Patent Description:
The advent of small, mobile multipurpose devices such as smartphones and tablet or pad devices has resulted in a need for high-resolution, small form factor cameras that are lightweight, compact, and capable of capturing high resolution, high quality images at low F-numbers for integration in the devices. However, due to limitations of conventional camera technology, conventional small cameras used in such devices tend to capture images at lower resolutions and/or with lower image quality than can be achieved with larger, higher quality cameras. Achieving higher resolution with small package size cameras generally requires use of a photosensor with small pixel size and a good, compact imaging lens system. Advances in technology have achieved reduction of the pixel size in photosensors. However, as photosensors become more compact and powerful, demand for compact imaging lens systems with improved imaging quality performance has increased. In addition, there are increasing expectations for small form factor cameras to be equipped with higher pixel count and/or larger pixel size image sensors (one or both of which may require larger image sensors) while still maintaining a module height that is compact enough to fit into portable electronic devices. Thus, a challenge from an optical system design point of view is to provide an imaging lens system that is capable of capturing high brightness, high resolution images under the physical constraints imposed by small form factor cameras. The paper by<NPL>) describes an occlusion capable optical see-through head-mounted display using freeform optics. <CIT> describes an imaging optical system and imaging optical unit equipped with at least three or more optical prisms PR1 to PR3 through which a light beam from an object side passes, with at least one of the optical prisms having positive power. <CIT> describes an image pickup optical system and optical apparatus using the same in which the image pickup optical system includes, in order from the object side, a front unit having at least one reflecting surface with power that is rotationally asymmetrical, an aperture stop, and a rear unit having at least one reflecting surface with power that is rotationally asymmetrical. <CIT> describes a compact folded thin lens including first and second optical elements each having a reflecting surface and first and second refracting surfaces.

Embodiments of the present disclosure may provide a folded optical system that may, for example, be used as a camera lens in small form factor cameras. Embodiments of a folded optical system are described that include two prisms with refractive power that together form the optical system. At least one surface of at least one of the prisms is a "freeform" surface, and thus the prism(s) may be referred to as freeform prisms. A freeform prism may be broadly defined as a prism with at least one surface that provides refractive power and that is asymmetric (not rotationally symmetric) (i.e., is a "freeform" surface). The prisms provide a "folded" optical axis for the camera, for example to reduce the Z-height of the camera. A first prism (P1) redirects light from an object field from a first axis to a second axis. A second prism (P2) receives the light on the second axis and redirects the light onto a third axis on which a photosensor of the camera is disposed. The redirected light forms an image at an image plane at or near the surface of a photosensor.

Each of the two prisms includes three surfaces that affect light passing through the prism. A first surface (S1) receives the light from an object side of the prism; a second surface (S2) reflects or redirects the light received through the first surface to a third surface (S3); the light then passes through or is refracted by the third surface to the next prism or to the photosensor. For each prism, a given surface may be flat/plano with no refractive power; symmetrically concave, convex, or aspherical with refractive power; or freeform (asymmetrically concave, convex, or aspherical with refractive power). As noted above, in some embodiments, at least one surface of at least one of the prisms is a freeform surface. In some embodiments, at least two of the six surfaces of the prisms in the optical system are freeform surfaces. In some embodiments, the first and third surfaces in both prisms are freeform surfaces, while the second surfaces in both prisms are flat/plano. However, in some embodiments, one or both of the second surfaces may be freeform surfaces with refractive power or symmetrical surfaces with refractive power.

The materials and surfaces of the prisms in the optical system may be selected to capture high resolution, high quality images. Parameters and relationships of the prisms, including but not limited to the materials and surface shapes may be selected at least in part to reduce, compensate, or correct for optical aberrations and artifacts and effects across the field of view. In some embodiments, the materials and surfaces of the prisms in the optical system may be selected to provide a low F-number (e.g., <= <NUM>), full field of view (FOV) of <NUM> degrees or less, and high brightness, high resolution images with high image quality.

In some embodiments, an aperture stop is located in the optical system at the first (object side) surface of the first prism. In some embodiments, the aperture stop may be elliptical; however, circular or other shapes may be used for the aperture in some embodiments. In some embodiments, the folded camera may include an infrared (IR) filter to reduce or eliminate interference of environmental noise on the photosensor. The IR filter may, for example, be located between the second prism and the photosensor.

This specification includes references to "one embodiment" or "an embodiment. " The appearances of the phrases "in one embodiment" or "in an embodiment" do not necessarily refer to the same embodiment. Particular features, structures, or characteristics may be combined in any suitable manner consistent with this disclosure.

"Comprising. " This term is open-ended. As used in the appended claims, this term does not foreclose additional structure or steps. Consider a claim that recites: "An apparatus comprising one or more processor units. Such a claim does not foreclose the apparatus from including additional components (e.g., a network interface unit, graphics circuitry, etc.).

"Configured To. " Various units, circuits, or other components may be described or claimed as "configured to" perform a task or tasks. In such contexts, "configured to" is used to connote structure by indicating that the units/circuits/components include structure (e.g., circuitry) that performs those task or tasks during operation. As such, the unit/circuit/component can be said to be configured to perform the task even when the specified unit/circuit/component is not currently operational (e.g., is not on). The units/circuits/components used with the "configured to" language include hardware-for example, circuits, memory storing program instructions executable to implement the operation, etc. Reciting that a unit/circuit/component is "configured to" perform one or more tasks is expressly intended not to invoke <NUM> U. § <NUM>, sixth paragraph, for that unit/circuit/component. Additionally, "configured to" can include generic structure (e.g., generic circuitry) that is manipulated by software and/or firmware (e.g., an FPGA or a general-purpose processor executing software) to operate in manner that is capable of performing the task(s) at issue. "Configure to" may also include adapting a manufacturing process (e.g., a semiconductor fabrication facility) to fabricate devices (e.g., integrated circuits) that are adapted to implement or perform one or more tasks.

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

" As used herein, this term is used to describe one or more factors that affect a determination. This term does not foreclose additional factors that may affect a determination. That is, a determination may be solely based on those factors or based, at least in part, on those factors. Consider the phrase "determine A based on B. " While in this case, B is a factor that affects the determination of A, such a phrase does not foreclose the determination of A from also being based on C. In other instances, A may be determined based solely on B.

Embodiments of a folded optical system are described that include two prisms with refractive power that together form the optical system. At least one surface of at least one of the prisms is a "freeform" surface, and thus the prism(s) may be referred to as freeform prisms. A freeform prism may be broadly defined as a prism with at least one surface that provides refractive power and that is asymmetric (not rotationally symmetric) (i.e., is a "freeform" surface).

Embodiments of the folded optical system as described herein may be implemented in a small package size while still capturing sharp, high-resolution images, making embodiments of a camera including the optical system suitable for use in small and/or mobile multipurpose devices such as cell phones, smartphones, pad or tablet computing devices, laptop, netbook, notebook, subnotebook, and ultrabook computers, and so on. <FIG> illustrates an example device that may include one or more small form factor cameras that use embodiments of the folded optical system as described herein. However, note that aspects of the camera (e.g., the optical system and photosensor) may be scaled up or down to provide cameras with larger or smaller package sizes. In addition, embodiments of the camera may be implemented as stand-alone digital cameras. In addition to still (single frame capture) camera applications, embodiments of the camera may be adapted for use in video camera applications.

<FIG> illustrates a conventional folded camera <NUM> that includes a lens stack positioned between two prisms, according to some embodiments. The prisms <NUM> and <NUM> provide a "folded" optical axis for the camera <NUM>, for example to reduce the Z-height of the camera <NUM> when compared to conventional straight camera lenses. A lens stack <NUM> including one or more refractive lens elements is located between prisms <NUM> and <NUM>. A first prism <NUM> redirects light from an object field from a first axis to the lens stack <NUM> on a second axis. The lens element(s) in the lens stack <NUM> refract the light to a second prism <NUM> that redirects the light onto a third axis on which a photosensor <NUM> of the camera <NUM> is disposed. The redirected light forms an image at an image plane <NUM> at or near the surface of the photosensor <NUM>.

<FIG> illustrates a camera <NUM> that includes a folded optical system that consists of two freeform prisms <NUM> and <NUM> with refractive power, according to some embodiments. The prisms <NUM> and <NUM> provide a "folded" optical axis for the camera <NUM>, for example to reduce the Z-height of the camera. For example, a camera <NUM> with a conventional folded lens system as illustrated in <FIG> may have a Z-axis height of > <NUM>, for example <NUM>, while a camera <NUM> with a folded optical system as illustrated in <FIG> may have a Z-axis height of < <NUM>, for example <NUM>, while providing similar performance to the camera <NUM> of <FIG>. In addition, the freeform prisms <NUM> and <NUM> in the folded optical system of camera <NUM> may eliminate the need for a lens stack between the prisms as shown in the camera <NUM> of <FIG>, which may reduce the length of the long axis of the camera <NUM> when compared to the camera <NUM> of <FIG>. Further, the folded optical system of <FIG> requires fewer optical elements (two freeform prism) when compared to the folded lens system of <FIG> (two prisms and at least one refractive lens element in the lens stack). Having fewer optical elements may, for example, simplify packaging and alignment of the optical system during manufacture when compared to the lens system of <FIG>.

In the folded optical system of <FIG>, a first freeform prism <NUM> (P1) receives light from an object field through an aperture stop <NUM> and refracts and redirects the light from a first axis to a second axis. Prism <NUM> includes three surfaces that affect light passing through the prism <NUM>. A first surface (P1S1) refracts light received from an object field through aperture stop <NUM>; a second surface (P1S2) reflects or redirects the light to a third surface (P1S3); the light is refracted by the third surface to the second prism <NUM>.

A second freeform prism <NUM> (P2) receives the light on the second axis and refracts and redirects the light onto a third axis on which a photosensor <NUM> of the camera is disposed. The refracted and redirected light forms an image at an image plane <NUM> at or near the surface of the photosensor <NUM>. Prism <NUM> includes three surfaces that affect light passing through the prism <NUM>. A first surface (P2S1) refracts light received from the first prism <NUM>; a second surface (P2S2) reflects or redirects the light to a third surface (P2S3); the light is refracted by the third surface to form an image at an image plane <NUM> at or near the surface of the photosensor <NUM>. In some embodiments, an infrared (IR) filter <NUM> may be located between the second prism <NUM> and the photosensor <NUM>.

According to the invention, the first and third surfaces in both prisms are freeform surfaces, while the second surfaces in both prisms are.

In the example embodiment illustrated in <FIG>, P1S1 is a freeform convex surface with positive refractive power, P1S2 is a flat/plano surface, P1S3 is a freeform convex surface with positive refractive power, P2S1 is a freeform concave surface with negative refractive power, P2S2 is a flat/plano surface, and P2S3 is a freeform concave surface with negative refractive power. In some embodiments, P1S2 and P2S2 may be coated with a reflective material to redirect light. However, in some embodiments, at least one of P1S2 and P2S2 may reflect light via total internal reflection (TIR). Further, in some embodiments, one or both of P1S2 and P2S2 may be freeform surfaces with refractive power or symmetrical surfaces with refractive power.

The materials and surfaces of prisms <NUM> and <NUM> may be selected to capture high resolution, high quality images. Parameters and relationships of the prisms <NUM> and <NUM>, including but not limited to the materials and surface shapes may be selected at least in part to reduce, compensate, or correct for optical aberrations and artifacts and effects across the field of view. In some embodiments, the materials and surfaces of the prisms in the optical system may be selected to provide a low F-number (e.g., <= <NUM>), full field of view (FOV) of <NUM> degrees or less, and high brightness, high resolution images with high image quality.

In some embodiments, an aperture stop <NUM> is located in the folded optical system at the first (object side) surface of the first prism <NUM>. In some embodiments, the aperture stop <NUM> may be elliptical; however, circular or other shapes may be used for the aperture in some embodiments. In some embodiments, the camera <NUM> may include an infrared (IR) filter <NUM> to reduce or eliminate interference of environmental noise on the photosensor <NUM>. The IR filter <NUM> may, for example, be located between the second prism <NUM> and the photosensor <NUM>.

<FIG>, and <FIG> are diagrams illustrating orientation of the x and y axes at the surfaces of the freeform prisms as shown in <FIG>, according to some embodiments. <FIG> is s cross-sectional illustration of a folded optical system, according to some embodiments. Referring to <FIG>, optical characteristics of the freeform surfaces of the prisms in an optical system as illustrated in <FIG> may be defined for a paraxial region of the surfaces along two axes of symmetry (x and y) relative to the optical axis at the surfaces of the prisms <NUM> and <NUM>. As shown in <FIG>, the optical axis is a line that passes through surface P1S1 at a center point of aperture stop <NUM> and perpendicular to a tangent plane at that point of surface P1S1. A light ray on the optical axis passes through the folded optical system to strike at or near the center of photosensor <NUM> and perpendicular to the surface plane of photosensor <NUM>. At the photosensor, the x axis corresponds to a horizontal axis of the photosensor <NUM> that intersects the optical axis, and the y axis corresponds to a vertical axis of the photosensor <NUM> that intersects the optical axis. The y axis and the optical axis are on the plane of the cross-section, and the x axis is perpendicular to the plane of the cross-section. At each surface of prisms <NUM> and <NUM>, the x axis is on a tangent plane at the intersection of the optical axis with the surface and is parallel to the x axis at the photosensor <NUM> and perpendicular to the optical axis. However, at each surface of prisms <NUM> and <NUM>, the y axis rotates around the x axis to conform to the tangent plane, and thus is not necessarily parallel to the y axis at the photosensor <NUM>. <FIG> graphically illustrates the x, y, and optical axes on a 3D model of a prism. As shown in <FIG>, the x axes at S1, S2, and S3 are parallel to each other and perpendicular to the optical axis. However, the y axis at each surface rotates around the x axis to conform to the tangent plane at the respective surface.

As noted above, the optical characteristics of the freeform surfaces of the prisms in an optical system as illustrated in <FIG> may be defined for a paraxial region around the optical axis along two axes of symmetry (x and y). <FIG> graphically illustrates the effective aperture and paraxial region of a surface of a prism as illustrated in <FIG>. At P1S1, the aperture is defined by aperture stop <NUM>. At each successive surface (P1S2, P1S3, P2S1, P2S2, and P2S3), the aperture may be defined by the light that the surface receives from the preceding surface. As previously noted, in some embodiments, the aperture stop <NUM> may be elliptical; however, circular or other shapes may be used for the aperture in some embodiments. <FIG> shows the x and y axes at the aperture as previously defined at the surface. The paraxial region is a region around the optical axis that extends <NUM>% or less of the width of the aperture in each direction from the optical axis on the x and y axes.

<FIG> is a 3D cross-sectional illustration of an example folded optical system that includes two freeform prisms, according to some embodiments. A telephoto camera <NUM> may include a folded optical system that consists of two freeform prisms <NUM> and <NUM>. An aperture stop may be located at a first (object side) surface of the first prism <NUM>. The aperture stop may be elliptical or circular. The camera <NUM> also includes a photosensor <NUM>. In some embodiments, an infrared filter may be located between the second prism <NUM> and the photosensor. In some embodiments, the folded optical system may be configured to provide a low F-number (e.g., <= <NUM>), full field of view (FOV) of <NUM> degrees or less, and high brightness, high resolution images with high image quality.

The folded optical system consists of two freeform prisms <NUM> (P1) and <NUM> (P2). Each of the two prisms <NUM> and <NUM> includes three surfaces that affect light passing through the prism. A first surface (S1) receives the light from an object side of the prism; a second surface (S2) reflects or redirects the light received through the first surface to a third surface (S3); the light then passes through or is refracted by the third surface to the next prism or to the photosensor <NUM>. Each of the prisms includes at least one freeform surface in the imaging path that is not rotationally symmetric.

At prism <NUM>, incoming light through aperture stop <NUM> is converged by P1S1, reflected by P1S2, and converged by P1S3 to exit prism <NUM>. At prism <NUM>, the light from prism <NUM> is diverged by P2S1, reflected by P2S2, diverged by P2S3, and exits prism <NUM> to form an image at an image plane at or near the surface of photosensor <NUM>. The folding surfaces (surfaces P1S2 and P2S2) may reflect light either through total internal reflection (TIR) or via a mirror coating.

In some embodiments, the aperture stop <NUM> of the folded optical system is at or near the object side surface (P1S1) of prism <NUM>. In some embodiments, the aperture stop <NUM> is at or near (within <NUM>) surface P1S1 for imaging purposes.

In some embodiments, the folded optical system has same focal lengths along the x axis and along the y axis. The folded optical system satisfies the following condition: <MAT> where fx is the focal length through the folded optical system on the x axis, fy is the focal length through the folded optical system on the y axis, and fsys is the effective focal length of the folded optical system.

For each of the prisms <NUM> and <NUM>, focal lengths along the x axis (fP1X, fP2X) are different than focal lengths along the y axis (fP1Y, fP2Y), respectively, which defines both prisms <NUM> and <NUM> as freeform prisms: <MAT>.

In some embodiments, an optional infrared cutoff filter (IRCF) is positioned in front of the photosensor <NUM> to remove unwanted infrared light and thus improve the signal-to-noise ratio (SNR).

<FIG> is a cross-sectional illustration of an example folded optical system as illustrated in <FIG> that includes two freeform prisms <NUM> and <NUM>, according to some embodiments. On the optical axis, prism <NUM> includes three surfaces with power. The refractive power of prism <NUM> along the x axis is stronger than the refractive power along the y axis. Prism <NUM> satisfies the following conditions: <MAT> <MAT> where fP1y is the focal length of prism <NUM> along the y axis, fP1x is the focal length of prism <NUM> along the x axis, and fsys is the effective focal length of the freeform folded optical system.

Prism <NUM> has three surfaces along the optical axis from an object side to an image side: P1S1, P1S2, and P1S3. P1S1 is convex in the paraxial region, and satisfies the following conditions: <MAT> <MAT> where fP1S1y and fP1S1x are focal lengths of surface P1S1 on the y and x axes, respectively.

P1S2 is reflective coated to reflect visible light and fold the optical axis.

P1S3 is convex in the paraxial region, and satisfies the following conditions: <MAT> <MAT> where fP1S3y and fP1S3x are focal lengths of surface P1S3 on the y and x axes, respectively.

In some embodiments, prism <NUM> may be formed of an optical plastic material. In some embodiments, prism <NUM> is formed of an optical material with an Abbe number vd1 that satisfies the following condition: <MAT>.

On the optical axis, prism <NUM> includes three surfaces with power. The refractive power of prism <NUM> along x axis is stronger than that along the y axis. Prism <NUM> satisfies the following conditions: <MAT> <MAT> where fP2y is the focal length of prism <NUM> along the y axis, fP2x is the focal length of prism <NUM> along the x axis, and fsys is the effective focal length of the freeform folded optical system.

Prism <NUM> has three surfaces along the optical axis from an object side to an image side: P2S1, P2S2, and P2S3. P2S1 is concave in the paraxial region, and satisfies the following conditions: <MAT> <MAT> where fP2S1y and fP2S1x are focal lengths of surface P2S1 on the y and x axes, respectively.

P2S2 is reflective coated to reflect visible light and fold the optical axis.

P2S3 is concave in the paraxial region, and satisfies the following conditions: <MAT> <MAT> where fP2S3y and fP2S3x are focal lengths of surface P2S3 on the y and x axes, respectively.

In some embodiments, prism <NUM> may be formed of an optical plastic material. In some embodiments, prism <NUM> is formed of an optical material with an Abbe number vd2 that satisfies the following condition: <MAT>.

<FIG> is a cross-sectional illustration of an example folded optical system that includes two freeform prisms and shows the angles between surfaces of the freeform prisms, according to some embodiments. The angle between the tangent line of P1S1 and the tangent line of P1S3 is Alpha <NUM>. In some embodiments, Alpha <NUM> satisfies the following condition: <MAT>.

The angle between the tangent line of P2S1 and the tangent line of P2S3 is Alpha <NUM>. In some embodiments, Alpha <NUM> satisfies the following condition: <MAT>.

<FIG> is a flowchart of a method for capturing images using embodiments of a camera as illustrated in <FIG>, according to some embodiments. As indicated at <NUM>, light from an object field in front of the camera is received through an aperture stop at a first surface of a first freeform prism on a first axis. As indicated at <NUM>, the light is refracted and redirected by the first freeform prism to a second axis. As indicated at <NUM>, the light is received at a first surface of a second freeform prism. As indicated at <NUM>, the light is refracted and redirected by the second freeform prism to a third axis. As indicated at <NUM>, the light forms an image at an image plane at or near the surface of a photosensor or sensor module on the third axis. As indicated at <NUM>, the image is captured by the photosensor.

While not shown in <FIG>, in some embodiments, the light may pass through an infrared filter that may for example be located between the second freeform prism and the photosensor.

In some embodiments, the components of the folded optical system referred to in <FIG> may be configured as illustrated in any of <FIG>, <FIG>, <FIG>, <FIG>, or <FIG>. However, note that variations on the examples given in the Figures are possible while achieving similar optical results.

<FIG> illustrates an example computing device, referred to as computer system <NUM>, that may include or host embodiments of a camera with a folded optical system as illustrated in <FIG>. In addition, computer system <NUM> may implement methods for controlling operations of the camera and/or for performing image processing of images captured with the camera. In different embodiments, computer system <NUM> may be any of various types of devices, including, but not limited to, a personal computer system, desktop computer, laptop, notebook, tablet or pad device, slate, or netbook computer, mainframe computer system, handheld computer, workstation, network computer, a camera, a set top box, a mobile device, a wireless phone, a smartphone, a consumer device, video game console, handheld video game device, application server, storage device, a television, a video recording device, a peripheral device such as a switch, modem, router, or in general any type of computing or electronic device.

In the illustrated embodiment, computer system <NUM> includes one or more processors <NUM> coupled to a system memory <NUM> via an input/output (I/O) interface <NUM>. Computer system <NUM> further includes a network interface <NUM> coupled to I/O interface <NUM>, and one or more input/output devices <NUM>, such as cursor control device <NUM>, keyboard <NUM>, and display(s) <NUM>. Computer system <NUM> may also include one or more cameras <NUM>, for example one or more cameras as described above with respect to <FIG>, which may also be coupled to I/O interface <NUM>, or one or more cameras as described above with respect to <FIG> along with one or more other cameras such as conventional wide-field cameras.

In various embodiments, computer system <NUM> may be a uniprocessor system including one processor <NUM>, or a multiprocessor system including several processors <NUM> (e.g., two, four, eight, or another suitable number). Processors <NUM> may be any suitable processor capable of executing instructions. For example, in various embodiments processors <NUM> may be general-purpose or embedded processors implementing any of a variety of instruction set architectures (ISAs), such as the x86, PowerPC, SPARC, or MIPS ISAs, or any other suitable ISA. In multiprocessor systems, each of processors <NUM> may commonly, but not necessarily, implement the same ISA.

System memory <NUM> may be configured to store program instructions <NUM> and/or data <NUM> accessible by processor <NUM>. In various embodiments, system memory <NUM> may be implemented using any suitable memory technology, such as static random access memory (SRAM), synchronous dynamic RAM (SDRAM), nonvolatile/Flash-type memory, or any other type of memory. In the illustrated embodiment, program instructions <NUM> may be configured to implement various interfaces, methods and/or data for controlling operations of camera <NUM> and for capturing and processing images with integrated camera <NUM> or other methods or data, for example interfaces and methods for capturing, displaying, processing, and storing images captured with camera <NUM>. In some embodiments, program instructions and/or data may be received, sent or stored upon different types of computer-accessible media or on similar media separate from system memory <NUM> or computer system <NUM>.

In one embodiment, I/O interface <NUM> may be configured to coordinate I/O traffic between processor <NUM>, system memory <NUM>, and any peripheral devices in the device, including network interface <NUM> or other peripheral interfaces, such as input/output devices <NUM>. In some embodiments, I/O interface <NUM> may perform any necessary protocol, timing or other data transformations to convert data signals from one component (e.g., system memory <NUM>) into a format suitable for use by another component (e.g., processor <NUM>). In some embodiments, I/O interface <NUM> may include support for devices attached through various types of peripheral buses, such as a variant of the Peripheral Component Interconnect (PCI) bus standard or the Universal Serial Bus (USB) standard, for example. In some embodiments, the function of I/O interface <NUM> may be split into two or more separate components, such as a north bridge and a south bridge, for example. Also, in some embodiments some or all of the functionality of I/O interface <NUM>, such as an interface to system memory <NUM>, may be incorporated directly into processor <NUM>.

Network interface <NUM> may be configured to allow data to be exchanged between computer system <NUM> and other devices attached to a network <NUM> (e.g., carrier or agent devices) or between nodes of computer system <NUM>. Network <NUM> may in various embodiments include one or more networks including but not limited to Local Area Networks (LANs) (e.g., an Ethernet or corporate network), Wide Area Networks (WANs) (e.g., the Internet), wireless data networks, some other electronic data network, or some combination thereof. In various embodiments, network interface <NUM> may support communication via wired or wireless general data networks, such as any suitable type of Ethernet network, for example; via telecommunications/telephony networks such as analog voice networks or digital fiber communications networks; via storage area networks such as Fibre Channel SANs, or via any other suitable type of network and/or protocol.

Input/output devices <NUM> may, in some embodiments, include one or more display terminals, keyboards, keypads, touchpads, scanning devices, voice or optical recognition devices, or any other devices suitable for entering or accessing data by computer system <NUM>. Multiple input/output devices <NUM> may be present in computer system <NUM> or may be distributed on various nodes of computer system <NUM>. In some embodiments, similar input/output devices may be separate from computer system <NUM> and may interact with one or more nodes of computer system <NUM> through a wired or wireless connection, such as over network interface <NUM>.

As shown in <FIG>, memory <NUM> may include program instructions <NUM>, which may be processor-executable to implement any element or action to support integrated camera <NUM>, including but not limited to image processing software and interface software for controlling camera <NUM>. In some embodiments, images captured by camera <NUM> may be stored to memory <NUM>. In addition, metadata for images captured by camera <NUM> may be stored to memory <NUM>.

Those skilled in the art will appreciate that computer system <NUM> is merely illustrative and is not intended to limit the scope of embodiments. In particular, the computer system and devices may include any combination of hardware or software that can perform the indicated functions, including computers, network devices, Internet appliances, PDAs, wireless phones, pagers, video or still cameras, etc. Computer system <NUM> may also be connected to other devices that are not illustrated, or instead may operate as a stand-alone system. In addition, the functionality provided by the illustrated components may in some embodiments be combined in fewer components or distributed in additional components. Similarly, in some embodiments, the functionality of some of the illustrated components may not be provided and/or other additional functionality may be available.

Those skilled in the art will also appreciate that, while various items are illustrated as being stored in memory or on storage while being used, these items or portions of them may be transferred between memory and other storage devices for purposes of memory management and data integrity. Alternatively, in other embodiments some or all of the software components may execute in memory on another device and communicate with the illustrated computer system <NUM> via inter-computer communication. Some or all of the system components or data structures may also be stored (e.g., as instructions or structured data) on a computer-accessible medium or a portable article to be read by an appropriate drive, various examples of which are described above. In some embodiments, instructions stored on a computer-accessible medium separate from computer system <NUM> may be transmitted to computer system <NUM> via transmission media or signals such as electrical, electromagnetic, or digital signals, conveyed via a communication medium such as a network and/or a wireless link. Various embodiments may further include receiving, sending or storing instructions and/or data implemented in accordance with the foregoing description upon a computer-accessible medium. Generally speaking, a computer-accessible medium may include a non-transitory, computer-readable storage medium or memory medium such as magnetic or optical media, e.g., disk or DVD/CD-ROM, volatile or non-volatile media such as RAM (e.g. SDRAM, DDR, RDRAM, SRAM, etc.), ROM, etc. In some embodiments, a computer-accessible medium may include transmission media or signals such as electrical, electromagnetic, or digital signals, conveyed via a communication medium such as network and/or a wireless link.

Claim 1:
A folded optical system (<NUM>), comprising:
a first prism (<NUM>); and
a second prism (<NUM>);
wherein each prism has a first surface S1, a second surface S2, and a third surface S3 on an optical axis of the folded optical system consecutively along an optical path from an object side to an image side and wherein the first surface S1 and the third surface S3 are freeform surfaces;
wherein the first prism (<NUM>) has refractive power and has only one reflecting surface that is the second surface (P1S2) of the first prism, for internally reflecting the light and is configured to receive light from an object field along a first axis and redirect the light from the first axis to the second axis, toward the second prism (<NUM>);
wherein the second prism (<NUM>) is configured to receive the light that enters the second prism along the second axis and has only one reflecting surface that is the second surface (P2S2) of the second prism (<NUM>) for internally reflecting the light received along the second axis and has refractive power to refract the light to form an image of the object field at an image plane;
wherein the second surfaces (P1S2, P2S2) of the first and second prisms, that affects the light passing through the first and second prisms is flat/plano; and
wherein a freeform surface is defined as being a non rotationally symmetric surface.