阅读说明：本技术 基于vcm的光学装置、系统及其成像方法 (VCM-based optical device, system and imaging method thereof ) 是由 戴维·J·白瑞迪 庞武斌 于 2018-09-27 设计创作，主要内容包括：本发明公开了一种光学装置、系统、及其成像方法。所述光学装置包括前透镜组(321)以及VCM单元(322)；其中,所述VCM单元(322)包括后透镜组(323)、VCM型致动器以及传感器阵列(324)；其中,所述前透镜组(321)的位置相对于所述传感器阵列(324)的位置是静止的；其中,所述前透镜组(321)和所述后透镜组(323)限定出公共光轴；其中,所述VCM型致动器通过沿所述公共光轴平移所述后透镜组(323)来调整所述后透镜组(323)和所述传感器阵列(324)之间的距离。(The invention discloses an optical device, an optical system and an imaging method thereof. The optical device includes a front lens group (321) and a VCM unit (322); wherein the VCM unit (322) comprises a rear lens group (323), a VCM type actuator, and a sensor array (324); wherein the position of the front lens group (321) is stationary with respect to the position of the sensor array (324); wherein the front lens group (321) and the rear lens group (323) define a common optical axis; wherein the VCM-type actuator adjusts a distance between the rear lens group (323) and the sensor array (324) by translating the rear lens group (323) along the common optical axis.)

1. An optical device, comprising:

a front lens group and a VCM unit;

wherein the VCM unit includes a rear lens group, a VCM type actuator, and a sensor array;

wherein the position of the front lens group is stationary relative to the position of the sensor array;

wherein the front lens group and the rear lens group define a common optical axis;

wherein the VCM-type actuator adjusts a distance between the rear lens group and the sensor array by translating the rear lens group along the common optical axis.

2. The optical device of claim 1, wherein the front lens group has a positive focal length and the rear lens group has a negative focal length.

3. The optical device of claim 2, wherein the focal length of the front lens group is less than 0.71f, where f is the focal length of the optical device.

4. The optical apparatus according to claim 1, wherein, in order to image two objects on two object planes, a stroke of the rear lens group upon focusing is smaller than a stroke of a focusing lens group in the second optical apparatus;

wherein the second optical arrangement comprises the focusing lens group and a sensor array; and is

Wherein a distance between the focusing lens group and the sensor array is adjusted upon focusing.

5. The optical device of claim 1, wherein the optical device further comprises an objective lens group, and the objective lens group is located before the front lens group;

wherein the front and rear lens groups and the objective lens group share the common optical axis.

6. An optical system, comprising:

an objective lens group receiving light from a scene of an image field;

a camera array comprising a plurality of pre-fabricated camera modules, each camera module comprising a front lens group and a VCM unit, wherein the VCM unit comprises a rear lens group, a VCM-type actuator, and a sensor array;

wherein the objective lens group is disposed in front of the camera array, the objective lens group directing light into the camera array;

wherein the position of the front lens group is stationary relative to the position of the sensor array;

wherein the front lens group and the rear lens group define a common optical axis;

wherein the VCM-type actuator is configured to adjust a distance between the rear lens group and the sensor array by translating the rear lens group along the common optical axis.

7. The optical system of claim 6, wherein the plurality of VCM units corresponding to the plurality of camera modules are identical.

8. The optical system of claim 6, wherein for each camera module, the objective lens group is cylindrical aligned with the camera module.

9. The optical system of claim 6, wherein the front lens group has a positive focal length and the rear lens group has a negative focal length.

10. The optical system of claim 9, wherein the focal length of the front lens group is less than 0.71f, where f is the focal length of the optical device.

11. A method of imaging an optical device, the method comprising:

directing light into an optical device with a front lens group, wherein the optical device comprises the front lens group and a VCM unit;

wherein the VCM unit includes a rear lens group, a VCM type actuator, and a sensor array;

wherein the front lens group generates an intermediate image that is a virtual image of the rear lens group;

wherein the position of the front lens group is stationary relative to the position of the sensor array;

adjusting a distance between the rear lens group and the sensor array to transfer the virtual image onto the sensor array;

generating a set of image signals based on the light received by the sensor array;

based on the set of image signals, an image is reconstructed.

12. The imaging method according to claim 11, wherein the front lens group and the rear lens group define a common optical axis;

wherein the adjustment of the distance between the rear lens group and the sensor array is achieved by translating the rear lens group along the common optical axis by the VCM-type actuator.

13. The imaging method according to claim 11, wherein the front lens group has a positive focal length and the rear lens group has a negative focal length.

14. The imaging method of claim 11, wherein the focal length of the front lens group is less than 0.71f, where f is a focal length of the optical device.

15. A method of imaging an optical system, the method comprising:

receiving incident light with an objective lens group;

directing the incident light into a camera array, wherein the camera array comprises a plurality of pre-fabricated camera modules, each camera module comprising a front lens group and a VCM unit, wherein the VCM unit comprises a rear lens group, a VCM-type actuator, and a sensor array;

for each of the camera modules it is provided that,

adjusting, by the VCM-type actuator, a distance between the rear lens group and the sensor array so that light from the rear lens group can be focused onto the sensor array;

generating a set of image signals based on the received light of the sensor array;

reconstructing an image based on a plurality of sets of image signals corresponding to the plurality of sets of camera modules.

16. The imaging method of claim 15, wherein reconstructing an image based on the sets of image signals corresponding to the plurality of camera modules comprises:

generating a plurality of partial images based on the plurality of sets of image signals;

and generating an image by splicing the plurality of partial images.

17. The imaging method of claim 15, wherein the plurality of pre-fabricated camera modules are distributed behind the objective lens group and in a fixed position.

18. The imaging method of claim 15, wherein light corresponding to different portions of an image field is directed to different camera modules, respectively.

19. The imaging method of claim 15, wherein the front lens group and the rear lens group define a common optical axis, and the distance between the lens groups and the sensor array is adjusted by translating the rear lens group along the common optical axis.

20. The imaging method according to claim 15, wherein the front lens group has a positive focal length and the rear lens group has a negative focal length.

21. The imaging method of claim 20, wherein the focal length of the front lens group is less than 0.71f, where f is a focal length of the optical device.

22. The imaging method according to claim 15, wherein the plurality of VCM units corresponding to the plurality of camera modules are the same.

23. A method of providing an imaging optical system, the method comprising:

acquiring target optical characteristics of an optical system;

wherein the optical system comprises an objective lens group and a camera module;

wherein the camera module includes a front lens group and a VCM unit;

wherein the VCM unit includes a rear lens group, a sensor array, and a VCM type actuator;

wherein the VCM-type actuator is configured to adjust a distance between the rear lens group and the sensor array;

acquiring optical characteristics of a camera module;

determining an optical characteristic of the objective lens group based on the target optical characteristic of the optical system, the optical characteristic of the camera module, and a relative position of the camera module and the objective lens group;

wherein the target optical characteristic of the optical system or the optical characteristic of the camera module comprises at least one of a focal length, an aperture, and a field of view.

24. The method of claim 23, wherein the method further comprises:

providing a first optical system and a second optical system;

wherein the camera module in the first optical system and the camera module in the second optical system may share a common VCM unit.

Technical Field

The present invention relates to an optical apparatus, a system, an imaging method thereof, and a design method thereof, and more particularly, to an optical apparatus focused by a VCM type actuator.

Background

From the first development of 19 th century photography technology to the middle of the 20 th century, lenses and cameras are generally manufactured as a whole. In the middle of the 20 th century, companies such as canon, nikang and come cards developed "system cameras" which combine standard lenses with standard film sizes developed by companies such as kodak and fuji films. An advantage of the system camera is that one can set the field of view, resolution and zoom capability by interchanging the lens on a standard mount with a standard film.

However, this traditional system camera model is not suitable for modern system cameras because the digital back does not need to be opened to remove the film. The traditional configuration is then to some extent copied into modern system cameras by replacing the film with a standard digital back. A standard sized camera body with a standard lens holder can accommodate a lens that matches the camera body. For example, a long focal length lens is used to obtain high angular resolution images with a narrow field of view, while a short focal length lens is used to obtain more moderate angular resolution with a wide field of view.

To increase the efficiency of semiconductor manufacturing, it is no longer meaningful to separate the lens from the sensor body. The lens/sensor alignment is more accurate if the lens is permanently integrated with the sensor during the manufacturing process. Therefore, in modern systems, a system made up of lens/sensor modules is more meaningful than using a lens alone.

In principle, this approach can be implemented using large sensors (e.g., full frame sensors), but the cost per pixel and performance of such sensors is much slower than that of small sensors (e.g., sensors used in cell phones). Although creating wide-field high-resolution images using small sensors requires computational image stitching, the cost per pixel and system performance can be greatly improved by parallel processing, as described in "parallel cameras" published by David j. brady, Wubin Pang, Han Li, Zhan Ma, Yue Tao, and Xun Cao in optics (Optica) volume 5, 127 & 137 (2018).

Parallel cameras offer new opportunities for radically increasing pixel capacity, weight and cost per unit camera volume. In practice, however, most of the cost of high performance lenses comes from the cost and complexity of the focusing and zooming mechanisms, and the "parallel camera" in optics 5, 127 and 137 (2018) discusses the cost of the lens from the perspective of the manufacturing cost of the lens, which can significantly reduce the cost and volume of the lens to a large extent. The zoom cost of a parallel camera is largely eliminated because in such a system the mechanical zoom can be replaced by digital zoom, but the optical focus mechanism is still necessary. US patent US9432591B2 "multi-scale optical system with dynamic camera setup" discloses a method with independent focusing mechanism in each miniature camera of a parallel camera. However, the independent focusing mechanism of each miniature camera is based on a customized mechanical scheme, and the cost is difficult to maintain in the manufacturing process.

Disclosure of Invention

One aspect of the present invention provides an optical device. The optical device may include a front lens group and a VCM unit, wherein the VCM unit includes a rear lens group, a VCM type actuator, and a sensor array; wherein the position of the front lens group is stationary relative to the position of the sensor array. The front lens group and the rear lens group define a common optical axis. The VCM-type actuator adjusts a distance between the rear lens group and the sensor array by translating the rear lens group along the common optical axis.

In some embodiments, the front lens group may have a positive focal length and the rear lens group may have a negative focal length.

In some embodiments, the focal length of the front lens group may be less than 0.71f, where f is the focal length of the optical device.

In some embodiments, to image two objects on two object planes, the stroke of the rear lens group upon focusing may be smaller than the stroke of the focusing lens group in the second optical device; wherein the second optical arrangement may comprise the focusing lens group and a sensor array; and wherein the distance between the focusing lens group and the sensor array is adjustable upon focusing.

In some embodiments, the optical device may further comprise an objective lens group, and the objective lens group may be located before the front lens group; wherein the front lens group and the rear lens group may share the common optical axis with the objective lens group.

Another aspect of the present invention provides an optical system comprising: an objective lens group configured to receive light from a scene of an image field; a camera array comprising a plurality of pre-fabricated camera modules, each camera module comprising a front lens group and a VCM unit, wherein the VCM unit may comprise a rear lens group, a VCM type actuator, and a sensor array. The objective lens group may be disposed in front of the camera array, and the objective lens group may direct light into the camera array. The position of the front lens group may be stationary relative to the position of the sensor array. The front lens group and the rear lens group define a common optical axis. The VCM-type actuator may be configured to adjust a distance between the rear lens group and the sensor array by translating the rear lens group along the common optical axis.

In some embodiments, the plurality of VCM units corresponding to the plurality of camera modules may be the same.

In some embodiments, for each camera module, the objective lens group may be cylindrical aligned with the camera module.

In some embodiments, the front lens group may have a positive focal length and the rear lens group may have a negative focal length.

In some embodiments, the focal length of the front lens group may be less than 0.71f, where f is the focal length of the optical device.

Yet another aspect of the present invention provides an imaging method of an optical apparatus. The method may include one or more of the following operations. Directing light into an optical device with a front lens group, wherein the optical device comprises the front lens group and a VCM unit; wherein the VCM unit includes a rear lens group, a VCM type actuator, and a sensor array; wherein the front lens group generates an intermediate image that is a virtual image of the rear lens group; wherein the position of the front lens group is stationary relative to the position of the sensor array. The distance between the rear lens group and the sensor array may be adjusted to transfer the virtual image onto the sensor array. A set of image signals may be generated based on light received by the sensor array. An image may be reconstructed based on the set of image signals.

In some embodiments, the front lens group and the rear lens group may define a common optical axis, and the adjustment of the distance between the rear lens group and the sensor array may be achieved by translating the rear lens group along the common optical axis by the VCM-type actuator.

In some embodiments, the front lens group may have a positive focal length and the rear lens group may have a negative focal length.

In some embodiments, the focal length of the front lens group may be less than 0.71f, where f is the focal length of the optical device.

Yet another aspect of the present invention provides an imaging method of an optical system. The method may include one or more of the following operations. Incident light can be received by an objective lens. The incident light may be directed into a camera array, wherein the camera array comprises a plurality of pre-fabricated camera modules, each camera module comprising a front lens group and a VCM unit, wherein the VCM unit comprises a rear lens group, a VCM-type actuator, and a sensor array. For each camera module, the distance between the rear lens group and the sensor array is adjustable by the VCM-type actuator such that light from the rear lens group can be focused onto the sensor array; a set of image signals may be generated based on the received light of the sensor array. Images may be reconstructed based on sets of image signals corresponding to the sets of camera modules.

In some embodiments, the image may be reconstructed by two operations. A plurality of partial images may be generated based on the plurality of sets of image signals. An image may be generated by stitching the plurality of partial images.

In some embodiments, the plurality of pre-fabricated camera modules may be distributed behind the objective lens group and in a fixed position.

In some embodiments, light corresponding to different portions of the image field may be separately directed to different camera modules.

In some embodiments, the front lens group and the rear lens group may define a common optical axis, and the distance between the lens groups and the sensor array is adjusted by translating the rear lens group along the common optical axis.

In some embodiments, the front lens group may have a positive focal length and the rear lens group may have a negative focal length.

In some embodiments, the focal length of the front lens group may be less than 0.71f, where f is the focal length of the optical device.

In some embodiments, the plurality of VCM units corresponding to the plurality of camera modules may be the same.

Yet another aspect of the present invention provides a method of providing an imaging optical system. The method may include one or more of the following operations. The target optical characteristics of the optical system can be obtained; wherein the optical system comprises an objective lens group and a camera module; wherein the camera module includes a front lens group and a VCM unit; wherein the VCM unit includes a rear lens group, a sensor array, and a VCM type actuator; wherein the VCM-type actuator is configured to adjust a distance between the rear lens group and the sensor array. The optical characteristics of the camera module may be acquired. An optical characteristic of the objective lens group may be determined based on the target optical characteristic of the optical system, the optical characteristic of the camera module, and the relative positions of the camera module and the objective lens group; wherein the target optical characteristic of the optical system or the optical characteristic of the camera module comprises at least one of a focal length, an aperture, and a field of view.

In some embodiments, the method further comprises: providing a first optical system and a second optical system; wherein the camera module in the first optical system and the camera module in the second optical system may share a common VCM unit.

Some additional features will be set forth in the description which follows, and some additional features will be apparent to those skilled in the art upon examination of the following and the accompanying drawings, or may be learned by production or operation of the examples. The features of the present invention may be realized and obtained by means of the instruments and methods described in the detailed examples discussed below.

Drawings

The invention is further described in terms of exemplary embodiments. These exemplary embodiments are described in detail with reference to the accompanying drawings. These embodiments are non-limiting exemplary embodiments in which like reference numerals represent similar structures throughout the several views of the drawings. Wherein:

FIG. 1 is an exemplary diagram of a prior art optical design of a generic camera module in a mobile phone;

FIG. 2 is an exemplary diagram of an optical design of a camera module according to some embodiments of the invention;

FIG. 3A is an exemplary diagram of an optical system according to some embodiments of the invention;

FIG. 3B is an exemplary diagram of a camera module according to some embodiments of the invention;

FIG. 3C is a VCM unit in a camera module according to some embodiments of the invention;

FIG. 3D is a table of optical parameters for lens elements in the optical system shown in FIG. 3A according to some embodiments of the present invention;

FIG. 3E illustrates an OTF curve of the camera module shown in FIG. 3B, according to some embodiments of the present invention;

FIG. 4A is a schematic diagram of a first application of the optical system of FIG. 3A, in accordance with some embodiments of the present invention;

FIG. 4B is a schematic diagram of a second application of the optical design of FIG. 3A, according to some embodiments of the present invention;

FIG. 5A is a schematic diagram of an optical system with a VCM focus mechanism according to some embodiments of the present invention;

FIG. 5B is a schematic diagram of a camera module in an optical system with a VCM focus mechanism according to some embodiments of the present invention;

FIG. 5C is a VCM unit in a camera module according to some embodiments of the invention;

fig. 5D is a production diagram of a VCM camera module according to some embodiments of the invention;

FIG. 6 is a method of imaging the camera module shown in FIG. 2 or 3 according to some embodiments of the invention;

FIG. 7 illustrates a method of the optical system depicted in FIG. 5, in accordance with some embodiments of the present invention;

FIG. 8 illustrates a method of providing an imaging optical system according to some embodiments of the invention; and

FIG. 9 illustrates a different optical system with a generic VCM unit according to some embodiments of the invention.

Detailed Description

In the following detailed description, numerous specific details are set forth by way of examples in order to provide a thorough understanding of the relevant disclosure. It will be apparent, however, to one skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, systems, components, and/or circuits have been described at a relatively high-level, without detail, in order to avoid unnecessarily obscuring aspects of the present invention. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present invention. Thus, the present invention is not limited to the embodiments shown, but is to be accorded the widest scope consistent with the claims.

It will be understood that the terms "system," "engine," "unit," "module," and/or "block" as used herein are a way of distinguishing, in ascending order, different components, elements, components, parts, or assemblies at different levels. However, these terms may be substituted by other expressions if the same object can be achieved.

Generally, the words "module," "unit," or "block" as used herein refers to a collection of logic, or software instructions, embodied in hardware or firmware. The modules, units, or blocks described herein may be implemented as software and/or hardware and may be stored in any type of non-transitory computer-readable medium or other storage device. In some embodiments, software modules/units/blocks may be compiled and linked into an executable program. It should be understood that software modules may be called from other modules/units/blocks or themselves, and/or may be called in response to detected events or interrupts. Software modules/units/blocks configured for execution on a computing device may be provided on a computer readable medium, such as a compact disc, digital video disc, flash drive, magnetic disk, or any other tangible medium, or downloaded as digital (and may be initially stored, decompressed, or decrypted before execution in a compressed or installable format requiring installation). Such software code may be stored, in part or in whole, on a storage device executing the computing device for execution by the computing device. Software such as an EPROM may be included in firmware. It should also be understood that hardware modules/units/blocks may be included in connected logic components, such as gates and flip-flops, and/or may include programmable units, such as programmable gate arrays or processors. The modules/units/blocks or computing device functions described herein may be implemented as software modules/units/blocks, but may be represented in hardware or firmware. Generally, a module/unit/block described herein refers to a logical module/unit/block that may be combined with other modules/units/blocks or divided into sub-modules/sub-units/sub-blocks, even though they have a physical organization or storage. The description may apply to the system, the engine, or a portion thereof.

It will be understood that when an element, engine, module or block is referred to as being "on," "connected to" or "coupled to" another element, engine, module or block, it can be directly on, connected or coupled to the other element, engine, module or block or an intermediate element, engine, module or block, unless the context clearly dictates otherwise. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed transactions.

These and other features of the present invention, as well as the methods of operation and functions of the related elements of structure and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description with reference to the accompanying drawings, all of which form a part of this disclosure. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the disclosure. It is understood that the drawings are not to scale.

The terminology used herein is for the purpose of describing particular examples and embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this disclosure, specify the presence of integers, means, acts, features, steps, elements, operations, and/or components, but do not preclude the presence or addition of one or more other integers, means, acts, features, steps, elements, operations, components, and/or groups thereof.

The invention provided herein relates to an optical system and an imaging method thereof. The detailed description will be explained in conjunction with the following embodiments.

Fig. 1 is an exemplary diagram of a prior art optical design of a generic camera module in a mobile phone. As shown in fig. 1, the focusing lens group 130 focuses light reflected by the first object 110 or the second object 120 onto the sensor array 140. In some embodiments, the camera module 100 may further include a VCM type actuator (not shown in fig. 1). The first object 110 may be located in a first object plane, the second object may be located in a second object plane, and the sensor array may be located in a sensor plane (also referred to as a focal plane). In some embodiments, the first object plane, the second object plane and the sensor plane are parallel to each other. Upon focusing, since the sensor array 140 typically has tighter tolerances than the focusing lens group 130, the focusing lens group 130 can only move to focus objects on different object planes onto the sensor plane, with the sensor array 140 lying on some fixed sensor plane.

As shown in fig. 1, the focusing operation does not change a conjugate distance defined as a distance between the object plane and the image plane. Farthest distanceConjugate distance of object plane is L₁The conjugate distance of the nearest plane is L₂Where the conjugate distance represents the distance between the object plane in which the object is located and the sensor plane 140.

As shown in FIG. 1, the lens stroke S is the back image distance l₁' and l₂' where the back image distance is the distance between the focusing lens group 130 and the sensor plane (focal plane). Thus, the back image distance is an intermediate quantity that relates the conjugate distance to the lens stroke. Equation (1) is how to calculate the back image distance L' for a given conjugate distance L:

where, the back image distance l' represents the distance between the focusing lens group 130 and the sensor array 140, and f is the focal length of the focusing lens group 130.

This approximation applies only to L > 4f, which is typically the case when the subject is far from the camera module 100 (e.g., photography). Thus, the moving stroke of the focusing lens group isIf the first object is at infinity, thenFor example, a focusing lens group with a focal length of 30mm focuses from infinity to 2m with a stroke ofHowever, for the range of travel of the widely available VCM type actuator used in common cell phone camera modules, this 450 μm travel is too large, which means that the optical design in fig. 1 cannot be cost-effective using the widely available VCM type actuator.

FIG. 2 is an exemplary diagram of an optical design of a camera module according to some embodiments of the invention. As shown in fig. 2, the camera module 200 may include a front lens group 210, a rear lens group 220, and a sensor array 230. In some embodiments, the front lens group may be stationary and the rear lens group may be driven in motion for focusing. Sensor array 230 may function the same as sensor array 140 shown in fig. 1. In some embodiments, the aperture of the front lens group 210 may be larger than the aperture of the rear lens group 220. In some embodiments, the front lens group 210 and the rear lens group may share a common optical axis, and a first plane in which the front lens group 210 is located, a second plane in which the rear lens group 220 is located, and a third plane in which the sensor array 230 is located may be parallel to each other. Upon focusing, rear lens group 220 may translate along the optical axis, and the position of front lens group 210 may be stationary with respect to the position of sensor array 230. In some embodiments, the camera module may further include a VCM-type actuator (not shown in fig. 2), and the translation along the optical axis of the rear lens group 220 may be achieved by the VCM-type actuator. In some embodiments, the rear lens group 220, the sensor array 230, and the VCM-type actuator may be packaged together as a VCM focusing module.

The arrangement shown in fig. 2 may divide the imaging process into two stages. In the first stage, the front lens group 210 may form an intermediate image of an object (e.g., the first object 110 or the second object 120). In the second stage, the intermediate image may be diverted or re-imaged by the rear lens group 220 onto the sensor array 230.

Let L_bRepresenting the conjugate distance of the rear lens group, i.e. the distance between the intermediate image and the sensor plane, the back image distance l can be calculated according to equation (2)_b’：

Wherein the back image distance l_b' denotes a distance between the rear lens group 220 and the sensor array 230, f_bIs the focal length of the rear lens group 220. The subscript letter b herein denotes these quantities associated with the rear lens group 220.

Since the first object 110 and the second object 120 are located on the object plane with the distance difference shown in fig. 1. If the camera module 200 needs to image two objects (the first object 110 and the second object 120) in turn, which means that the object plane moves from the first object plane to the second object plane, the focusing operation of the rear lens group 220 may be performed. The stroke of the rear lens group 220 in fig. 2 is:

wherein f is_aIs the focal length of the front lens group. If selected such thatLens parameters of, then, | S_b|<And | S |, the moving stroke can be reduced for focusing:

wherein f is_bIs the focal length of the rear lens group, and D represents the distance between the front lens group and the rear lens group. And f denotes a focal length of the camera module (an optical device group including a front lens group and a rear lens group).

The solution of inequality (4) can be described as:

0<f_a<0.71f and f_b<0 (5)

As shown in the inequality (5), by designing a camera module satisfying the inequality (5), a stroke can be reduced. In some embodiments, rear lens group 220 may include one or more lens elements, and in order for the rear lens group to have a negative focal length, at least one of the one or more lens elements may have a negative focal length.

Fig. 3A is an illustration of an optical system according to some embodiments of the inventions. In some embodiments, the optical system 300 may include an objective lens group 310 and a camera module 320. In some embodiments, the incident light received by the objective lens group 310 may correspond to a scene of the image field. Then, the camera module 320 receives the light, and finally the camera module 320 may generate an image. As shown in fig. 3A, the aperture of the objective lens group 310 is 21.76mm and the total track length of the optical system 300 is 40.73mm, wherein the track length represents the distance from the first lens vertex to the image plane (sensor plane, sensor array or focal plane). With proper design, the focal length of the optical system (EFFL) is 25 mm; the F-number (expressed as F/#, or F/#) was 2.5 and the field of view (FoV) was 16.4 deg.. In some embodiments, the camera module 320 may be cylindrical in shape aligned with the objective lens group 310.

It should be noted that the objective lens assembly shown in fig. 3A is provided for illustrative purposes only, and is not intended to limit the scope of the present invention. Many variations and modifications may be made to the teachings of the present invention by those of ordinary skill in the art in light of the present disclosure. However, such changes and modifications do not depart from the scope of the present invention. For example, one or more lens elements in the objective lens group 310 may be of any type (convex, concave, or compound).

Fig. 3B is an exemplary diagram of a camera module according to some embodiments of the invention. As shown in fig. 3B, the camera module 320 may include a front lens group 321 and a VCM unit 322. The aperture of the front lens group is 6.35mm and the track length of the camera module 320 is 8.91 mm.

Fig. 3C is a VCM cell in a camera module according to some embodiments of the invention. As shown in fig. 3C, the VCM unit 322 may include a rear lens group 323 and a sensor array 324. The aperture of the rear lens group 323 is 6mm, the track length of the VCM unit is 4.82mm, and the sensor array can be of a Sony IMX274LQC type. In some embodiments, the rear lens group 323 may include one or more lens elements, and at least one of the one or more lens elements may have a negative focal length. In some embodiments, the front lens group 322 and the rear lens group 323 may be separate, and the rear lens group 323 and the sensor array 324 may be packaged together in a VCM unit. In some embodiments, the front lens group 321 and the rear lens group 323 share or define a common optical axis. In addition, the front lens group 321 and the rear lens group 323 can share a common optical axis with the objective lens group 310. As a result, the objective lens group 310 and the camera module 320 in the optical system 300 may be precisely aligned, and the optical system 300 may achieve diffraction limit resolution. The camera module 320 may be designed to follow the optical design of inequality (5) discussed in fig. 2. In some embodiments, at least one of the one or more lens elements in the rear lens group has a negative focal length.

In some embodiments, the VCM unit may further include a VCM type actuator (not shown in fig. 3C). The VCM type actuator can adjust the distance between the rear lens group 323 and the sensor array 324. Specifically, the VCM type actuator can adjust the distance between the rear lens group 323 and the sensor array 324 by translating the rear lens group 323 along the common optical axis. As a result, the distance between the rear lens group 323 and the front lens group 321 can also be adjusted accordingly, and the focusing operation can be carried out.

It should be noted that the values of the optical parameters of the objective lens group, such as the aperture, are provided for illustrative purposes only and are not intended to limit the scope of the present invention. Many variations and modifications may be made to the teachings of the present invention by those of ordinary skill in the art in light of the present disclosure. However, such changes and modifications do not depart from the scope of the present invention. For example, the VCM unit 322 in the camera module 320 may be applied to an objective lens group having different optical characteristics (focal length, f-number, and FoV), and by proper design, different objective lens groups may be used to achieve different optical characteristics (focal length, f-number, and FoV) of the optical system. As another example, the aperture of the rear lens group 323 may be less than 6mm to achieve a narrower field of view for the camera module 320. As a third example, the lens element in the rear lens group may be aspherical, and the lens element may be made of plastic. Such a VCM unit is therefore compatible with the widely used mobile phone VCM platform, which can be manufactured economically and efficiently on a large scale. Therefore, the entire optical system can achieve higher cost efficiency.

FIG. 3D is a table of optical parameters of an objective lens group of the optical system shown in FIG. 3A according to some embodiments of the present invention. As shown in fig. 3D, different optical parameters are applied to achieve different optical characteristics of the optical system 300. Since this optical design is a common method for those skilled in the art, the optical design will not be discussed here.

Fig. 3E illustrates an Optical Transfer Function (OTF) curve of the camera module shown in fig. 3B, according to some embodiments of the invention. As shown in fig. 3A, incident light passes through the objective lens group 310 and is then received by the camera module 320 at an angle. The light received by the camera module 320 eventually reaches the sensor array and generates an imaging signal. In some embodiments, the maximum light angle that can ultimately hit the sensor array is 27.6 °. As shown in fig. 3E, the rear lens group can be translated along the optical axis in the range of 100 μm. By translating the rear lens group 323 within this range, the optical system shown in fig. 3A can focus in a range of 5m to infinity. Three OTF curves corresponding to images at different focal planes (5m, 10m and infinity) of the optical system 300 are shown in fig. 3E.

Parallel cameras offer new opportunities for radically increasing pixel capacity, weight and cost per unit camera volume. A particularly significant advantage is that lens cost and bulk can be significantly reduced. In practice, most of the cost of high performance lenses comes from the cost and complexity of the focus and zoom mechanisms. The zoom cost of a parallel camera is largely eliminated because in such a system, the mechanical zoom can be replaced by digital zoom, but the optical focus mechanism is still necessary. The parallel camera can further reduce the focusing cost by applying the configuration described in fig. 1 to 3. Fig. 4 depicts an application of two parallel cameras.

Fig. 4A is a schematic diagram of a first application of a camera module or optical system according to some embodiments of the invention. As illustrated in fig. 3A, the field of view of the optical system 300 is 16.4 °, as shown in fig. 4A, multiple camera modules (such as the camera module shown in fig. 2) or multiple optical systems (such as the optical system shown in fig. 3) can be arranged in a circle to achieve 360 ° imaging.

Fig. 4B is a schematic diagram of a second application of a camera module or optical system according to some embodiments of the invention. As illustrated in fig. 3A, the FoV of the optical system 300 is 16.4 °. As shown in fig. 4B, the camera modules or the array of optical systems may be arranged to obtain an image with a larger FoV.

FIG. 5A is a schematic diagram of an optical system with a VCM focus mechanism according to some embodiments of the inventions. As shown in fig. 5A, optical system 500 may include an objective lens group 510 and a camera array 520. In imaging, the objective lens group 510 may receive light from a scene of the image field and form an intermediate image of the scene at the image field. Further, the objective lens group 510 may direct the received light into a camera array, and the camera modules in the camera array 520 may receive light corresponding to different portions of the image field. The camera module may be a miniature camera. In some embodiments, a plurality of camera modules may be arranged in fixed positions, with each camera module being cylindrical in alignment with an objective lens group. In some embodiments, each camera module may image a portion of a scene of the image field, and the image may be reconstructed by stitching multiple portions of the image generated by multiple camera modules.

It should be noted that the foregoing description is provided for the purpose of illustration only, and is not intended to limit the scope of the invention. Many variations and modifications may be made to the teachings of the present invention by those of ordinary skill in the art in light of the present disclosure. However, such changes and modifications do not depart from the scope of the present invention. For example, the objective lens group 510 shown in FIG. 5 is a single central lens with the camera modules radially distributed around and behind the objective lens group. The objective lens assembly 510 may be a non-single center lens. If the objective lens group is a single central lens, a plurality of camera modules may be radially distributed around and behind the objective lens group.

Fig. 5B is a schematic diagram of a camera module in an optical system with a VCM focus mechanism according to some embodiments of the invention. As shown in fig. 5B, the camera module 530 may include a front lens group 531 and a VCM unit 532. In some embodiments, the camera module 530 may be the same as described in fig. 2. The position of the front lens group may be fixed or stationary relative to the position of the sensor array. As shown in fig. 5B, the front lens group 531 may include three lens elements, and the front lens group may guide light to the VCM unit 532. However, the number of lens elements of the front lens group may be variable. For example, the number of lens elements of the front lens group may be one or more.

Fig. 5C is a VCM cell in a camera module according to some embodiments of the invention. As shown in fig. 5C, VCM unit 532 may include rear lens group 533 and sensor array 534. In some embodiments, front lens group 531 and rear lens group 533 may be separated, and rear lens group 533 and sensor array 534 may be packaged together in a VCM unit. In some embodiments, the camera modules in camera array 520 may be cylindrical in shape aligned with objective lens group 510. More specifically, each camera module in the camera array may be cylindrical in alignment with the objective lens group 510. As a result, the objective lens group 510 and the camera array 520 in the optical system 500 can be accurately aligned, and the optical system 500 can achieve diffraction limited resolution. In some embodiments, the front lens group 531 and the rear lens group 533 may share or define a common optical axis. In some embodiments, to make the camera module more compact, the camera module may be designed to follow the optical design of inequality (5) discussed in fig. 2. In some embodiments, rear lens group 220 may include one or more lens elements, and at least one of the one or more lens elements may have a negative focal length. In some embodiments, the VCM unit may further include a VCM type actuator (not shown in fig. 5). As described in fig. 2, when the camera module needs to image two objects on two different object planes, focusing can be performed by the VCM type actuator. The VCM type actuator can adjust the distance between the rear lens group 533 and the sensor array 534. Specifically, the VCM type actuator can translate the rear lens group along the common optical axis.

In some embodiments, the objective lens group 510 may direct light corresponding to different portions of the image field into different camera modules in the camera array 520. For each camera module, light passing through the front lens group 531 and the rear lens group 533 may eventually reach the sensor array. The sensor array may generate a set of image signals based on the received light, and may then generate a partial image corresponding to a portion of the image field based on the set of image signals. Further, a plurality of camera modules in the camera array may generate a plurality of partial images based on the plurality of sets of image signals. In some embodiments, a plurality of partial images may be stitched together to form an image corresponding to an image field.

Fig. 5D is a product image of a VCM camera module according to some embodiments of the invention. The VCM camera module is a camera that may include a rear lens group, a sensor array, and a VCM type actuator, meaning that the rear lens group may be packaged with the sensor array and the VCM type actuator as a VCM camera module, while the rear lens group may not be packaged with the front lens group.

It should be noted that the above description is provided for illustrative purposes only, and is not intended to limit the scope of the present invention. Many variations and modifications may be made to the teachings of the present invention by those of ordinary skill in the art in light of the present disclosure. However, such changes and modifications do not depart from the scope of the present invention. For example, multiple VCM units may be identical in multiple camera modules. As another example, the rear lens group may have a negative focal length.

Fig. 6 is a method of imaging the camera module shown in fig. 2 or 3 according to some embodiments of the invention. In some embodiments, method 600 may be performed during imaging of an object by a focusing operation.

At 602, light may be directed into an optical device having a front lens group. In some embodiments, the optical device may be a camera module. The optical device may include a front lens group and a VCM unit. In some embodiments, the VCM unit may include a rear lens group, a VCM-type actuator, and a sensor array. The front lens group and the rear lens group may define a common optical axis. The camera module may be designed to follow the optical design of inequality (5) discussed in fig. 2. Since the optical device or camera module may be the same as in fig. 2 or 3, the configuration or arrangement of the optical device or camera module may not be discussed in detail herein.

At 604, a distance between the rear lens group and the sensor array may be adjusted to transfer the virtual image onto the sensor array. During imaging, the front lens group may generate an intermediate image that is a virtual image of the rear lens group, and then the rear lens group may relay or re-image the virtual image. In some embodiments, the position of the front lens group may be stationary relative to the position of the sensor array. Focusing may be performed, for example, when two objects on two different object planes need to be imaged consecutively by the optical device. The rear lens group is translatable along a common optical axis to focus the two objects onto different object planes such that light can be focused onto a sensor array of a camera module or an optical device. In some embodiments, the translation of the rear lens group may be achieved by a VCM type actuator.

At 606, a set of image signals may be generated based on light received by the sensor array. In some embodiments, light corresponding to a scene of an image field may be transmitted from the front lens group, the rear lens group, and the generated set of image signals may correspond to the scene of the image field.

At 608, an image may be reconstructed based on the set of image signals. In some embodiments, the reconstructed image may correspond to a scene of the image field. Using the method 600, a scene of an imaged image field can be focused accurately.

FIG. 7 illustrates a method of the optical system depicted in FIG. 5 according to some embodiments of the invention. In some embodiments, method 700 may be performed during imaging of a subject by a focusing operation.

At 702, incident light may be received with an objective lens. In some embodiments, the objective lens group may have one or more lens elements, and the one or more lens elements may be of any type (convex, concave, or compound).

At 704, the objective lens group can direct incident light into the camera array. In some embodiments, the camera array may include a plurality of pre-fabricated camera modules. The camera module may include a front lens group and a VCM unit. In some embodiments, the VCM unit may include a rear lens group, a VCM-type actuator, and a sensor array. The front lens group and the rear lens group may define a common optical axis. In some embodiments, a scalar product of a focal length of the front lens group and a focal length of the rear lens group may have a negative power sign, and further, the front lens group may have a positive focal length and the rear lens group may have a negative focal length. Details of the configuration or arrangement of the camera module can also be seen in fig. 2, and details of the configuration or arrangement of the optical system can also be seen in fig. 5.

At 706, the distance between the rear lens group and the camera array may be adjusted by a VCM type actuator so that light from the rear lens group may be focused onto the sensor array. In some embodiments, the distance between the lens group and the sensor array may be adjusted by translating the rear lens group along the common optical axis.

At 708, for each camera module, a set of image signals may be generated based on the light received by the sensor array. In some embodiments, step 708 may be performed in the same manner as described in 606. The difference between step 708 and step 606 is that multiple sets of image signals corresponding to multiple camera modules in the optical system may be generated.

At 710, an image may be reconstructed based on a plurality of sets of image signals corresponding to a plurality of camera modules. In some embodiments, the reconstruction process may include two steps. First, a plurality of partial images may be generated based on a plurality of sets of image signals. Second, an image corresponding to the scene of the image field may be generated by stitching the plurality of partial images.

FIG. 8 illustrates a method of providing an imaging optical system according to some embodiments of the invention. In some embodiments, an imaging optical system may include an objective lens group and a camera module. The camera module may include a front lens group and a VCM unit. The VCM unit may include a rear lens group, a sensor array, and a VCM type actuator. The front lens group and the rear lens group may define a common optical axis. The VCM type actuator may be configured to adjust a distance between the rear lens group and the sensor array. In some embodiments, the distance between the rear lens group and the sensor array may be adjusted by translating the rear lens group along the common optical axis.

At 810, a target optical characteristic of the optical system may be obtained. In some embodiments, the target optical characteristic may include at least one of a focal length, an aperture, and a field of view.

At 820, optical characteristics of the camera module may be obtained. In some embodiments, the optical characteristics of the camera module may include at least one of a focal length, an aperture, and a field of view.

At 830, the optical characteristics of the objective lens group are based on target optical characteristics of the optical system, optical characteristics of the camera module, and relative positions of the camera module and the objective lens group. The optical properties of the objective lens group may further comprise at least one of a focal length, an aperture and a field of view.

In some embodiments, the first optical system and the second optical system may be designed, wherein the VCM unit in the first optical system and the VCM unit in the second optical system may be the same. The first optical system and the second optical system may have different optical characteristics by selecting different objective lens groups or by setting different distances between the objective lens groups and the camera module. Fig. 9 shows a generic focusing scheme that uses the same focusing VCM unit with the same optical elements inside to provide different optical systems with different specifications. As shown in fig. 9, the aperture of the VCM unit is 6mm, and the track length of the VCM unit is 4.82 mm. The size of the sensor array is 7.2 mm. Optical systems with different optical characteristics (focal length, f-number, etc.) are realized for the same VCM unit by applying objective lens groups with different optical characteristics or by changing the distance between the camera module and the objective lens group.

Having thus described the basic concepts, it will be apparent to those skilled in the art from this detailed disclosure that the foregoing detailed disclosure is intended to be presented by way of example only, and not by way of limitation. Various alterations, improvements, and modifications may occur, though not expressly stated herein. Such alterations, improvements, and modifications are intended to be suggested by this disclosure, and are within the spirit and scope of the exemplary embodiments of the invention.

Furthermore, certain terminology has been used to describe embodiments of the invention. For example, the terms "one embodiment," "an embodiment," and/or "some embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Therefore, it is emphasized and should be appreciated that two or more references to "one embodiment" or "an alternative embodiment" in various portions of this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures or characteristics may be combined together in one or more embodiments of the invention.

Moreover, those skilled in the art will appreciate that various aspects of the invention may be illustrated and described in any of a number of patentable classes or contexts, including any new and useful methods, machines, manufacture, or composition of matter, or any new and useful modifications thereof. Accordingly, various aspects of the present invention may be implemented in hardware entirely, in software entirely (including firmware, resident software, micro-code, etc.), or in a combination of software and hardware, which may be referred to herein generally as "blocks," modules, "" engines, "" units, "" components, "or" systems. Furthermore, various aspects of the present invention may take the form of a computer program product, embodied in one or more computer-readable media, having computer-readable program code embodied therein.

Furthermore, the order in which the elements or sequences are described, or the use of numbers, letters, or other designations therefore, is not intended to limit the claimed processes and methods to any order except as may be specified in the claims. While the foregoing disclosure discusses, by way of various examples, what are presently considered to be various useful embodiments of the invention, it is to be understood that such detail is solely for that purpose and that the appended claims are not limited to the disclosed embodiments, but, on the contrary, are intended to cover modifications and equivalent arrangements that are within the spirit and scope of the disclosed embodiments. For example, although implementations of the various components described above may be embodied in a hardware device, they may also be implemented as a software-only solution, e.g., an installation on an existing processing device or mobile device.

Similarly, it should be appreciated that in the foregoing description of embodiments of the invention, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure aiding in the understanding of one or more of the various inventive embodiments. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed subject matter requires more features than are expressly recited in each claim. Rather, inventive embodiments lie in less than all features of a single foregoing disclosed embodiment.