Deformable lens assembly

Abstract

A lens assembly according to the present disclosure includes a deformable lens component and a main lens component. The deformable lens component comprises a first cylindrical lens element, a second cylindrical lens element and a first spherical lens element, and the first spherical lens element is arranged between the first cylindrical lens element and the second cylindrical lens element; and is translatable relative to the first cylindrical lens element and the second cylindrical lens element along an optical axis of the morphing lens assembly. As the first spherical lens element translates along the optical axis, the optical characteristics of the deformable lens component can be adjusted, so that the combination of the first cylindrical lens element, the first spherical lens element and the second cylindrical lens element generates first astigmatism; the first astigmatism is opposite a second astigmatism generated in the image plane by the main lens component as the object moves from the infinity focus towards the lens assembly.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the priority of U.S. Provisional Application Serial No. 63 / 396,566, filed on August 9, 2022. The entire content of the priority application is incorporated herein by reference as if fully set forth. Background Art

[0003] Anamorphic format is a cinematography technique for shooting widescreen images on standard 35mm film or other visual recording media with a non - widescreen native aspect ratio. Anamorphic format also refers to a projection format in which a distorted image is stretched by an anamorphic projection lens to recreate the original aspect ratio on a viewing screen. An anamorphic lens typically includes a spherical main lens, plus an anamorphic attachment (or integrated lens element) that performs the anamorphosis. The anamorphic element operates at infinite focal length such that it has little effect on the focal point of the main lens to which it is mounted, but still deforms (distorts) the light field. When the film is projected, the distortion introduced in the camera must be corrected, so another lens is used in the projection room which restores the picture to its correct proportions to restore normal geometry. The picture is not manipulated in any way in the dimension perpendicular to the dimension being distorted.

[0004] Typically, an anamorphic lens captures (or projects) a wider horizontal field of view than a spherical lens would typically be able to achieve in order to create a widescreen presentation. The anamorphic lens achieves this by optically distorting the image horizontally during capture, and then this distortion is reversed during presentation. By distorting the image before recording, and then undistorting the compressed image during post - production or during display, this widescreen image capture method is able to capture widths up to twice that of the imager.

[0005] Traditional anamorphic lenses optically compress a wider field of view onto a standard imager size by distorting the image's scale, compressing the image horizontally. An alternative method to achieve nearly the same result is to expand the image vertically. Either way, this horizontally squeezed (or vertically stretched) image is then undistorted into a widescreen aspect ratio by a corresponding anamorphic lens on a projector or by digital correction of the distorted image.

[0006] Anamorphic lens assemblies typically include a spherical main lens, plus a deformable attachment (usually an integrated multi-cylindrical lens assembly) called an anamorphot that performs the squeezing (deformation). The refractive power of this attachment is typically zero on the vertical axis, making it act like a sheet of plate glass, and 0.5x on the horizontal axis, which halves the effective focal length of the spherical lens in the horizontal direction. Most anamorphic systems operate with this 0.5x compression (squeezing) ability to capture images, which results in a 2x widening when presenting the unsqueezed image, although other compression ratios and the aforementioned vertical stretching methods are available. Generally, this all means that a 50mm anamorphic lens will have the vertical viewing angle of a 50mm spherical lens, but equivalently the horizontal viewing angle of a 25mm spherical lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Various embodiments in accordance with the present disclosure will be described with reference to the accompanying drawings, in which:

[0008] Figure 1A and Figure 1B is a schematic diagram illustrating an anamorphic lens assembly according to some embodiments;

[0009] Figure 2A and Figure 2B are schematic diagrams respectively illustrating the convergence of light rays passing through the Figure 1A and Figure 1B anamorphic lens assemblies;

[0010] Figure 3 is a graph illustrating two exemplary polynomial relationships between the rotation angle of a focusing ring and the position of a first spherical lens element in an anamorphic lens assembly according to some embodiments;

[0011] Figure 4A and Figure 4B are schematic diagrams illustrating the general processing of the Figure 1A and Figure 1B anamorphic lens assemblies viewed along the y-axis using paraxial optics;

[0012] Figure 4C and Figure 4D are schematic diagrams illustrating the general processing of the Figure 1A and Figure 1B anamorphic lens assemblies viewed along the x-axis using paraxial optics such that the cylindrical lens has no optical power;

[0013] Figure 5A and Figure 5B is a schematic diagram illustrating another anamorphic lens assembly according to some embodiments;

[0014] Figure 6A and Figure 6Bis a schematic diagram illustrating another anamorphic lens assembly according to some embodiments;

[0015] Figure 7A and Figure 7B is a schematic diagram illustrating another anamorphic lens assembly according to some embodiments; and

[0016] Figure 8A and Figure 8B is a schematic diagram illustrating another anamorphic lens assembly according to some embodiments. DETAILED DESCRIPTION

[0017] The present disclosure relates to anamorphic lens assemblies. Conventionally, anamorphic lenses have different focal lengths along the horizontal and vertical axes because of the cylindrical lenses that perform the anamorphosis. These different focal lengths in the vertical direction create astigmatism. A lens with astigmatism is one in which light rays passing through the lens in two perpendicular planes have different foci (the points where the light rays converge). For example, if a lens with astigmatism is used to form an image of a cross, the vertical and horizontal lines of the cross will be sharply focused at two different distances.

[0018] Previous solutions to the astigmatism problem in anamorphic lenses have several drawbacks. For example, previous solutions have focused on adding cylindrical lenses to correct astigmatism, resulting in large, complex, and expensive lens assemblies. These solutions also create unwanted artifacts, such as the anamorphic mumps effect at near focus (e.g., at distances less than 10 feet from the object). Due to the nature of practical optics, in conventional anamorphic systems (whether cylindrical, prism-based, or mirror-based), the anamorphic squeeze is non-uniform across the image field. This variation causes some areas of the film image to appear more stretched than others. In the case of an actor's face, when positioned at the center of the screen, the face appears somewhat as if the actor has mumps, hence the term mumps phenomenon.

[0019] Some embodiments of the present disclosure solve the above problems by providing a deformable lens assembly having a first cylindrical lens element, a second cylindrical lens element, and a spherical lens element that is translatable along the optical axis of the deformable lens assembly between the first cylindrical lens element and the second cylindrical lens element. These embodiments use a movable spherical lens element to correct the above-mentioned astigmatism problem. Compared with previous deformable lens assemblies, these embodiments have a less complex structure, which advantageously reduces the cost of manufacturing the deformable lens assembly according to the embodiments of the present disclosure and reduces their volume. Also, while previous solutions have attempted to keep the deformation ratio constant when the distance between the camera and the object changes, some embodiments of the present disclosure allow the deformation ratio to change within a small range, such as less than 2% in some examples. Such a small change is imperceptible to the human eye, so when the distance between the camera and the object changes, embodiments in which the change in the deformation ratio is below the threshold of 2% still advantageously do not result in a significant change in the deformation ratio. In alternative embodiments, the deformation ratio can vary over a somewhat larger range, such as less than 5%, or less than 4%, or less than 3% in some examples. In some embodiments, the change in the deformation ratio with focus can be adjusted as needed to match the characteristics of a given deformable lens.

[0020] Figure 1A and Figure 1B Illustrates a deformable lens assembly 100 according to some embodiments. The deformable lens assembly 100 includes a deformable lens member 102 and a main lens member 104. In some embodiments, the deformable lens member 102 and the main lens member 104 may be configured as modules that are attachable to and removable from other components of a camera system including an image plane 106. In other embodiments, the deformable lens member 102 and the main lens member 104 may be configured as separate modules that are attachable to and removable from each other, and attachable to and removable from other components of the camera system.

[0021] Referring Figure 1A , the deformable lens member 102 may include a first housing 108 that forms the exterior of the deformable lens member 102. Similarly, the main lens member 104 may include a second housing 110 that forms the exterior of the main lens member 104. In some embodiments, the first housing 108 and the second housing 110 may be sections of the overall housing for the deformable lens assembly 100. In the illustrated embodiment, only a portion of the first housing 108 is shown, and it should be understood that the first housing 108 at least partially surrounds and holds all of the lens elements of the deformable lens member 102.

[0022] In Figure 1AIn [reference], the anamorphic lens assembly 100 is shown arranged at an infinite focus, while in Figure 1B it is shown arranged at a near focus. Referring to Figure 1A , the anamorphic lens member 102 includes a first cylindrical lens element 112, a second cylindrical lens element 114, and a first spherical lens element 116 disposed between the first cylindrical lens element 112 and the second cylindrical lens element 114. The relative positions of the first cylindrical lens element 112 and the second cylindrical lens element 114 are fixed along the optical axis 118 of the anamorphic lens assembly 100, while the first spherical lens element 116 is capable of translating along the optical axis 118 relative to the first cylindrical lens element 112 and the second cylindrical lens element 114. In some embodiments, the fixed distance between the first cylindrical lens element 112 and the second cylindrical lens element 114, in combination with the ability of the first spherical lens element 116 to translate along the optical axis 118 between the first cylindrical lens element 112 and the second cylindrical lens element 114, advantageously allows the spacing between the first spherical lens element 116 and the first cylindrical lens element 112 and the second cylindrical lens element 114, respectively, to be adjustable. This feature contributes to the advantageous optical properties of some of the embodiments of the present disclosure, as further described below.

[0023] In some embodiments, the first cylindrical lens element 112 has a first radius of curvature along a first axis, and the second cylindrical lens element 114 has a second radius of curvature along the first axis, where the first axis is perpendicular to the optical axis 118. For example, in some embodiments, the first cylindrical lens element 112 and the second cylindrical lens element 114 have an arcuate shape including a recess or a protrusion on at least one side, such that in the horizontal direction (e.g., along the x-axis 120), one or both of the first cylindrical lens element 112 and the second cylindrical lens element 114 increase or decrease the beam diameter by the refractive force provided by the arcuate shape of the recess or protrusion, while in the vertical direction (e.g., along the y-axis), neither the first cylindrical lens element 112 nor the second cylindrical lens element 114 has a refractive force, or has a negligible refractive force, or the first cylindrical lens element 112 and the second cylindrical lens element 114 have equal and opposite refractive forces such that their combined refractive force is zero. In the illustrated embodiment, the first cylindrical lens element 112 has a negative refractive force in the horizontal direction, and the second cylindrical lens element 114 has a positive refractive force in the horizontal direction. However, in alternative embodiments, the first cylindrical lens element 112 and the second cylindrical lens element 114 may have any combination of refractive forces, including negative refractive force, positive refractive force, and / or zero refractive force.

[0024] In some embodiments, the combined refractive power of the first spherical lens element 116 and the first cylindrical lens element 112 and the second cylindrical lens element 114 (the lenses of the deformable lens assembly 102) is zero in the vertical direction and 0.5x in the horizontal direction. However, in other embodiments, the refractive power of the deformable lens assembly 102 in the horizontal direction can be any other value, such as 0.75x, or 0.56x, or 0.33x, or 0.25x, or any other value. In still other embodiments, the refractive power of the deformable lens assembly 102 is zero in the horizontal direction and 2x (or 1.5x, or 1.8x, or 3x, or 4x, or any other value) in the vertical direction. The refractive power of the deformable lens assembly 102 provides a desired amount of squeezing or stretching (deformation) along the desired axis to achieve the specified deformation pattern.

[0025] In Figure 1A and Figure 1B the illustrated embodiment, each of the first spherical lens element 116, the first cylindrical lens element 112, and the second cylindrical lens element 114 is shown as a single lens (a singlet). However, this embodiment is merely an example. In alternative embodiments, any one of the lens elements 112, 114, 116 can include multiple lenses (e.g., a lens group), such as a pair of lenses (a doublet). For example, in some embodiments, the first spherical lens element 116 can include a singlet, while the first cylindrical lens element 112 and the second cylindrical lens element 114 can include doublets. In another example, in some embodiments, the first spherical lens element 116 can include a doublet, while the first cylindrical lens element 112 and the second cylindrical lens element 114 can include singlets.

[0026] Referring Figure 1A to, the main lens assembly 104 is disposed on a side of the second cylindrical lens element 114 opposite the first spherical lens element 116 and includes one or more second spherical lens elements 122. The second spherical lens elements 122 can be configured to provide main imaging by, for example, changing the focus of the image formed by the main lens assembly 104. The one or more second spherical lens elements 122 can thus be translated along the optical axis 118 relative to the first cylindrical lens element 112 and the second cylindrical lens element 114, as further described below. In some embodiments, the second spherical lens elements 122 can be configured to change other optical properties of the image, such as the softness of the image, the size of the image, or can be configured to correct blurring or aberrations in the image, or change other optical properties as needed. Although the second spherical lens elements 122 are described herein as spherical, in some embodiments, one or more of the second spherical lens elements 122 can be aspherical if desired.

[0027] Reference Figure 1A , and as described above, the relative positions of the first cylindrical lens element 112 and the second cylindrical lens element 114 are fixed along the optical axis 118 of the anamorphic lens assembly 102. However, the first spherical lens element 116 is capable of translating along the optical axis 118 relative to the first cylindrical lens element 112 and the second cylindrical lens element 114. For example, Figure 1A illustrates the anamorphic lens assembly 100 in an infinite focus arrangement, where the first spherical lens element 116 is set at the limit of its travel in the direction of the first cylindrical lens element 112, while Figure 1B illustrates the anamorphic lens assembly 100 in a near focus arrangement, where the first spherical lens element 116 is set at the limit of its travel in the direction of the second cylindrical lens element 114.

[0028] In some embodiments, the movement of the first spherical lens element 116 can be controlled by a focus adjustment member 124 (e.g., a focusing ring) disposed around the main lens assembly 104. In embodiments where the focus adjustment member 124 is a focusing ring, the focusing ring 124 is capable of rotating around the main lens assembly 104. The focusing ring 124 can be mechanically coupled to one or more additional focus adjustment members (not shown), which can be mechanically coupled to the first spherical lens element 116 such that rotation of the focusing ring 124 adjusts the focus of the main lens assembly 104 while causing the first spherical lens element 116 to translate along the optical axis 118 between the first cylindrical lens element 112 and the second cylindrical lens element 114. The focus adjustment member 124 and the one or more additional focus adjustment members that mechanically couple the focus adjustment member 124 to the first spherical lens element 116 together can include a translation mechanism for the first spherical lens element 116. Thus, for example, when the focusing ring 124 rotates around the main lens assembly 104 in a first rotational direction, the main lens assembly 104 can be adjusted away from the infinite focus arrangement ( Figure 1A ) and toward the near focus arrangement ( Figure 1B ), while the first spherical lens element 116 travels away from the first cylindrical lens element 112 and toward the second cylindrical lens element 114. Conversely, when the focusing ring 124 rotates around the main lens assembly 104 in a second rotational direction, the main lens assembly 104 can be adjusted away from the near focus arrangement ( Figure 1B ) and toward the infinite focus arrangement ( Figure 1A) Meanwhile, the first spherical lens element 116 travels away from the second cylindrical lens element 114 and toward the first cylindrical lens element 112. In some embodiments, the focusing of the main lens assembly 104 can be controlled by a threaded focus adjustment mechanism or by a cam mechanism. For example, as described below, in some embodiments, the relative movement of the first spherical lens element 116 with respect to the main lens assembly 104 can be non-linear. In such embodiments, one of the first spherical lens element 116 or the main lens assembly 104 can be linearly moved using threads, while the other can be moved via a cam mechanism.

[0029] Reference Figure 1A , according to some embodiments of the anamorphic lens assembly 100 is configured to generate a focused image (on the image side 130 of the anamorphic lens assembly 100) of an object 126 (on the object side 128 of the anamorphic lens assembly 100) at the image plane 106 of the camera. In some embodiments, the camera can be a digital camera, and the image plane 106 can include an image sensor having an imaging area for receiving an image from the anamorphic lens assembly 100. In other embodiments, the camera can be a film camera, and the image plane 106 can include a film having an imaging area for receiving an image from the anamorphic lens assembly 100 on the film. In some embodiments, the anamorphic lens assembly 100 can be configured as a module that can be attached to and removed from the camera, while in other embodiments, the anamorphic lens assembly 100 can be integrated within the camera. In some embodiments, the camera can be a motion picture camera configured to generate images for presentation by a movie projector. In some embodiments, the main lens assembly 104 can have an internal focusing mechanism (not shown) that enables one or more lenses within the main lens assembly 104 to move to achieve focusing.

[0030] In some embodiments, when the first spherical lens element 116 travels along the optical axis 118 relative to the first cylindrical lens element 112 and the second cylindrical lens element 114, the spacing between the second cylindrical lens element 114 and the main lens assembly 104 changes. For example, reference Figure 1A and Figure 1B both, as the first spherical lens element 116 moves away from Figure 1A the infinite focus arrangement (away from the first cylindrical lens element 112) and toward Figure 1Btravels to the near focus arrangement (towards the second cylindrical lens element 114), and the spacing between the second cylindrical lens element 114 and the main lens assembly 104 decreases. This relative movement of the first spherical lens element 116 with respect to the main lens assembly 104 maintains the focus of the image at the image plane 106, and in some embodiments, the image plane 106 may move relative to the main lens assembly 104 as the deformable lens assembly 100 transitions between the infinite focus arrangement and the near focus arrangement. In an alternative embodiment, such as where the first spherical lens element 116 has a positive refractive power, the direction of relative movement of the second cylindrical lens element 114 with respect to the main lens assembly 104 may be reversed such that as the first spherical lens element 116 moves away from the infinite focus arrangement and towards the near focus arrangement, the spacing between the second cylindrical lens element 114 and the main lens assembly 104 increases.

[0031] In some embodiments, the relative movement of the first spherical lens element 116 with respect to the focusing ring 124 and the relative movement of the main lens assembly 104 with respect to the focusing ring 124 may be defined by a polynomial relationship. For example, referring to Figure 3 , two example polynomial relationships are plotted, where the x-axis represents the rotation angle of the focusing ring 124 and the y-axis represents the positions of the first spherical lens element 116 and the main lens assembly 104 along the optical axis 118. In some embodiments, the positions of the first spherical lens element 116 and the main lens assembly 104 along the optical axis 118 may be measured with reference to respective origins at the respective travel limits of each of the first spherical lens element 116 and the main lens assembly 104 corresponding to the infinite focus arrangement of Figure 1A . Thus, when the focusing ring 124 rotates about the main lens assembly 104 in the first rotational direction, the rotation angle of the focusing ring 124 increases (moves in the positive x-axis direction), while both the first spherical lens element 116 and the main lens assembly 104 move away from the infinite focus arrangement ( Figure 1A , origin) and towards the near focus arrangement ( Figure 1B , end point) along the optical axis 118. The first of the example polynomial relationships 302 is y = -0.0001x 2 + 0.1227x - 0.0879, and represents the relative movement of the focusing ring 124 with respect to the first spherical lens element 116, while the second of the example polynomial relationships 304 is y = -0.0000001x 2 + 0.0155x - 0.0026, and represents the relative movement of the focusing ring 124 with respect to the main lens assembly 104. However, it should be understood that these equations are merely examples and are in no way limiting. In some embodiments, the movement of the first spherical lens element 116 with respect to the main lens assembly 104 is related such that the combination of all optical elements maintains a constant (or nearly constant) deformation ratio and focus along the x-axis and y-axis.

[0032] Reference Figure 1A and Figure 1B both, when the object 126 moves from the first position ( Figure 1A ), astigmatism is created by the main lens component 104 due to different focal lengths along the horizontal and vertical axes. Therefore, refocusing only the main lens component 104 will not achieve good focus at the image plane 106. In some embodiments, the ability of the first spherical lens element 116 to translate along the optical axis 118 relative to the cylindrical lens elements 112, 114, and the main lens component 104 creates astigmatism opposite to the astigmatism created by the movement of the object 126 relative to the main lens component 104, such that the anamorphic lens assembly 100 can achieve good focus at the image plane 106 regardless of the distance of the object 126 to the lens assembly 100.

[0033] In some embodiments, the combined optical properties of the first cylindrical lens element 112, the first spherical lens element 116, and the second cylindrical lens element 114 produce zero astigmatism at the image plane 106 for an object 126 at an infinite focus. For example, as Figure 2A shown, when the object 126 is at an infinite focus and the anamorphic lens assembly 100 is in an infinite focus arrangement, the coaxial rays 202 converge at the image plane 106, and the off-axis rays 204 similarly converge at the image plane 106. In some embodiments, as the first spherical lens element 116 translates along the optical axis 118 relative to the first cylindrical lens element 112 and the second cylindrical lens element 114, the combined optical properties of the first cylindrical lens element 112, the first spherical lens element 116, and the second cylindrical lens element 114 can be adjusted such that the combination of the first cylindrical lens element 112, the first spherical lens element 116, and the second cylindrical lens element 114 produces a first astigmatism that is opposite to a second astigmatism produced in the image plane 106 by one or more second spherical lens elements 122 as the object 126 moves from a first position at an infinite focus toward the anamorphic lens assembly 100. For example, as Figure 2B shown, when the object 126 is at a close distance and the anamorphic lens assembly 100 is in a near focus arrangement, the coaxial rays 202 converge at the image plane 106, and the off-axis rays 204 similarly converge at the image plane 106.

[0034] In some embodiments, the spherical aberration of the first spherical lens element 116 is corrected to match the optical characteristics of the entire anamorphic lens assembly 100. In some embodiments, because the first spherical lens element 116 is movable relative to the first cylindrical lens element 112, the second cylindrical lens element 114, and the main lens component 104, its spherical aberration cannot be perfectly corrected for every position of the first spherical lens element 116 along the optical axis 118. Thus, there may not be an ideal shape for the first spherical lens element 116. Instead, based on the optical characteristics of these lenses, its shape is selected to balance other aberrations from the first cylindrical lens element 112, the second cylindrical lens element 114, and the main lens component 104.

[0035] Reference Figure 1A and Figure 1B , as the anamorphic lens assembly 100 transitions between an infinite focus arrangement ( Figure 1A ) and a near focus arrangement ( Figure 1B ), the horizontal focal length and the vertical focal length of the combination of the first cylindrical lens element 112, the first spherical lens element 116, and the second cylindrical lens element 114 change due to the change in the spacing between these lens elements. The changing focal lengths cause the anamorphic ratio of the anamorphic lens component 102 to also change slightly. In some embodiments, the difference in the anamorphic ratio between the infinite focus arrangement and the near focus arrangement is less than 2% (or less than 5%, or less than 4%, or less than 3%).

[0036] In the illustrated embodiment, the first spherical lens element 116 has a negative refractive power, and as the anamorphic lens assembly 100 transitions away from the infinite focus arrangement and toward the near focus arrangement, the first spherical lens element 116 moves away from the first cylindrical lens element 112 and toward the second cylindrical lens element 114. In an alternative embodiment, the first spherical lens element 116 may have a positive refractive power, and in such an embodiment, as the anamorphic lens assembly 100 transitions away from the infinite focus arrangement and toward the near focus arrangement, the first spherical lens element 116 will move away from the second cylindrical lens element 114 and toward the first cylindrical lens element 112.

[0037] Figures 4A to 4D Illustrated is a general treatment of the anamorphic lens assembly 100 using paraxial optics for Figure 1A and Figure 1B . In Figure 4A and Figure 4B , the viewing point is along the y-axis 121, while in Figure 4C and Figure 4D , the viewing point is along the x-axis 120. Each of the lens elements / components 104, 112, 114, 116 is illustrated as having a focal length f xThe thin lens. The distances between the lens elements / components 104, 112, 114, 116 are denoted as d x , where d 1 is the distance between the first cylindrical lens element 112 and the first spherical lens element 116, d 2 is the distance between the first spherical lens element 116 and the second cylindrical lens element 114, and d 3 is the distance between the second cylindrical lens element 114 and the main lens component 104. The back focal length (BFL) of the anamorphic lens assembly 100 is the distance between the main lens component 104 and the image plane 106.

[0038] In the illustrated embodiment, the first cylindrical lens element 112 has a negative focal length f along the x-axis 120 1 , the first spherical lens element 116 has a negative focal length f 2 , the second cylindrical lens element 114 has a positive focal length f along the x-axis 120 3 , and the main lens component 104 has a positive focal length f 4 . In some embodiments, the focal lengths of the lens elements / components 104, 112, 114, 116 are selected such that the effective focal length of the anamorphic lens assembly 100 along the x-axis 120 (horizontal) is shorter than the effective focal length along the y-axis (vertical) by a desired anamorphic ratio. In some embodiments, the BFL of the anamorphic lens assembly 100 is the same along the x-axis 120 and the y-axis (zero astigmatism).

[0039] The EFL (effective focal length) of the anamorphic lens assembly 100 along the y-axis can be calculated from the focal length (f 2 ) of the first spherical lens element 116 and the focal length (f 4 ) of the main lens component 104 and the distance d 2 +d 3 between them. For the y-axis case, the first cylindrical lens element 112 and the second cylindrical lens element 114 can be ignored because they have zero refractive power along the y-axis (at least in this exemplary embodiment). The formula for the EFL of the first spherical lens element 116 and the main lens component 104 along the y-axis (when represented as two thin lenses) is:

[0040]

[0041] where, d 2 +d 3 represents the total distance between the first spherical lens element 116 and the main lens component 104.

[0042] The calculation of the EFL of the anamorphic lens assembly 100 along the x-axis 120 (which includes the cylindrical refractive powers of the first cylindrical lens element 112 and the second cylindrical lens element 114) is more complex, but can be represented using ABCD matrix techniques. For the anamorphic lens assembly 100 including four lens elements / components 104, 112, 114, 116, the Gaussian transfer matrix is represented by the following product:

[0043]

[0044] The resulting ABCD transfer matrix can be used to determine the EFL of the anamorphic lens assembly 100 along the x-axis 120, which is represented by the C term (lower left) of the matrix. The formula for the EFL of the anamorphic lens assembly 100 along the x-axis 120 is:

[0045]

[0046] The solution to the above paraxial problem can also be found using damped least squares optimization, with the constraint that the horizontal EFL and the vertical EFL differ by the anamorphic ratio, while also forcing the BFL to be the same on both axes within the range of the focusing position.

[0047] An example solution to the paraxial problem is shown below. Referring to Figure 4A and Figure 4C for the infinity focus arrangement, the following values are assigned:

[0048] f 1 = -100 mm, cylindrical (x-axis)

[0049] f 2 = -240 mm, spherical

[0050] f 3 = 200 mm, cylindrical (x-axis)

[0051] f 4 = 50 mm, spherical

[0052] d 1 = 18 mm

[0053] d 2 = 37 mm

[0054] d 3 = 12.7 mm

[0055] The foregoing paraxial combination ultimately results in a 50 mm EFL along the y-axis and a 33.4 mm EFL of 120 along the x-axis, with a paraxial BFL of 60.4 mm. In this example, the anamorphic ratio at the infinite focus arrangement is 1.5x. When the object 126 is moved closer to the anamorphic lens assembly 100 (e.g., to a distance of 500 mm; the distance between the object 126 and the anamorphic lens assembly 100 is not drawn to scale in Figures 4A to 4D ), the relative positions of the four lens elements / components 104, 112, 114, 116 are adjusted (e.g., by rotating the focusing ring 124) to form a focused image at the image plane 106. In this configuration, and referring to the near focus arrangements of Figure 4B and Figure 4D :

[0056] d 1 = 43.51 mm

[0057] d 2 = 11.49 mm

[0058] d 3 = 4.55 mm

[0059] It should be noted that the sum of d 1 and d 2 remains constant as the anamorphic lens assembly 100 is focused, since the distance between the first cylindrical lens element 112 and the second cylindrical lens element 114 is fixed. In this paraxial representation, the anamorphic ratio changes slightly (e.g., to 1.468x), and the EFLs along the y-axis and x-axis change to 58.2 mm and 39.7 mm, respectively, while in the near focus arrangements of Figure 4B and Figure 4D , the paraxial BFL increases to 67.48 mm. Since astigmatism is corrected by the combination of the three lens elements 112, 114, 116, refocusing by adjusting the main lens component 104 (relative to f 3 moving f 4 ) or by moving the image plane 106 has no effect on the image quality.

[0060] It should be noted that not all solutions of the foregoing paraxial system are viable, since there can be solutions in which one or more of the distances d 1 , d 2 or d 3 are negative. The actual solution may also require a slight change in the anamorphic ratio between the infinite focus arrangement and the near focus arrangement, but in practice, this change in the anamorphic ratio can be limited to less than a few percent.

[0061] Table 1 below presents Figure 1A and Figure 1BOptical specifications of an exemplary embodiment of the deformable lens assembly 100 shown in

[0062] Table 1

[0063]

[0064]

[0065] In some embodiments, the following paraxial solving process can be used to narrow down the range of possible configurations for the deformable lens assembly. The paraxial solving process defines the following ten variables:

[0066] Focal length of the lens: f 1 , f 2 , f 3 , f 4 ;

[0067] Distance between the lenses at the infinite focus arrangement: d 1inf , d 2inf , d 3inf ; and distance between the lenses at the near focus arrangement: d 1close , d 2close , d 3close .

[0068] Using these ten variables and based on the known and / or desired properties of the resulting deformable lens assembly, the paraxial solving process defines the following six equations:

[0069] (1) d 1inf + d 2inf = d 1close + d 2close (Due to the fixed spacing f 1 , f 3 )

[0070] (2)

[0071] (3)

[0072] (4) EFL xinf = constant (expected value of EFL at the infinite focus arrangement)

[0073] (5) BFL xinf = BFL yinf (Due to zero astigmatism at the infinite focus arrangement)

[0074] (6) BFL xclose = BFL yclose (Due to zero astigmatism at the near focus arrangement)

[0075] Using six equations out of ten variables, there are an infinite number of solutions. However, setting two or three of the variables as constants reduces the scope of the solution set enough to enable finding the solutions using, for example, iterative techniques.

[0076] In some embodiments, the above equations (2) and (3) will be equal to each other because the deformation ratio will be the same at both the infinite focus arrangement and the near focus arrangement. However, as described above, in some embodiments of the disclosed anamorphic lens assembly, the deformation ratio can vary slightly between the infinite focus arrangement and the near focus arrangement. For example, the deformation ratio can vary by less than 2% between the infinite focus arrangement and the near focus arrangement. In embodiments where the deformation ratio at the infinite focus arrangement is not equal to the deformation ratio at the near focus arrangement, the above equations (2) and (3) will not be equal to each other. In such embodiments, the lens design process can advantageously attempt to match the change in the deformation ratio of a conventional or classical anamorphic lens. In a classical anamorphic lens, the deformation ratio at the near focus is typically less than the deformation ratio at the infinite focus. There are paraxial solutions where the deformation ratio does not change between the near focus and the infinite focus, but in practice, due to the interaction between the principal planes of different sets of lenses, this condition may not be achievable.

[0077] As described above, in some embodiments, one or more of the lens elements can include multiple lenses, such as a doublet lens. Figure 5A and Figure 5B Illustrates one such exemplary embodiment. Figure 5A and Figure 5B The anamorphic lens assembly 500 of includes a first cylindrical lens element 502 and a second cylindrical lens element 504, both of which include doublet lenses. The doublet lens of the first cylindrical lens element 502 includes two negative cylinders, while the doublet lens of the second cylindrical lens element 504 includes two cylinders that together have a positive refractive power and reduce chromatic aberration. In some embodiments, the doublet lens of the second cylindrical lens element 504 can include two positive cylinders. The first spherical lens element 506 has a negative refractive power such that as the anamorphic lens assembly 500 moves away from Figure 5A the infinite focus arrangement of and towards Figure 5B the near focus arrangement of, the first spherical lens element 506 moves towards the main lens component 508. In the illustrated embodiment, the deformation ratio of the anamorphic lens assembly 500 can include, for example, a 1.8x squeeze (or any other squeeze).

[0078] As discussed above, in some embodiments, the first spherical lens element can have a positive refractive power. Figure 6A and Figure 6B Illustrates one such exemplary embodiment. Figure 6A and Figure 6BThe deformable lens assembly 600 includes a first spherical lens element 602, which includes a doublet lens having a positive refractive power. As the deformable lens assembly 600 is arranged away from Figure 6A the infinite focus and towards Figure 6B the near focus, the first spherical lens element 602 moves towards the main lens component 604.

[0079] In the paraxial representation of some embodiments, when adjusting the focus of the deformable lens assembly, the distance d 3 may remain unchanged. Alternatively, the BFL (the distance between f 4 and the image plane 106) may change. Figure 7A and Figure 7B illustrate an exemplary embodiment of such a deformable lens assembly 700. Figure 7A illustrates the deformable lens assembly 700 in the infinite focus arrangement, and Figure 7B illustrates the deformable lens assembly 700 in the near focus arrangement. When the deformable lens assembly 700 changes from the infinite focus arrangement ( Figure 7A ) to the near focus arrangement ( Figure 7B ), d 1 increases, while d 2 decreases, such that the sum of d 1 and d 2 remains constant. d 3 remains constant when the BFL of the deformable lens assembly 700 increases. In an alternative embodiment, the relative changes in d 1 , d 2 , d 3 and the BFL may change, especially when the focal lengths of different lenses change. For example, if Figure 7A and 7B the first spherical lens element 116 in the illustrated example has a negative focal length f 2 , then in an alternative embodiment where the first spherical lens element 116 has a positive focal length f 2 , when the deformable lens assembly changes from the infinite focus arrangement to the near focus arrangement, d 1 may decrease, while d 2 increases, d 3 remains constant, and the BFL of the deformable lens assembly decreases. In addition, for where d 3Embodiments in which BFL changes and remains constant have paraxial solutions, and the focusing mechanism of the main lens component 104 does not necessarily need to move the main lens component 104 away from the image plane 106. For example, these conditions can be met in embodiments where the main lens component 104 includes an internal focusing mechanism in which the internal lens elements of the main lens component 104 can move, but the main lens component 104 as a whole does not move relative to the anamorphic lens component 102.

[0080] Figure 8A and 8B illustrates another anamorphic lens assembly 800 according to some embodiments. Similar to Figure 1A and Figure 1B embodiments, the anamorphic lens assembly 800 includes an anamorphic lens component 802, a main lens component 804, a first cylindrical lens element 812, a second cylindrical lens element 814, and a first spherical lens element 816 disposed between the first cylindrical lens element 812 and the second cylindrical lens element 814. The relative positions of the first cylindrical lens element 812 and the second cylindrical lens element 814 are fixed along the optical axis 818 of the anamorphic lens assembly 800, while the first spherical lens element 816 is capable of translating along the optical axis 818 relative to the first cylindrical lens element 812 and the second cylindrical lens element 814. Table 2 below presents Figure 8A and Figure 8B the optical specifications of an example embodiment of the anamorphic lens assembly 800 shown in

[0081] Table 2

[0082]

[0083]

[0084] In the foregoing description, various embodiments have been described. For purposes of explanation, specific configurations and details have been set forth in order to provide a thorough understanding of the embodiments. However, it will also be apparent to those skilled in the art that the embodiments may be practiced without these specific details. In addition, well-known features may be omitted or simplified in order not to obscure the described embodiments.

[0085] References to "one embodiment", "an embodiment", "example embodiment", etc. indicate that the described embodiment may include a particular feature, structure, or characteristic, but not every embodiment must include that particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. In addition, when a particular feature, structure, or characteristic is described in connection with an embodiment, the combination of other embodiments, whether or not explicitly described, affects such feature, structure, or characteristic within the knowledge of those skilled in the art.

[0086] In addition, in the various embodiments described above, unless otherwise specifically indicated, disjunctive language such as the phrase "at least one of A, B, or C" is intended to be understood to mean any one of A, B, or C, or any combination thereof (e.g., A, B, and / or C). Similarly, language such as "at least one or more of A, B, and C" (or "one or more of A, B, and C") is intended to be understood to mean any one of A, B, or C, or any combination thereof (e.g., A, B, and / or C). Thus, disjunctive language is not intended to and should not be understood to imply that a given embodiment requires the presence of at least one of A, at least one of B, and at least one of C each.

[0087] As used herein, the term "based on" (or similar terms) is an open-ended term used to describe one or more factors that influence a determination or other action. The term does not exclude additional factors that may influence the determination or action. For example, a determination may be based solely on the listed factors or on the factors and one or more additional factors. Thus, if action A is "based on" B, then B is one factor that influences action A, but this does not exclude action A also being based on one or more other factors, such as factor C. However, in some cases, action A may be based entirely on B.

[0088] Unless otherwise clearly stated, articles such as "a" or "an" should generally be construed to include one or more of the items being described. Thus, phrases such as "a device configured to..." or "a computing device" are intended to include one or more of the recited devices. Such one or more recited devices may be configured together to perform the stated operations. For example, "a processor configured to perform operations A, B, and C" may include a first processor configured to perform operation A working in cooperation with a second processor configured to perform operations B and C.

[0089] In addition, the words "may" or "can" are used in a permissive sense (meaning having the possibility), rather than a mandatory sense (meaning must). The words "comprise," "comprising," and "containing" are used to indicate an open-ended relationship and thus mean including but not limited to. Similarly, the words "have," "having," and "with" also indicate an open-ended relationship and thus mean having but not limited to. As used herein, terms such as "first," "second," "third," etc. are used as labels for the nouns they modify and do not imply any type of ordering (e.g., spatial, temporal, logical, etc.), unless such ordering is explicitly indicated otherwise.

[0090] Accordingly, the specification and drawings are to be regarded as illustrative rather than restrictive. However, it is obvious that various modifications and changes can be made to the present disclosure without departing from the broader scope of the present disclosure as set forth in the claims.

Claims

1. A anamorphic lens assembly for a camera, the anamorphic lens assembly comprises: an anamorphic lens member; and a main lens member; The anamorphic lens member includes: a first cylindrical lens element with a negative refractive power having a first radius of curvature along a first axis; a second cylindrical lens element with a positive refractive power having a second radius of curvature along the first axis, the relative positions of the first cylindrical lens element and the second cylindrical lens element being fixed along the optical axis of the anamorphic lens assembly; and a first spherical lens element, the first spherical lens element being disposed between the first cylindrical lens element and the second cylindrical lens element and being translatable along the optical axis relative to the first cylindrical lens element and the second cylindrical lens element; The main lens member includes: one or more second spherical lens elements disposed on a side of the second cylindrical lens element opposite to the first spherical lens element; Looking from the object side towards the image side, the order of the lens elements includes: the first cylindrical lens element, the first spherical lens element, the second cylindrical lens element, and the one or more second spherical lens elements; the optical characteristics of the combination of the first cylindrical lens element, the first spherical lens element, and the second cylindrical lens element produce zero astigmatism in the image plane for an object at an infinite focus; and by translating the first spherical lens element along the optical axis relative to the first cylindrical lens element and the second cylindrical lens element, the optical characteristics of the combination of the first cylindrical lens element, the first spherical lens element, and the second cylindrical lens element can be adjusted such that the combination of the first cylindrical lens element, the first spherical lens element, and the second cylindrical lens element produces a first astigmatism, the first astigmatism being opposite to a second astigmatism produced by the one or more second spherical lens elements in the image plane as the object moves from the infinite focus towards the anamorphic lens assembly.

2. The anamorphic lens assembly for a camera according to claim 1, wherein the first spherical lens element is movable along the optical axis relative to the main lens member.

3. The anamorphic lens assembly for a camera according to claim 2, the main lens member further includes a focusing ring, wherein the relative movement between the focusing ring and the first spherical lens element is defined by a polynomial relationship.

4. An anamorphic lens assembly, the anamorphic lens assembly comprises: a first cylindrical lens element; a second cylindrical lens element; and a first spherical lens element, the first spherical lens element being disposed between the first cylindrical lens element and the second cylindrical lens element and being movable relative to the first cylindrical lens element and the second cylindrical lens element; As the first spherical lens element moves relative to the first cylindrical lens element and the second cylindrical lens element, the optical characteristics of the combination of the first cylindrical lens element, the first spherical lens element, and the second cylindrical lens element can be adjusted such that the combination of the first cylindrical lens element, the first spherical lens element, and the second cylindrical lens element produces a first astigmatism that is opposite to a second astigmatism generated by one or more second spherical lens elements in the image plane as an object moves from an infinite focus toward the anamorphic lens assembly.

5. The anamorphic lens assembly according to claim 4, wherein, the one or more second spherical lens elements include a main lens member that includes a focus adjustment member disposed around the main lens member.

6. The anamorphic lens assembly according to claim 5, wherein, the focus adjustment member, the main lens member, and the first spherical lens element are mechanically coupled such that when the focus adjustment member rotates around the main lens member in a first rotational direction, the main lens member is adjusted to be disposed away from the infinite focus and toward the near focus, and at the same time the first spherical lens element travels in one of the following: a first direction toward the second cylindrical lens element and away from the first cylindrical lens element; or a second direction away from the second cylindrical lens element and toward the first cylindrical lens element.

7. The anamorphic lens assembly according to claim 5, wherein, the first spherical lens element is movable along the optical axis relative to the main lens member.

8. The anamorphic lens assembly according to claim 7, the main lens member further includes a focus adjustment member, wherein the relative movement between the focus adjustment member and the first spherical lens element is defined by a polynomial relationship.

9. The anamorphic lens assembly according to claim 7, wherein, when the first spherical lens element travels along the optical axis relative to the first cylindrical lens element and the second cylindrical lens element, the spacing between the second cylindrical lens element and the main lens member changes.

10. The anamorphic lens assembly according to claim 4, wherein, the optical characteristics of the combination of the first cylindrical lens element, the first spherical lens element, and the second cylindrical lens element produce zero astigmatism in the image plane for an object at the infinite focus.

11. The anamorphic lens assembly according to claim 4, wherein, as the anamorphic lens assembly transitions between an infinite focus arrangement and a near focus arrangement, the horizontal focal length and the vertical focal length of the combination of the first cylindrical lens element, the first spherical lens element, and the second cylindrical lens element change due to a change in a first spacing between the first cylindrical lens element and the first spherical lens element and a second spacing between the second cylindrical lens element and the first spherical lens element.

12. The anamorphic lens assembly according to claim 11, wherein, the change in the focal length causes the anamorphic ratio of the anamorphic lens assembly to also change.

13. The anamorphic lens assembly according to claim 12, wherein, the difference in the anamorphic ratio between the infinity focus arrangement and the near focus arrangement is less than 2%.

14. A camera system, the camera system comprising: an image plane; an anamorphic lens member; and a main lens member; the anamorphic lens member includes: a first cylindrical lens element; a second cylindrical lens element; and a first spherical lens element disposed between the first cylindrical lens element and the second cylindrical lens element and movable relative to the first cylindrical lens element and the second cylindrical lens element; the main lens member includes: one or more second spherical lens elements disposed on a side of the second cylindrical lens element opposite to the first spherical lens element; as the first spherical lens element moves relative to the first cylindrical lens element and the second cylindrical lens element, the optical characteristics of the combination of the first cylindrical lens element, the first spherical lens element, and the second cylindrical lens element can be adjusted such that the combination of the first cylindrical lens element, the first spherical lens element, and the second cylindrical lens element generates a first astigmatism that is opposite to a second astigmatism generated by the one or more second spherical lens elements in the image plane as an object moves from an infinity focus towards the camera system.

15. The camera system according to claim 14, the camera system further comprising a focus adjustment member disposed around the main lens member.

16. The camera system according to claim 15, wherein, the focus adjustment member, the main lens member, and the first spherical lens element are mechanically coupled such that when the focus adjustment member rotates around the main lens member in a first rotational direction, the main lens member is adjusted to move away from the infinity focus arrangement and towards the near focus arrangement, while the first spherical lens element travels in one of the following: a first direction towards the second cylindrical lens element and away from the first cylindrical lens element; or a second direction away from the second cylindrical lens element and towards the first cylindrical lens element.

17. The camera system according to claim 14, wherein, the first spherical lens element is movable along the optical axis relative to the main lens member.

18. The camera system according to claim 17, the main lens member further comprising a focus adjustment member, wherein, the relative movement between the focus adjustment member and the first spherical lens element is defined by a polynomial relationship.

19. The camera system according to claim 17, wherein, when the first spherical lens element travels along the optical axis relative to the first cylindrical lens element and the second cylindrical lens element, the spacing between the second cylindrical lens element and the main lens member changes.

20. The camera system according to claim 14, wherein, The optical characteristics of the combination of the first cylindrical lens element, the first spherical lens element, and the second cylindrical lens element produce zero astigmatism in the image plane for an object at an infinite focus.

Images