DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claim(s) 1-8, 11-16, and 18-22 are rejected under 35 U.S.C. 103 as being unpatentable over Lu et al. (US 2022/0206121 A1) in view of Hutchin (US 2015/0069216 A1, IDS), Braun et al. (US 2005/0195505 A1, IDS), Bellah et al. (US 2022/0065586 A1), and further in view of Driscoll et al. (US 2017/0025754 A1).
Regarding Claim 1, Lu et al. disclose a transmitter containing a Risley prism-based scanning mechanism for steering optical signals. See, for example, paragraphs [0019]-[0020], [0026]-[0027], [0037]-[0042], [0043]-[0052]. Lu et al. teach a plurality of prisms arranged along an optical axis, wherein at least one prism rotates relative to another prism to refract optical signals toward different directions. Lu et al. further discloses a controller configured to control the rotation of the prisms and steer the beam toward a target. Hutchin discloses a bidirectional beam director including a pair of optically coupled diffraction gratings, each independently rotatable such that a laser beam passing through the pair can be steered by rotation of at least one of the gratings. See, for example, paragraphs [0015]-[0020], [0039]-[0045], [0051]-[0060]. Hutchin further teaches that the beam director may be used to direct both outgoing and incoming beams, and that the rotatable steering elements may be arranged substantially parallel and in series to provide compact bidirectional beam steering. Braun et al. discloses a prism device and beam steering system in which multiple prism devices are arranged in series to simultaneously direct signal beams of different wavelengths in substantially the same direction. See, for example, paragraphs [0006]-[0012], [0022]-[0027], [0031]-[0033], [0049]-[0055]. Braun et al. further teach that a prism-based beam steering assembly can be incorporated into a communication device or optical/RF system mounted on an airborne platform. See, for example, paragraphs [0002]-[0005], [0010], [0052]-[0055]. Bellah et al. discloses a weapon aiming system having a riflescope and a laser rangefinder, wherein an encoder senses a relative position change and a controller responds by directing motors to reposition Risley prisms so that an aimpoint remains aligned. See, for example, paragraphs [0005]-[0006], [0014]-[0019]. Bellah et al. thus teaches closed-loop control of Risley prisms based on sensed positional information and reorientation of the prisms in response thereto. Driscoll et al. discloses an electromagnetic beam steering apparatus including first and second beam deflecting structures having artificially structured effective media and electronically-selectable tangential refractive index gradients, wherein the beam deflecting structures are independently rotatable relative to a coaxial axis to steer an electromagnetic beam in different planes. See, for example, paragraphs [0006]-[0013], [0058]-[0060], [0074]-[0080], [0149]-[0166]. Driscoll et al. further teaches that the deflecting structures may be arranged in substantially orthogonal relationship to each other and may be used to point a steered beam at a target. It would have been obvious to one of ordinary skill in the art at the time of the invention to modify the Risley prism-based beam steering system of Lu et al. with the independent paired beam-steering and bidirectional steering teachings of Hutchin and the simultaneous multi-wavelength steering teachings of Braun et al. in order to provide a compact free space optical communications terminal capable of steering both transmit and receive beams along a principal axis. It would further have been obvious to incorporate the controller and position-sensing teachings of Bellah et al. to maintain alignment of the beam steering elements and
Additionally, it would have been obvious to employ the electronically selectable beam-deflecting structures of Driscoll et al. as an alternative or equivalent implementation of rotatable beam steering elements, especially where orthogonal or decoupled steering planes are desired.
Accordingly, claim 1 would have been obvious over the combined teachings of the cited references.
Regarding claim 2, it depends from claim 1 and further recites that the reference rotational position of the first pair of steering elements is at 90 degrees from the reference rotational position of the second pair of steering elements, and the second plane is perpendicular to the first plane. Lu et al. teach Risley prism-based beam steering with selectable beam direction in multiple axes, and Driscoll et al. teaches beam-deflecting structures arranged in substantially orthogonal relationship. It would have been obvious to orient the reference rotational position of a first pair of steering elements 90 degrees from that of a second pair in order to steer beams in orthogonal planes, as expressly taught or suggested by the decoupled orthogonal steering concepts of Driscoll et al. and the multi-axis beam steering teachings of Lu et al..
Regarding claim 3, it depends from claim 1 and further recites that the rotation of the first and second steering elements comprises, for at least one of the pairs of steering elements, rotation of the first and second steering elements of the at least one pair in opposite directions and at the same speed. Lu et al. teach rotation of prisms about an optical axis, and Bellah et al. teaches controller-driven repositioning of Risley prisms in response to encoder signals. It would have been obvious to rotate the steering elements in opposite directions and at the same speed to maintain equal and opposite angular displacements from a reference position and thereby achieve smooth beam tracking, as such counter-rotation is a well-known and predictable way to control Risley prism steering.
Regarding claim 4, it depends from claim 1 and further recites that the first and second steering elements of at least one pair have the same shape and same mass. Lu et al. and Hutchin teach paired beam-steering elements that may be implemented as identical or substantially similar optical elements. Selecting steering elements of the same shape and mass would have been an obvious design choice to simplify manufacture, balance the assembly, and facilitate predictable rotational behavior.
Regarding claim 5, it depends from claim 1 and further recites that the first steering angle has a magnitude that is the same as a magnitude of the second steering angle. Braun et al. and Lu et al. teach prism-based beam steering by multiple optically coupled elements. Matching the first and second steering angles would have been an obvious optimization to provide symmetric or balanced steering coverage and to simplify control of the beam director.
Regarding claim 6, it depends from claim 1 and further recites that a maximum magnitude of an overall steering angle of each respective pair of the steering elements is at least 45 degrees. Braun et al. expressly teach beam steering assemblies with a wide field of regard and maximum deviation angles sufficient to provide broad angular coverage. It would have been obvious to configure the respective pairs of steering elements to provide a maximum overall steering angle of at least 45 degrees in order to achieve a broad field of regard suitable for vehicle-mounted or airborne communication systems.
Regarding claims 7 and 8, they depend from claim 1 and further recite metamaterial elements and silicon meta-prisms. Driscoll et al. teach electromagnetic beam deflecting structures including artificially structured effective media, electronically-selectable tangential refractive index gradients, and metasurface-based beam steering. Lu et al. teach Risley prism-based beam steering. It would have been obvious to employ metamaterial elements, including silicon meta-prisms, as an equivalent beam steering implementation because Driscoll et al. expressly teaches such electronically controllable beam deflecting structures and because the substitution would have predictably reduced size and weight while preserving beam steering functionality.
Regarding claim 11, it depends from claim 1 and further recites that the first and second steering elements in the first and second pairs of steering elements are separated by no more than 10 mm. Lu et al. teach adjacent steering elements arranged along an optical path, and Hutchin and Braun et al. teach compact beam steering assemblies suitable for conformal mounting. Positioning the steering elements no more than 10 mm apart would have been an obvious compactness optimization to reduce beam clipping and maintain a small form factor.
Regarding claims 12-16, they depend from claim 1 and recite supporting elements, gear teeth, Hall sensors, motors, and stepper motors. Bellah et al. teach stepper motor control, encoder sensing, and controller-based repositioning of Risley prisms. Lu et al. teach controller-based prism steering for optical beam steering. Hutchin teaches independently rotatable beam steering elements and associated actuation mechanisms. It would have been obvious to house steering elements in supporting elements, provide gear teeth for rotation, and use Hall sensors or stepper motors to determine and control rotational position, as these are conventional, predictable mechanisms for implementing the control functions expressly taught in the art.
Regarding claims 18 and 19, they depend from claim 1 and recite a vehicle, including an aircraft and/or spacecraft. Braun et al. expressly teach beam steering assemblies usable in ground-based, airborne, satellite-based, ship-borne, or underwater platforms, including aircraft. Hutchin likewise teaches conformal beam steering systems mountable on aircraft. It would have been obvious to include the claimed free space optical communications terminal in a vehicle, including an aircraft and/or spacecraft, because the cited references expressly contemplate airborne and spaceborne applications.
Regarding claim 20, Lu et al. teach a method of operating a Risley prism-based pointing unit for steering a beam toward a target.
Hutchin teaches independently rotatable beam-steering elements in a bidirectional transmit/receive system.
Braun et al. teach simultaneously steering multiple beams through a prism-based beam steering assembly in a communication terminal.
Bellah et al. teach controller-driven rotational repositioning of prisms in response to sensed position changes.
Driscoll et al. teach electronically controllable beam deflecting structures and selectable tangential refractive index gradients.
It would have been obvious to combine these teachings to arrive at the claimed method of operating a pointing unit for a free space optical communications terminal.
Regarding claim 21, it depends from claim 1 and recites an aircraft comprising a first communication node and a second communication node each including the claimed terminal, with quadrilateral fields of regard facing along orthogonal axes. Braun et al. and Hutchin both teach aircraft-mounted beam steering assemblies having a field of regard and bidirectional operation. Lu et al. teach quadrilateral or pyramidal fields of regard achieved by decoupled beam steering. It would have been obvious to arrange first and second communication nodes on orthogonal axes of an aircraft to obtain broad angular coverage and reduce blind spots.
Regarding claim 22, it depends from claim 1 and recites an aircraft comprising six communication nodes, each node having a quadrilateral field of regard with an opening angle of at least 90 degrees, such that a combined field of regard covers a solid angle of 4π steradians. Braun et al. teach multiple prism-based beam steering assemblies mounted on an aircraft and arranged to provide broad coverage over a field of regard. Hutchin similarly teaches conformal beam director arrangements for aircraft and broad angular coverage. Lu et al. teach multiple pointing units with quadrilateral fields of regard that can be combined to cover a larger angular region without blind spots. It would have been obvious to provide six communication nodes facing different directions along orthogonal axes to achieve full surrounding coverage of the aircraft, as such an arrangement is a predictable design choice to extend angular coverage and eliminate blind spots.
Conclusion
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/QUAN ZHEN WANG/Supervisory Patent Examiner, Art Unit 2685
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