Patent Application
20210157107
The disclosed invention generally relates to optical lenses and more specifically to a folded telescopic lens system.
Imaging devices such as cameras, microscopes and telescopes are heavy and large. A large portion of this weight is due to the design of the optical lens elements, which include heavy curved lenses, and the structure to support these lenses separated by long and bulky focal distances. These imaging devices are large, mainly because in a typical lens system, the opening aperture to system depth ratio is small. Moreover, to optically improve image resolution with the traditional lens systems, more depth is required in order to reduce lens refraction and minimize lens aberrations. This can set limitations on the imaging systems' performance and design, particularly with mobile devices (e.g., smart phones), and lens systems with a long focal length, and narrow field of view.
The proliferation of compact, mobile camera devices such as smartphones and tablet devices has resulted in a need for higher magnification, high-resolution camera devices with a compact form factor. However, due to packaging constraints of standard mobile camera device technology, these devices tend to capture wide field-of-view images with limited magnification. Achieving higher magnification images in a compact form factor has been limited by photo-sensor size and lens geometry. As camera technology advances there is a demand for compact imaging lens system with improved image quality and higher magnifications for long range viewing.
In some embodiments, a folding lens system includes: one or more objective lenses for receiving a light path from an object along a first optical path; a beam steering device for redirecting the light path along a second optical path at an angle α to the first optical path; and two or more focusing lenses disposed in the second optical path for focusing the reflected light path on an image plane, wherein the two or more focusing lenses include a positive-powered lens, and one or more negative-powered lenses disposed between the positive-powered lens and the image plane.
In some embodiments, at least one of the one or more objective lenses includes low dispersion material to reduce chromatic aberration. In some embodiments, the beam-steering device is a refractive element that changes the direction of the received light path in the folding lens system. The second optical path may be configured to change the angle α for tuning and calibration of the lens system. The positive-powered lens may comprise of a low-dispersion material and one or more negative-powered lenses are comprised of a high-dispersion material.
In some embodiments, the positive-powered lens may be stationary relative to the folded lens system, and the one or more negative-powered lenses may be movable relative to the positive-powered lens for focusing. The folding lens system may be positioned within or attachable to a display of a phone or a camera to display the image of the object. The one or more objective lenses may include an aspheric lens element and the two or more focusing lenses may include at least one aspheric lens
A more complete appreciation of the disclosed invention, and many of the attendant features and aspects thereof, will become more readily apparent as the disclosed invention becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate like components.
Embodiments of the present invention are directed to a folding lens system, for example, for a compact camera to obtain a high-quality image with a more compact optical lens system. In some embodiments, the folded lens system includes one or more objective lenses with refractive power, a light path folding element and one or more focusing lenses. Light enters the camera through lenses on a first optical path or axis is refracted to the folding element, which redirects the light to a second optical axis with lenses that focus the light to form an image at a photo-sensor plane. At least one of the lenses is made of low dispersion material to improve color correction of the image. Materials, radii of curvature, shapes, sizes, and spacing, of the optical elements may be selected to achieve quality optical performance and high image resolution in a compact form factor camera.
In some embodiments, the folded telescopic lens system according to the disclosed invention provides a light path to an image plane and may include one or more positive powered objective lenses, at least one of which includes low dispersion material. In addition, the lens system includes a beam-steering optics and a focusing lens group with at least one stationary lens and one moveable lens. In some embodiments, a sensor is positioned at the image plane behind the image plane to capture the image. In some embodiments, the sensor may be a camera film, a CCD sensor, a CMOS sensor or the like. In some embodiments, the folded telescope is positioned within or attachable to a display device, for example, the display device of a phone, tabled, or other mobile devices.
In some embodiments, the beam-steering device 103 is a reflective object 103 that changes the direction the beam is transmitted. In some embodiments, beam steering device 103 is or uses mirrors, prisms, or lenses to perform beam-steering. This way, the folding angle α, which is the angle between the first optical path and the second optical path, may be easily changed for tuning and calibration of the lens system. The beam-steering could be used to pan or tilt of the lens mechanism.
In some embodiments, the one or more focusing lenses 104 include a positive-powered lens 105 and one or more negative-powered lens 107. As known in the art, a positive-powered lens may be biconvex, convex-concave, plano-convex or a combination of more than one lenses, where a collimated beam of light passing through the lens converges (focuses) to a spot behind the lens. A negative-powered lens may be a biconcave, plano-concave lens or concave-convex or a combination of more than one lens, where a collimated beam of light passing through the lens is diverged or spread coming out of the lens. As a result, the light beam will focus to a particular point on the axis at the image plane 107, after passing through the lens. The combination of the positive-powered lens 105 and the negative-powered lens(es) 106, ensure an optimum image quality for a telescopic lens for an object to be viewed or imaged located at various distances, while maintaining a good image quality.
In some embodiments, the positive-powered lens 105 is made of a low-dispersion glass/plastic, while the negative-powered lens 106 is made from a high-dispersion glass/plastic. To counteract the effect of the negative lens, the positive-powered lens is typically more powerful than the negative-powered lens. Achromatic doublets therefore have higher thickness and weight than the equivalent non-chromatic-corrected single lenses.
In some embodiments, the beam steering device 103 is one or more mirrors. In these folded lens systems, the magnification of the image is increased by reducing the field of view. High magnification images typically have a narrow field of view (for example, 5 degrees or less), which can limit the practical use of these lens system to long focal length applications. Because the imaging system has a relatively large aperture size with lots of light, images can be captured very quickly.
As depicted, the line 201 shows the change in focus locations of the relevant lenses. For example, for the left side, the focus is at infinity and for the right side the focus is at 10 meters. The arrow shows the direction of motion for the lens group 106.
In some embodiments, a processor, such as an image processor, may receive image information from the image sensor and modify/enhance this information, as required by the application of the folded lens. The processor may be part of a mobile device that includes a camera that contain the folded telescopic lens system, and may include all of the features of a smart mobile device, such as a smart phone or tablet for processing, enhancing and manipulating the images.
In some embodiments, the objective lens 102 is a positive-powered lens. In some embodiments, the objective lens 102 is an aspheric lens element. In some embodiments, the focusing lens group 104 contains at least one aspheric lens element. For example, lens 111 may be an aspheric lens element. The aspheric surface profile of an aspheric lens element can reduce or eliminate aberrations, such as spherical, coma or astigmatism, compared to a simple lens.
The folded telescopic lens system may be positioned within or attachable to a display 109 device of, for example a phone or camera 110 to display the image of the object being viewed.
It will be recognized by those skilled in the art that various modifications may be made to the illustrated and other embodiments of the invention described above, without departing from the broad inventive scope thereof. It will be understood therefore that the invention is not limited to the particular embodiments or arrangements disclosed, but is rather intended to cover any changes, adaptations or modifications which are within the scope of the invention as defined by the appended claims and drawings.
This patent application claims the benefits of U.S. Provisional Patent Application Ser. No. 62/941,372, filed on Nov. 27, 2019, and entitled “Folded Telescopic Lens System,” the entire content of which is hereby expressly incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62941372 | Nov 2019 | US |
