Patent Description:
A co-located sensor system is disclosed in accordance with one or more embodiments of the present disclosure. In one illustrative embodiment, the co-located sensor system comprises a housing including an optical aperture. In another illustrative embodiment, the co-located sensor system comprises a window attached, secured, or adhered to the housing at the optical aperture. In another illustrative embodiment, the co-located sensor system comprises one or more antenna substrates attached, secured, or adhered to the window. In another illustrative embodiment, the co-located sensor system comprises a plurality of radiating elements attached, secured, or adhered to the one or more antenna substrates. In another illustrative embodiment, the co-located sensor system comprises an image sensor configured to capture an image in front of the body. The image sensor is behind the aperture and is configured to focus at an infinity focus in front of the body. The one or more antenna substrates include a plurality of holes arranged in a grid pattern configured to let photons pass through the antenna substrates from the window to the image sensor. The photons are parallel or collimated and the captured image does not include features of the antenna substrates.

In the following detailed description of embodiments of the present disclosure, numerous specific details are set forth in order to provide a more thorough understanding of the inventive concepts. However, it will be apparent to one of ordinary skill in the art having the benefit of the present disclosure that the inventive concepts disclosed herein may be practiced without these specific details. In other instances, well-known features may not be described in detail to avoid unnecessarily complicating the present disclosure.

Finally, as used herein any reference to "one embodiment" or "some embodiments" means that a particular element, feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the inventive concepts disclosed herein. The appearances of the phrase "in some embodiments" in various places in the specification are not necessarily all referring to the same embodiment, and embodiments of the inventive concepts disclosed may include one or more of the features expressly described or inherently present herein, or any combination or sub-combination of two or more such features, along with any other features which may not necessarily be expressly described or inherently present in the present disclosure.

Precision guided munitions (PGMs), also known as precision guided weapons (PGWs), precision guided missiles (PGMs), or homing missiles, are intended to identify and track a specific target, and to precisely hit the target to minimize collateral damage and to increase lethality against intended targets. Because the damage effects of explosive munitions generally increase with targeting accuracy, even modest improvements in accuracy (hence, a reduction in miss distance) may enable a target to be engaged with fewer assets.

To increase the accuracy of a small homing missile, an electro-optical infrared (EOIR) sensor (e.g., an imaging sensor) can be combined with a radio-frequency (RF) sensor (e.g., an active or passive radar) on the nose of the missile to capture two different signals of the same target. These sensors may reinforce each other such that they improve the ability to locate and identify the target. RF and EOIR sensors bring significant capabilities to precision munitions. As costs for electrical components are reduced, these sensors may be employed across a wider range of applications including smaller PGMs.

Smaller PGMs have less surface area on the nose for sensor apertures. Both the EOIR and active and passive radars achieve optimal performance when located in the nose of the missile such that they both capture an accurate signal from an area directly ahead of the missile. A large flat area on the front of the nose of the missile where each aperture can be separately located is impractical for aerodynamic purposes. Air drag may slow down the missile, which may make the missile an easier target for air defense systems (e.g., systems that intercept missiles, rockets, or other projectiles). Thus, solutions to alleviate the problem of limited area for sensor apertures on the nose of a missile are desirable.

The present disclosure is directed to a precision guided munition system including an aperture in which an EOIR sensor (e.g., image sensor or multispectral camera) and an RF sensor (e.g., an antenna, passive radar, active radar, etc.) are co-located. The co-located solution is enabled using aperture designs for EOIR and RF sensors that are agreeable with a PGM nose profile. The EOIR sensor and the RF sensor may share centers which are aligned to a longitudinal axis of the missile (i.e., concentric centers such that the longitudinal axis passes through the centers and is normal to a flat surface of the window). The co-located aperture may be implemented using one or more lenses and a window. The window may provide a flat support surface (i.e., substrate) for an RF antenna to be attached, secured, or adhered thereto. The shape of the antenna and the sizing of the antenna relative to the optics may be varied.

In some embodiments, the co-located aperture diameter may be dependent upon the opaque antenna area required for operation, the optical field of view (FOV), and the distance of a window from the EOIR sensor. The antenna includes unpopulated areas (i.e., voids or holes) configured to let photons (e.g., light, illumination, rays, etc.) to pass. The antenna is placed at a distance from the EOIR sensor such that when the EOIR sensor is configured to focus to a point of infinity in front of the PGM, rays that enter the window and pass through the voids or holes of the antenna are parallel or substantially parallel (e.g., collimated rays). The parallel rays, after passing through the voids or holes, may be captured by the EO-IR sensor.

The embodiments of the present disclosure are advantageous since the RF sensor does not block or obstruct the vision of the EOIR sensor, which is unintuitive and unexpected since the RF sensor is placed in the optical path (i.e., placed in front of) the EOIR sensor and is typically constructed from materials that are substantially opaque to the photons captured by the EOIR sensor. In other words, the EOIR sensor may capture a full scene of a target when the EOIR is configured to focus at infinity (e.g., greater than <NUM> feet away) in front of the munition. This optical effect may be combined with a relatively small radius of the aperture to provide a solution that is size-weight-and-power (SWaP) efficient and that maximizes the detection of signals by orienting each sensor to receive the strongest possible signal (i.e., as many photons as possible) from the direction of a target.

<FIG> is a drawing illustrating an experiment including a camera <NUM> (i.e., image sensor or EOIR sensor) and an opaque patch <NUM> in front of the camera. During the experiment, the patch <NUM> was placed at varying distances in front of the camera <NUM>. Images and metrics were collected by the camera <NUM> and compared to a baseline image without the patch <NUM>. <FIG> shows the image captured with the patch <NUM> in front of the camera <NUM>. <FIG> shows the image captured without the patch <NUM> in front of the camera <NUM>. A full image is evident with a gain and integration time indicating a relatively low loss of light entering the optics.

<FIG> is a drawing illustrating a perforated grid pattern <NUM> (i.e., a mask) that has a shape that is substantially similar to the shape of a substrate for a radiating element array antenna (e.g., Ka radiating element array antenna) and its input lines. As shown, the perforated grid pattern <NUM> has a plurality of holes that allow photons to pass through. The pattern <NUM> was tested in an experiment substantially similar to the experiment described with respect to <FIG>, except that the pattern <NUM> replaced the patch <NUM>.

The pattern <NUM> was placed at varying distances in front of the camera <NUM>. Images and metrics were collected by the camera <NUM> and compared to a baseline image without the pattern <NUM>. <FIG> shows the image captured without the pattern <NUM> in front of the camera <NUM>. <FIG> shows the image captured with the pattern <NUM> in front of the camera <NUM>. The results of the experiment shown in the images of 2B-2C are substantially similar to the results of the experiment shown in the images 1B-1C, with a full image evident with a gain and integration time indicating a relatively low loss of light entering the optics.

<FIG> is a front view of an aperture window <NUM>, in accordance with one or more embodiments of the present disclosure. The aperture window <NUM> includes a substrate <NUM> thereon. An array (not shown) comprising a plurality of radiating elements (e.g., antennas) is adhered, attached, or secured to the substrate <NUM>.

Each radiating element is placed at the intersections of the grid pattern of the substrate <NUM>. Each radiating element may be a transceiver such that it operates as an active radar (e.g., transmits and receives RF radiation to detect targets). Each radiating element may act as a node and may be addressed (e.g., may have an [x, y] address). Input/output (IO) lines (e.g., traces, connections) may be connected to the radiating elements to transmit and receive signals and communicatively couple them to a controller, and power lines may supply power to the radiating elements. The substrate <NUM> contains holes (e.g., unpopulated areas) configured to allow photons to pass (e.g., parallel or collimated photons to be collected by a sensor focused at infinity).

<FIG> is a side view of a precision guided missile (PGM) system <NUM>, in accordance with one or more embodiments of the present disclosure. The precision guided missile system <NUM> includes a body <NUM>, the window <NUM>, the antenna substrate <NUM> with the array thereon, lenses 330a-d, and an EOIR sensor <NUM>. The body <NUM> may be, for example, a missile body having a propulsion portion, a payload portion, a nose portion, one or more wings, and one or more fins. The propulsion portion may be configured to propel (e.g., self-propel) the missile body <NUM>, and may include fuel and an engine (e.g., rocket engine). The payload portion may contain munitions or explosives that detonate upon impact of the missile body <NUM> with a target. The wings and fins may include spoilers configured to steer the missile body <NUM> in response to control signals (e.g., to accurately track and strike the identified target).

The nose portion of the body <NUM> may include an aperture. The EO-IR sensor <NUM> and the lenses 330a-d may be situated completely inside the aperture. The window <NUM> with the antenna substrate <NUM> thereon is attached, adhered or secured to the body <NUM> and may seal the aperture. In some embodiments, the antenna substrate <NUM> with the radiating element array thereon may be situated inside the aperture (i.e., on the side of the window <NUM> facing the sensor <NUM>). In some embodiments, the antenna substrate <NUM> with the radiating element array thereon may be situated outside the aperture (i.e., on the side of the window <NUM> facing the front of the body <NUM>).

The EOIR sensor <NUM> may be an optical sensor, an IR sensor, a UV sensor, or another other photon measurement sensor. In some embodiments, the EOIR sensor <NUM> is a charge-coupled device (CCD) sensor. The radius of the EO-IR sensor <NUM>, the numerical aperture (NA) value of the aperture, and the lenses 330a-d are configured so that the EO-IR sensor <NUM> is focused at an infinity focus (e.g., greater than <NUM> feet in front of the body <NUM>). The EOIR sensor <NUM>, the optically transparent substrate <NUM>, and the antenna array <NUM> may share centers which are aligned to a longitudinal axis of the missile body <NUM> (i.e., concentric centers such that the longitudinal axis passes through the centers and is normal to a flat surface of the window <NUM>). As shown in <FIG>, in some embodiments, the longitudinal axis may be angled to the flat surface of the window <NUM>. The EOIR sensor <NUM> may capture images to be transmitted to a controller (i.e., computing system; not shown) including one or more processors and a memory. The one or more processors may include one or more central processing unit (CPUs), graphics processing units (GPUs), application-specific integrated circuits (ASICs), and/or field-programmable gate arrays (FPGA). The memory may include nonvolatile memory (e.g., hard disk drive, SSD, flash memory, ROM, etc.) and volatile memory (RAM, SDRAM, etc.).

The one or more processors may be configured to execute program instructions stored on the memory that cause the one or more processors perform various functions, procedures, algorithms, etc. described in the present disclosure. For example, the program instructions may cause the one or more processors to receive the images and apply a target identification algorithm to the images. This algorithm may track a target and send control signals to one or more control surfaces on the body <NUM> to control the trajectory of the missile <NUM> and steer it toward the target. In some embodiments, the images are transmitted to a remote controller (e.g., wirelessly) and the images are processed remotely. Remote processing may advantageously save valuable computing capacity in the PGM system <NUM>. Additionally, the controller may be communicatively coupled to the radiating element array and the program instructions may track or identify a target using radar information.

Since the optically transparent substrate <NUM> with the radiating element array thereon does not block or obstruct the vision of the EOIR sensor <NUM>, which is unintuitive and unexpected since the substrate <NUM> is placed in the optical path (i.e., placed in front of) the EOIR sensor <NUM>, the EOIR sensor <NUM> may capture a full scene of a target when the EOIR sensor <NUM> is configured to focus at infinity (e.g., greater than <NUM> feet away) in front of the missile body <NUM>. This optical effect may be combined with a relatively small radius of the aperture to provide a solution that is size-weight-and-power (SWaP) efficient and that maximizes the detection of signals by orienting each sensor to receive the strongest possible signal (i.e., as many photons as possible) from the direction of a target.

<FIG> is a front view of the aperture window <NUM> of <FIG> including antenna substrate elements <NUM>, in accordance with one or more embodiments of the present disclosure. <FIG> is a side view of the precision guided munition system <NUM> with the antenna substrate elements <NUM> on the window <NUM>. This embodiment may be substantially similar to the embodiment shown in <FIG>, and may produce a similar result of a full scene being captured by the sensor <NUM>. In this embodiment, each respective one of the antenna substrate elements includes a radiating element thereon. Voids <NUM> between the substrates <NUM> are configured to let photons pass (e.g., parallel rays) to be captured by the EO-IR sensor <NUM> that is focused at infinity.

Claim 1:
A precision guided munition system, comprising:
a body (<NUM>) including a nose portion, wherein the nose portion includes an aperture;
a window (<NUM>) attached, secured, or adhered to the body at the nose portion;
one or more antenna substrates (<NUM>) attached, secured, or adhered to the window;
a plurality of radiating elements, wherein each respective one of the plurality of radiating elements is attached, secured, or adhered to the one or more antenna substrates; and
an image sensor (<NUM>) configured to capture an image in front of the body,
wherein the image sensor is behind the aperture,
wherein the image sensor is configured to focus at an infinity focus in front of the body,
the precision guided munition system being characterized in that:
the one or more antenna substrates include a plurality of holes arranged in a grid pattern configured to let photons, which are parallel or collimated, pass through the antenna substrates from the window to the image sensor, so
that the captured image does not include features of the antenna substrates, and in that
the plurality of radiating elements are placed at the intersections of the grid pattern.