Dual focal plane electronic rifle scope

Abstract

An electronic rifle scope comprising a first objective lens assembly 2 with a fixed focal length configured to project an image onto a first focal plane 5, a second lens assembly 3 configured to optic

Description

FIELD OF INVENTION The present disclosure generally relates to electronic rifle scopes, and more specifically to dual focal plane optical systems for enhancing magnification capabilities in electronic rifle scopes utilizing Focal Plane Arrays (FPAs). BACKGROUND Electronic rifle scopes have revolutionized the field of marksmanship by incorporating digital image processing technologies. These advanced scopes utilize Focal Plane Arrays (FPAs) to capture images from the scene, which are then electronically and digitally enhanced. This technology has proven particularly beneficial in conditions where conventional see-through optics struggle, such as poor weather, low light, or nighttime scenarios. Modern electronic rifle scopes, often referred to as thermal or digital rifle scopes, can operate across a wide spectrum of light, from visible wavelengths to long-wave infrared. The core components of these scopes typically include an objective lens and an FPA sensor, which together determine the scope's field of view (FOV) and magnification capabilities. The relationship between these parameters is inverse; a longer focal length objective lens provides higher magnification but a narrower FOV, while a shorter focal length offers a wider FOV but lower magnification. One of the primary challenges in electronic rifle scope design is balancing the need for a wide FOV for rapid target acquisition with the requirement for high magnification for accurate target identification and aiming. Current solutions often involve either variable magnification objective lenses or digital magnification techniques. Variable magnification objective lenses, while effective, can be expensive to manufacture and may result in bulky, heavy scopes. Digital magnification, on the other hand, can lead to reduced image quality and pixelation as magnification increases, potentially rendering the image unusable at higher levels of zoom. It has been appreciated that a dual focal plane electronic rifle scope is needed that overcomes one or more of these problems. SUMMARY OF INVENTION This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. In a first aspect, an electronic rifle scope is provided. The electronic rifle scope includes: a first objective lens assembly with a fixed focal length configured to project an image onto a first focal plane; a second lens assembly configured to optically magnify the image from the first focal plane and project it onto a second focal plane; and a Focal Plane Array (FPA) situated at the second focal plane for capturing images, characterized in that the second lens assembly has variable focus capability and is configured to transfer either a full image ora magnified portion of the image from the first focal plane to the second focal plane. This configuration allows for enhanced optical magnification capabilities without the need for a bulky or expensive variable focal length objective lens. The two-focal-plane setup provides flexibility in image magnification while maintaining image quality, addressing the limitations of digital magnification. The second lens assembly may comprise mechanically movable optical elements to adjust its focal length. The use of mechanically movable optical elements in the second lens assembly enables precise control over the magnification level, allowing users to seamlessly switch between full field of view and higher magnification as needed. The electronic rifle scope may further comprise a digital signal processor configured to electronically enhance images captured by the FPA. The inclusion of a digital signal processor allows for additional image enhancement, improving visibility and target identification in various environmental conditions. The first objective lens assembly and the second lens assembly may be arranged in a folded optical path configuration using at least one mirror or prism to reduce the overall length of the scope. This folded optical path configuration enables a more compact design of the electronic rifle scope, making it easier to handle and mount on a rifle without compromising on optical performance. In a second aspect, a method of operating an electronic rifle scope is provided. The method comprises: projecting an image onto a first focal plane using a first objective lens assembly with a fixed focal length; optically magnifying the image from the first focal plane using a second lens assembly; projecting the magnified image onto a second focal plane; and capturing the image at the second focal plane using a Focal Plane Array (FPA), characterized in that the second lens assembly has variable focus capability and is configured to transfer either a full image or a magnified portion of the image from the first focal plane to the second focal plane. This method allows for efficient operation of the electronic rifle scope, providing users with the ability to switch between different magnification levels while maintaining image quality. The method may further comprise adjusting the focal length of the second lens assembly to switch between transferring the full image and the magnified portion of the image from the first focal plane to the second focal plane. This adjustment capability provides users with real-time control over the scope's magnification, enhancing target acquisition and identification capabilities. The method may further comprise electronically enhancing the image captured by the FPA using a digital signal processor. Electronic enhancement of the captured image can significantly improve visibility in challenging environmental conditions, such as low light or adverse weather. In a third aspect, a system for electronic rifle sighting is provided. The system comprises an electronic rifle scope and a rifle to which the electronic rifle scope is attached, characterized in that the electronic rifle scope comprises: a first objective lens assembly with a fixed focal length configured to project an image onto a first focal plane; a second lens assembly with variable focus capability configured to optically magnify the image from the first focal plane and project it onto a second focal plane; and a Focal Plane Array (FPA) situated at the second focal plane for capturing images, wherein the second lens assembly is configured to transfer either a full image or a magnified portion of the image from the first focal plane to the second focal plane. This system integrates the advanced electronic rifle scope with a rifle, providing a complete sighting solution that offers enhanced magnification capabilities and image quality. The system may further comprise a control mechanism coupled to the second lens assembly for adjusting the focal length to switch between transferring the full image and the magnified portion of the image from the first focal plane to the second focal plane. The inclusion of a control mechanism allows for easy and precise adjustment of the scope's magnification, enhancing the user's ability to acquire and engage targets at various distances. The system may further comprise a digital signal processor configured to electronically enhance images captured by the FPA, wherein the digital signal processor is programmed to apply different image enhancement algorithms based on whether the full image or the magnified portion of the image is being transferred to the second focal plane. This adaptive image enhancement capability optimizes the visual output for different magnification levels, ensuring optimal image quality and target visibility across various operating conditions. The foregoing general description of the illustrative embodiments and the following detailed description thereof are merely exemplary aspects of the teachings of this disclosure and are not restrictive. BRIEF DESCRIPTION OF FIGURES Non-limiting and non-exhaustive examples are described with reference to the following figures. FIG. 1 illustrates a schematic view of an electronic rifle scope system, according to aspects of the present disclosure. FIG. 2 illustrates a schematic view of an electronic rifle scope with two optical configurations, according to an embodiment. Figures explain only image capturing optical tract and do not demonstrate viewfinding elements, elements of the rifle scope controls, processing boards, batteries, etc. DETAILED DESCRIPTION The following description sets forth exemplary aspects of the present disclosure. It should be recognized, however, that such description is not intended as a limitation on the scope of the present disclosure. Rather, the description also encompasses combinations and modifications to those exemplary aspects described herein. The present disclosure provides an electronic rifle scope that utilizes a dual focal plane system. This system may include a first objective lens assembly with a fixed focal length and a second lens assembly with variable focus capability. The first objective lens assembly may be configured to project an image onto a first focal plane. The second lens assembly may be configured to optically magnify the image from the first focal plane and project it onto a second focal plane. A Focal Plane Array (FPA) may be situated at the second focal plane for capturing images. The second lens assembly may have variable focus capability and may be configured to transfer either a full image or a magnified portion of the image from the first focal plane to the second focal plane. This dual focal plane system may offer enhanced optical magnification capabilities, potentially overcoming limitations associated with conventional designs that rely on variable focal length objective lenses or digital magnification techniques. The system may also allow for a more compact form factor, potentially improving the balance and handling of the rifle scope. In some cases, the electronic rifle scope may further include a digital signal processor configured to electronically enhance images captured by the FPA, potentially improving visibility and target identification in various environmental conditions. The present disclosure also provides methods of operating the electronic rifle scope and systems for electronic rifle sighting that incorporate the electronic rifle scope. These methods and systems may offer users flexibility in image magnification while maintaining image quality, potentially enhancing target acquisition and identification capabilities. Referring to FIG. 1, the electronic rifle scope system includes a first lens assembly 2 with a fixed focal length. This first lens assembly 2 projects an image onto a first focal plane 5. The first lens assembly 2 may be designed and configured to capture a wide field of view, providing a comprehensive view of the scene in front of the rifle scope. The system also includes a second lens assembly 3, which is configured to optically magnify the image from the first focal plane 5 and project it onto a second focal plane 6. The second lens assembly 3 has variable focus capability, allowing it to transfer either a full image or a magnified portion of the image from the first focal plane 5 to the second focal plane 6. This variable focus capability of the second lens assembly 3 provides flexibility in image magnification, enabling the user to adjust the magnification level according to the specific requirements of the situation. The second lens assembly 3 includes mechanically movable optical elements that allow for adjustment of its focal length. These mechanically movable optical elements may be controlled by a user-operated mechanism, such as a dial ora lever, or they may be controlled electronically, for example, by a motor driven by a control signal from a user interface or a control circuit. The electronic rifle scope system further includes a Focal Plane Array (FPA) 4 situated at the second focal plane 6. The FPA 4 captures the image projected onto the second focal plane 6. The FPA 4 may be a digital image sensor, such as a charge-coupled device (CCD), complementary metal-oxide-semiconductor (CMOS) sensor, thin film bolometers vanadium oxide (VOX) and amorphous silicon alternative technologies and others. The electronic signal may then be processed to generate a digital image that can be displayed on a display device or stored in a memory device. In this way, the electronic rifle scope system provides enhanced optical magnification capabilities by using a two-focal-plane setup. This setup allows for a balance between a wide field of view and high magnification, potentially improving target acquisition and identification capabilities in various environmental conditions. Referring to FIG. 1, the operation of the electronic rifle scope system begins with the first lens assembly 2 projecting an image onto the first focal plane 5. The first lens assembly 5, having a fixed focal length, captures a broad field of view, providing a comprehensive view of the scene in front of the rifle scope. The second lens assembly 3, receives the image from the first focal plane 1. The second lens assembly 3 is designed to optically magnify the image from the first focal plane 5. The magnification process involves the second lens assembly 3 focusing the light from the image onto the second focal plane 6. The second lens assembly 3 has variable focus capability, which allows it to transfer either a full image or a magnified portion of the image from the first focal plane 5 to the second focal plane 6. This variable focus capability of the second lens assembly 3 provides flexibility in image magnification, enabling the user to adjust the magnification level according to the specific requirements of the situation. The second lens assembly 3 includes mechanically movable optical elements that allow for adjustment of its focal length. These mechanically movable optical elements may be controlled by a user-operated mechanism, such as a dial ora lever, or they may be controlled electronically, for example, by a motor driven by a control signal from a user interface or a control circuit. In this way, the electronic rifle scope system provides enhanced optical magnification capabilities by using a two-focal-plane setup. This setup allows for a balance between a wide field of view and high magnification, potentially improving target acquisition and identification capabilities in various environmental conditions. The ability to adjust the focal length of the second lens assembly 6 provides the user with flexibility in choosing the level of magnification for the image from the first focal plane 1. This flexibility allows the user to adapt the electronic rifle scope system to different situations, such as varying distances to the target or different sizes of the target. In this way, the electronic rifle scope system provides enhanced optical magnification capabilities by using a two-focal-plane setup. This setup allows for a balance between a wide field of view and high magnification, potentially improving target acquisition and identification capabilities in various environmental conditions. Referring to FIG. 2, the electronic rifle scope system may be arranged in many different optical configurations, namely a linear optical path A configuration and a folded optical path B configuration. In the linear configuration, the first lens assembly 2 and the second lens assembly 3 are arranged in a straight line. Light enters from the left, passes through the first lens assembly 2, then through the second lens assembly 3, and finally reaches the focal plane array 4. This linear arrangement of the lens assemblies may be suitable for certain applications where the overall length of the rifle scope is not a critical factor. In contrast, the folded optical path configuration involves using at least one mirror or prism within the optical assembly to divert the light path. One example of such configuration demonstrates first lens assembly 7 shortened, therefor reducing overall length of the scope. By folding the light path, the overall length of the rifle scope may be substantially reduced, potentially making the scope more compact and easier to handle. The folded optical path configuration enables the electronic rifle scope to maintain a compact form factor while providing variable magnification capabilities. The electronic rifle scope system includes a digital signal processor that is configured to electronically enhance the images captured by the Focal Plane Array (FPA) 4. The digital signal processor may be a dedicated hardware component within the electronic rifle scope system, or it may be a software module running on a general-purpose processor. The digital signal processor receives the electronic signal from the FPA 4, which represents the image projected onto the second focal plane 3, and applies various image enhancement techniques to improve the quality of the image. The image enhancement techniques applied by the digital signal processor may include, but are not limited to, adjusting the brightness, contrast, or sharpness of the image; applying noise reduction algorithms to reduce the amount of random noise in the image; and performing edge detection to highlight the boundaries of objects within the image. These techniques may be applied individually or in combination, depending on the specific requirements of the situation. In some aspects, the digital signal processor is programmed to apply different image enhancement algorithms based on whether the full image or a magnified portion of the image from the first focal plane 1 is being transferred to the second focal plane 3. For example, when the full image is being transferred, the digital signal processor may apply a set of image enhancement algorithms that are optimized for a wide field of view. On the other hand, when a magnified portion of the image is being transferred, the digital signal processor may apply a different set of image enhancement algorithms that are optimized for high magnification. A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other implementations are within the scope of the following claims.

Claims

1. An electronic rifle scope, comprising:a first objective lens assembly with a fixed focal length configured to project an image onto a first focal plane;a second lens assembly configured to optically magnify the image from the first focal plane and project it onto a second focal plane; anda Focal Plane Array (FPA) situated at the second focal plane for capturing images,characterised in that the second lens assembly has variable focus capability and is configured to transfer either a full image or a magnified portion of the image from the first focal plane to the second focal plane.

2. The electronic rifle scope of claim 1, wherein the second lens assembly comprises mechanically movable optical elements to adjust its focal length.

3. The electronic rifle scope of claim 1 or 2, further comprising a digital signal processor configured to electronically enhance images captured by the FPA.

4. The electronic rifle scope of any of claims 1 to 3, wherein the first objective lens assembly and the second lens assembly are arranged in a folded optical path configuration using at least one mirror or prism to reduce the overall length of the scope.

5. The electronic rifle scope of claim 4, wherein the folded optical path configuration enables the scope to maintain a compact form factor while providing variable magnification capabilities.

6. A method of operating an electronic rifle scope, comprising:projecting an image onto a first focal plane using a first objective lens assembly with a fixed focal length;optically magnifying the image from the first focal plane using a second lens assembly;projecting the magnified image onto a second focal plane; andcapturing the image at the second focal plane using a Focal Plane Array (FPA),characterised in that the second lens assembly has variable focus capability and is configured to transfer either a full image or a magnified portion of the image from the first focal plane to the second focal plane.

7. The method of claim 6, further comprising adjusting the focal length of the second lens assembly to switch between transferring the full image and the magnified portion of the image from the first focal plane to the second focal plane.

8. The method of claim 7, wherein adjusting the focal length of the second lens assembly comprises mechanically moving optical elements within the second lens assembly.

9. The method of any of claims 6 to 8, further comprising electronically enhancing the image captured by the FPA using a digital signal processor.

10. The method of claim 9, wherein electronically enhancing the image comprises at least one of: adjusting sensitivity, brightness, contrast, or sharpness; applying noise reduction; or performing edge detection.

11. The method of any of claims 6 to 10, further comprising arranging the first objective lens assembly and the second lens assembly in a folded optical path configuration using at least one mirror or prism to reduce the overall length of the electronic rifle scope.

12. The method of claim 11, wherein the folded optical path configuration enables the electronic rifle scope to maintain a compact form factor while providing variable magnification capabilities.

13. A system for electronic rifle sighting, comprising:an electronic rifle scope and a rifle to which the electronic rifle scope is attached,characterized in that the electronic rifle scope comprises:a first objective lens assembly with a fixed focal length configured to project an image onto a first focal plane;a second lens assembly with variable focus capability configured to optically magnify the image from the first focal plane and project it onto a second focal plane; anda Focal Plane Array (FPA) situated at the second focal plane for capturing images,wherein the second lens assembly is configured to transfer either a full image or a magnified portion of the image from the first focal plane to the second focal plane.

14. The system of claim 13, wherein the second lens assembly comprises mechanically movable optical elements to adjust its focal length, and wherein the system further comprises a control mechanism coupled to the second lens assembly for adjusting the focal length to switch between transferring the full image and the magnified portion of the image from the first focal plane to the second focal plane.

15. The system of claim 14, further comprising a digital signal processor configured to electronically enhance images captured by the FPA, wherein the digital signal processor is programmed to apply different image enhancement algorithms based on whether the full image or the magnified portion of the image is being transferred to the second focal plane.13

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