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Multi-mode optical imagerRelated Patent Categories: Radiant Energy, Invisible Radiant Energy Responsive Electric Signalling, Infrared Responsive, With Beam Deflector Or Focussing MeansMulti-mode optical imager description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060208193, Multi-mode optical imager. Brief Patent Description - Full Patent Description - Patent Application Claims
RELATED APPLICATIONS [0001] This application is a divisional of U.S. patent application Ser. No. 10/325,129, filed Dec. 20, 2002, which claims priority to U.S. Patent Application 60/344,130, filed Dec. 21, 2001. The above-identified related applications are hereby incorporated by reference in their entirety as though fully set forth herein. BACKGROUND [0002] Dual-mode imagers are known in the art to provide a device detecting both visible light and infrared radiation. However, current art dual-mode imagers are costly, complex, bulky and heavy. Further, refractive lenses often used in dual-mode imagers fair poorly in focusing an image having differing electromagnetic wavelengths. Other problems arise in dual-mode imagers when attempting to align pixel data for the differing electromagnetic wavelengths. Despite known military and commercial value, dual-mode imagers have not gained wide acceptance. SUMMARY [0003] A multi-mode optical imager is provided as a common aperture device for multiple bandwidth imaging. By this design, a simple and compact optical system is formed for such imaging while maximizing image quality and resolution. [0004] In one aspect, a multi-mode optical imager is provided for simultaneous visible light and infrared imaging. The multi-mode optical imager has fore-optics that may provide image magnification and may, for example, utilize a broadband optical system such as mirrored telescope design (e.g., a Newtonian reflective telescope or a Cassegrain reflective telescope). The fore-optics receive electromagnetic radiation from a field of view of the multi-mode optical imager and focus such radiation through a common aperture, into an imaging module, to form an intermediate image at a focal plane of the fore-optics. In one example, the f-number of the fore-optics is considered a "moderate" f-number, for example f/4. The fore-optics may be interchangeable with other fore-optics to provide user customizable imaging specifications (e.g., to customize focal length, magnification, filters, cold shielding, and/or other desired separation, such as a spectral or polarization state). After passing through the fore-optics and the common aperture, the electromagnetic radiation may be divided by the imaging module into two bands, one being a visible light wavelength band ("channel I") and another being an infrared wavelength band ("channel II"). In one aspect, the imaging module includes a beam-splitter or filter, such as a dichroic beam-splitter, to divide the two bands. The visible light wavelength band is directed to a first detector along channel I for visible imaging and the infrared wavelength band is directed to a second detector along channel II for infrared imaging. [0005] Those of skill in the art will appreciate that the systems and methods described herein may be implemented to support imaging of other desired wavebands (e.g., ultraviolet (UV), near infrared (NIR), midwave infrared (MWIR), millimeter waves, etc.) other than the infrared wavelength and visible bands, and may also be implemented in more than two wavelength bands. For example, in one aspect the multi-mode optical imager forms more than two channels (e.g., channel I, II and III) within the imaging module to accommodate more than two wavelength bands (e.g., visible light waveband, long-wave infrared (LWIR) waveband, and MWIR waveband), each channel having a corresponding detector. In another example, the imaging module supports imaging in one or more wavebands (e.g., visible light waveband and LWIR waveband) and is removable, so that a user can replace one imaging module with another imaging module supporting one or more other wavebands (e.g., MWIR waveband and UV waveband). Accordingly, the multi-mode optical imager of one aspect supports multiple imaging modules selectable by a user to accommodate imaging of several wavebands in accordance with user needs. In one aspect, each imaging module supports dual-mode imaging, each with channel I and channel II supporting two separate wavebands. [0006] In yet another aspect, the imaging module after the common aperture includes an f-number reducer that processes the infrared wavelength band after the intermediate image into a lower f-number (e.g., f/1) image for detection by an uncooled microbolometer array infrared detector. The f-number reducer may be accomplished by several methods or combination of methods, for example: a) optical re-imaging and magnification reduction through transmissive lenses; b) a fiber optic taper; c) micro-optics of the microbolometer array image detector; d) an array of Compound Parabolic Concentrators (CPC); and/or (e) an array of hollow tapered capillaries. [0007] Certain uncooled microbolometer array infrared detectors operate better with an f-number of about f/1. As one skilled in the art would appreciate, improvements in uncooled microbolometer infrared detectors may facilitate additional techniques of f-number reduction, or even eliminate f-number reduction within the imaging module. In one aspect, the imaging module does not substantially modify, or alternatively increase, the f-number of the infrared wavelength band after the intermediate image, so as to be nearly identical in f/# to the visible light waveband. The f-number reducer may be constructed of germanium or other infrared lens material (e.g., IR fused silica, zinc selenide, calcium fluoride, AMTIR-1). [0008] In still another aspect, the divided channels I, II (e.g., for visible light and infrared wavebands) may include imaging optics to condition the visible light wavelength band and/or the infrared wavelength band. Such conditioning may, for example include: modifying f-number, modifying magnification, providing cold shielding, providing filtering, and/or providing spectral separation (e.g., hyperspectral imaging). [0009] In another aspect, the detectors and imaging optics are combined into the monolithic imaging module. The imaging module has an interchangeable interface to facilitate attachment to different fore-optics. The different fore-optics may thus provide selectable optical characteristics, e.g., wide-to-narrow fields of view, microscopy, and/or other system features described herein. [0010] Once the multi-mode optical imager is pointed at a target, additional information may be gathered about the target. In one aspect, a distance finder provides distance-to-target information to an operator. In one aspect, distance finding is performed via Doppler Shift, for applications such as astronomical observations: the Doppler Shift is generated by a signal emitted and received by the multi-mode optical imager. In another aspect, distance finding includes a time lapse determination between an emitted signal (e.g., from a laser within the multi-mode optical imager) and subsequent reception of the signal by the multi-mode optical imager. The signal may be of any wavelength for which the multi-mode optical imager is receptive. In still another aspect, distance finding may utilize the origin of a signal emitted from the target, and/or calculated from reflective material "painted" on the target, to which the multi-mode optical imager illuminates with an internally generated radiation source. In one aspect, distance finder signals (e.g., LIDAR) from the multi-mode optical imager may be sent through the same fore-optics used for reception of electromagnetic radiation. Additional imaging devices within the imaging module may further provide friend-or-foe detection. [0011] In another aspect, a global positioning system ("GPS") provides the operator with the location of the multi-mode optical imager. The direction of aim may be provided by a magnetic compass, gyroscopic compass, multiple GPS receivers, inclinometer, accelerometer, rate gyros, and/or magnetometer, for example. With the implementation of the distance finder and GPS, the multi-mode optical imager may thus provide the location of a target. [0012] In another aspect, image stabilization is provided by mechanical or post-processing means. Target tracking may be provided independently or in collaboration with image stabilization means. [0013] In another aspect, the multi-mode optical imager is coupled with a vehicle, such as an unmanned aerial vehicle (UAV) or truck, so that a target object may be imaged, identified and targeted during surveillance activities. [0014] In one aspect, a LWIR channel within the imaging module may be removed and replaced with a MWIR channel, and vice versa. This provides a "swappable" channel configuration to provide additional choices for a user. Accordingly, a user may swap one imaging module for another, in one aspect, and/or swap one channel with another channel within a given imaging module, in another aspect. [0015] In one aspect, the multi-mode optical imager provides automatic target recognition (ATR) to identify a certain object (e.g., a tank) depending on the types of spectral bands within a specific wavelength band (e.g., visible light spectral bands within visible light wavelength band) that are detected by a detector array. ATR is used in conjunction with imaging of other wavebands (e.g., infrared wavelength band) to better identify the object in many ambient conditions. Dual-mode imagers were originally conceived to be missile seekers, to improve the man in the loop target recognition, and for use with onboard ATR processors. However, most ATR processors are trained on visible light data (e.g., from satellite or reconnaissance plane), and have to use infrared missile data to finally identify a target and for homing in on the target. On the other hand, the multi-mode optical imager described herein gives the ATR the option to get visible light data, along with infrared data, for a more accurate identification of a target in various conditions (e.g., use visible light ATR during the day, infrared imaging at night, MMW imaging in foul weather, such as heavy precipitation). [0016] The multi-mode optical imager of one aspect eliminates the need in the prior art to carefully align pixel data for differing wavelengths. By utilizing the common aperture for both the visible light waveband and the infrared waveband, the multi-mode optical imager can be formed as a smaller and more compact system with high optical sensitivity, as compared to the prior art. BRIEF DESCRIPTION OF DRAWINGS [0017] FIG. 1 is a schematic illustration of one multi-mode optical imager; [0018] FIG. 2 is a schematic illustration of another multi-mode optical imager; [0019] FIG. 3 shows a compound parabolic concentrator in use with an optical detector; [0020] FIG. 4 is a perspective view of another multi-mode optical imager; Continue reading about Multi-mode optical imager... Full patent description for Multi-mode optical imager Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Multi-mode optical imager patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Multi-mode optical imager or other areas of interest. ### Previous Patent Application: Radiator module Next Patent Application: Microwave mass measuring device and process Industry Class: Radiant energy ### FreshPatents.com Support Thank you for viewing the Multi-mode optical imager patent info. IP-related news and info Results in 0.31477 seconds Other interesting Feshpatents.com categories: Software: Finance , AI , Databases , Development , Document , Navigation , Error 174 |
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