TIR) ​​or via specular coating, thereby folding the optical axis of optical system 700. Light reflected by the second surface 714 leaves prism 710 through a third flat or planar surface 716 and reaches the first lens 721 in lens stack 720. The lenses in lens stack 720 then refract the light to form an image at the image plane.

[0075] Figure 7A An example lens stack 720 is shown, comprising four refractive lenses: a lens 721 with positive refractive power, a lens 722 with negative refractive power, a lens 723 with negative refractive power, and a lens 724 with positive refractive power. However, it should be noted that some embodiments may include more or fewer lenses in the lens stack 720. In some embodiments, at least one surface of at least one lens in the second lens group may be an aspherical surface. The refractive lenses in the second lens group may be formed of optical plastic or glass material. Furthermore, the materials, shapes, optical powers, optical power orders, positions, and distances between lenses are given by way of example and are not intended to be limiting.

[0076] Figure 7AThe single-fold optical system 700 can form an image at or near an image plane on the image side of the image sensor 740, located on the lens stack 720. In some embodiments, an infrared (IR) filter 730 may be located between the lens stack 720 and the image sensor 740. The optical system 700, sensor 740, and filter 730 (if present) may be components of a camera, which may be used, for example, as a small-form-factor camera in a mobile multi-purpose device such as a smartphone or tablet computer.

[0077] Figure 7B Show Figure 7A The optical characteristics and performance metrics of the example optical system 700 shown are illustrated. The example optical system 700 may have an X length of 17.2 mm and a Z height of 6.5 mm. The distortion of the optical system may be <+ / -0.25%. The graphs show the modulation transfer function (MTF) of the single-fold optical system at infinity (inf) and at micro-pitch.

[0078] Figure 8A Another example of a single-fold optical system, including a glass prism and a glass lens located on the object side of the prism, is shown according to some embodiments. The optical system 800 may include a lens 804 formed of an optical glass material and a prism 810 formed of an optical glass material (collectively referred to as a first lens group) and a lens stack 820 (also referred to as a second lens group) comprising four refractive lenses: lens 821, lens 822, lens 823, and lens 824. However, it should be noted that some embodiments may include more or fewer lenses in the lens stack 820. An aperture stop 802 may be located on or near the object side of lens 804.

[0079] Prism 810 may be formed of an optical glass material. The object-side surface 812 of prism 810 is a flat or planar surface. A glass lens 804 with positive refractive power may be attached to the object-side surface 812 of prism 8710, for example, using an adhesive material. The object-side surface of lens 804 may be a spherical or aspherical convex surface; the image-side surface of lens 804 is a flat or planar surface. A second surface 814 of prism 810 is a flat or planar surface that reflects light received from the object field through the object-side surface 812 of prism 810 via total internal reflection (TIR) ​​or via specular coating, thereby folding the optical axis of optical system 800. Light reflected by the second surface 814 leaves prism 810 through a third flat or planar surface 816 and reaches the first lens 821 in lens stack 820. The lenses in lens stack 820 then refract the light to form an image at the image plane.

[0080] Figure 8AAn example lens stack 820 is shown, comprising four refractive lenses: a lens 821 with positive refractive power, a lens 822 with negative refractive power, a lens 823 with negative refractive power, and a lens 824 with positive refractive power. However, it should be noted that some embodiments may include more or fewer lenses in the lens stack 820. In some embodiments, at least one surface of at least one lens in the second lens group may be an aspherical surface. The refractive lenses in the second lens group may be formed of optical plastic or glass material. Furthermore, the materials, shapes, optical powers, power orders, positions, and distances between lenses are given by way of example and are not intended to be limiting.

[0081] Figure 8A The single-fold optical system 800 can form an image at or near an image plane on the image side of the image sensor 840, located on the lens stack 820. In some embodiments, an infrared (IR) filter 830 may be located between the lens stack 820 and the image sensor 840. The optical system 800, sensor 840, and filter 830 (if present) may be components of a camera, which may be used, for example, as a small-form-factor camera in a mobile multi-purpose device such as a smartphone or tablet computer.

[0082] Figure 8B Show Figure 8A The optical characteristics and performance metrics of the example optical system 800 shown are illustrated. The example optical system 800 may have an X length of 17.2 mm and a Z height of 7.1 mm. The distortion of the optical system may be <+ / -0.25%. The graphs show the modulation transfer function (MTF) of the single-fold optical system at infinity (inf) and at micro-pitch.

[0083] Figure 9A Another example of a single-fold optical system including a refracting prism is shown according to some embodiments. The optical system 900 may include a refracting prism 910 (also referred to as a first lens group) and a lens stack 920 (also referred to as a second lens group), the lens stack including four refractive lenses: lens 921, lens 922, lens 923, and lens 924. However, it should be noted that some embodiments may include more or fewer lenses in the lens stack 920. An aperture stop 902 may be located on or near the object side of the refracting prism 910.

[0084] The refractive prism 910 may be formed of an optically plastic material. In some embodiments, the object-side surface 912 of the prism 910 is a curved aspherical surface that provides a positive refractive force to the prism 910. The second surface 914 of the prism 910 is a flat or planar surface that reflects light received from the object field through the object-side surface 912 of the refractive prism 910 via total internal reflection (TIR) ​​or via specular coating, thereby folding the optical axis of the optical system 900. The light reflected by the second surface 914 leaves the prism 910 through a third flat or planar surface 916 and reaches the first lens 921 in the lens stack 920. The lenses in the lens stack 912 then refract the light to form an image at the image plane.

[0085] Figure 9A An example lens stack 920 is shown, comprising four refractive lenses: a lens 921 with positive refractive power, a lens 922 with negative refractive power, a lens 923 with negative refractive power, and a lens 924 with positive refractive power. However, it should be noted that some embodiments may include more or fewer lenses in the lens stack 920. In some embodiments, at least one surface of at least one lens in the second lens group may be an aspherical surface. The refractive lenses in the second lens group may be formed of optical plastic or glass material. Furthermore, the materials, shapes, optical powers, power orders, positions, and distances between lenses are given by way of example and are not intended to be limiting.

[0086] Figure 9A The single-fold optical system 900 can form an image at or near the image plane of the image sensor 940 located on the image side of the lens stack 920. In some embodiments, an infrared (IR) filter 930 may be located between the lens stack 920 and the image sensor 940. The optical system 900, sensor 940, and filter 930 (if present) may be components of a camera, which may be used, for example, as a small-form-factor camera in a mobile multi-purpose device such as a smartphone or tablet computer.

[0087] Figure 9B Show Figure 9A The optical characteristics and performance metrics of the example optical system 900 shown are illustrated. The example optical system 900 may have an X length of 17.6 mm and a Z height of 7.2 mm. The distortion of the optical system may be <+ / -0.25%. The graphs show the modulation transfer function (MTF) of the single-fold optical system at infinity (inf) and at micro-pitch.

[0088] Figure 10 It is for use according to some implementation schemes, such as Figure 1The flowchart above Figure 9 illustrates a method for capturing an image using an embodiment of a single-fold optical system. As indicated at 1000, light from the object field is received through an aperture at a first surface of a refracting prism. As indicated at 1010, the first surface of the refracting prism refracts light onto a second (reflective) surface. As indicated at 1020, the second surface of the refracting prism reflects light onto a third surface. As indicated at 1030, the third surface of the prism transmits light through a lens stack. As indicated at 1040, refractive lenses in the lens stack refract the light to form an image at or near the surface of the image sensor. In some embodiments, an infrared filter may be positioned between the lens stack and the image sensor.

[0089] The table below provides the optical and physical characteristics of the example single-fold lens system described in this article. Figure 11 The surfaces of an example single-fold optical system, as mentioned in the table, are shown. The position of each surface is determined by global coordinates based on prism S1.

[0090] An aspherical surface can be defined as:

[0091]

[0092] in

[0093]

[0094] And the radius of curvature r is:

[0095] 4th order (A);

[0096] 6th order (B);

[0097] 8th order (C);

[0098] 10th order (D);

[0099] 12th order (E); and

[0100] 14th order (F).

[0101] Table 1 provides Figure 1 , Figure 6A , Figure 7A , Figure 8A and Figure 9A The range of optical and physical properties of the example implementations shown in the figure.

[0102] Table 1

[0103] characteristic scope Figure 1 Figure 6A Figure 7A Figure 8A Figure 9A B / A 0.6 to 2.3 1.24 0.81 0.81 0.81 2.10 CD -0.2 to 0.1 -0.128 0.047 0.047 0.046 -0.106 Vd1 >50 55.97 55.73 55.73 55.73 55.73 Z-height <7.3 6.8 6.8 6.5 7.1 7.2 X length <18 15.5 17.2 17.2 17.2 17.6

[0104] Tables 2A to 2F are as follows: Figure 1The example single-fold optical system shown provides optical and physical properties.

[0105] Table 2A shows the results based on, for example Figure 1 All surface positions of the prism S1 in the example single-fold optical system shown:

[0106] Table 2A

[0107]

[0108]

[0109] Tables 2B to 2D show the requirements for, for example Figure 1 The aspherical values ​​of the surface of the optical component in the example single-fold optical system shown are:

[0110] Table 2B

[0111] Prism S1 L1S1 L1S2 radius of curvature 6.7203 -5.2935 14.2603 Level 4 -4.26730E-04 -2.88851E-03 -1.48664E-03 Level 6 -1.29339E-05 -3.95461E-04 9.32386E-04 Level 8 -7.66845E-07 9.90583E-05 -6.91378E-05 Level 10 6.66654E-08 -1.12263E-05 -3.43883E-06 Level 12 -5.16169E-09 2.23130E-06 3.08245E-06 Level 14 4.49321E-07 -2.03270E-07

[0112] Table 2C

[0113] L2S1 L2S2 L3S1 radius of curvature -16.1429 -2.7451 3.7738 Level 4 1.41735E-02 1.19869E-02 1.31664E-02 Level 6 -6.22662E-04 -2.57413E-03 -2.21852E-03 Level 8 -1.17735E-04 4.39224E-04 6.21870E-04 Level 10 -3.12763E-05 -5.79999E-04 -1.72582E-04 Level 12 -4.96180E-07 2.09980E-04 Level 14 -4.53847E-07 -4.24766E-05

[0114] Table 2D

[0115]

[0116]

[0117] Table 2E shows the following: Figure 1 The material properties of the optical components in the example single-fold optical system shown are illustrated. Nd refers to the refractive index, and Vd refers to the Abbe number of the material. L1 to L4 refer to the four lenses in the second lens group from the object side to the image side of the optical system.

[0118] Table 2E

[0119] Prism L1 L2 L3 L4 Nd 1.544 1.544 1.671 1.544 1.671 Vd 55.97 55.97 19.23 55.97 19.23

[0120] Table 2F shows the following: Figure 1 The optical specifications of the example single-fold optical system shown are as follows. EFL is the effective focal length, and Fno is the aperture number of the optical system.

[0121] Table 2F

[0122] EFL 15.3 Fno 3.0 Half sensor diagonal 2.52 Macro distance 80cm

[0123] Tables 3A to 3F are as follows: Figure 6AThe example single-fold optical system shown provides optical and physical properties.

[0124] Table 3A shows the results based on, for example Figure 6A All surface positions of the prism S1 in the example single-fold optical system shown:

[0125] Table 3A

[0126] x z Angle (α) aperture 0 0.28 0 Prism S1 0.000 0.000 0 Prism S2 0.000 3.450 45 Prism S3 -3.100 3.450 90 L1 S1 -3.600 3.450 90 L1S2 -4.645 3.450 90 L2S1 -4.898 3.450 90 L2S2 -5.288 3.450 90 L3S1 -8.974 3.450 90 L3S4 -9.634 3.450 90 L4S1 -10.375 3.450 90 L4S2 -11.475 3.450 90 IRcut S1 -13.359 3.450 90 IRcut S2 -13.569 3.450 90 Image plane (INF) -13.669 3.450 90

[0127] Tables 3B to 3D show examples such as Figure 6A The aspherical values ​​of the surface of the optical component in the example single-fold optical system shown are:

[0128] Table 3B

[0129]

[0130]

[0131] Table 3C

[0132] L2S1 L2S2 L3S1 radius of curvature -5.8392 -2.7004 7.9220 Level 4 2.08846E-02 2.80123E-02 4.36643E-02 Level 6 -6.99973E-03 -1.15153E-02 -8.56777E-03 Level 8 9.61573E-04 2.21425E-03 4.95687E-04 Level 10 -3.49028E-05 -6.01848E-04 -4.46371E-05 Level 12 -8.47955E-07 1.40503E-04 Level 14 -2.38157E-06 -2.85205E-05

[0133] Table 3D

[0134] L3S2 L4S1 L4S2 radius of curvature -5.3114 -81.4716 6.5864 Level 4 3.90863E-02 -1.94553E-03 8.73233E-04 Level 6 -8.82724E-03 1.24447E-03 -2.40538E-04 Level 8 1.21063E-03 -3.53784E-04 4.64840E-05 Level 10 -9.15778E-05 8.00536E-05 -2.44547E-06 Level 12 -7.42994E-06 1.63492E-06 Level 14 4.81112E-07 -3.05210E-08

[0135] Table 3E shows the following: Figure 6A The material properties of the optical components in the example single-fold optical system shown are illustrated. Nd refers to the refractive index, and Vd refers to the Abbe number of the material. L1 to L4 refer to the four lenses in the second lens group from the object side to the image side of the optical system.

[0136] Table 3E

[0137]

[0138]

[0139] Table 3F shows the following: Figure 6A The optical specifications of the example single-fold optical system shown are as follows. EFL is the effective focal length, and Fno is the aperture number of the optical system.

[0140] Table 3F

[0141] EFL 15.37 Fno 3.0 Half sensor diagonal 2.52 Macro distance 125cm

[0142] Tables 4A to 4F are as follows: Figure 7AThe example single-fold optical system shown provides optical and physical properties.

[0143] Table 4A shows the results based on, for example Figure 7A All surface positions of the prism S1 in the example single-fold optical system shown:

[0144] Table 4A

[0145] x z Angle (α) aperture 0 0.28 0 Prism S1 0.000 0.000 0 prism inner surface 0.000 0.349 0 Prism S2 0.000 3.134 45 Prism S3 -2.785 3.134 90 L1 S1 -4.220 3.134 90 L1S2 -5.265 3.134 90 L2S1 -5.518 3.134 90 L2S2 -5.908 3.134 90 L3S1 -9.594 3.134 90 L3S2 -10.254 3.134 90 L4S1 -10.995 3.134 90 L4S2 -12.095 3.134 90 IRcut S1 -13.946 3.134 90 IRcut S2 -14.156 3.134 90 Image plane (INF) -14.256 3.134 90

[0146] Tables 4B to 4D show the requirements for, for example Figure 7A The aspherical values ​​of the surface of the optical component in the example single-fold optical system shown are:

[0147] Table 4B

[0148] Prism S1 L1S1 L1S2 radius of curvature 9.6677 -4.5962 24.1370 Level 4 -5.32525E-04 -4.96952E-03 -6.96106E-03 Level 6 -8.96273E-06 3.25426E-04 2.34753E-03 Level 8 1.55564E-06 -2.59701E-05 -5.13966E-04 Level 10 -1.69683E-07 3.54569E-05 1.47389E-04 Level 12 7.82692E-09 -7.43090E-06 -1.18246E-05 Level 14 1.91989E-06 1.99593E-07

[0149] Table 4C

[0150] L2S1 L2S2 L3S1 radius of curvature -5.8392 -2.7004 7.9220 Level 4 2.08846E-02 2.80123E-02 4.36643E-02 Level 6 -6.99973E-03 -1.15153E-02 -8.56777E-03 Level 8 9.61573E-04 2.21425E-03 4.95687E-04 Level 10 -3.49028E-05 -6.01848E-04 -4.46371E-05 Level 12 -8.47955E-07 1.40503E-04 Level 14 -2.38157E-06 -2.85205E-05

[0151] Table 4D

[0152] L3S2 L4S1 L4S2 radius of curvature -5.3114 -81.4716 6.5864 Level 4 3.90863E-02 -1.94553E-03 8.73233E-04 Level 6 -8.82724E-03 1.24447E-03 -2.40538E-04 Level 8 1.21063E-03 -3.53784E-04 4.64840E-05 Level 10 -9.15778E-05 8.00536E-05 -2.44547E-06 Level 12 -7.42994E-06 1.63492E-06 Level 14 4.81112E-07 -3.05210E-08

[0153] Table 4E shows the following... Figure 7A The material properties of the optical components in the example single-fold optical system shown are illustrated. Nd refers to the refractive index, and Vd refers to the Abbe number of the material. L1 to L4 refer to the four lenses in the second lens group from the object side to the image side of the optical system.

[0154] Table 4E

[0155] Prism L1 L2 L3 L4 Nd 1.514 1.834 1.544 1.671 1.544 Vd 51.35 37.16 55.97 19.23 55.97

[0156] Table 4F shows the following: Figure 7A The optical specifications of the example single-fold optical system shown are as follows. EFL is the effective focal length, and Fno is the aperture number of the optical system.

[0157] Table 4F

[0158] EFL 15.3 Fno 3.0 Half sensor diagonal 2.52 Macro distance 125cm

[0159] Tables 5A to 5F are as follows: Figure 8A The example single-fold optical system shown provides optical and physical properties.

[0160] Table 5A shows the data based on, for example Figure 8AAll surface positions of the prism S1 in the example single-fold optical system shown:

[0161] Table 5A

[0162]

[0163]

[0164] Tables 5B to 5D show the requirements for, for example Figure 8A The aspherical values ​​of the surface of the optical component in the example single-fold optical system shown are:

[0165] Table 5B

[0166] Prism S1 L1S1 L1S2 radius of curvature 10.9936 -4.5962 24.1370 Level 4 -4.47670E-04 -4.96952E-03 -6.96106E-03 Level 6 -1.61255E-06 3.25426E-04 2.34753E-03 Level 8 -1.31071E-07 -2.59701E-05 -5.13966E-04 Level 10 3.27852E-08 3.54569E-05 1.47389E-04 Level 12 -1.37757E-09 -7.43090E-06 -1.18246E-05 Level 14 1.91989E-06 1.99593E-07

[0167] Table 5C

[0168] L2S1 L2S2 L3S1 radius of curvature -5.8392 -2.7004 7.9220 Level 4 2.08846E-02 2.80123E-02 4.36643E-02 Level 6 -6.99973E-03 -1.15153E-02 -8.56777E-03 Level 8 9.61573E-04 2.21425E-03 4.95687E-04 Level 10 -3.49028E-05 -6.01848E-04 -4.46371E-05 Level 12 -8.47955E-07 1.40503E-04 Level 14 -2.38157E-06 -2.85205E-05

[0169] Table 5D

[0170] L3S2 L4S1 L4S2 radius of curvature -5.3114 -81.4716 6.5864 Level 4 3.90863E-02 -1.94553E-03 8.73233E-04 Level 6 -8.82724E-03 1.24447E-03 -2.40538E-04 Level 8 1.21063E-03 -3.53784E-04 4.64840E-05 Level 10 -9.15778E-05 8.00536E-05 -2.44547E-06 Level 12 -7.42994E-06 1.63492E-06 Level 14 4.81112E-07 -3.05210E-08

[0171] Table 5E shows the following: Figure 8A The material properties of the optical components in the example single-fold optical system shown are illustrated. Nd refers to the refractive index, and Vd refers to the Abbe number of the material. L1 to L4 refer to the four lenses in the second lens group from the object side to the image side of the optical system.

[0172] Table 5E

[0173] Prism L1 L2 L3 L4 Nd 1.583 1.834 1.544 1.671 1.544 Vd 59.38 37.16 55.97 19.23 55.97

[0174] Table 5F shows the following: Figure 8A The optical specifications of the example single-fold optical system shown are as follows. EFL is the effective focal length, and Fno is the aperture number of the optical system.

[0175] Table 5F

[0176] EFL 15.3 Fno 3.0 Half sensor diagonal 2.52 Macro distance 125cm

[0177] Tables 6A to 6F are as follows: Figure 9A The example single-fold optical system shown provides optical and physical properties.

[0178] Table 6A shows the data based on, for example Figure 9A All surface positions of the prism S1 in the example single-fold optical system shown:

[0179] Table 6A

[0180]

[0181]

[0182] Tables 6B to 6D show examples such as Figure 9A The aspherical values ​​of the surface of the optical component in the example single-fold optical system shown are:

[0183] Table 6B

[0184] Prism S1 L1S1 L1S2 radius of curvature 5.6321 -11.6936 21.5932 Level 4 -2.68374E-04 -2.40165E-03 -1.27735E-03 Level 6 -7.96206E-06 9.06400E-04 1.10220E-03 Level 8 2.54679E-07 1.27434E-05 -1.35119E-04 Level 10 -5.97297E-08 1.21772E-05 1.10012E-05 Level 12 2.34852E-09 -9.78359E-06 1.83952E-05 Level 14 3.15343E-06 -1.67661E-06

[0185] Table 6C

[0186] L2S1 L2S2 L3S1 radius of curvature -298.9651 -4.7109 5.5578 Level 4 2.63966E-03 -1.33363E-03 -2.38091E-02 Level 6 -2.23391E-03 -2.71636E-03 1.24316E-02 Level 8 3.72586E-04 4.30366E-04 -1.91564E-03 Level 10 9.73830E-05 2.05012E-04 -8.41607E-05 Level 12 -3.53637E-05 -1.05166E-04 1.12014E-04 Level 14 3.18196E-06 1.25474E-05 -2.07762E-05

[0187] Table 6D

[0188]

[0189]

[0190] Table 6E shows the following... Figure 9A The material properties of the optical components in the example single-fold optical system shown are illustrated. Nd refers to the refractive index, and Vd refers to the Abbe number of the material. L1 to L4 refer to the four lenses in the second lens group from the object side to the image side of the optical system.

[0191] Table 6E

[0192] Prism L1 L2 L3 L4 Nd 1.535 1.544 1.671 1.544 1.671 Vd 55.73 55.97 19.23 55.97 19.23

[0193] Table 6F shows the following: Figure 9A The optical specifications of the example single-fold optical system shown are as follows. EFL is the effective focal length, and Fno is the aperture number of the optical system.

[0194] Table 6F

[0195] EFL 22.03 Fno 4.0 Half sensor diagonal 2.268 Macro distance 175cm

[0196] Deformable lenses in folding optical systems

[0197] Such as Figures 1 to 11The folded optical system illustrated in the single-folded optical system includes at least one prism having a reflective, flat second surface to fold the optical axis of the system. However, surface errors of the reflective surface of the prism in the folded optical system can cause aberrations in the optical system, particularly astigmatism. In other words, while ideally perfectly flat, the reflective surface of the prism will typically be flat within a certain tolerance level (e.g., a few micrometers) of the manufacturing process. Therefore, the second (reflective) surface can be slightly curved, which causes the aforementioned aberrations. When compared to plastic prisms, using glass prisms can help limit these aberrations because glass can be polished to provide tighter tolerance levels in the manufacturing process than plastic. However, the reflective surface of a glass prism can only be guaranteed to be flat within a certain tolerance level. Furthermore, due to variations in the manufacturing process, different prism sets or prism batches (whether glass or plastic) can vary in the "flatness" of the second reflective surface.

[0198] In an optical system with astigmatism, rays propagating in two perpendicular planes have different focal points. For example, if an optical system with astigmatism is used to form an intersecting image, the vertical and horizontal lines will be sharply focused at two different distances.

[0199] An embodiment of a folding optical system is described, comprising at least one deformable lens configured and oriented to correct aberrations, including astigmatism caused by surface errors of the reflecting surfaces of prisms in the folding optical system. The deformable lens described herein can, for example, be used in an embodiment of a single-folding optical system, which includes, as referenced herein... Figures 1 to 11 The single-folding prism described herein. However, deformable lenses as described herein can also be used in other single-folding or double-folding optical systems to correct aberrations, including astigmatism caused by surface errors of the reflecting surfaces of the prisms in the folding optical system. Deformable lenses as described herein can be used to correct astigmatism caused by the flat reflecting surfaces of a folding prism or triangular prism, or by the curved reflecting surfaces of a prism (such as a freeform prism).

[0200] Spherical lenses have one or two curved (concave or convex) surfaces. The curvature of the surfaces is the same on all axes (e.g., on the X and Y axes). Spherical lenses transmit images to the sensor without affecting the aspect ratio. Deformable lenses have at least one curved (convex or concave) surface, where the curvature is different on at least one axis (e.g., different on the X-axis than on the Y-axis). Therefore, the effective surface of a deformable lens may be elliptical rather than circular, as in a typical spherical lens. Consequently, deformable lenses distort the image, compressing it in one direction (e.g., horizontally) while leaving another (e.g., vertical) unaffected. Spherical lenses can be designed and manufactured with different curvatures on different axes to correct aberrations (e.g., astigmatism) caused by surface errors (e.g., curvature in one or more directions) of the reflective surfaces of prisms used in folding optical systems. In folding telephoto optical systems, deformable lenses can be used to correct astigmatism up to 20 μm without causing distortion problems because deformable lenses have a relatively small effect on distortion.

[0201] The astigmatism caused by the reflecting surfaces of prisms can vary. For example, one batch of prisms may have more or less surface error than another batch, and therefore more or less astigmatism, or the "direction" of the astigmatism may be different. Therefore, in an embodiment, a deformable lens can be configured to rotate 90 degrees to correct different astigmatism in different prisms. Alternatively, two or more different deformable lenses with different amounts or curvature orientations can be provided to correct different levels of astigmatism, and the correct deformable lens and lens orientation can be selected for use with one or more prisms. For example, one deformable lens can be configured to correct 2 micrometers of astigmatism, another deformable lens to correct 10 micrometers of astigmatism, another deformable lens to correct 20 micrometers of astigmatism, and so on.

[0202] A manufacturing process for a folded optical system is also described, the folded optical system including a deformable lens to correct aberrations, including astigmatism caused by surface errors of the reflective surface of a prism.

[0203] Figures 12A to 12D The illustration shows the use of morphing lenses in a lens stack to correct aberrations, including astigmatism caused by surface errors of the reflecting surfaces of prisms in a single-fold optical system, according to some embodiments. Figure 12A Display as Figure 1 The example single-fold lens system shown includes a refractive prism 1210 with a reflective surface 1214. In this example, the second lens 1222 in the lens stack 1220 has been... Figure 12B and Figure 12C The deformable lens replacement shown in the figure is used to correct astigmatism caused by surface errors (curvature) of the reflective surface 1214. Figure 12B and Figure 12CThe curvature of the second (object-side) surface of the morphing lens 1222 differs along the X-axis from that along the Y-axis. To correct for the different astigmatism caused by the reflecting surface 1214 of the prism 1210, the lens 1222 can be rotated 90 degrees. Alternatively, different morphing lenses 1222 with different curvatures can be selected to correct different levels of astigmatism, and these morphing lenses can be used in conjunction with the prism 1210.

[0204] Although Figure 12A The image shows a deformable lens as the second lens 1222 in the lens stack 1220, but the deformable lens can alternatively be used at other lenses in the optical system 1200, such as as the first lens in the lens stack 1220. In some embodiments, more than one deformable lens may be used in the optical system 1200.

[0205] Figure 12D The diagram is shown graphically in a format such as Figures 12A to 11 Astigmatism correction in an example optical system 1200 with the deformable lens 1222 shown in C. (A)(0) shows the ideal MTF of the optical system, (A)(1) shows the MTF with +0.2 micrometer astigmatism, and (A)(1) shows the MTF with -0.2 micrometer astigmatism. (B)(1) shows the MTF of correcting the astigmatism of (A)(1) with the deformable lens 1122 oriented at 0 degrees azimuth, and (B)(2) shows the MTF of correcting the astigmatism of (A)(2) with the deformable lens 1122 oriented at 90 degrees azimuth.

[0206] Figure 13 The illustration shows the use of a deformable lens 1322 in a lens stack 1320 to correct aberrations, including astigmatism caused by surface errors of the reflecting surface 1314 of the first prism 1310 in a double-folded optical system 1300, which includes two optical folding elements (e.g., a first prism and a second prism, or a first prism and a mirror). In this example, the second lens 1322 in the lens stack 1320 has been (e.g.) as... Figure 11 B and Figure 11 The deformable lens shown in C is used to correct astigmatism caused by surface errors (curvature) of the reflecting surface 1314 of the first prism 1310. To correct different astigmatism caused by the reflecting surface 1314 of the prism 1310, lens 1322 can be rotated 90 degrees. Alternatively, different deformable lenses 1322 with different curvatures can be selected to correct different levels of astigmatism, and these deformable lenses can be used in conjunction with prism 1310.

[0207] Although Figure 13The image shows a deformable lens as the second lens 1322 in the lens stack 1320, but the deformable lens can alternatively be used at other lenses in the optical system 1300, such as as the first lens in the lens stack 1320. In some embodiments, more than one deformable lens may be used in the optical system 1300.

[0208] Figure 14 The illustration shows the use of a deformable lens to correct aberrations, including astigmatism caused by a freeform prism, according to some embodiments. As previously mentioned, freeform optics involve an optical design having at least one surface that does not have translational or rotational symmetry about an axis perpendicular to the average plane of the surface. Therefore, a freeform prism is a prism having at least one surface that does not have translational or rotational symmetry about an axis perpendicular to the average plane of the surface. An example folded optical system 1400 includes, from the object side to the image side, a deformable lens 1410, a first freeform prism 1420, and a second freeform prism 1430. The optical system 1400 may also include, for example, an aperture stop located between the deformable lens 1410 and the freeform prism 1420. Light from the object field is refracted by the deformable lens 1410 onto surface S1 of the freeform prism 1420. The light is refracted from surface S1 to surface S2, which reflects the light back to surface S1, thereby folding the optical axis once. Surface S1 reflects light to surface S3, thus folding the optical axis a second time. Light is refracted by surface S3 to surface S4 of the freeform prism 1430. Surface S4 refracts the light to surface S5, which reflects the light to surface S6, thus folding the optical axis a third time. Surface S6 reflects the light back to surface S5, thus folding the optical axis a fourth time. Surface S5 refracts the light received from surface S6 to form an image at, for example, at or near the sensor surface in an image plane.

[0209] Figure 14 The optical system 1400 is given by way of example. For example, the optical system may include only one freeform prism, may include a freeform prism and a standard prism or refractive prism, and / or may include additional spherical, aspherical, or deformable lenses. In this example, deformable lens 1410 is configured to correct astigmatism caused by one or more surfaces of the two freeform prisms, such as astigmatism caused by surface S2 of freeform prism 1420. To correct different astigmatisms caused by the freeform prisms, deformable lens 1410 can be rotated 90 degrees. Alternatively, different deformable lenses 1410 with different curvatures can be selected to correct different levels of astigmatism, and this deformable lens can be used in conjunction with the freeform prism.

[0210] Figure 15This is a high-level flowchart of a method for manufacturing a folded optical system according to some embodiments, the folded optical system including a deformable lens oriented to correct for aberrations, including astigmatism caused by surface errors of the reflecting surfaces of prisms in the folded optical system. As indicated at 1500, the optical properties of one or more prisms can be measured to determine the astigmatism caused by the reflecting surfaces of the prisms. Various methods can be used to measure the astigmatism of the prisms, including but not limited to optical measurement methods (e.g., measuring the MTF of the prism) and physical measurement methods (e.g., directly measuring the surface errors of the reflecting surfaces). As indicated at 1510, the deformable lens can be selected based on the measured astigmatism of the prism. As previously noted, different deformable lenses with different levels of correction can be provided. As indicated at 1520, a folded optical system including prisms and lenses including the selected deformable lens, the selected deformable lens being oriented to correct the measured astigmatism, can be assembled. As previously noted, the deformable lens can be rotated 90 degrees according to the measured astigmatism. This process can be repeated, for example, for different batches of prisms.

[0211] Exemplary computing device

[0212] Figure 16 An example computing device, referred to as computer system 3000, is shown. This computer system may include or control a device having, for example, Figures 1 to 14 The illustrated folding optical system is an embodiment of a camera. Furthermore, the computer system 3000 can implement methods for controlling the operation of the camera and / or for performing image processing on images captured by the camera. In various embodiments, the computer system 3000 can be any device of various types, including but not limited to: personal computer systems, desktop computers, laptop computers, notebook computers, tablet computers or tablet devices, all-in-one computers or netbook computers, mainframe computers, handheld computers, workstations, network computers, cameras, set-top boxes, mobile devices, wireless phones, smartphones, consumer devices, video game controllers, handheld video game devices, application servers, storage devices, televisions, video recording devices, peripherals such as switches, modems, routers, or generally any type of computing or electronic device.

[0213] In the illustrated embodiment, computer system 3000 includes one or more processors 3010 coupled to system memory 3020 via input / output (I / O) interface 3030. Computer system 3000 also includes a network interface 3040 coupled to I / O interface 3030, and one or more input / output devices 3050, such as cursor control device 3060, keyboard 3070, and one or more displays 3080. Computer system 3000 may also include one or more cameras 3090, such as those described above for... Figures 1 to 14At least one camera in the described single-fold optical system.

[0214] In various implementations, computer system 3000 may be a single-processor system including one processor 3010, or a multiprocessor system including several processors 3010 (e.g., two, four, eight, or another suitable number). Processor 3010 may be any suitable processor capable of executing instructions. For example, in various implementations, processor 3010 may be a general-purpose or embedded processor implementing any of a variety of instruction set architectures (ISAs) (such as x86, PowerPC, SPARC, or MIPS ISA or any other suitable ISA). In a multiprocessor system, each processor in processor 3010 may typically, but does not necessarily, implement the same ISA.

[0215] System memory 3020 may be configured to store program instructions 3022 and / or data 3032 accessible by processor 3010. In various embodiments, any suitable memory technology may be used to implement system memory 3020, such as static random access memory (SRAM), synchronous dynamic RAM (SDRAM), non-volatile / flash memory, or any other type of memory. In an exemplary embodiment, program instructions 3022 may be configured to implement various interfaces, methods, and / or data for controlling the operation of camera 3090 and for capturing and processing images using integrated camera 3090 or other methods or data, such as interfaces and methods for capturing, displaying, processing, and storing images captured using camera 3090. In some embodiments, program instructions and / or data may be received, transmitted, or stored on a different type of computer-accessible medium or similar medium separate from system memory 3020 or computer system 3000.

[0216] In one embodiment, I / O interface 3030 may be configured to coordinate I / O communication between processor 3010, system memory 3020, and any peripheral devices (including network interface 3040 or other peripheral device interfaces, such as input / output devices 3050) within the device. In some embodiments, I / O interface 3030 may perform any necessary protocols, timing, or other data transformations to convert data signals from one component (e.g., system memory 3020) into a format suitable for use by another component (e.g., processor 3010). In some embodiments, I / O interface 3030 may include support for devices attached, for example, via various types of peripheral buses (e.g., variants of the Peripheral Component Interconnect (PCI) bus standard or the Universal Serial Bus (USB) standard). In some embodiments, the functionality of I / O interface 3030 may be divided among two or more separate components, such as a northbridge and a southbridge. Additionally, in some embodiments, some or all of the functionality of I / O interface 3030 (such as the interface with system memory 3020) may be directly incorporated into processor 3010.

[0217] Network interface 3040 can be configured to allow data exchange between computer system 3000 and other devices (e.g., bearers or agent devices) attached to network 3085, or between nodes of computer system 3000. In various embodiments, network 3085 may include one or more networks, including but not limited to: local area network (LAN) (e.g., Ethernet or enterprise network), wide area network (WAN) (e.g., the Internet), wireless data network, some other electronic data network, or some combination thereof. In various embodiments, network interface 3040 may support communication via wired or wireless general-purpose data networks (such as any suitable type of Ethernet network), for example; communication via telecommunications / telephone networks (such as analog voice networks or digital fiber optic communication networks); communication via storage area networks (such as Fibre Channel SAN), or communication via any other suitable type of network and / or protocol.

[0218] In some embodiments, the input / output device 3050 may include one or more display terminals, keyboards, keypads, touchpads, scanning devices, voice or optical recognition devices, or any other device suitable for inputting or accessing data by the computer system 3000. Multiple input / output devices 3050 may be present in the computer system 3000 or distributed across various nodes of the computer system 3000. In some embodiments, such input / output devices may be separate from the computer system 3000 and may interact with one or more nodes of the computer system 3000 via wired or wireless connections (such as through network interface 3040).

[0219] like Figure 16 As shown, memory 3020 may include program instructions 3022, which may be processor-executable, to implement any elements or actions to support the integrated camera 3090, including but not limited to image processing software and interface software for controlling the camera 3090. In some embodiments, images captured by camera 3090 may be stored in memory 3020. Furthermore, metadata of images captured by camera 3090 may be stored in memory 3020.

[0220] Those skilled in the art will understand that the computer system 3000 is merely illustrative and not intended to limit the scope of embodiments. Specifically, the computer system and device may include any combination of hardware or software capable of performing the indicated functions, including computers, network devices, internet devices, PDAs, wireless telephones, pagers, cameras, or still cameras, etc. The computer system 3000 may also be connected to other devices not shown, or alternatively may operate as a standalone system. Furthermore, the functionality provided by the illustrated components may, in some embodiments, be combined into fewer components or distributed across additional components. Similarly, in some embodiments, the functionality of some of the illustrated components may not be provided, and / or other additional functions may be available.

[0221] Those skilled in the art will also recognize that while various items are shown as being stored in memory or on storage devices during use, these items, or portions thereof, may be transferred between memory and other storage devices for memory management and data integrity. Alternatively, in other embodiments, some or all of these software components may be executed in memory on another device and communicate with the illustrated computer system 3000 via inter-computer communication. Some or all of the system components or data structures may also be stored (e.g., as instructions or structured data) on a computer-accessible medium or portable article of manufacture for reading by a suitable drive, various examples of which are described above. In some embodiments, instructions stored on a computer-accessible medium separate from the computer system 3000 may be transmitted to the computer system 3000 via a transmission medium or signal (such as electrical, electromagnetic, or digital signals transmitted via communication media such as networks and / or wireless links). Various embodiments may also include receiving, transmitting, or storing instructions and / or data implemented according to the above description on a computer-accessible medium. Generally, computer-accessible media may include non-transitory computer-readable storage media or memory media, such as magnetic or optical media, like discs or DVD / CD-ROMs, and volatile or non-volatile media, such as RAM (e.g., SDRAM, DDR, RDRAM, SRAM, etc.), ROM, etc. In some embodiments, computer-accessible media may include transmission media or signals, such as electrical signals, electromagnetic signals, or digital signals transmitted via communication media such as networks and / or wireless links.

[0222] In various implementations, the methods described herein can be implemented in software, hardware, or a combination thereof. Furthermore, the order of the blocks of the method can be changed, and various elements can be added, reordered, combined, omitted, modified, etc. Various modifications and changes will be apparent to those skilled in the art who benefit from this disclosure. The various implementations described herein are intended to be illustrative and not restrictive. Many variations, modifications, additions, and improvements are possible. Thus, multiple examples may be provided for a component described herein as a single example. The boundaries between various components, operations, and data repositories are somewhat arbitrary, and specific operations are shown in the context of a particular exemplary configuration. Other allocations of functionality are contemplated, which may fall within the scope of the appended claims. Finally, the structures and functions of discrete components presented in exemplary configurations can be implemented as combined structures or components. These and other variations, modifications, additions, and improvements may fall within the scope of the implementations as defined in the following claims.

[0223] The following clauses describe various aspects of optical systems, cameras, and / or methods that incorporate the implementation schemes described above.

[0224] Clause 1. An optical system comprising:

[0225] From the object side to the image side of the optical system, the sequence is as follows:

[0226] A first lens group, comprising a refractive prism, the refractive prism including a first surface, a second surface, and a third surface located on the optical axis of the optical system, wherein the first surface is a transmissive aspherical surface providing positive refractive force to the prism, wherein the second surface is a reflective surface that folds the optical axis of the optical system, and wherein the third surface is a transmissive surface; and

[0227] The second lens group includes two or more refractive lenses;

[0228] and

[0229] The optical system described above satisfies the following conditional expression:

[0230] 0.6

[0231] Where A is the optical power of the optical system, and B is the optical power of the first lens group.

[0232] Clause 2. An optical system according to Clause 1, wherein the optical system satisfies the conditional expression:

[0233] -0.2 <CD<0.1,

[0234] Where C is the optical power of the second lens group, and D is the length of the second lens group.

[0235] Clause 3. The optical system according to Clause 1, the optical system further comprising an aperture stop located on the object side of the refracting prism.

[0236] Clause 4. The optical system according to Clause 1, wherein the refracting prism is formed of an optically plastic material.

[0237] Clause 5. The optical system according to Clause 1, wherein the refracting prism comprises a glass prism and a refractive lens attached to the object-side surface of the glass prism, the refractive lens being made of an optically plastic material.

[0238] Clause 6. The optical system according to Clause 1, wherein the refracting prism comprises a glass prism and a refractive lens attached to the object-side surface of the glass prism, the refractive lens being made of optical glass material.

[0239] Clause 7. The optical system as described in Clause 1, wherein the Z-height of the optical system is 7.3 mm or less.​

[0240] Clause 8. The optical system as described in Clause 1, wherein the X length of the optical system is 18 mm or less.

[0241] Clause 9. The optical system according to Clause 1, wherein the second lens group comprises four refractive lens elements.

[0242] Clause 10. The optical system according to Clause 9, wherein the four refractive lens elements comprise, from the object side to the image side of the optical system, in sequence:

[0243] The first lens with positive refractive power

[0244] A second lens with negative refractive power;

[0245] A third lens with negative refractive power; and

[0246] A fourth lens with positive refractive power.

[0247] Clause 11. The optical system according to Clause 9, wherein the second lens in the second lens group from the object side of the optical system is a morphing lens, the morphing lens being configured to correct astigmatism caused by the second surface of the refracting prism.

[0248] Clause 12. The optical system according to Clause 11, wherein the second lens is configured to rotate 90 degrees to correct for different amounts of astigmatism caused by the second surface of the refracting prism.

[0249] Clause 13. The optical system according to Clause 9, wherein at least one of the lenses in the second lens group is a morphing lens configured to correct astigmatism caused by the second surface of the refracting prism.

[0250] Clause 14. The optical system according to Clause 1, the optical system further comprising an optical folding element located on the image side of the second lens group and configured to fold the optical axis of the optical system a second time, wherein the second lens in the second lens group from the object side of the optical system is a morphing lens configured to correct astigmatism caused by the second surface of the refracting prism.

[0251] Clause 15. A camera, the camera comprising, from the object side of the camera to the image side of the camera, in sequence:

[0252] An optical system, the optical system comprising:

[0253] A first lens group, comprising a refractive prism, the refractive prism including a first surface, a second surface, and a third surface located on the optical axis of the optical system, wherein the first surface is a transmissive aspherical surface providing positive refractive force to the prism, wherein the second surface is a reflective surface that folds the optical axis of the optical system, and wherein the third surface is a transmissive surface; and

[0254] The second lens group includes two or more refractive lenses;

[0255] and

[0256] An image sensor configured to capture light projected onto the surface of the image sensor through the optical system;

[0257] The optical system described above satisfies the following conditional expression:

[0258] 0.6

[0259] -0.2 <CD<0.1,

[0260] Where A is the optical power of the optical system, B is the optical power of the first lens group, C is the optical power of the second lens group, and D is the length of the second lens group.

[0261] Clause 16. The camera pursuant to Clause 15, wherein the Z-height of the optical system is 7.3 mm or less, and wherein the X-length of the optical system is 18 mm or less.

[0262] Clause 17. The camera according to Clause 15, the camera further comprising an aperture stop located on the object side of the refracting prism.

[0263] Clause 18. The camera according to Clause 15, the camera further comprising an infrared filter located between the second lens group and the image sensor.

[0264] Clause 19. The camera according to Clause 15, wherein at least one of the lenses in the second lens group is an anamorphic lens configured to correct astigmatism caused by the second surface of the refracting prism.

[0265] Clause 20. An optical system comprising:

[0266] A prism comprising a first surface, a second surface, and a third surface located on the optical axis of the optical system, wherein the second surface is a reflective surface that folds the optical axis of the optical system, and the third surface is a transmissive surface; and ​

[0267] One or more refractive lenses, wherein at least one of the one or more refractive lenses is a morphing lens, the morphing lens being configured to correct astigmatism caused by the prism.

[0268] Clause 21. The optical system according to Clause 20, wherein the first surface of the prism is a transmissive aspherical surface.

[0269] Clause 22. The optical system according to Clause 20, wherein the deformable lens is configured to rotate 90 degrees to correct for varying amounts of astigmatism caused by the prism.

[0270] Clause 23. The optical system of Clause 20, wherein the optical system comprises four refractive lenses located on the image side of the prism, wherein a second lens of the four refractive lenses from the object side of the optical system is the deformable lens configured to correct astigmatism caused by the prism.

[0271] Clause 24. The optical system according to Clause 23, wherein the second lens is configured to rotate 90 degrees to correct for varying amounts of astigmatism caused by the prism.

[0272] Clause 25. The optical system of Clause 20, wherein the one or more refractive lenses are located on the image side of the prism, the optical system further comprising an optical folding element located on the image side of the one or more lenses and configured to fold the optical axis of the optical system a second time.

[0273] Clause 26. The optical system according to Clause 20, wherein the prism is a refractive prism having positive refractive power.

[0274] Clause 27. The optical system according to Clause 20, the optical system further comprising a refractive lens having positive refractive power attached to the object-side surface of the prism.

[0275] Clause 28. The optical system according to Clause 20, the optical system further comprising an aperture stop located on the object side of the prism.

[0276] Clause 29. The optical system pursuant to Clause 20, wherein the prism is a freeform prism.

[0277] Clause 30. The optical system as described in Clause 29, wherein the optical system further comprises a second freeform prism.

[0278] Clause 31. The optical system according to Clause 20, wherein the deformable lens is located on the object side of the prism.

[0279] Clause 32. The optical system according to Clause 20, wherein the deformable lens is located on the image side of the prism.

[0280] Clause 33. A camera, the camera comprising, from the object side of the camera to the image side of the camera, in sequence:

[0281] An optical system, the optical system comprising:

[0282] A prism comprising a first surface, a second surface, and a third surface located on the optical axis of the optical system, wherein the second surface is a reflective surface that folds the optical axis of the optical system, and the third surface is a transmissive surface; and

[0283] One or more refractive lenses, wherein at least one of the one or more refractive lenses is an anamorphic lens, the anamorphic lens being configured to correct astigmatism caused by the prism; and

[0284] An image sensor configured to capture light projected onto the surface of the image sensor through the optical system.

[0285] Clause 34. The camera according to Clause 33, wherein the first surface of the prism is a transmissive aspherical surface.

[0286] Clause 35. The camera according to Clause 33, wherein the optical system includes four refractive lenses located on the image side of the prism, wherein a second lens of the four refractive lenses from the object side of the optical system is a deformable lens configured to correct astigmatism caused by the prism, and wherein the second lens is configured to rotate 90 degrees to correct different amounts of astigmatism caused by the prism.

[0287] Clause 36. The camera according to Clause 33, the camera further comprising an optical folding element located between the four refractive lenses and the image sensor, and configured to fold the optical axis of the optical system a second time.

[0288] Clause 37. The camera according to Clause 33, the camera further comprising an aperture stop located on the object side of the prism.

[0289] Clause 38. The camera according to Clause 33, the camera further comprising an infrared filter located between the lens group and the image sensor.

[0290] Clause 39. The camera as described in Clause 33, wherein the prism is a refractive prism having positive refractive power.

[0291] Clause 40. The camera described in Clause 33, wherein the prism is a freeform prism.

[0292] Clause 41. The camera as described in Clause 40, wherein the optical system further includes a second freeform prism.

[0293] Clause 42. The camera as described in Clause 33, wherein the deformable lens is located on the object side of the prism.

[0294] Clause 43. The camera as described in Clause 33, wherein the anamorphic lens is located on the image side of the prism.

[0295] Clause 44. A method comprising:

[0296] One or more prisms formed of optical glass or plastic material, wherein each prism includes a first surface, a second reflective surface and a third transmissive surface located on the optical axis;

[0297] Measure the optical properties of the one or more prisms to determine the astigmatism caused by the prisms;

[0298] Select one or more deformable lenses based on the determined astigmatism of the one or more prisms; and

[0299] Assemble one or more optical systems, each optical system comprising:

[0300] A first lens group, the first lens group including the prism; and

[0301] The second lens group includes one or more refractive lens elements, wherein at least one of the one or more refractive lens elements is a deformable lens oriented to correct the determined astigmatism of the corresponding prism.

[0302] Clause 45. The method according to Clause 44, wherein the optical system further comprises a second prism located on the image side of the second lens group.

[0303] Clause 46. The method described in Clause 44, wherein the prism is a refractive prism.

[0304] Clause 47. The method described in Clause 45, wherein the prism is a free-form prism.

Claims

1. An optical system, the optical system comprising: From the object side to the image side of the optical system, the sequence is as follows: A first lens group, comprising a refractive prism, the refractive prism comprising a first surface, a second surface and a third surface located on the optical axis of the optical system, wherein the first surface is a transmissive aspherical surface that provides positive refractive force to the prism, wherein the second surface is a reflective surface that folds the optical axis of the optical system, and wherein the third surface is a transmissive surface. and The second lens group comprises two or more refractive lenses; and The optical system described above satisfies the following conditional expression: 0.6 where A is the optical power of the optical system, and B is the optical power of the first lens group, and -0.2 <CD<0.1, Where C is the optical power of the second lens group, and D is the length of the second lens group.

2. The optical system according to claim 1, further comprising an aperture stop located on the object side of the refracting prism.

3. The optical system according to claim 1, wherein the refracting prism is formed of an optically plastic material.

4. The optical system according to claim 1, wherein the refracting prism comprises a glass prism and a refractive lens attached to the object-side surface of the glass prism, the refractive lens being made of an optically plastic material.

5. The optical system of claim 1, wherein the refracting prism comprises a glass prism and a refractive lens attached to the object-side surface of the glass prism, the refractive lens being made of optical glass material.

6. The optical system of claim 1, wherein the Z-height of the optical system is 7.3 mm or less.

7. The optical system of claim 1, wherein the X length of the optical system is 18 mm or less.

8. The optical system according to claim 1, wherein the second lens group comprises four refractive lens elements.

9. The optical system of claim 8, wherein the four refractive lens elements, from the object side to the image side of the optical system, sequentially comprise: The first lens with positive refractive power A second lens with negative refractive power; A third lens with negative refractive power; and A fourth lens with positive refractive power.

10. The optical system of claim 8, wherein the second lens in the second lens group from the object side of the optical system is a morphing lens, the morphing lens being configured to correct astigmatism caused by the second surface of the refracting prism.

11. The optical system of claim 10, wherein the second lens is configured to rotate 90 degrees to correct for different amounts of astigmatism caused by the second surface of the refracting prism.

12. The optical system of claim 8, wherein at least one lens in the second lens group is a morphing lens configured to correct astigmatism caused by the second surface of the refracting prism. ​ 13. The optical system of claim 1, further comprising an optical folding element located on the image side of the second lens group and configured to fold the optical axis of the optical system a second time, wherein the second lens in the second lens group from the object side of the optical system is a morphing lens configured to correct astigmatism caused by the second surface of the refracting prism.

14. A camera, the camera comprising, from the object side of the camera to the image side of the camera, the following components in sequence: An optical system, the optical system comprising: A first lens group, comprising a refractive prism, the refractive prism including a first surface, a second surface, and a third surface located on the optical axis of the optical system, wherein the first surface is a transmissive aspherical surface providing positive refractive force to the prism, wherein the second surface is a reflective surface that folds the optical axis of the optical system, and wherein the third surface is a transmissive surface; and The second lens group, comprising two or more refractive lenses; and An image sensor configured to capture light projected onto the surface of the image sensor through the optical system; The optical system described above satisfies the following conditional expression: 0.6 where A is the optical power of the optical system, and B is the optical power of the first lens group, and -0.2 <CD<0.1, Where C is the optical power of the second lens group, and D is the length of the second lens group.

15. The camera of claim 14, wherein the Z-height of the optical system is 7.3 mm or less, and wherein the X-length of the optical system is 18 mm or less.

16. The camera of claim 14, further comprising an aperture stop located on the object side of the refracting prism.

17. The camera of claim 14, further comprising an infrared filter located between the second lens group and the image sensor.

18. The camera of claim 14, wherein at least one lens in the second lens group is a morphing lens configured to correct astigmatism caused by the second surface of the refracting prism. ​

Images