MAGNIFICATION VIEWING SYSTEM

TECHNICAL FIELD

[0001] The present disclosure relates to a compact high magnification folded optical system. In particular, described is a folded optical system that provides long range high resolution imaging capability that can fit in a thin handheld or mobile device such as a smartphone.

BACKGROUND

[0002] Smartphone cameras are very compact devices, and this limits the available space for an imaging system. Because focal lengths and apertures are limited due to space constraints, there is a limit to increasing the magnification and resolution of a smartphone camera. High magnification and resolution are required to produce high resolution images of objects further from the smartphone. Because of the large apertures and long focal lengths required within the thin device depth of smartphones, folded optical systems are desired. Attempts to efficiently mass produce high resolution long range folded optical system for smartphones has been limited by the high manufacturing tolerances required. These high manufacturing tolerances are required because the lens elements are small, have high optical power to save space, and have complex surface geometries to minimize aberrations and retain image quality.

[0003] Current smartphone devices often contain multiple optical systems with different fields of view and focal lengths. For example, dual camera systems have been used with cameras requiring support of both wide field view and high magnification narrow field of view. Although it is relatively easy to define a wide field of view camera with short focal length able to fit into a smartphone, it is much more difficult to design a higher magnification optical system that can be reliably mass produced at low cost.

SUMMARY

[0004] Disclosed is a folded optical lens system providing a light path to a sensor, the system including a powered prism to redirect an image through an approximately right angle and a multiple lens group including at least 4 lens elements to receive the image from the powered prism, correct aberrations, and focus the light onto an image sensor. The folded optical lens system has an aperture is between 3 and 15 mm. In one embodiment only the first surface of the powered prism is powered. The maximum chief ray angle (CRA) at the image sensor can be less than 30° and, in some embodiments, less than 15°. In some embodiments, the described folded optical system can be held within a mobile viewing system such as a smartphone or other suitable device containing an image sensor.

[0005] In another embodiment, a folded optics system providing a light path to an image sensor includes a powered prism to redirect light through an angle to a lens assembly, the lens assembly including a first aspheric lens having a first convex surface and a second convex surface; a second aspheric lens having a first concave surface and a second concave surface; a third aspheric lens having a first convex surface and a second convex surface; a fourth aspheric lens having a first convex surface and a second concave surface; and a fifth aspheric lens having a first convex surface and a second concave surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Non-limiting and non-exhaustive embodiments of the present disclosure are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various figures unless otherwise specified.

[0007] FIGS. 1 A and 1B respectively illustrate lens layout and representative lens ray paths for another embodiment of a folded optical system suitable for use in a smartphone;

[0008] FIGS. 1C and 1D illustrate alternative powered prism designs;

[0009] FIG. 1 E illustrates lens features to aid assembly; and

[0010] FIG. 2 illustrates a system with imaging and communication electronics suitable for holding a folded optic powered prism.

DETAILED DESCRIPTION

[0011] FIGS. 1A and 1B respectively illustrate lens layout 100A and representative lens ray paths 100B for an embodiment of a folded optical system suitable for use in a smartphone or other space constrained image capture or viewing system (including but not limited to digital binoculars, security cameras, optical or laser rangefinders, infrared imagers, flash lighting systems, structured UV or IR light emitters and imagers or the like) that includes an imaging sensor. As shown, light from an image 110 can pass through a powered prism 120A. The light is reflected off the back surface (by a reflective surface, or by total internal reflection). The reflected light exits the powered prism 120A and can pass into a series of lens 122A (Lensl), 124A (Lens 2), 126A (Lens 3), 128A (Lens 4), and 130A (Lens 5). The light exits the lens assembly to form an image on one or more image sensor(s) 150A. In one embodiment, the image sensor 150A can be 1/2.3" format sensor (~6.2mm x 4.55mm), but the described lens layout 100A will work with any smaller sensor. Advantageously, the described lens layout 100 A has a maximum chief ray angle (CRA) of less than 30° and in some embodiments less than 15° (e.g. 11.4°), significantly less than most mobile lens system designs that require higher CRA numbers.

[0012] In the illustrated embodiment, selected lens characteristics for powered prism 120A and lenses 1-5 are described in the below Table 1, Table 2, and Table 3 :

Table 1

Table 2

Table 3

[0013] In an alternative embodiment, lens characteristics are described in the following Table 4:

Table 4 In yet another embodiment, lens characteristics are described in the following Table 5:

Table 5

In yet another embodiment, additional lens elements can be used. For example, a suitable seven lens element design has characteristics as described in the following Table 6:

Table 6

[0014] A powered prism such as disclosed herein can include an approximately right angle prism (typically varying between about 85 to 95 degrees, with 89 to 91 degrees preferred) with one or more optically powered sides. FIGS. 1C and 1D are examples of powered prisms 160C and 162D that are able to be manufactured and aligned to the optical system using existing manufacturing techniques. In certain embodiments it is possible to add power to two or more surfaces of the powered system, however this may make the system significantly more difficult to align accurately with current alignment methods.

[0015] In still another embodiment, lens elements can include structures to simplify and allow for precision assembly. For example, FIG. 1E illustrates lens elements 3 and 4 that include a large outer ring structure (170E and 172E, respectively) that is used to snap the lenses together. This allows for precise centering of the lenses and fine control over the lens separation. In some embodiments, partial or slotted rings can be used, or other non-ring structures able to act as aligning spacers. As will be appreciated, such alignment structures can be used with other lens elements or powered prism, and can include additional features such as guidance notches, spacers, or alignment marks or indicia.

[0016] As will be appreciated, folding the optics using powered prisms allows for a substantial reduction in necessary depth of case able to support the folded optics, along with providing an increase in focal length and ability to support large lens apertures and optic sensors. Lens systems can include either/both glass or plastic lens elements, or reflective optically powered mirrors. Symmetrical, aspheric, flat, or graded index lenses can be used, as well as advanced metamaterial/nanomaterial lenses. In some embodiments rectangular or“trimmed” rectangular lens (i.e. circular lens with top and bottom having flat sides, while left and right sides remain curved) can be used. Use of rectangular lens systems allow more light to be captured in a compact space, and to maximize the effective resolution for a given volume. In some embodiments, optics and sensors can be arranged to allow viewing in non-visible spectrums such as near infrared, or infrared, or ultraviolet. For example, sensors having pixels sensitive to infrared or ultraviolet wavelengths can be used. In some embodiments, use of additional filters or optics with reduced ultraviolet absorption may be required.

[0017] FIG. 2 illustrates a viewing system 200 capable of operation in conjunction with the described folded optical system including a powered prism. The viewing system 200 can include an associated remote image storage and transfer to facilitate or encourage social interactions. In some embodiments, the viewing system can include a smartphone or similar mobile communication device. The digital electronics of the viewing system includes a power system 212 and communication and I/O system 214. Also included are a control system 202 that includes image processing 204, data logging and storage 206, a user interface and display screen 208, and object identification and machine learning 210. Typically, a display screen is a backlit LCD, OLED, or bistable screen similar to that commonly used in mobile devices such as smartphones. The screen can be about 5 to 15 centimeters in width, and can be rectangular with a 4:3, 16:9, or other width to height ratios. In alternative embodiments, square, circular, elliptical display screens can be used. In some embodiments, multiple screens can be used, or a single screen used in a split screen or tiled mode.

[0018] The communication system and EO system 214 can engage (via wireless connection 201) with another viewing system 220 to transfer images and information. Engagement with a smartphone 222 (via wireless connection 203 or a cloud service 224 (via wireless connection 205) is also possible. In some embodiments, data can be indirectly transferred. For example, using a Wi-Fi, LTE, 4G, 5G or similar connection to cloud service 224, data can be successively sent via 205, to smartphone 222 via 207, to another viewing system 220 via wireless connection 209. In some embodiments, multiple viewing systems or smartphones can simultaneously receive images and video from a selected viewing system. This allows, for example, a tour guide to provide real time video to multiple smartphones of a group of tourists. Additionally, a smartphone or other wired or wirelessly connected system can control the device’s functions remotely.

[0019] In some embodiments, digital electronics of the viewing system 200 or subsystems including the communication and I/O system 214 can support additional sensors or output devices including but not limited to microphones, audio speakers, accelerometers, gyroscopes, magnetometers, or thermal sensors. Applications supporting a range of functions can be downloaded and installed in the digital electronics of the viewing system. For example, applications that support sharing, commenting, image processing, audio based processing, or object identification can be supported. As an example, an application having access to GPS/GNSS navigation and three-dimensional orientation from optional on-board sensors, can be used to identify constellations or individual stars in the sky targeted by the viewing system. Alternatively, or in addition, stellar pattern matching can be used to identify sky targets. In other embodiments, downloaded applications can support contests or games in which numbers of distinct birds, animals, or plants are viewed within a specific time period. Downloaded applications can support direct streaming or transfer or data or can communicate and act in coordination with a user (or others) smartphone.

[0020] Built-in or downloaded applications can also support real-time or near real-time custom image processing. For example, in many situations, objects blend into the background or are otherwise camouflaged. Using real-time auto-contrast, color enhancement, or motion detection, an image or video can be altered to increase the likelihood that an object can be visually detected. In some embodiments, applications that provide a tracking box around moving objects, indicate direction of object movement, and/or provide continuous updating of target range and speed can be enabled in viewing systems equipped with suitable sensing systems. In other embodiments, automated mode switching between IR and visual modes can be used to improve tracking of individuals or vehicles moving between low and high light areas (e.g. cars or people moving between streetlights). In still other embodiments, applications can be used to reduce atmospheric or optical distortions.

[0021] Machine learning can be directly supported by digital electronics of the viewing system, or indirectly supported by cloud services or through connection to a local smartphone. Convolutional or recurrent neural networks can be used to identify objects, animals, or people. In some embodiments, continued use and training can improve accuracy of target identification. For example, with repeated training a machine learning system can at first only identify an object as a bird. For example, with repeated tests, field training, and confirmed identifications made in the bird’s environment, the bird can be identified as a hawk, and with time, identified as a red-tailed hawk. Machine learning can also support multiple input types, including audio input. In some embodiments, the machine learning system can use the combination of a partially obscured bird image combined with detected birdsong to provide identification.

[0022] Advantageously, a smartphone connection via Bluetooth or WiFi allows sending data that includes images, videos, and targeting information. This data can be shared on available social media or web sites, can be live streamed in real time, or can provide a secure data backup. A smartphone or other wired or wirelessly connected system can be used for secondary or custom processing of images, including resizing, sharpening, labelling, or providing improved image contrast and color. In other embodiments, the smartphone can provide additional information related to captured images or videos. For example, an unknown bird can be imaged with the power prism based viewing system and identified with name and locality information using an application accessible or provided by the smartphone. A smartphone can also be used to facilitate firmware or software updates to the viewing system 200.

[0023] In the foregoing description, reference is made to the accompanying drawings that form a part thereof, and in which is shown by way of illustration specific exemplary embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the concepts disclosed herein, and it is to be understood that modifications to the various disclosed embodiments may be made, and other embodiments may be utilized, without departing from the scope of the present disclosure. The foregoing detailed description is, therefore, not to be taken in a limiting sense. [0024] Reference throughout this specification to“one embodiment,”“an embodiment,” “one example,” or“an example” means that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment of the present disclosure. Thus, appearances of the phrases“in one embodiment,” “in an embodiment,”“one example,” or“an example” in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, databases, or characteristics may be combined in any suitable combinations and/or sub-combinations in one or more embodiments or examples. In addition, it should be appreciated that the figures provided herewith are for explanation purposes to persons ordinarily skilled in the art and that the drawings are not necessarily drawn to scale.

[0025] Embodiments may also be implemented in cloud computing environments. In this description and the following claims,“cloud computing” may be defined as a model for enabling ubiquitous, convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned via virtualization and released with minimal management effort or service provider interaction and then scaled accordingly. A cloud model can be composed of various characteristics (e.g., on-demand self-service, broad network access, resource pooling, rapid elasticity, and measured service), service models (e.g., Software as a Service (“SaaS”), Platform as a Service (“PaaS”), and Infrastructure as a Service (“IaaS”)), and deployment models (e.g., private cloud, community cloud, public cloud, and hybrid cloud).

[0026] The flow diagrams and block diagrams in the attached figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present disclosure. In this regard, each block in the flow diagrams or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It will also be noted that each block of the block diagrams and/or flow diagrams, and combinations of blocks in the block diagrams and/or flow diagrams, may be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions. These computer program instructions may also be stored in a computer-readable medium that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable medium produce an article of manufacture including instruction means which implement the function/act specified in the flow diagram and/or block diagram block or blocks. Many modifications and other embodiments of the invention will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the invention is not to be limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included within the scope of the appended claims. It is also understood that other embodiments of this invention may be practiced in the absence of an element/step not specifically disclosed herein.