System and method for detecting an object in a search space

A system for detecting an object of interest in a search space, comprising a radiation signal generator capable of generating a spatially-encoded radiation signal in the search space. The spatially-encoded radiation signal comprises a series of n beams, each having a unique characteristic, radially extending from the radiation signal generator, where n is a positive integer greater than one. The system also comprises a radiation signal collector disposed to detect and transform a reflected radiation signal reflected from the object of interest into a first data signal. The system also comprises a processor capable of transforming the first data signal into positional and vectoral data of the object of interest.

BACKGROUND OF THE INVENTION

Many industries, such as air traffic control, rely on the ability to accurately detect and track moving objects. Current systems and methods, however, have had difficulty detecting and tracking objects in close proximity to a surface or boundary between a search space and another medium.

A system and method is needed to overcome some of the difficulties encountered in detecting and tracking an object in close proximity to a boundary between a search space and another medium.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1adepicts a system10for detecting an object of interest75in a search space100comprising at least one spatially encoded radiation signal generator20, at least one radiation signal collector22, and a processor24. The radiation signal generator20may generate a spatially encoded radiation signal (SERS)120, which may propagate into search space100. Search space100may be water, or atmosphere. Once the SERS120encounters the object of interest75, a reflected radiation signal175may reflect off of the object of interest75and propagate in the direction of the radiation signal collector22. If the reflected radiation signal175is detected by the radiation signal collector22, the radiation signal collector22may transform the reflected radiation signal22into a first data signal23. The first data signal23may then be transmitted to the processor24where the first data signal23may be transformed into positional and vectoral data25of said object of interest75. The vectoral and positional data25of the object of interest75may be based on an encoded characteristic of the reflected radiation signal175. The vectoral and positional data25may then be sent to another processor, stored on a memory device, or displayed to a user.FIG. 1bshows an output device26which may communicate the vectoral and positional data25of the object of interest75to a user. AlthoughFIG. 1bdepicts the output device26as a visual display, it is to be understood that the output device is not limited to visual displays but may be any device—visual, audio, or tactile—that may be used to generate a user-comprehendible output of vectoral and positional data25of an object of interest75. Additional encoding of the search space100may be realized by employing two or more radiation signal generators20. Also, multiple radiation signal collectors22may be utilized to detect reflected radiation signal175.

Also shown inFIGS. 1aand1b, the SERS120comprises a series of n beams α1-αnradially extending from the SERS generator20, where n is an integer greater than one and a represents an electromagnetic wave with a unique defining characteristic, as described below. The SERS120may be encoded such that each of the beams α1-αnis distinguishable from the other beams comprising SERS120. For example, each of the beams α1-αnof SERS120may be characterized as having a different wavelength λ1-λn. In order to generate the SERS120comprised of beams α1-αneach having a different wavelength λ1-λn, the radiation signal generator20may be comprised of multiple electromagnetic sources, filters, grids, beam splitters, fiber splitters, diffractive optics, or any other comparable device capable of generating one or more wavelength-encoded spatial patterns. However, it is to be understood that the encoding of SERS120is not limited to wavelength, but that the SERS120may be encoded by wavelength, waveform (including temporal dependence), polarization state, spatial separation, or any combination thereof. It is also to be understood that the SERS120is not limited to electromagnetic radiation, but other types of radiation, such as acoustic radiation, may also be employed. Also,FIGS. 1a-7show the cross-section of beams α1-αnof SERS120as being rectangular, but it is to be understood that the cross-sections of beams α1-αnof SERS120may be any shape in which a radiation signal may propagate, including polygons, ellipses, and circles, to name a few.FIG. 1aalso shows how SERS120may be stratified in the x direction with beams1-n, where x may be any defined direction.

In one example embodiment of system10, SERS120may be wavelength encoded with the wavelength of beam α1corresponding to wavelength λ1. If beam α1encounters an object of interest75then the reflected radiation signal175will have a wavelength of λ1provided the object of interest75is stationary. Positional data of the object of interest75may be determined quickly by correlating the wavelength λ, of the reflected radiation signal175with the wavelength λ1of beam α1, which is known to propagate in a specific region of search space100. When the SERS120is wavelength encoded, the radiation signal collector22may comprise a low-resolution detector combined with simple collecting optics and a prism or color filter to identify the wavelength of the scattered radiation. If the object of interest75is moving, the wavelength of the reflected radiation signal175will be Doppler shifted. Vectoral data of the object of interest75may be determined by the processor24based on the degree of Doppler shift of the wavelength of reflected radiation signal175from wavelength λ1. Providing sufficient spectral or spatial separation of beams α1-αnin the encoding of SERS120should avoid any spatial overlap of similar wavelengths resulting from a Doppler shifted reflected radiation signal175and the reflected radiation signal175from a stationary object of interest75.

FIG. 2shows an embodiment of beam α1in which beam α1, representative of each of beams α1-αn, may be encoded in they direction. In other words, beam α1may be stratified in the y direction with m constituent sub-beams, where m is a positive integer greater than one, and where each of said constituent sub-beams has a unique characteristic such as wavelength, waveform (including temporal dependence), polarization state, or spatial separation. In one embodiment, x may be horizontal and y may be vertical such that the SERS120is encoded horizontally and each of beams α1-αnmay be encoded vertically. It is to be understood that direction x and direction y are not limited to horizontal and vertical, but each may be any well-defined orientation that is not equal to the other. By way of example, in one embodiment, each of the beams α1-αnmay be encoded by wavelength, wherein the wavelength of each beam varies in they direction.FIG. 2shows the beam al encoded by wavelengths λ11-λ1m. However, it is to be understood that the encoding of each of the beams α1-αn, is not limited to wavelength, but that each of the beams α1-αnmay be encoded by wavelength, waveform (including temporal dependence), polarization state, spatial separation, or any combination thereof. As the SERS120, encoded in both the x and y directions, propagates into search space100, detailed positional and vectoral information may be determined in the manner described above from the reflected radiation signal175.FIG. 2also shows the cross-section of constituent sub-beams1-mas being rectangular, but it is to be understood that the cross-section constituent sub-beams1-mmay be any shape in which a radiation signal may propagate, including polygons, ellipses, and circles, to name a few.

FIG. 3depicts another embodiment of system10comprising a remote reference object85, which is disposed to emit a reference signal185. In one embodiment, the reference signal185may be a sample of SERS120that is reflected off of the remote reference object85in the direction of the radiation signal collector22. In another embodiment, the reference signal185may be generated by the remote reference object85and emitted in the direction of the radiation signal collector22. Reference signal185may have known properties such as wavelength, waveform (including temporal dependence), polarization state, and spatial separation. By generating a known reference signal185at one or more remote positions within the radiation signal collector's22field of view, distortion corrections may be determined by the processor24by comparing the reference signal185actually received by the radiation signal collector22with the theoretical reference signal185calculated from the remote reference object's85known properties. The distortion corrections may then be applied to any reflected radiation signal175received by the radiation signal collector22to determine corrected vectoral and positional information of the object of interest75. The use of one or more remote reference objects85may provide information regarding possible wave front distortion and multipath effects due to propagation of reference signal185through a search space100for a series of possible object of interest75positions. The remote reference object85may be non-physical such as a guide star produced by a laser, or a physical object of any shape with known reflective properties such as a point reflector that emits a spherical wave front. Other examples and a detailed description of remote reference object85may be found in U.S. Pat. No. 6,288,974 entitled, “System and Method for Enhancing Detection of Objects Through an Obscuring Medium.”

FIG. 4shows another embodiment of a system for detecting an object of interest75in a search space100, where the remote reference object85is a physical object capable of serving as a secondary source of radiation for illuminating (in part) the search space100. In this embodiment the remote reference object85may generate a reference signal185, which may propagate into search space100and in the direction of the radiation signal collector22. If reference signal185encounters an object of interest75in search space100, a reflected reference signal186may be reflected in a direction of propagation towards the radiation signal collector22.

FIG. 5depicts another embodiment of the SERS generator20, where the search space100is separated from a boundary medium200by a boundary222and where the SERS120reflects off of the boundary222. The boundary medium200may be atmosphere, water or earth. The boundary222is the interface between the search space100and the boundary medium200. For example, in one embodiment the search space100inFIG. 5may be atmosphere; the boundary medium200, water; and the boundary222, the water surface. In another embodiment, the search space100, as shown inFIG. 5, may be ocean; the boundary medium200, earth; and the boundary222, the ocean floor.FIG. 6depicts another embodiment where the search space100may be water; the boundary medium200, atmosphere; and the boundary222, the atmosphere-water interface. Allowing SERS120to reflect off of boundary222creates two opportunities for an object of interest75(if the object of interest75is moving) to pass through the SERS120(i.e. before and after the SERS120reflects off of boundary222), thus providing two opportunities to emit a reflected radiation signal175.

FIG. 7illustrates another embodiment of the SERS generator20, where the orientation of the SERS generator20with respect to the boundary222may vary, thus altering the reflection point of SERS120off of boundary222. The ability to vary the reflection point of the SERS120off of boundary222allows more of the search space100to be interrogated by SERS120.

From the above description of the System and Method for Detecting an Object in a Search Space, it is manifest that various techniques may be used for implementing the concepts of system10without departing from its scope. The described embodiments are to be considered in all respects as illustrative and not restrictive. It should also be understood that system10is not limited to the particular embodiments described herein, but is capable of many embodiments without departing from the scope of the claims.